Idiopathic intracranial hypertension

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idiopathic intracranial hypertension ( IIH ) is a condition characterized by an increase in intracranial pressure (pressure around the brain) without detectable causes. The main symptoms are headache, vision problems, ringing in the ears with heart rate, and shoulder pain. Complications may include loss of vision.

Risk factors include being overweight or recent weight gain. Tetracycline can also trigger the condition. The diagnosis is based on the high intracranial symptoms and pressure found during lumbar puncture with no specific cause found in brain scans.

Treatments include a healthy diet, salt restriction, and exercise. Bariatric surgery can also be used to help you lose weight. Acetazolamide drugs can also be used in conjunction with the above steps. A small number of people may need surgery to reduce the pressure.

About 2 per 100,000 new people are affected per year. This condition is most common in women aged 20-50 years. Women are affected about 20 times more often than men. This condition was first described in 1897.

Video Idiopathic intracranial hypertension

Signs and symptoms

The most common symptom of IIH is headache, which occurs in almost all (92-94%) cases. It is characteristically worse in the morning, generalized in character and pulsating in nature. It may be associated with nausea and vomiting. Headaches can be aggravated by any activity that further increases intracranial pressure, such as coughing and sneezing. Pain can also be experienced in the neck and shoulders. Many experienced pulsatile tinnitus, a whizzing sensation in one or both ears (64-87%); This sound is in sync with the pulse. Other symptoms, such as limb numbness, generalized weakness, odor loss, and loss of coordination, are reported less frequently; nothing is specific to IIH. In children, many nonspecific signs and symptoms may be present.

Increased pressure causes compression and cranial nerve traction, a group of nerves that arise from the brain stem and supply the face and neck. Most often, nerve abducens (sixth nerve) are involved. These nerves supply the muscles that pull the eye out. Those who experience sixth nerve palsy therefore experience a worse horizontal double vision when looking towards the affected side. More rarely, oculomotor and trochar nerves (third and fourth nerve palsy, respectively) are affected; both play a role in eye movement. The facial nerve (seventh cranial nerve) is sometimes exposed - the result is a total or partial weakness of the facial expression muscles on one or both sides of the face.

The increased pressure causes papilledema, which is a swelling of the optical disc, the spot where the optic nerve enters the eyeball. This happens in almost all cases of IIH, but not everyone has symptoms of this. Those who experience symptoms usually report "temporary visual blurring", episodes of difficulty seeing that occur in both eyes but not necessarily at the same time. Untreated long-term papilledema causes vision loss, initially at the periphery but progressively toward the center of vision.

Physical examination of the nervous system is normally normal regardless of papilledema, which is seen in an eye exam with a small device called ophthalmoscope or more detailed with a fundus camera. If there is cranial nerve abnormality, this can be seen in eye examination in the form of squint (third, fourth or sixth nerve palsy) or as facial nerve paralysis. If papilledema has been prolonged, the visual field may be limited and visual acuity may decrease. Visual field testing with automated perimetry (Humphrey) is recommended because other test methods may be less accurate. Prolonged papilledema causes optical atrophy, where the pear looks pale and the loss of vision tends to progress.

Maps Idiopathic intracranial hypertension

Cause

"Idiopathic" means an unknown cause. Therefore, IIH can only be diagnosed if there is no alternative explanation for symptoms. Intracranial pressure may increase due to drugs such as high doses of vitamin A derivatives (eg, isotretinoin for acne), long-term tetracycline antibiotics (for various skin conditions) and hormonal contraceptives.

There are many other diseases, most of which are rare, which can cause intracranial hypertension. If there is an underlying cause, this condition is called "secondary intracranial hypertension". Common causes of secondary intracranial hypertension include obstructive sleep apnea, systemic lupus erythematosus (SLE), chronic renal disease, and BehÃÆ'§et disease.

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Mechanism

The cause of IIH is unknown. The Monro-Kellie rule states that intracranial pressure is determined by the amount of brain tissue, cerebrospinal fluid (CSF) and blood within the bone skull vault. Therefore, there are three theories as to why pressure may increase in IIH: CSF overproduction, increased blood volume or brain tissue, or venous obstruction that drains blood from the brain.

The first theory, that increased production of cerebrospinal fluid, is proposed in the initial description of the disease. However, no experimental data support the role for this process at IIH.

The second theory holds that either increased blood flow to the brain or increased brain tissue itself can cause increased pressure. Little evidence has been gathered to support the suggestion that increased blood flow plays a role, but more recently Bateman et al. in the contrast phase, the MRA study measured brain blood flow (CBF) in vivo and showed that CBF increased abnormally in many patients with IIH. Both biopsy samples and various types of brain scans have shown elevated water levels in brain tissue. It is still unclear why this is possible.

The third theory suggests that limited venous drainage from the brain can be disrupted resulting in congestion. Many patients with IIH have narrowed transverse sinuses. It is not clear whether this narrowing is a pathogenesis of the disease or a secondary phenomenon. It has been suggested that a positive biofeedback loop may be present, where increased ICP (intracranial pressure) causes narrowing of blood vessels in the transverse sinus, resulting in venous hypertension (increased venous pressure), decreased CSF resorption via arachnoid granulation and further ICP increases.

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Diagnosis

Diagnosis can be suspected based on history and examination. To confirm the diagnosis, and excluding alternative causes, some investigations are needed; more investigations can be done if history is not typical or patients are more likely to have alternative problems: children, men, elderly, or women who are not overweight.

Investigation

Neuroimaging, usually with computed tomography (CT/CAT) or magnetic resonance imaging (MRI), is used to exclude mass lesions. In IIH this scan usually appears normal, although the ventricle is small or like a gap, dilated and buckling the optic nerve sheath and "empty marks" (pituitary gland alignment due to increased pressure) and Meckel cave enlargement may be seen.

An MR venogram is also performed in most cases to rule out the possibility of venous sinus stenosis/obstruction or cerebral venous sinus thrombosis. Improved MRV (ATECO) scanning has a high detection rate for abnormal transverse sinus stenosis. This stenosis can be more adequately identified and assessed with cerebral catheter and manometric venography. Bilateral optic nerve bilateral with increased perineural fluid is also frequently noted in MRI imaging.

The 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 increases, CSF can be removed for temporary assistance (see below). CSF is examined for abnormal cells, infection, antibody levels, glucose levels, and protein levels. By definition, all of these are within normal limits in IIH. Sometimes, CSF pressure measurements may be normal even if symptoms are very suggestive. This may be due to the fact that CSF pressure can fluctuate during normal days. If the suspicion of the problem remains high, it may be necessary to perform longer-term ICP monitoring with a pressure catheter.

Classification

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

They were modified by Smith in 1985 to become "modified Dandy criteria". Smith included the use of more advanced imaging: Dandy had needed ventriculography, but Smith replaced it with computed tomography. In a 2001 paper, Digre and Corbett changed Dandy's criteria further. They add to the requirement that the patient be alert and alert, because coma precludes adequate neurological assessment, and requires the exclusion of venous sinus thrombosis as the underlying cause. Furthermore, they added the requirement that no other cause for the ICP being removed was found.

In a 2002 review, Friedman and Jacobson proposed a set of alternative criteria, derived from Smith's. This requires the absence of symptoms that can not be explained by the diagnosis of IIH, but does not require the real presence of any symptoms (such as headache) caused by IIH. This criterion also requires that the lumbar puncture be performed with the patient lying on his side, since lumbar puncture performed in an upright sitting position can lead to artificial high-pressure measurements. Friedman and Jacobson also do not insist on MR venography for each patient; on the contrary, this is only necessary in atypical cases (see "diagnosis" above).

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Treatment

The primary goals in the treatment of IIH are the prevention of vision loss and blindness, as well as symptom control. IIH is treated primarily through reduced CSF pressure and, if possible, weight loss. IIH may be cured after initial treatment, may experience spontaneous remission (although it can still recur at a later stage), or may progress chronically.

Lumbar puncture

The first step in symptom control is cerebrospinal fluid drainage by lumbar puncture. If necessary, this can be done at the same time as a diagnostic LP (as done to look for CSF infections). In some cases, this is enough to control the symptoms, and no further treatment is required.

This procedure may be repeated if necessary, but this is generally taken as a hint that additional treatment may be needed to control symptoms and maintain vision. Recurrent lumbar puncture is considered unpleasant by the patient, and they present the danger of introducing spinal infections if done too often. Recurrent lumbar puncture is sometimes required to control ICP immediately if the patient's vision deteriorates rapidly.

Medication

The most studied medical treatment for intracranial hypertension is acetazolamide (Diamox), which acts by inhibiting carbonic anhydrase enzyme, and reduces CSF production by as much as six to 57 percent. May cause symptoms of hypokalemia (low blood potassium levels), which include muscle weakness and tingling in the fingers. Acetazolamide can not be used in pregnancy, as it has been shown to cause embryonic abnormalities in animal studies. Also, in humans it has been shown to cause metabolic acidosis as well as disturbances in the blood electrolyte level of newborns. The furosemide diuretics are sometimes used for treatment if acetazolamide is not tolerated, but this drug sometimes has little effect on ICP.

Various analgesics (painkillers) can be used in controlling intracranial hypertensive headaches. In addition to conventional agents such as paracetamol, low-dose amitriptyline antidepressants or topiramate anticonvulsants have shown some additional benefits for pain relief.

The use of steroids in an attempt to reduce ICP is controversial. This can be used on severe papilledema, but if not, its use is not recommended.

Stenting the venous sinus

Venous venous stenosis leading to venous hypertension appears to play an important role in relation to increased ICT, and the installation of transverse sinus stent may resolve venous hypertension, leading to increased CSF resorption, decreased ICT, healing of papillema and other symptoms of IIH.

Extending metallic stents are permanently placed permanently within the dominant transverse sinus throughout the stenosis under general anesthesia. Generally the patient is discharged the next day. Patients require dual antiplatelet therapy for up to 3 months after procedure and aspirin therapy for up to 1 year.

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

Due to the sustainability of stent risk and small but definite complications, most experts would recommend that patients with IIH should have papillema and have failed medical therapy or are intolerant of the drug before installation is done.

Consultation with neurologists, neurologists and/or ophthalmologists in combination with the neurointerventionalist who perform the procedure is generally recommended.

Surgery

Two major surgical procedures exist in the treatment of IIH: decompression of the optic nerve sheath and fenestration and shunting. Surgery will usually only be offered if medical therapy is unsuccessful or not tolerated. The choice between these two procedures depends on the main problem in IIH. There is no perfect procedure: both can cause significant complications, and both may eventually fail to control the symptoms. There are no randomized controlled trials to guide decisions on which procedures are best.

Fistestration of the optic nerve sheath is an operation involving the making of incisions in the lining of the optic nerve tissue at the back of the eye. It is not entirely clear how to protect the eyes from elevated pressure, but may result from the transfer of CSF into orbit or the creation of scarring areas that lower the pressure. The effect on intracranial pressure itself is simpler. In addition, this procedure can cause significant complications, including blindness in 1-2%. Therefore, this procedure is recommended especially in those who have symptoms of limited headache but papillary or threatened vision, or in those who have undergone unsuccessful treatment with shunt or have contraindications for shunt surgery.

Shunt surgery, usually performed by neurosurgeons, involves the creation of channels in which CSF can be dried into other body cavities. The initial procedure is usually the lumboperitoneal (LP) shunt, which connects the subarachnoid space in the lumbar spine with the peritoneal cavity. Generally, pressure valves are inserted into the circuit to avoid excessive drainage when the patient is erect. LP shunting provides long-term assistance in about half the cases; others require revisions of the shunt, often on more than one occasion - usually due to shunt obstruction. If lumboperitoneal shunt requires repeated revision, ventriculoatrial or ventriculoperitoneal shunt may be considered. These shunts are inserted into 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, respectively. Given the reduced need for revision in the ventricular shunt, it may be the first type of shunt treatment.

It has been shown that in obese people, bariatric surgery (and especially gastric bypass surgery) may cause the resolution of the condition in more than 95%.

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Prognosis

It is not known what percentage of people with IIH will send spontaneously, and what percentage will develop chronic diseases.

IIH usually does not affect life expectancy. The major complications of IIH arise from untreated or resistant papilledema. In various series of cases, the long-term risk of a vision significantly affected by IIH is reported to be between 10 and 25%.

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Epidemiology

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 mainly in women, especially at age 20 to 45 years, who are four to eight times more likely than men. Obesity and obesity greatly affect a person for IIH: women who are over ten percent of their ideal weight are thirteen times more likely to develop IIH, and this figure rises to nineteen times in women who are more than twenty percent above their ideal. weight. In men this relationship also exists, but the increase is only five-fold in those who are over 20 percent above their ideal weight.

Despite some IIH reports in the family, no genetic cause is known for IIH. People from all ethnic groups can develop IIH. In children, there is no difference in incidence between men and women.

From a national hospital admissions database it appears that the need for neurosurgical intervention for IIH has increased sharply during the period between 1988 and 2002. This has been attributed at least in part to the increasing prevalence of obesity, although some of this increase may be explained by the increasing popularity of shunting during the fenestration of the optic nerve sheath.

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History

The first report of IIH was by German doctor Heinrich Quincke, who described it in 1893 under the name serosa meningitis The term "pseudotumor cerebri" was introduced in 1904 by compatriot Max Nonne. Many other cases appear in later literature; in many cases, increased intracranial pressure may actually be derived from the underlying conditions. For example, the autochemical hydrocephalus reported by London neurologist Sir Charles Symonds may be due to venous sinus thrombosis caused by middle ear infections. The diagnostic criteria for IIH were developed in 1937 by Baltimore Walter Dandy neurosurgeon; Dandy also introduced subtemporal decompression surgery in the treatment of this condition.

The terms "benign" and "pseudotumor" stem from the fact that increased intracranial pressure can be associated with brain tumors. Patients with no tumor found were diagnosed with a "cerebral pseudotumor" (a disease that mimics a brain tumor). The disease was renamed to benign intracranial hypertension in 1955 to distinguish it from intracranial hypertension due to life-threatening disease (such as cancer); However, it also feels misleading because any disease that can blind a person should not be considered benign, and therefore the name was revised in 1989 to "idiopathic (unidentifiable) intracranial hypertension".

The shunt operation was introduced in 1949; initially, ventriculoperitoneal shunt is used. In 1971, good results were reported with lumboperitoneal shunting. Negative reports on shunting in the 1980s led to a short period (1988-1993) during optic nerve fenestration (originally described in unrelated conditions in 1871) more popular. Since then, shunting is recommended especially, with the occasional exception.

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References

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External links

• idiopathic intracranial hypertension in Curlie (based on DMOZ)

Source of the article : Wikipedia