In the absence of a financial source for disability or worker's compensation, other psychological features may limit the ability of the patient to recover from surgery.  Some patients are simply unfortunate, and fall into the category of "chronic pain" despite their desire to recover and the best efforts of the physicians involved in their care. [ 140 ] [ 141 ] [ 142 ] [ 143 ] [ 144 ] [ 145 ] [ 146 ] [ 147 ] [ 148 ] [ 149 ] [ 150 ]  Even less invasive forms of surgery are not uniformly successful; approximately 30,000-40,000  laminectomy  patients obtain either no relief of symptomatology or a recurrence of symptoms. [ 151 ]  Another less invasive form of spinal surgery, percutaneous disc surgery, has reported revision rates as high as 65%. [ 152 ]  It is no surprise, therefore, that FBS is a significant medical concern which merits further research and attention by the medical and surgical communities. [ 21 ] [ 22 ]


Lumbar  total disc replacement was originally designed to be an alternative to lumbar  arthrodesis  (fusion). The procedure was met with great excitement and heightened expectations both in the United States and Europe. In late 2004, the first lumbar total disc replacement received approval from the  U.S. Food and Drug Administration  (FDA). More experience existed in Europe.  Since then, the initial excitement has given way to skepticism and concern. [ 153 ] [ 154 ] [ 155 ] [ 156 ] [ 157 ] [ 158 ] [ 159 ]  Various failure rates and strategies for revision of total disc replacement have been reported. [ 160 ]


The role of artificial or total disc replacement in the treatment of spinal disorders remains ill-defined and unclear. [ 161 ]  Evaluation of any new technique is difficult or impossible because physician experience may be minimal or lacking.  Patient expectations may be distorted. [ 162 ] [ 163 ]  It has been difficult to establish clear cut indications for artificial disc replacement.  It may not be a replacement procedure or alternative to fusion, since recent studies have shown that 100% of fusion patients had one or more contraindications to disc replacement. [ 164 ] [ 165 ] [ 166 ]    The role of disc replacement must come from new indications not defined in today's literature or a relaxation of current contraindications. [ 161 ]


A study by Regan found the result of replacement was the same at L4-5 and L5-S1 with the CHARITE disc.  However, the ProDisc II had more favorable results at L4-5 compared with L5-S1. [ 167 ] [ 168 ]


A younger age was predictive of a better outcome in several studies. [ 158 ] [ 169 ] [ 170 ]  In others it has been found to be a negative predictor or of no predictive value. [ 171 ] [ 172 ] [ 173 ] [ 174 ] [ 175 ]  Older patients may have more complications. [ 174 ]


Prior spinal surgery has mixed effects on disc replacement.  It has been reported to be negative in several studies. [ 171 ] [ 176 ] [ 177 ] [ 178 ] [ 175 ] [ 179 ]  It has been reported to have  no effect in other studies. [ 180 ] [ 169 ] [ 173 ] [ 178 ] [ 181 ] [ 158 ]  Many studies are simply inconclusive. [ 171 ]  Existing evidence does not allow drawing definite conclusions about the status of disc replacement at present. [ 161 ]


Many failed back patients are significantly impaired by chronic pain in the back and legs. Many of these will be treated with some form of electrical stimulation. This can be either a  transcutaneous electrical nerve stimulation  device placed on the skin over the back or a nerve stimulator implanted into the back  with electrical probes which directly touch the spinal cord. Also, some chronic pain patients utilize  fentanyl  or narcotic patches.  These patients are generally severely impaired and it is unrealistic to conclude that application of  neurostimulation  will reduce that impairment. For example, it is doubtful that  neurostimulation  will improve the patient enough to return to competitive employment.  Neurostimulation  is  palliative . TENS units work by blocking  neurotransmission  as described by the pain theory of Melzack and Wall. [ 182 ]  Success rates for implanted  neurostimulation  has been reported to be 25% to 55%. Success is defined as a relative decrease in pain. [ 183 ]


Limited case series have shown improvement for patients with failed back surgery who were managed with  chiropractic care . [ 184 ] [ 185 ] [ 186 ]


Smaller procedures that do not remove  bone  (such as Endoscopic Transforaminal Lumbar Discectomy and Reconfiguration) do not cause post  laminectomy / laminotomy  syndrome. [ 187 ]


Under rules promulgated by Titles II and XVI of the United States  Social Security Act , chronic  radiculopathy ,  arachnoiditis  and spinal stenosis are recognized as disabling conditions under Listing 1.04 A ( radiculopathy ), 1.04 B ( arachnoiditis ) and 1.04 C ( spinal stenosis ). [ 188 ]


In a groundbreaking  Canadian  study, Waddell  et al.  reported on the value of repeat surgery and the return to work in worker's compensation cases. They concluded that workers who undergo spinal surgery take longer to return to their jobs. Once two spinal surgeries are performed, few if any ever return to gainful employment of any kind. After two spinal surgeries, most people in the worker's comp system will not be made better by more surgery. Most will be worse after a third surgery. [ 189 ]


Episodes of back pain associated with on the job injuries in the worker's compensation setting are usually of short duration. About 10% of such episodes will not be simple, and will degenerate into chronic and disabling back pain conditions, even if surgery is not performed. [ 190 ] [ 191 ]


It has been hypothesized that  job dissatisfaction  and individual perception of physical demands are associated with an increased time of recovery or an increased risk of no recovery at all. [ 192 ]  Individual psychological and social work factors, as well as worker-employer relations are also likely to be associated with time and rates of recovery. [ 193 ] [ 194 ] [ 195 ]


A Finnish study of return to work in patients with  spinal stenosis  treated by surgery found that:


In fact, women's and men's working capacity do not differ after  lumbar spinal stenosis  operation. If the aim is to maximize working capacity, then, when a lumbar spinal stenosis operation is indicated, it should be performed without delay. In lumbar spinal stenosis patients who are older than 50 years old and on sick leave, it is unrealistic to expect that they will return to work. Therefore, after such an extensive surgical procedure, re-education of patients for lighter jobs could improve the chances of these patients returning to work. [ 196 ]


In a related  Finnish  study, a total of 439 patients operated on for lumbar spinal stenosis during the period 1974–1987 was re-examined and evaluated for working and functional capacity approximately 4 years after the  decompressive surgery . The ability to work before or after the operation and a history of no prior back surgery were variables predictive of a good outcome. Before the operation 86 patients were working, 223 patients were on sick leave, and 130 patients were retired. After the operation 52 of the employed patients and 70 of the unemployed patients returned to work. None of the retired patients returned to work. Ability to work preoperatively, age under 50 years at the time of operation and the absence of prior back surgery predicted a postoperative ability to work. [ 197 ]


A report from Belgium noted that patients reportedly return to work an average of 12 to 16 weeks after surgery for lumbar disc herniation. However, there are studies that lend credence to the value of an earlier stimulation for return to work and performance of normal activities after a limited  discectomy . At follow-up assessment, it was found that no patient had changed employment because of back or leg pain. The sooner the recommendation is made to return to work and perform normal activities, the more likely the patient is to comply. Patients with ongoing disabling back conditions have a low priority for return to work. The probability of return to work decreases as time off work increases.   This is especially true in Belgium, where 20% of individuals did not resume work activities after surgery for a disc herniation of the lumbar spine. [ citation needed ]


In Belgium, the medical advisers of sickness funds have an important role legally in the assessment of working capacity and medical rehabilitation measures for employees whose fitness for work is jeopardized or diminished for health reasons. The measures are laid down in the sickness and invalidity legislation. They are in accordance with the principle of preventing long-term disability. It is apparent from the authors' experience that these measures are not adapted consistently in medical practice. Most of the medical advisers are focusing purely on evaluation of corporal damage, leaving little or no time for rehabilitation efforts. In many other countries, the evaluation of work capacity is done by social security doctors with a comparable task. [ 198 ]


In a comprehensive set of studies carried out by the  University of Washington School of Medicine , it was determined that the outcome of lumbar fusion performed on injured workers was worse than reported in most published case series.  They found 68% of lumbar fusion patients still unable to return to work two years after surgery.  This was in stark contrast to reports of 68% post-op satisfaction in many series. [ 199 ] [ 142 ]  In a follow-up study it was found that the use of intervertebral fusion devices rose rapidly after their introduction in 1996.  This increase in metal usage was associated with a greater risk of complication  without improving disability or re-operation rates. [ 200 ] [ 201 ] [ 202 ] [ 203 ]


The identification of  tumor necrosis factor-alpha  (TNF) as a central cause of inflammatory spinal pain now suggests the possibility of an entirely new approach to selected patients with FBS.  Specific and potent inhibitors of TNF became available in the U.S. in 1998, and were demonstrated to be potentially effective for treating  sciatica  in experimental models beginning in 2001. [ 204 ] [ 205 ] [ 206 ]  Targeted anatomic administration of one of these anti-TNF agents,  etanercept , a patented treatment method, [ 207 ]  has been suggested in published pilot studies to be effective for treating selected patients with chronic disc-related pain and FBS. [ 208 ] [ 209 ]  The scientific basis for pain relief in these patients is supported by the many current review articles. [ 210 ] [ 211 ]  In the future new imaging methods may allow non-invasive identification of sites of neuronal inflammation, thereby enabling more accurate localization of the "pain generators" responsible for symptom production. These treatments are still experimental. [ citation needed ]


If chronic pain in FBS has a chemical component producing inflammatory pain, then prior to additional surgery it may make sense to use an anti-inflammatory approach. Often this is first attempted with non-steroidal anti-inflammatory medications, but the long-term use of  Non-steroidal anti-inflammatory drugs  (NSAIDS) for patients with persistent back pain is complicated by their possible cardiovascular and gastrointestinal toxicity; and NSAIDs have limited value to intervene in TNF-mediated processes. [ 22 ]  An alternative often employed is the injection of cortisone into the spine adjacent to the suspected pain generator, a technique known as "epidural steroid injection". [ 212 ]  Although this technique began more than a decade ago for FBS, the efficacy of epidural steroid injections is now generally thought to be limited to short term pain relief in selected patients only. [ 213 ]  In addition, epidural steroid injections, in certain settings, may result in serious complications. [ 214 ]  Fortunately there are now emerging new methods that directly target TNF. [ 208 ]  These TNF-targeted methods represent a highly promising new approach for patients with chronic severe spinal pain, such as those with FBS. [ 208 ]  Ancillary approaches, such as rehabilitation,  physical therapy ,  anti-depressants , and, in particular, graduated exercise programs, may all be useful adjuncts to anti-inflammatory approaches. [ 22 ]  In addition, more invasive modalities, such as spinal cord stimulation, may offer relief for certain patients with FBS, but these modalities, although often referred to as "minimally invasive", require additional surgery, and have complications of their own. [ 215 ] [ 216 ]


A report from  Spain  noted that the investigation and development of new techniques for instrumented  surgery  of the  spine  is not free from  conflicts of interest . The influence of financial forces in the development of new technologies and its immediate application to spine surgery, shows the relationship between the published results and the industry support. Authors who have developed and defended fusion techniques have also published new articles praising new spinal technologies. The author calls spinal surgery the  "American Stock and Exchange" and "the bubble of spine surgery". The scientific literature doesn't show clear evidence in the cost-benefit  studies  of most instrumented surgical interventions of the spine compared with the conservative treatments. It has not been yet demonstrated that fusion surgery and disc replacement are better options than the conservative treatment. It's necessary to point out that at present " there are relationships between the industry and back pain, and there is also an industry of the back pain ".


Nonetheless, the "market of the spine surgery" is growing because patients are demanding solutions for their back problems. The tide of scientific evidence seems to go against the spinal fusions in the degenerative disc disease,  discogenic pain  and in specific back pain. After decades of advances in this field, the results of spinal fusions are mediocre. New epidemiological studies show that " spinal fusion must be accepted as a non proved or experimental method for the treatment of back pain ". The surgical literature on  spinal fusion  published in the last 20 years establishes that instrumentation seems to slightly increase the fusion rate and that instrumentation doesn't improve the clinical results in general. We still are in need of randomized studies to compare the surgical results with the natural history of the disease, the placebo effect, or conservative treatment. The European Guidelines for lumbar chronic pain management show  "strong evidence" indicating that complex and demanding spine surgery where different instrumentation is used, is not more effective than a simple, safer and cheaper  posterolateral  fusion without instrumentation. Recently, the literature published in this field is sending a message to use "minimally invasive techniques"; – the abandonment of transpedicular fusions. Surgery in general, and usage of metal fixation should be discarded in most cases. [ 217 ]


In  Sweden , the national registry of lumbar spine surgery reported in the year 2000 that 15% of patients with spinal stenosis surgery underwent a concomitant fusion. [ 218 ]  Despite the traditionally conservative approach to spinal surgery in Sweden, there have been calls from that country for a more aggressive approach to lumbar procedures in recent years. [ citation needed ]


Finally, Cherkin et al. evaluated worldwide surgical attitudes. [ 219 ]  There were twice the number of surgeons per capita in the  United States  compared to the  United Kingdom . Numbers were similar to  Sweden . Despite having very few spinal surgeons, the  Netherlands  proved to be quite aggressive in surgery. Sweden, despite having a large number of surgeons was conservative and produced relatively few surgeries. The most surgeries were done in the United States. In the UK, more than a third of non-urgent patients waited over a year to see a spinal surgeon. In  Wales , more than half waited over three months for consult. Lower rates of referrals in the United Kingdom was found to discourage surgery in general. Fee for service and easy access to care was thought to encourage spinal surgery in the United States, whereas salaried position and a conservative philosophy led to less surgery in the United Kingdom. There were more spinal surgeons in Sweden than in the United States.  However, it was speculated that the Swedish surgeons being limited to compensation of 40–48 hours a week might lead to a  conservative  philosophy. There have been calls for a more aggressive approach to lumbar surgery in both the United Kingdom and Sweden in recent years. [ 71 ] [ 220 ] [ 221 ]


Foraminotomy  is a medical operation used to relieve pressure on  nerves  that are being compressed by the  intervertebral foramina , the passages through the bones of the  vertebrae  of the  spine  that pass nerve bundles to the body from the  spinal cord .


A foraminotomy is performed to relieve the symptoms of nerve root compression in cases where the foramen is being compressed by bone, disc, scar tissue, or excessive ligament development and results in a pinched nerve.


The procedure is often performed as a  minimally invasive procedure  in which an incision is made in the back, the muscle peeled away to reveal the bone underneath, and a small hole cut into the vertebra itself.  Through this hole, using an  arthroscope , the foramen can be visualized, and the impinging bone or disk material removed. Surgery is typically short in duration, taking around 6 hours. Patients stay in hospital for 5-8 nights, can drive after 8 weeks, perform light duties after 8 weeks and make a full recovery within 18 months.


A foraminotomy that removes a large amount of bone or other material may occasionally be described as a  foraminectomy .


A  ganglionectomy , also called a  gangliectomy , is the  surgical  removal of a  ganglion . [ 1 ]  The removal of a ganglion  cyst  usually requires a ganglionectomy. Such cysts usually form on the hand, foot or wrist and may cause  pain  or impair body function. Aspiration of the cyst and  steroid  injections are typically performed first. If they fail, the cyst is excised under local, regional or even general  anesthetic . Ganglionectomies are also performed for other reasons, such as the treatment of  chronic pain .


Global neurosurgery  is a field at the intersection of  public health  and clinical  neurosurgery . It aims to expand provision of improved and equitable neurosurgical care globally. [ 1 ]


Global neurosurgery is "the clinical and public health practice of neurosurgery with the primary purpose of ensuring timely, safe, and affordable neurosurgical care to all who need it." [ 2 ]  The term  global neurosurgery  was first used in 1995 by Canadian neurosurgeon Dwight Parkinson to describe comprehensive clinical neurosurgery care in Manitoba; [ 3 ]  however, the field as defined today was born in the mid-2010s. [ 4 ]  The modern definition of global neurosurgery was born from a combination of  global health  and  neurosurgery . Hence, global neurosurgery is conceived as a subspecialty of  global health  within  global surgery . [ 2 ] [ 5 ]


Around 22.6 million people are affected by diseases amenable to  neurosurgery  each year, and 13.8 million require surgical intervention. [ 6 ]  The burden of diseases amenable to neurosurgery is disproportionately distributed globally, with  low- and middle-income countries  bearing more than 78.1% of cases. [ 6 ]   Low- and middle-income countries  lack the workforce, infrastructure, funding, and data needed to address the disease burden. [ 6 ] [ 7 ] [ 8 ] [ 9 ] [ 10 ]   High-income country  patients, especially in rural areas and from economically-disadvantaged backgrounds, face unique challenges in accessing safe, timely, and affordable neurosurgical care. [ 11 ]  For this reason, most global neurosurgery work has focused on access to care in low- and middle-incomce countries despite the global nature of disparities in accessing neurosurgical care. [ 12 ]


Global neurosurgery practice involves advocacy, education, policy, research, and service delivery. [ 2 ]  The components of global neurosurgery practice are interdependent but global neurosurgeons tend to focus their practice on one or two of them. This trend has allowed for specialization within the field and greater collaboration between individuals and institutions. [ 12 ]


Advocacy  efforts happen at the international, regional, and local levels and in collaboration with health initiatives that share similar goals with global neurosurgery - universal health coverage and sustainable development. Internationally, global neurosurgery advocacy groups participate in high-level health policy events like the  World Health Assembly  and the  United Nations General Assembly . [ 13 ]  Global neurosurgery advocates have contributed to numerous high-level decisions including folate fortification, detection and management of congenital malformations, and injury prevention. [ 13 ] [ 14 ]  Locally, global neurosurgery advocacy groups are constituted of health workers and other patient advocates. These groups affect local decision making but they are equally active internationally. Many local advocacy groups are members of international advocacy groups like the G4 Alliance, [ 15 ] [ 14 ]  People and Organisations United for Spina Bifida and Hydrocephalus (PUSH!) Global Alliance, [ 16 ]  and International Federation Spina Bifida and Hydrocephalus (IFSBH). [ 17 ]  Local global neurosurgery advocacy groups work within these international organizations to coordinate advocacy efforts regionally and globally.


Global neurosurgery education focuses on two aspects. First, global neurosurgery educators train specialists to serve under-resourced regions. The training focuses primarily on safe and quality service delivery within underserved communities. These global neurosurgery education efforts can be divided into non-specialized and specialized training. Non-specialized training or education for task-sharing/-shifting targets non-specialized healthcare workers such as general surgeons, clinical officers, and general practitioners. [ 18 ] [ 19 ]  Non-specialized training is especially important in increasing access to essential and emergency neurosurgical care rapidly. [ 20 ]  Non-specialized training, unlike specialized training, can be done in shorter periods, with larger cohorts, and with fewer resources. [ 19 ]  Specialized neurosurgery training can last anywhere from a few months to 8 years depending on the training level. [ 21 ]  Postgraduate medical fellowships in one of the neurosurgical subspecialties are open to graduate neurosurgery residents/registrars and can last between three and 24 months. On the other hand, neurosurgery residencies last between 4 and 8 years. [ 22 ]


The other focus of global neurosurgery education is fellowships that introduce trainees to global and  public health  concepts. Global neurosurgery fellowships are relatively new but increasingly popular with institutions like Cambridge, [ 23 ]  Cornell, [ 24 ]  Duke, [ 25 ]  Harvard, [ 26 ]  and the University of Cape Town [ 27 ]  offering specialized training. [ 28 ]


Global neurosurgeons contribute significantly to the design and implementation of health policies that improve access to safe, timely, and affordable neurosurgical care globally. Prime examples of global neurosurgery policy efforts include the comprehensive health policy guidelines for traumatic brain and spine injuries [ 29 ] [ 30 ]  and for spina bifida and hydrocephalus. [ 31 ]  The comprehensive policy guidelines address challenges that affect the patient continuum of care and suggest solutions for every component of the healthcare system. [ 29 ] [ 30 ] [ 31 ]  These documents were designed for policymakers in areas with a large burden of diseases amenable to neurosurgery. Traumatic brain and spine injuries were chosen because they constitute more than 47.1% of the global neurosurgical disease burden while hydrocephalus and spina bifida were chosen for their deleterious impact on children. [ 6 ]


Research is an indispensable aspect of global neurosurgery practice called  academic global neurosurgery . [ 2 ]  Academic global neurosurgery has a broad focus and uses concepts from epidemiology,  health economics , health policy, health services, health systems, implementation & dissemination science, and patient safety & quality improvement research. [ 2 ]  Academic global neurosurgery's exponential growth since 2016 is the result of increased interest and support from the neurosurgical community characterized by the creation of an ad-hoc committee within the World Federation of Neurosurgical Societies, [ 32 ]  publication of special issues in reputable peer-reviewed journals, [ 33 ] [ 34 ]  creation of a specialized journal, [ 35 ]  and the creation of global neurosurgery centers. [ 12 ]  Academic global neurosurgery identifies challenges to accessing neurosurgical care and proposes solutions that increase access to care. [ 12 ]  The evidence generated by academic global neurosurgery informs the other aspects of global neurosurgery practice.


Service delivery is the oldest component of global neurosurgery practice and can be traced back to the colonial era when surgeons would deliver care in colonies. [ 21 ] [ 36 ]  Global neurosurgery aims to reduce barriers to essential and emergency neurosurgery procedures such as those needed for acute stroke, neural tube defects, traumatic brain injuries, and traumatic spine injuries. [ 37 ] [ 38 ]


Low- and middle-income country patients have worse outcomes than their high-income country counterparts because they regularly face barriers to accessing timely and safe neurosurgical care. [ 39 ] [ 40 ] [ 10 ]


The workforce deficit in low- and middle-income countries constitutes a significant barrier to receiving care. Although former colonies have trained local neurosurgeons since their independence, the neurosurgical workforce density in many low- and middle-income countries remains below the World Federation of Neurosurgical Societies' recommendation of 1 neurosurgeon per 200,000 people. [ 41 ]  In addition, the majority of low- and middle income countries have geographical disparities in the neurosurgical workforce with most neurosurgeons working in urban areas whereas the majority of people in these countries are rural-dwellers. [ 19 ]  In addition, surgical non-governmental organizations from high-income countries help fill the service delivery gap in some low- and middle-income countries. [ 42 ]  Although most neurosurgical non-governmental organizations offer short-term service delivery in low- and middle-income countries, some like CURE International offer long-term care. [ 43 ]


The neurosurgical workforce in low- and middle-income countries has increased gradually in the past decade thanks to targeted efforts from the global neurosurgery community. For example, the  World Federation of Neurosurgical Societies  supports the training of aspiring neurosurgeons from understaffed countries through scholarships at accredited centers in Africa, Asia, and South America. [ 44 ] [ 45 ] [ 46 ] [ 21 ] [ 47 ]


Young neurosurgeons from under-resourced regions who have been trained in advanced neurosurgical techniques report their patients do not get safe and timely care because of inadequate infrastructure. [ 19 ]  Access to neurosurgical infrastructure can be assessed summarily using the  World Federation of Neurosurgical Societies  facility three-tier classification or using hospital assessment tools. [ 48 ]  The  World Federation of Neurosurgical Societies  facility three-tier classification groups facilities into  level 1  (equipment for emergency neurosurgery procedures),  level 2  (equipment to perform basic microneurosurgical procedures), and  level 3  (equipment for complex and advanced neurosurgery).


Idiopathic intracranial hypertension  ( IIH ), previously known as  pseudotumor cerebri  and  benign intracranial hypertension , is a condition characterized by increased  intracranial pressure  (pressure around the brain) without a detectable cause. [ 2 ]  The main symptoms are  headache , vision problems,  ringing in the ears , and shoulder pain. [ 1 ] [ 2 ]  Complications may include  vision loss . [ 2 ]


This condition is idiopathic, meaning there is no known cause. Risk factors include being overweight or a recent increase in weight. [ 1 ]   Tetracycline  may also trigger the condition. [ 2 ]  The diagnosis is based on symptoms and a high opening pressure found during a  lumbar puncture  with no specific cause found on a  brain scan . [ 1 ] [ 2 ]


Treatment includes a healthy diet, salt restriction, and exercise. [ 2 ]  The medication  acetazolamide  may also be used along with the above measures. [ 2 ]  A small percentage of people may require surgery to relieve the pressure. [ 2 ]


About 2 per 100,000 people are newly affected per year. [ 4 ]  The condition most commonly affects women aged 20–50. [ 2 ]  Women are affected about 20 times more often than men. [ 2 ]  The condition was first described in 1897. [ 1 ]


The most common symptom of IIH is severe headache, which occurs in almost all (92–94%) cases. It is characteristically worse in the morning, generalized in character and throbbing in nature. It may be associated with nausea and vomiting. The headache can be made worse by  any activity that further increases the intracranial pressure , such as  coughing  and  sneezing . The pain may also be experienced in the neck and shoulders. [ 5 ]  Many have  pulsatile tinnitus , a whooshing sensation in one or both ears (64–87%); this sound is synchronous with the pulse. [ 5 ] [ 6 ]  Various other symptoms, such as numbness of the extremities, generalized weakness, pain and/or numbness in one or both sides of the face, loss of smell, and  loss of coordination , are reported more rarely; none are specific for IIH. [ 5 ]  In children, numerous nonspecific signs and symptoms may be present. [ 7 ]


The increased pressure leads to compression and traction of the  cranial nerves , a group of nerves that arise from the  brain stem  and supply the face and neck. Most commonly, the  abducens nerve  (sixth nerve) is involved. This nerve supplies the muscle that pulls the eye outward. Those with  sixth nerve palsy  therefore experience horizontal double vision which is worse when looking towards the affected side. More rarely, the  oculomotor nerve  and  trochlear nerve  ( third  and  fourth nerve palsy , respectively) are affected; both play a role in eye movements. [ 7 ] [ 8 ]  The  facial nerve  (seventh cranial nerve) is affected occasionally – the result is total or partial  weakness of the muscles of facial expression  on one or both sides of the face. [ 5 ]


The increased pressure leads to  papilledema , which is swelling of the  optic disc , the spot where the  optic nerve  enters the  eyeball . This occurs in practically all cases of IIH, but not everyone experiences symptoms from this. Those who do experience symptoms typically report "transient visual obscurations", episodes of difficulty seeing that occur in both eyes but not necessarily at the same time. Long-term untreated papilledema leads to visual loss, initially in the periphery but progressively towards the center of vision. [ 5 ] [ 9 ]


Physical examination of the nervous system  is typically normal apart from the presence of papilledema, which is seen on examination of the eye with a small device called an  ophthalmoscope  or in more detail with a  fundus camera . If there are cranial nerve abnormalities, these may be noticed on  eye examination  in the form of a  squint  (third, fourth, or sixth nerve palsy) or as facial nerve palsy. If the papilledema has been longstanding,  visual fields  may be constricted and  visual acuity  may be decreased.  Visual field testing  by automated ( Humphrey ) perimetry is recommended as other methods of testing may be less accurate. Longstanding papilledema leads to  optic atrophy , in which the disc looks pale and visual loss tends to be advanced. [ 5 ] [ 9 ]


"Idiopathic" means of unknown cause. Therefore, IIH can only be diagnosed if there is no alternative explanation for the symptoms.  Intracranial pressure  may be increased due to medications such as high-dose  vitamin A  derivatives (e.g.,  isotretinoin  for  acne ), [ 10 ]  long-term  tetracycline antibiotics  (for a variety of skin conditions). [ 11 ]   Hormonal contraceptives , particularly the oral contraceptive pill (OCP), are not associated with IIH. [ 12 ]  A systematic review published in 2020 suggests the use of the term " drug-induced intracranial hypertension (DIIH) " after having applied a 'strict drug-causality algorithm' in determining IIH cases likely caused by the drugs they evaluated. [ 13 ]


There are numerous other diseases, mostly rare conditions, that may lead to intracranial hypertension. If there is an underlying cause, the condition is termed "secondary intracranial hypertension". [ 5 ]  Common causes of secondary intracranial hypertension include  obstructive sleep apnea  (a sleep-related breathing disorder),  systemic lupus erythematosus  (SLE),  chronic kidney disease , and  Behçet's disease . [ 9 ]


On July 1, 2022, the FDA issued an update that gonadotropin-releasing hormone agonists, drugs that are approved for treating precocious puberty, may be a risk factor for developing pseudotumor cerebri. [ 14 ]


The cause of IIH is not known. The  Monro–Kellie rule  states that the intracranial pressure is determined by the amount of brain tissue,  cerebrospinal fluid  (CSF) and blood inside the bony cranial vault. Three theories therefore exist as to why the pressure might be raised in IIH: an excess of CSF production, increased volume of blood or brain tissue, or obstruction of the  veins that drain blood from the brain . [ 5 ]


The first theory, that of increased production of cerebrospinal fluid, was proposed in early descriptions of the disease. However, there is no experimental data that supports a role for this process in IIH. [ 5 ]


The second theory posits that either increased blood flow to the brain or increase in the brain tissue itself may result in the raised pressure. Little evidence has accumulated to support the suggestion that increased blood flow plays a role, but recently Bateman et al. in phase contrast MRA studies have quantified cerebral blood flow (CBF) in vivo and suggests that CBF is abnormally elevated in many people with IIH. Both  biopsy  samples and various types of brain scans have shown an increased water content of the brain tissue. It remains unclear why this might be the case. [ 5 ]


The third theory suggests that restricted venous drainage from the brain may be impaired resulting in congestion. Many people with IIH have narrowing of the  transverse sinuses . [ 15 ]  It is not clear whether this narrowing is the pathogenesis of the disease or a secondary phenomenon. It has been proposed that a positive biofeedback loop may exist, where raised ICP ( intracranial pressure ) causes venous narrowing in the  transverse sinuses , resulting in venous hypertension (raised venous pressure), decreased CSF resorption via  arachnoid granulation  and further rise in ICP. [ 16 ]


The diagnosis may be suspected on the basis of the history and examination. To confirm the diagnosis, as well as excluding alternative causes, several investigations are required; more investigations may be performed if the history is not typical or the person is more likely to have an alternative problem: children, men, the elderly, or women who are not overweight. [ 8 ]


Neuroimaging , usually with  computed tomography  (CT/CAT) or  magnetic resonance imaging  (MRI), is used to exclude any mass lesions. In IIH these scans typically appear to be normal, although small or slit-like  ventricles , dilatation and buckling [ 18 ]  of the optic nerve sheaths and " empty sella sign " (flattening of the  pituitary gland  due to increased pressure) and enlargement of Meckel's caves may be seen.


An MR venogram is also performed in most cases to exclude the possibility of venous sinus stenosis/obstruction or  cerebral venous sinus thrombosis . [ 5 ] [ 7 ] [ 8 ]  A contrast-enhanced MRV (ATECO) scan has a high detection rate for abnormal transverse sinus stenoses. [ 15 ]  These stenoses can be more adequately identified and assessed with catheter cerebral venography and manometry. [ 16 ]  Buckling of the bilateral optic nerves with increased perineural fluid is also often noted on MRI imaging.


Lumbar puncture  is performed to measure the opening pressure, as well as to obtain  cerebrospinal fluid  (CSF) to exclude alternative diagnoses. If the opening pressure is increased, CSF may be removed for transient relief (see below). [ 8 ]  The CSF is examined for abnormal cells, infections, antibody levels, the  glucose  level, and  protein  levels. By definition, all of these are within their normal limits in IIH. [ 8 ]  Occasionally, the CSF pressure measurement may be normal despite very suggestive symptoms. This may be attributable to the fact that CSF pressure may fluctuate over the course of the normal day. If the suspicion of problems remains high, it may be necessary to perform more long-term monitoring of the ICP by a pressure catheter. [ 8 ]


The original criteria for IIH were described by  Dandy  in 1937. [ 19 ]


They were modified by Smith in 1985 to become the "modified Dandy criteria". Smith included the use of more advanced imaging: Dandy had required  ventriculography , but Smith replaced this with  computed tomography . [ 20 ]  In a 2001 paper, Digre and Corbett amended Dandy's criteria further. They added the requirement that the person is awake and alert, as coma precludes adequate neurological assessment, and require exclusion of venous sinus thrombosis as an underlying cause. Furthermore, they added the requirement that no other cause for the raised ICP is found. [ 5 ] [ 9 ] [ 21 ]


In a 2002 review, Friedman and Jacobson propose an alternative set of criteria, derived from Smith's. These require the absence of symptoms that could not be explained by a diagnosis of IIH, but do not require the actual presence of any symptoms (such as headache) attributable to IIH. These criteria also require that the lumbar puncture is performed with the person lying sideways, as a lumbar puncture performed in the upright sitting position can lead to artificially high pressure measurements. Friedman and Jacobson also do not insist on MR venography for every person; rather, this is only required in atypical cases (see "diagnosis" above). [ 8 ]


The primary goal in treatment of IIH is the prevention of visual loss and blindness, as well as symptom control. [ 9 ]  IIH is treated mainly through the reduction of CSF pressure and IIH may resolve after initial treatment, may go into spontaneous remission (although it can still relapse at a later stage), or may continue chronically. [ 5 ] [ 8 ]  There are three main treatment approaches: weight loss, different medications and surgical interventions. Remission is seen for most patients that achieve a weight loss of around 6–10%. Bariatric surgery can be an option for those patients that don't achieve weight loss with lifestyle changes and diet. [ 22 ]


The first step in symptom control is drainage of cerebrospinal fluid by lumbar puncture. If necessary, this may be performed at the same time as a diagnostic LP (such as done in search of a CSF infection). In some cases, this is sufficient to control the symptoms, and no further treatment is needed. [ 7 ] [ 9 ]


The procedure can be repeated if necessary, but this is generally taken as a clue that additional treatments may be required to control the symptoms and preserve vision. Repeated lumbar punctures are regarded as unpleasant by people, and they present a danger of introducing spinal infections if done too often. [ 5 ] [ 7 ]  Repeated lumbar punctures are sometimes needed to control the ICP urgently if the person's vision deteriorates rapidly. [ 9 ]


The best-studied medical treatment for intracranial hypertension is  acetazolamide  (Diamox), which acts by inhibiting the enzyme  carbonic anhydrase , and it reduces CSF production by six to 57 percent. It can cause the symptoms of  hypokalemia  (low blood potassium levels), which include muscle weakness and tingling in the fingers. Acetazolamide cannot be used in pregnancy, since it has been shown to cause embryonic abnormalities in animal studies. Also, in human beings it has been shown to cause  metabolic acidosis  as well as  disruptions in the blood electrolyte levels  of newborn babies. The diuretic  furosemide  is sometimes used for a treatment if acetazolamide is not tolerated, but this drug sometimes has little effect on the ICP. [ 5 ] [ 9 ]


Various  analgesics  (painkillers) may be used in controlling the headaches of intracranial hypertension. In addition to conventional agents such as  paracetamol , a low dose of the antidepressant  amitriptyline  or the anticonvulsant  topiramate  have shown some additional benefit for pain relief. [ 9 ]


The use of  steroids  in the attempt to reduce the ICP is controversial. These may be used in severe papilledema, but otherwise their use is discouraged. [ 5 ]


Venous sinus stenoses leading to venous hypertension appear to play a significant part in relation to raised  ICP , and stenting of a  transverse sinus  may resolve venous hypertension, leading to improved  CSF  resorption, decreased ICP, cure of papilledema and other symptoms of IIH. [ 16 ]


A self-expanding metal stent is permanently deployed within the dominant  transverse sinus  across the stenosis under general anaesthesia. In general, people are discharged the next day. People require double antiplatelet therapy for a period of up to 3 months after the procedure and aspirin therapy for up to 1 year.


In a systematic analysis of 19 studies with 207 cases, there was an 87% improvement in overall symptom rate and 90% cure rate for treatment of papilledema. Major complications only occurred in 3/207 people (1.4%). [ 23 ]  In the largest single series of transverse sinus stenting there was an 11% rate of recurrence after one stent, requiring further stenting. [ 16 ]


Due to the permanence of the stent and small but definite risk of complications, most experts will recommend that person with IIH must have papilledema and have failed medical therapy or are intolerant to medication before stenting is undertaken.


Two main surgical procedures are used for the treatment of IIH:  optic nerve sheath decompression and fenestration  and  cerebral shunting . Surgery would normally only be offered if medical therapy is either unsuccessful or not tolerated. [ 7 ] [ 9 ]  The choice between these two procedures depends on the predominant problem in IIH. Neither procedure is perfect: both may cause significant complications, and both may eventually fail in controlling the symptoms. There are no  randomized controlled trials  to guide the decision as to which procedure is best. [ 9 ]


Optic nerve sheath fenestration  is an operation that involves the making of an incision in the connective tissue lining of the  optic nerve  in its portion behind the eye. It is not entirely clear how it protects the eye from the raised pressure, but it may be the result of either diversion of the CSF into the  orbit  or the creation of an area of scar tissue that lowers the pressure. [ 9 ]  The effects on the intracranial pressure itself are more modest. Moreover, the procedure may lead to significant complications, including blindness in 1–2%. [ 5 ]  The procedure is therefore recommended mainly in those who have limited headache symptoms but significant papilledema or threatened vision, and those who have undergone unsuccessful treatment with a shunt or have a contraindication for shunt surgery. [ 9 ]


Shunt surgery, usually performed by  neurosurgeons , involves the creation of a conduit by which CSF can be drained into another body cavity. The initial procedure is usually a  lumboperitoneal (LP) shunt , which connects the subarachnoid space in the  lumbar spine  with the  peritoneal cavity . [ 24 ]  A pressure valve is usually included in the circuit to avoid excessive drainage when the person is erect. LP shunting provides long-term relief in about half the cases; others require revision of the shunt, often on more than one occasion, usually due to shunt obstruction. If the lumboperitoneal shunt needs repeated revisions, a  ventriculoatrial  or  ventriculoperitoneal shunt  may be considered. These shunts are inserted in one of the  lateral ventricles  of the brain, usually by  stereotactic surgery , and then connected either to the  right atrium  of the heart or the peritoneal cavity. [ 5 ] [ 9 ]  Given the reduced need for revisions in ventricular shunts, it is possible that this procedure will become [ when? ]  the first-line type of shunt treatment. [ 5 ]


It has been shown that in obese people,  bariatric surgery  (and especially  gastric bypass surgery ) can lead to resolution of the condition in over 95%. [ 5 ]


It is not known what percentage of people with IIH will remit spontaneously, and what percentage will develop chronic disease. [ 9 ]


IIH does not normally affect life expectancy. The major complications from IIH arise from untreated or treatment-resistant  papilledema . In various case series, the long-term risk of one's vision being significantly affected by IIH is reported to lie anywhere between 10 and 25%. [ 5 ] [ 9 ]


On average, IIH occurs in about one per 100,000 people, and can occur in children and adults. The  median  age at diagnosis is 30. IIH occurs predominantly in women, especially in the ages 20 to 45, who are four to eight times more likely than men to be affected.  Overweight  and  obesity  strongly predispose a person to IIH: women who are more than ten percent over their  ideal body weight  are thirteen times more likely to develop IIH, and this figure goes up to nineteen times in women who are more than twenty percent over their ideal body weight. In men this relationship also exists, but the increase is only five-fold in those over 20 percent above their ideal body weight. [ 5 ]


Despite several reports of IIH in families, there is no known genetic cause for IIH. People from all  ethnicities  may develop IIH. [ 5 ]  In children, there is no difference in incidence between males and females. [ 7 ]


From national hospital admission databases it appears that the need for  neurosurgical  intervention for IIH has increased markedly over the period between 1988 and 2002. This has been attributed at least in part to the rising prevalence of obesity, [ 25 ]  although some of this increase may be explained by the increased popularity of  shunting  over optic nerve sheath fenestration. [ 9 ]


The first report of IIH was by the German physician  Heinrich Quincke , who described it in 1893 under the name  serous meningitis . [ 26 ]  The term "pseudotumor cerebri" was introduced in 1904 by his compatriot  Max Nonne . [ 27 ]  Numerous other cases appeared in the literature subsequently; in many cases, the raised intracranial pressure may actually have resulted from underlying conditions. [ 28 ]  For instance, the  otitic hydrocephalus  reported by London neurologist Sir  Charles Symonds  may have resulted from venous sinus thrombosis caused by  middle ear infection . [ 28 ] [ 29 ]  Diagnostic criteria for IIH were developed in 1937 by the  Baltimore  neurosurgeon  Walter Dandy ; Dandy also introduced subtemporal decompressive surgery in the treatment of the condition. [ 19 ] [ 28 ]


The terms "benign" and "pseudotumor" derive from the fact that increased intracranial pressure may be associated with  brain tumors . Those people in whom no tumour was found were therefore diagnosed with "pseudotumor cerebri" (a disease mimicking a brain tumor). The disease was renamed  benign intracranial hypertension  in 1955 to distinguish it from intracranial hypertension due to life-threatening diseases (such as cancer); [ 30 ]  however, this was also felt to be misleading because any disease that can blind someone should not be thought of as benign, and the name was therefore revised in 1989 to "idiopathic (of no identifiable cause) intracranial hypertension". [ 31 ] [ 32 ]


Shunt surgery was introduced in 1949; initially, ventriculoperitoneal shunts were used. In 1971, good results were reported with lumboperitoneal shunting. Negative reports on shunting in the 1980s led to a brief period (1988–1993) during which optic nerve fenestration (which had initially been described in an unrelated condition in 1871) was more popular. Since then, shunting is recommended predominantly, with occasional exceptions. [ 5 ] [ 9 ]


Creutzfeldt–Jakob disease


An  infectious intracranial aneurysm  ( IIA , also called  mycotic aneurysm ) is a  cerebral aneurysm  that is caused by  infection  of the cerebral  arterial wall .


Many patients with unruptured IIA may have no symptoms. In patients who do have symptoms these are often related to rupture of the aneurysm and to its cause. [ 1 ]  Rupture of an IIA results in  subarachnoid hemorrhage , symptoms of which include headache, dizziness, seizures, altered mental status and focal  neurological deficits . [ citation needed ]


In contrast to other cerebral aneurysms, large aneurysm size does not increase the chance of rupture. Small IIAs
tend to have high rupture rates, while larger IIAs more commonly cause symptoms due to pressure on the surrounding brain tissue. [ citation needed ]


Most IIAs are caused by bacterial infection, most commonly  Staphylococcus aureus  and  Streptococcus  species. In most cases the infection originates from left-sided  bacterial endocarditis . [ 1 ]  Other common sources include  cavernous sinus thrombosis ,  bacterial meningitis , poor  dental hygiene  and  intravenous drug  use.
The use of the term infectious aneurysm by the above authors is incorrect. Refer to Holtzman RNN, Pile-Spellman JMD, Brust JCM, Hughes JEO, Dickinson PCT: Surgical Management of Intracranial Aneurysms Caused by Infection, in: Schmidek HH and Roberts DW(eds): Schmidek & Sweet Operative Neurosurgical Techniques: Indications, Methods, and Results ed.5. Philadelphia: Elsevier Inc. 2006 Vol 1: Chap. 87, pp1223-1259


Diagnosis of IIA is based on finding an intracranial aneurysm on  vascular imaging  in the presence of predisposing infectious conditions. [ 1 ]  Positive  bacterial cultures  from blood or the infected aneurysm wall itself may confirm the diagnosis, however blood cultures are often negative. Other supporting findings include  leukocytosis , an elevated  erythrocyte sedimentation rate  and elevated  C-reactive protein  in blood. [ citation needed ]


The term  mycotic aneurysm , initially attributed to Osler and used to describe bacterial intracranial aneurysms, is a misnomer. Most investigators currently agree that its use should be strictly limited to descriptions of aneurysms of fungal origin. Yet efforts to establish an accurate nomenclature have been generally unsuccessful. Therefore, we are resigned to the fact that the term mycotic aneurysm will remain in general parlance. At the same time, we prefer the use of a more specific and accurate heading, namely,  infected intracranial aneurysm , to include the categories of intracranial bacterial aneurysm, fungal aneurysm, spirochetal aneurysm, infested or amebic aneurysm, viral aneurysm and phytotic aneurysm, according to the specific infecting organism or agent. The terms  infectious aneurysm  and  infective aneurysm   are flawed because they imply that the aneurysm itself is the infecting agent rather than being the end point of an infecting process. Until such a pathogenesis has been detected, it is the intention of the authors to avoid catachresis and the application of archaic language (Marcus S, The George Delacorte Professor of English and Comparative Literature, Columbia University, New York, personal communication, 1993: "The correct usage is 'infected'. The term 'infectious' died out as a usage in termed of infected in 1726." And Jost, DA, former senior lexicographer of  The American Heritage Dictionary , Boston, personal communication, 1996: " Infectious aneurysm  will be interpreted by most users of English as an aneurysm that can communicate infection"). [ citation needed ]


The term  infected intracranial aneurysm  lacks the properties of complete definition because it refers to the initial process that affects the arterial wall and to aneurysms found to have bacteria in their walls at the time of excision (Table 87-1, Patient 3; see Case Report 9, Fig. 87-9), but not to the processes of focal dilatation or subsequent aneurysm formation and enlargement. It also accurately describes the congenital or berry aneurysm that has become secondarily infected. The terms  septic aneurysm  and  septic embolism  and  septic arteritis  are also commonly used. However, the word septic refers to infection involving the blood stream and is not really descriptive of the aneurysm themselves. [ citation needed ]


Treatment depends on whether the aneurysm is ruptured and may involve a combination of  antimicrobial drugs ,  surgery  and/or  endovascular treatment . [ 1 ]


Mortality  of IIA is high, unruptured IIA are associated with a mortality reaching 30%, while ruptured IIA has a mortality of up to 80%. [ 1 ]  IIAs caused by  fungal infections  have a worse prognosis than those caused by bacterial infection. [ 2 ]


IIAs are uncommon, accounting for 2.6% to 6% of all  intracranial aneurysms  in autopsy studies. [ 2 ]


The  International Subarachnoid Aneurysm Trial  ( ISAT ) was a large  multicenter  prospective  randomized   clinical medical trial  comparing the safety and efficacy of  endovascular coil  treatment and  surgical clipping  for the treatment of  brain aneurysms . The study began in 1994 with the first results being published in  The Lancet  in 2002, and the 10-year data were published again in  The Lancet  in early September 2005. A total of 2,143 study participants were mostly drawn from  U.K.  hospitals with the rest drawn from North American and European hospitals.


The study found superior results with  endovascular  coil treatment compared to surgical clipping. However, subsequent studies have questioned this conclusion. [ 1 ]  The study was criticized by many clinicians and not well accepted by surgeons. [ 2 ]  Primary criticisms were related to the study's generalizability and the long-term prognosis of coil embolization. [ 3 ]


ISAT sought to measure outcomes of  cerebral aneurysm  patients at 2 and 12 months using a type of a  Rankin scale . [ 4 ] : 114   The study was prematurely terminated in 2002 after the oversight committee determined there was increased morbidity with surgical clipping compared to  endovascular  coiling. [ 4 ] : 114


ISAT was criticized on several factors related to the randomization of the patient population. The randomized patient population in the ISAT was younger on average, the majority had aneurysms under 10mm and in anterior circulation compared to the population of  subarachnoid hemorrhage  patients in the U.S. and Japan. [ 1 ] [ 5 ] : 210   In response to these criticisms, a facility that participated in ISAT compared the clinical outcomes of their patients who were not selected for the study to those who were. They reported similar outcomes to the ISAT. [ 1 ]


Although the initial ISAT analysis appeared to favor endovascular coiling over microsurgical clipping, subsequent meta-analysis have questioned that conclusion finding higher incidences [ spelling? ]  of recurrence. [ 6 ]  A large meta-analysis from  Johns Hopkins University  published in  Neurosurgery  concluded that "there is no clear consensus in these two studies or in the 45 observational studies included." [ 6 ]


Updated data from the ISAT group in March 2008 shows that the higher aneurysm rate of recurrence is also associated with a higher re-bleeding rate, given that the re-bleed rate of coiled aneurysms appears to be 8 times higher than that of aneurysms treated with surgical clipping in this study. [ 7 ]  The ISAT authors conclude that "when treating ruptured cerebral aneurysms, the advantage of coil embolization over clip ligation cannot be assumed for patients younger than 40 years old." [ 7 ]  Other studies have directly questioned the ISAT's conclusions. [ 8 ]  This conclusion is based on a number of methodological assumptions itself and other authors have cautioned about extending it to other patient populations. [ 9 ]


It appears that although endovascular coiling is associated with a shorter recovery period as compared to surgical clipping, it is also associated with a significantly higher  recurrence  rate after treatment. The long-term data for unruptured  aneurysms  are still being gathered.


Total disc replacement  ( TDR ), or  artificial disc replacement  ( ADR ), is a type of  arthroplasty  in which degenerated  intervertebral discs  in the  vertebral column  are replaced with artificial disc implants in the lumbar (lower) or cervical (upper) spine.  The procedure is used to treat chronic, severe  low back pain  and cervical pain resulting from  degenerative disc disease . Disc replacement is also an alternative intervention for symptomatic disc herniation with associated arm and hand, or leg symptoms ( radicular pain ).


TDR has been developed as an alternative to  spinal fusion , with the goal of pain reduction or elimination, while still allowing motion throughout the spine.  Faster recoveries after surgery have also been widely reported by surgeons. [ 1 ]  Another possible benefit is the prevention of premature breakdown in adjacent levels of the spine, a potential risk in fusion surgeries. [ 2 ]  Recent studies have shown a strong correlation between providing motion in the spine and avoiding adjacent segment degeneration. [ 3 ]


Multiple artificial discs (or disc replacements) have been approved by the FDA for use in the US, although several have been discontinued by their manufacturers. The Charité, a mobile core device for use in the lumbar spine, was approved first, in 2004, but is no longer in use. prodisc, the longest continually used disc replacement device in the US, is a fixed core device manufactured by Centinel Spine and was approved in 2006 for the lumbar spine with a cervical device approved in 2007. The first cervical disc replacement available in the US was the Prestige, manufactured by  Medtronic . There have been several Prestige cervical disc replacement designs manufactured by Medtronic, with the current design being the Prestige LP.


FDA approvals for devices are for one- or two-level use and at specific levels in the cervical or lumbar spine. Clinical studies are currently required to obtain FDA approval for disc replacements. These studies are comparative, noting differences between patients receiving a new device versus patients that receive spinal fusion or another previously-approved disc replacement.
The below table illustrates currently-approved disc replacement devices, their approval dates, the number of approved levels for each device, and their current usage status.


While these discs have received FDA approval, reimbursement by insurance companies is not always automatic. Effective August 14, 2007, the Centers for Medicare & Medicaid Services (CMS) does not cover, on a national basis, Lumbar Artificial Disc Replacement (LADR) for patients over the age of 60. However, individual entities (Medicare Administrative Contractors, or  MACs ) regulate the determination of covered use of devices in patients 60 and under, and several approve the use of LADR for these patients.[1]
Approval by insurance companies is generally better for cervical disc replacements, with over 90% of the US population covered by a commercial payer that reimburses for cervical disc replacements, and over 85% for lumbar disc replacements. [ 17 ]


Many countries have their own individualized approval process for medical devices. In Europe,  Regulation (EU) 2017/745  defined the Medical Device Regulation (MDR) used for reviewing, approving, and monitoring the quality of medical devices. There are a large number of total disc replacements available and approved for use in Europe, including all of those available in the US. Some other international regulatory bodies base their approvals upon regulations in third party countries, such as the EU or the US. Nearly all countries have their own approval process.
The below table lists cervical disc replacement options available outside of the US.


The first artificial disc was implanted in 1959, with Swedish surgeon Ulf Fernström publishing a description of his experience implanting a stainless-steel ball bearing into an intervertebral disc space after  discectomy  in 1966. Fernström balls, used in approximately 250 patients, created segmental hypermobility and demonstrated a marked tendency to settle into the vertebral endplates.  Reports suggest that function, while initially good, degenerated over time.


During the 1970s, a new concept was introduced: achieving mobility through articulation between the concave and convex surfaces of a multi-component device. Designs patented at that time combined metal, ceramic, or other types of elastic bearings with components made of silicone composites, rubber, polyurethane, plastics, or fluid-filled membranes. Some designs incorporated balloons, cages, pegs, wire screens, hinged plates, or springs. Springs proved to be particularly impractical because they could not withstand biomechanical fatigue tests of stress and strain. [ 18 ]


The first design with wide clinical adoption was the Charité disc replacement, designed by East German scientists: two-time Olympic champion in women's artistic gymnastics Karin Büttner-Janz and Kurt Schellnack, a doctor, engineer, and professor—both of whom were affiliated with the Charité Center for Musculoskeletal Surgery at the Medical University of Berlin[2]. First implanted in 1984, the disc had a biconvex polyethylene nucleus within a radiopaque metal ring that interfaced with two cobalt-chromium-molybdenum alloy endplates, which were coated with calcium phosphate. Approved for use in the United States in 2004, after a 4-year clinical trial, Charité was removed from the market by 2012.


The second disc replacement to achieve wide clinical use was the prodisc total disc replacement; it continues to have worldwide use today. Designed by French orthopedic spine surgeon Thiery Marnay, M.D., in the late 1980s, early implantations of the prodisc device began in 1990, with a 7-11 year follow-up published in 2005. After implementing design changes to the bone-facing endplate, and after a clinical study in the United States, the new design was made available worldwide. In October 2001, as part of the FDA trial,  Jack Zigler , M.D., a spine surgeon at Texas Back Institute in Plano, Texas, performed the first prodisc L artificial disc replacement in the United States.


The US FDA requires manufacturers to conduct clinical studies to assess the safety and efficacy of disc replacements before obtaining approval to market the devices in the United States. Other devices can be approved for use with simpler non-clinical reviews. As a result, disc replacements have the highest level of clinical evidence of any spine devices. However, since this research is funded by industry, some controversy over data bias produced by the clinical studies exists [see Controversy].


Level 1 and level 1a studies (the highest quality levels: see  Hierarchy of Evidence ) have shown safety and efficacy for both lumbar and cervical discs, and have become the de facto standard of care for appropriate patients outside of the United States. [ 19 ] [ 20 ]   All prospective, randomized clinical studies that have been run in the United States have shown lumbar and cervical disc replacements to provide faster recovery, better long-term patient satisfaction, and fewer incidents of adjacent segment degeneration than comparative spinal fusion options. [ 19 ] [ 20 ]


A few non-industry funded studies also exist. In addition to the previously mentioned 7-11 year followup study on prodisc conducted by Thiery Marnay, M.D., [ 21 ]  a Norwegian study published in The Spine Journal in 2017 compared total disc replacement and multidisciplinary rehabilitation with an eight-year follow up. The study was randomized, controlled, multi-center and not funded by industry. 77 patients randomized to surgery and 74 patients randomized to rehabilitation responded at eight-year follow-up. The study found a statistically significant benefit in favor of surgery. [ 22 ]


The  AAOS  states that disc replacement requires a high level of technical skill for accurate placement and has a significant level of risk if revision surgery is needed. [ 23 ]


Members of AAOS and the American Association of Neurological Surgeons joined together as the Association for Ethics in Spine Surgery, formed to raise awareness of the ties between physicians and device manufacturers. [ 24 ]


Aetna rescinded its positive coverage for single level lumbar ADR after merger with Coventry in 2013. [ 25 ]  There is currently (in 2022) a class-action lawsuit against Aetna Life Insurance for denying patients seeking lumbar disc replacement surgery in the United States alleging that patients are being harmed by denials since Aetna has declared them 'experimental or investigational’. [ 26 ]


Despite published meta-analyses (the highest-level clinical evidence) that have illustrated that total disc replacement seems to be superior to fusion in most clinical parameters, new studies have identified concerns regarding long-term durability of some of these devices. One such recent study identifies a large “midterm failure rate” related to the M6-C. It recommends that “patients implanted with the M6-C prosthesis should be contacted, informed, and clinically and radiologically assessed”. [ 27 ]  Unfortunately, catastrophic failure of the M6-C prosthesis has also been reported. [ 28 ]


The monitoring of  intracranial pressure  (ICP) is used in the treatment of a number of neurological conditions ranging from severe  traumatic brain injury  to  stroke  and  brain bleeds . [ 1 ]  This process is called  intracranial pressure monitoring . Monitoring is important as persistent increases in ICP is associated with worse prognosis in brain injuries due to decreased oxygen delivery to the injured area and risk of brain herniation.


ICP monitoring is usually used on patients who have decreased score on the  Glasgow Coma Scale , indicating poor neurologic function. It is also used in patients who have non-reassuring imaging on CT, indicating compression of normal structures from swelling.


Most current clinically available measurement methods are invasive, requiring surgery to place the monitor in the brain itself. Of these,  external ventricular drainage  (EVD) is the current gold standard as it allows physicians to both monitor ICP and treat if necessary. Some  non-invasive intracranial pressure measurement methods  are currently being studied, however none are currently able to deliver the same accuracy and reliability of invasive methods.


Intracranial pressure monitoring is just one tool to manage ICP. It is used in conjunction with other techniques such as ventilator settings to manage levels of carbon dioxide in the blood, head and neck position, and other therapies such as hyperosmolar therapy, medications, and core temperature. [ 2 ]  However, there is no current consensus on the clinical benefit of ICP monitoring in overall ICP management, with evidence both supporting its use and finding no benefit in reducing mortality. [ 3 ]


Injury to the brain will often result in brain swelling. As the brain is encased in the skull, limited swelling can be accommodated until the brain is no longer able to maintain normal function. There are two potential negative consequences from this swelling: ischemia due to compression of the brain tissue resulting in lack of blood and oxygen, and herniation of the brain. [ 4 ]


The three main components in determining ICP is the blood circulation in the brain,  cerebrospinal fluid (CSF) , and the brain tissue itself. This relationship is dictated by the  Monro-Kellie  doctrine, which states that as the brain swells, intracranial pressure (ICP) rises and cerebral perfusion decreases. As the brain swelling exceeds a certain point called the critical closing pressure (CrCP), the arterioles feeding the brain oxygen-rich blood will collapse, and the brain becomes deprived of blood. [ 1 ]  This secondary injury can cause permanent brain damage from lack of oxygen.


Herniation of the brain can occur when the pressure inside the skull exceeds the pressure of the spinal canal. This is dangerous as it can result in the compression of important areas like the brainstem that regulate breathing leading to significant neurological impairment or death. [ citation needed ]


Under normal conditions, regular movements such as leaning forward, normal heartbeat and breathing can cause changes to the ICP. Intracranial monitoring accounts for this by averaging measurements over 30 minutes in non-comatose patients. Readings between 7-15mmHg are considered normal in an adult, 3-7mmHg in children, and 1.4-6mmHg in infants. [ 4 ]


The external ventricular drainage (EVD) method of intracranial pressure monitoring is the current gold standard. The placement of an EVD requires a catheter placed into one of the lateral ventricles from a burr hole made into the skull. Benefits of an EVD include its ability to not only measure changes in pressure but also drain CSF as needed, thus making it both diagnostic and therapeutic. [ 2 ]  Significantly, an EVD can also be re-calibrated after placement which is particularly useful clinically to manage measurement drift. Risks in the operation to place the EVD are minimal but include infection and brain bleeds. Drawbacks to EVDs are the difficulty to place in comparison to other methods -- especially in the setting of brain swelling or anatomical variation in ventricle size – and once placed, are at increased risk of blockage from blood, air bubbles, or other debris. [ citation needed ]


There are three types of intraparenchymal pressure monitors (IPM), also called  bolts : fiber optic, strain gauge, and pneumatic sensors. [ 1 ]  Fiber optic monitors use changes in light reflected back from a mirror at the end of the cable to reflect changes in the ICP. Strain gauge monitors use a diaphragm that is bent by surrounding pressure, which is then converted into electrical signals used to calculate changes in ICP.  Pneumatic sensors are fitted with a balloon which measures the surrounding pressure, thereby measuring the ICP. [ 4 ]  IPMs are as equally accurate as EVDs, but cannot be recalibrated after placement, which is a major clinical limitation of this method of intracranial pressure monitoring. Risks of IPMs are similar to risks of EVDs as both require a surgical procedure. However, placement of IPMs is still considered less invasive than placement of EVDs. Additionally, placement of IPMs do not require the precision needed for EVD placement, and they are less affected by structural changes to the brain such as brain swelling or midline shift. [ 2 ]  IPMs can be placed not only in the parenchyma but also in the ventricular, subarachnoid, subdural, or epidural spaces. Generally, IPMs are chosen when EVD placement is unsuccessful or if CSF drainage is determined to likely not be necessary. [ 4 ]


This method of intracranial pressure monitoring requires placement of an oxygen probe into the penumbra, the area surrounding the injury that is most at risk of secondary injury from hypoxia. The probe measures levels of oxygen in the area, with levels under 15mmHg treated with increasing oxygen levels in the body. [ 2 ]


There are many noninvasive methods for intracranial pressure monitoring such as transcranial doppler (TCD), and optic nerve sheath diameter (ONSD). While none of these methods have been able to have the accuracy, reliability, and independent validation of invasive methods, they may eventually be used in determining the severity of injury and if there is a need for more invasive measures. [ 1 ]


Intraoperative magnetic resonance imaging  (iMRI) is an operating room configuration that enables surgeons to image the patient via an  MRI  scanner while the patient is undergoing surgery, particularly brain surgery. iMRI reduces the risk of damaging critical parts of the brain and helps confirm that the surgery was successful or if additional resection is needed before the patient's head is closed and the surgery completed. [ 1 ]


Compared to other imaging types, high-field iMRI requires the additional cost of specialized operating suites, instrumentation and longer anesthesia and operating room time; however, published studies show use of iMRI increases physicians’ ability to detect residual tumor leading toward an improved rate of procedural success. [ 2 ]


iMRI is available in a range of strengths. Low-field units, less than 1  Tesla  (T), have the advantage of small size, simpler operating theater preparation and portability but are disadvantaged by relatively poor image resolution.  Higher field strengths, currently available in 1.5 and 3T options, provide better spatial and contrast resolution enabling surgeons to more accurately evaluate the findings on an image. [ 2 ]


High-field iMRI operating suites are configured in one of two ways. [ 3 ]   Both require that the MRI magnet be stored in an adjacent room. One configuration requires that the patient be moved to the magnet to obtain an image. [ 2 ] [ 4 ]   The second configuration (only offered by  IMRIS , Inc.) moves the MRI magnet to the patient via ceiling-mounted rails to obtain the image. [ 1 ]   The latter approach has the advantage of not moving the patient from the operating theater during the surgery and enhances workflow and safety in terms of airway control, monitoring and head fixation. [ 1 ] [ 4 ]


The most prevalent application for iMRI is  neurosurgery , especially for the removal of  brain tumors . [ 3 ] [ 5 ]  The system is also used for interventional neurovascular  [ 6 ]  procedures.


By providing iMRI during neurosurgery, clinicians can distinguish between tumor tissue and normal tissue, minimize disturbance of healthy tissue or critical areas of the brain, evaluate and confirm their results and make adjustments during a procedure without moving the patient (in the case of the rail-mounted configuration). Published clinical evidence shows the higher percentage of tumor removed the better the outcome. [ 1 ]   Use of an iMRI suite makes it more likely that surgeons will remove the entire tumor than if surgery is performed in a conventional operating room where iMRI is not used. [ 7 ]


Keen's point  is one of the  ventriculostomy  sites used in  neurosurgery , typically in pediatrics for  ventriculoperitoneal shunt  placement. Keen's point is located 3 cm superior and 3 cm posterior to the  helix of the ear . [ 1 ] [ 2 ]  A burr hole or small twist drill hole is made in the skull at the Keen's point, to introduce a catheter into the  lateral ventricle  of brain for the purpose of obtaining or diverting  cerebrospinal fluid . The procedure is done for both diagnostic and therapeutic purposes.


Kocher's point  is a common entry point through the  frontal bone  for an intraventricular  catheter  to drain  cerebrospinal fluid  from the anterior horn of the  lateral ventricle . It is located 2–3 centimeters lateral to the midline (at approximately the mid-pupillary line) and approximately 11 cm posterior to the  nasion , or 10 cm posterior from the  glabella . [ 1 ]  During cannulation of the  lateral ventricle , Kocher's point is landmarked as a point of entry, and care must be taken to be at least 1 cm anterior to the coronal suture to avoid damaging the  primary motor cortex . [ 2 ]  It is most often used to remove cerebrospinal fluid for the treatment of  hydrocephalus .


A  laminectomy  is a surgical procedure that removes a portion of a  vertebra  called the  lamina , which is the roof of the  spinal canal . It is a major spine operation with residual scar tissue and may result in  postlaminectomy syndrome . Depending on the problem, more conservative treatments (e.g., small endoscopic procedures, without bone removal) may be viable. [ 1 ]


The lamina is a posterior arch of the vertebral bone lying between the spinous process (which juts out in the middle) and the more lateral pedicles and the transverse processes of each  vertebra . The pair of laminae, along with the  spinous process , make up the posterior wall of the bony spinal canal. Although the literal meaning of laminectomy is 'excision of the lamina', a conventional laminectomy in neurosurgery and orthopedics involves excision of the  supraspinous ligament  and some or all of the spinous process. Removal of these structures with an open technique requires disconnecting the many muscles of the back attached to them. A laminectomy performed as a minimal spinal surgery procedure is a tissue-preserving surgery that leaves more of the muscle intact and spares the spinal process. Another procedure, called the laminotomy, is the removal of a mid-portion of one lamina and may be done either with a conventional open technique or in a minimalistic fashion with the use of tubular retractors and endoscopes. [ citation needed ]


The reason for lamina removal is rarely, if ever, because the lamina itself is diseased; rather, it is done to break the continuity of the rigid ring of the spinal canal to allow the soft tissues within the canal to:  1) expand (decompress); 2) change the contour of the vertebral column; or 3) permit access to deeper tissue inside the spinal canal. A laminectomy is also the name of a spinal operation that conventionally includes the removal of one or both lamina, as well as other posterior supporting structures of the vertebral column, including ligaments and additional bone. The actual bone removal may be carried out with a variety of surgical tools, including drills, rongeurs and lasers. [ citation needed ]


The success rate of a laminectomy depends on the specific reason for the operation, as well as proper patient selection and the surgeon's technical ability. The first laminectomy was performed in 1887 by  Victor Alexander Haden Horsley , [ 2 ]  a professor of surgery at  University College London . A laminectomy can treat severe  spinal stenosis  by relieving pressure on the  spinal cord  or nerve roots, provide access to a tumor or other mass lying in or around the spinal cord, or help in tailoring the contour of the vertebral column to correct a spinal deformity such as  kyphosis . A common type of laminectomy is performed to permit the removal or reshaping of a spinal disc as part of a lumbar  discectomy . This is a treatment for a  herniated , bulging, or degenerated disc. [ citation needed ]


The recovery period after a laminectomy depends on the specific operative technique, with minimally invasive procedures having significantly shorter recovery periods than open surgery. Removal of substantial amounts of bone and tissue may require additional procedures such as  spinal fusion  to stabilize the spine and generally require a much longer recovery period than a simple laminectomy.


With spinal fusion, the recovery time may be longer. In some cases after laminectomy and spinal fusion, it may take several months to return to normal activities. [ 1 ]  Potential complications include bleeding, infection, blood clots, nerve injury, and spinal fluid leak. [ 1 ]


Most commonly, a laminectomy is performed to treat spinal stenosis.  Spinal stenosis  is the single most common diagnosis that leads to spinal surgery, of which a laminectomy represents one component. The  lamina  of the  vertebra  is removed or trimmed to widen the  spinal canal  and create more space for the  spinal nerves  and  thecal sac . Surgical treatment that includes a laminectomy is the most effective remedy for severe spinal stenosis; however, most cases of spinal stenosis are not severe enough to require surgery. When the disabling symptoms of spinal stenosis are primarily  neurogenic claudication  and the laminectomy is done without spinal fusion, there is generally a more rapid recovery with less blood loss. [ 3 ]  However, if the spinal column is unstable and fusion is required, the recovery period can last from several months to more than a year, and the likelihood of symptom relief is far less probable. [ 4 ]


In most known cases of lumbar and thoracic laminectomies, [ 5 ]  patients tend to recover slowly, with recurring pain or  spinal stenosis  persisting for up to 18 months after the procedure. According to a  World Health Organization  census in 2001, most patients who had undergone a lumbar laminectomy recovered normal function within one year of their operation.


Back surgery can relieve pressure on the spine, but it is not a cure-all for spinal stenosis. There may be considerable pain immediately after the operation, and pain may persist on a longer-term basis. For some people, recovery can take weeks or months and may require long-term occupational and physical therapy. Surgery does not stop the degenerative process and symptoms may reappear within several years. [ 1 ]


A  laminotomy  is an  orthopaedic   neurosurgical  procedure that removes part of the  lamina of a vertebral arch  in order to relieve pressure in the  vertebral canal . [ 1 ]  A laminotomy is less invasive than conventional  vertebral column  surgery techniques, such as  laminectomy  because it leaves more  ligaments  and  muscles  attached to the spinous process intact and it requires removing less bone from the  vertebra . [ 1 ]  As a result, laminotomies typically have a faster recovery time and result in fewer postoperative complications. Nevertheless, possible risks can occur during or after the procedure like  infection ,  hematomas , and  dural tears . [ 2 ]  Laminotomies are commonly performed as treatment for  lumbar spinal stenosis  and  herniated disks . [ 2 ]   MRI  and  CT scans  are often used pre- and post surgery to determine if the procedure was successful. [ 2 ]


The  spinal cord  is housed in a bony hollow tube called the  vertebral column . [ 3 ]  The vertebral column is composed of many ring-like bones called  vertebra  (plural: vertebrae) and it spans from the  skull  to the  sacrum . Each vertebra has a hole in the center called the  vertebral foramen  through which the  spinal cord  traverses. [ 3 ]


Laminae  (singular: lamina) are the anatomical structures of primary importance in a laminotomy. Laminae are part of the  vertebral arch  which is the region of bone on the back side of each vertebra that forms a protective covering for the back side of the spinal cord. [ 3 ]


The  vertebral arch  is composed of several anatomical features in addition to laminae that must be taken into account when performing a laminotomy. In the center of the vertebral arch is a bony projection called the  spinous process . [ 3 ]  The spinous process is located on the posterior or back side of the  vertebra  and serves as the attachment point for  ligaments  and  muscles  which support and stabilize the  vertebral column . [ 3 ]  Each vertebra has two lateral bony projections called the  transverse processes  which are located on either side of the vertebral arch. Transverse processes come into contact with the  ribs  and serve as attachment points for muscles and ligaments that stabilize the vertebral column. [ 3 ]  The lamina is the segment of bone that connects the spinous process to the transverse process. Each vertebra has two  lamina , one on each side of the spinous process. [ 3 ]


Different types of laminotomy are defined by the type of instrument used to visualize the procedure, what  vertebra  the procedure is performed on, and whether or not both  lamina  of a vertebra are operated on or just one.G [ 4 ]


Common types of laminotomy:


These classifications of laminotomies can be combined to form the most descriptive name for the procedure possible. For example, an endoscopic unilateral lumbar laminotomy is the removal of bone from only one lamina of a lumbar vertebrae using an endoscope. [ 1 ]


The procedure of a laminotomy remains largely the same regardless of the instrument used, or the level of  vertebrae  operated on. Laminotomies require general or spinal  anesthesia  and frequently require a hospital stay following the procedure—although the duration of the stay depends on the physical condition of the individual and their reason for having a laminotomy. [ 1 ] [ 2 ]  A laminotomy takes about 70–85 minutes depending on the type of procedure used. [ 1 ]  Unilateral laminotomies typically require less time because bone is removed from only one lamina, whereas bilateral laminotomies usually take more time because bone is removed from both laminae. The level of the vertebrae that the laminotomy is performed on and what instrument is used produce no significant differences in the length of the procedure. [ 1 ]  Both unilateral and bilateral laminotomies are performed in a shorter time period compared to a conventional  laminectomy  which takes over 100 minutes on average. [ 1 ]


During a laminotomy, the individual lies on his or her stomach with the back facing up towards the physician. [ 1 ]  An initial incision is made down the middle of the back exposing the  vertebrae  on which the laminotomy will be performed. [ 1 ]  In this procedure, the  spinous process  and the ligaments of the  vertebral column  are kept intact, but the muscles adjacent to the vertebral column known as the paraspinous muscles (example:  spinalis muscle ) must be separated from the spinous process and  vertebral arch . [ 1 ]  In a unilateral laminotomy, these muscles are detached only from the side on which the laminotomy is being performed. During a bilateral laminotomy, these muscles must be removed on both sides of the vertebrae. [ 1 ]  The ligaments connecting the lamina of upper and lower vertebrae, known as  Ligamenta flava  are often removed or remodeled in this procedure to adjust for the small amount of bone lost. [ 2 ]  Using either a  microscope  or an  endoscope  to have a visual of the procedure, a small surgical drill is used to remove a part of bone from one or both laminae of the vertebrae. [ 1 ]  Laminotomies can be performed on multiple vertebrae during the same surgery; this is known as a multi-level laminotomy. [ 1 ]


A slightly different, but commonly used procedure of laminotomy is the unilateral laminotomy for bilateral spinal decompression. [ 4 ]  This minimally invasive procedure is often used to treat patients with excessive pressure in the  vertebral column  that must be relieved. [ 4 ]  In this procedure, the same spinal ligaments are kept intact and the paraspinous muscles must still be detached. [ 5 ]  A unilateral laminotomy is performed on one lamina of a vertebra. [ 5 ]  This removal of bone from one lamina provides an opening into the spinal canal. Using a  microscope  or an  endoscope  to visualize the procedure, surgical tools are inserted through this opening into the  spinal canal . The surgical tools are then navigated underneath the  spinous process  and across the spinal canal to reach the other lamina on the opposite side of the  vertebra  to perform a second laminotomy. [ 5 ]  The incision for this procedure is smaller because doctors need only access one lamina yet can perform a bilateral laminotomy—remove bone from both lamina of a single vertebra. [ 5 ]  The unilateral laminotomy with bilateral spinal decompression procedure was developed almost 20 years ago and is a common successful surgical treatment for  lumbar spinal stenosis . [ 4 ]


A laminotomy is typically used to relieve pressure from the  spinal canal . Excessive pressure in the spinal canal causes the  spinal canal  and  spinal nerves  to be compressed which can be very painful and can impair motor control and/or sensation. A common disorder that causes increased pressure in the spinal canal is  lumbar spinal stenosis . Lumbar spinal stenosis is formally defined as a decline in diameter length of either the  neural foramina ,  lateral recess , or  spinal canal . [ 1 ]  Stenosis is classified as a decaying disease because it causes the canal to gradually become more and more narrow which can cause pain or loss of function. [ 1 ]  Common symptoms of lumbar stenosis are pain, fatigue, weakness of the muscle and numbness. [ 2 ]  Stenosis can be caused by old age or an injury to the vertebral column and usually requires a  CT scan  or  MRI  to diagnose. [ 2 ]  Performing a laminotomy can relieve pressure in the spinal canal caused by lumbar stenosis and therefore alleviate symptoms. [ 1 ]


Laminotomies are also performed to create a window into the  spinal canal . [ 2 ]  Laminotomies are frequently used as a way to surgically repair a  spinal disc herniation  at any level of the vertebral column (cervical, thoracic, lumbar). [ 1 ]  A herniated disc can compress  spinal nerves  and cause intense pain and impaired sensation. [ 4 ]  Removing a portion of the lamina allows physicians to be able to access and repair the herniated disc. Laminotomies may also be used to treat intraspinal lesions such as  spinal tumor  or problems with the blood vessels supplying the spinal cord. [ 4 ]  In any scenario where the inside of the spinal canal must be accessed or there is an increase in pressure in the spinal canal, laminotomy may be used to treat the disorder or alleviate symptoms. [ 1 ]


The laminotomy procedure has many benefits as to why it is a preferred spinal surgery since it is less invasive than other spinal procedures such as a laminectomy or a spinal fusion. [ 2 ]  Once a laminotomy procedure is done, patients have a great improvement in their pain and mobility. [ 2 ]  Laminotomies are usually safer than other surgeries that are open or invasive. [ 2 ]  This surgery usually is shorter than other spinal decompression procedures by having an average duration of 70–85 minutes, whereas other decompression surgeries can have a duration anywhere from 90 to 109 minutes. Laminotomies are usually more cost efficient than other surgical decompression surgeries. In 2007, it was seen that laminotomies were around $10,000, whereas other surgical procedures were around $24,000. [ 2 ]  Smaller skin incisions and scarring as well as less surgical trauma are also a benefit of laminotomy. [ 4 ]  With this procedure there is usually a faster recovery time, and a shorter hospital stay if one is necessary at all. [ 4 ]  During the surgery there is also a benefit of minimizing the injury to muscles, ligaments, and bones in the spine since more invasive surgeries have a greater risk of damaging them. [ 4 ]  General anesthesia is usually required, but postoperative spinal instability is typically limited. [ 4 ]


Since this procedure is a surgical technique there are many complications that can occur either during or after the surgery. Some major complications that can occur are  cerebrospinal fluid leaks ,  dural tears , infection, or  epidural hematomas . [ 2 ]  Death is also a risk; however, it occurs only once per thousand surgeries. [ 2 ]  Other potential complications are nerve root damage, which can lead to nerve injury or  paraplegia , and a significant amount of blood loss that will lead to blood transfusions. [ 2 ]


Historically, laminectomies have been the primary way to treat lumbar spinal stenosis. [ 5 ]  A laminectomy is a more invasive method with the aim to decrease the total amount of pain and numbness associated with lumbar spinal stenosis. [ 2 ]  It is a surgery that eliminates the entire lamina to allow the nerves around this region to function properly. [ 2 ]  Laminectomies also often produce a longer recovery time as well as a greater risk for post-operative complications. There is typically more damage to the surrounding muscle tissue accompanied by a laminectomy. [ 5 ]  Since a laminectomy involves the excision of the entire lamina, a laminectomy will usually cause more spinal instability than a laminotomy. [ 5 ]  When going with the option of laminotomy, the procedure reduces the total amount of muscle severed. Because a laminotomy does not damage the spinous process and critical ligaments, there is not as much muscle weakness, pain, and lumbar instability seen with laminectomies. [ 4 ]  Laminotomies are fairly new compared to laminectomies, and it involves using less invasive methods with precise instruments to minimize the risk of tissue damage. [ 5 ]


For radiographic imaging, an x-ray is the least effective way to collect information when observing a patient with lumbar spinal stenosis. A  CT scan  provides a 360-degree compiled view of the vertebrae that is more precise than an  x-ray . [ 2 ]


Since an  MRI  provides excellent imaging of  blood vessels  and  tissues , it is recognized as the best type of imaging to observe signs associated with lumbar compression. The precise measurement of the diameter of the spinal canal is a particularly important component when determining the severity of the stenosis itself. [ 2 ]  High strength  3-Tesla  MRI machines are being utilized due to the increased vascular imaging capabilities. Better resolution capacity allows for more detailed observations by the healthcare provider. The sharp contrast of the high power MRI outlines details in the vertebra that are critical when examining a patient with lumbar spinal stenosis who may need a laminotomy. [ 1 ]  MRI scanning post invasive surgery is used to see the quality of the surgery itself, yet the appropriate postoperative time elapsed before conducting an MRI is a debated topic. [ 2 ]


A  CT scan  is not the most effective imaging technique when observing lumbar abnormalities, however it can supplement an MRI by detecting certain degenerative processes. When determining whether or not a laminotomy will be beneficial for the patient, a healthcare provider must assess the severity of the possible abnormalities. Out of all the potential reasons to have a laminotomy performed, lumbar  spinal stenosis  is the chief reason. CT scans are used specifically to pinpoint a buckled lumbar  ligamentum flavum  as well as facet  hypertrophy , which are some of the main pathophysiological changes indicative of lumbar spinal stenosis. [ 2 ]  Even though a CT scan can reveal these pertinent signs of lumbar spinal stenosis, it can sometimes give a cloudy image due to the shadowing of the tissue contrast. When this occurs, an  intrathecal myelography  contrast is conducted with the CT scan to fix the abnormal contrast. A CT scan can also reveal an increase in the cross sectional area of the  L3  vertebrae, which ultimately decreases the cross sectional area of the spinal canal. [ 2 ]  As an increase in the size of the L3 vertebrae occurs, pressure builds up on the  cauda equina , commonly causing pain in the lower back and lower extremities. Cauda equina compression can also be due to stenosis of L4-5 region as well. [ 1 ]  Even though the CT scan allows for intensive image studying, the fixed nature of the image collection process alone is not enough to reach a definitive diagnosis of lumbar spinal stenosis. The outcome of the CT scan can help compile physiological evidence that the patient has lumbar spinal stenosis, and that the patient may potentially benefit from a laminotomy to improve his or her quality of life. [ 1 ]


Other than static imaging processes, a CT scan can also be used for observing changes in spinal canal features before and after a laminotomy. One of the main signs of lumbar spinal stenosis is the thickening of the ligamentum flavum, causing it to expand towards the spinal canal. [ 2 ]  When observing the cross sectional area of the spinal canal of a human cadaver, it was found that the area had decreased due to ligamentum flavum thickening. The ligamentum flavum did not appear to alter the dynamic alterations in the dimensions of the spinal cord. Even after the intervertebral  disc  was removed, the ligamentum flavum did not appear to be a factor in the change in the dimensions of the spinal canal. [ 6 ]  By understanding the magnitude of the role that ligamentum flavum hypertrophy plays in lumbar sacral stenosis, the necessity of an invasive lumbar spinal procedure can be accurately measured. [ citation needed ]


Minimally invasive procedures  are a more common alternative due to the decreased risk of damaging significant muscle tissue. The difference between invasive and minimally invasive spinal surgeries is that minimally invasive procedures involves a series of small incisions. Minimally invasive procedures can be performed anywhere along the spine, and have been used to treat various abnormalities. [ 2 ]  The percutaneous pedicle screw fixation technique allows for a procedure that presents minimal risk to the patient.  Fluoroscopic  image  guided navigation  through these portals allows for surgeons to perform more efficient procedures. Minimally invasive procedures often yield a much faster recovery time than fully invasive surgeries, making them more appealing to patients.  Laminectomies  have always been the gold standard when treating lumbar spinal stenosis, but recently, less invasive surgeries have emerged as a safer alternative treatment that helps maintain the postoperative structural integrity of the spine. [ 4 ]


Spinal microsurgery is a minimally invasive unilateral laminotomy used to correct bilateral lumbar spinal compression. Spinal microsurgery is the most common and effective microsurgical decompression treatment for patients who present with moderate to severe spinal stenosis. [ 4 ]  Spinal microsurgeries are performed with high magnification 3-D imaging of the fixated area of the spine, reducing the potential risk of harming the architecture of the spine itself.


Endoscopic spine surgeries can be used to treat thoracic lesions, and have been proven to be a much safer option than a  thoracotomy . However, an endoscopic spine surgery can be performed to treat other spinal conditions, such as a herniated lumbar disc. [ 4 ]  Recovery time from this type of surgical treatment is often very quick, with patients ambulating within a few hours of the procedure. [ 2 ]


Spinal fusion  involves fusing two vertebrae together using a spacer, and is intended to prohibit movement at that particular segment.  Screws  are typically inserted to assure that the spacer is held in place. The most common lumbar spinal fusion occurs between L4 and L5. [ 4 ]  A lumbar spinal fusion may be recommended when non-surgical treatment options for severe  degenerative disc disease  are ineffective. A laminotomy would not be effective in this case, since this procedure is concerning a degenerated disc that needs to be removed in order to relieve certain symptoms. [ 2 ]