Benign intracranial hypertension (BIH), also known by the obsolete term pseudotumor cerebri is a neurologic disease that is caused by increased intracranial pressure in the subarachnoid space surrounding the brain without any indication of intracranial pathology. This pressure increase is believed to be attributed to either buildup or poor absorption of cerebrospinal fluid (CSF).

Signs and symptoms

It most commonly affects women between ages 20 and 50. Symptoms are severe headache, nausea, transient visual obscurations, and vomiting. Additional symptoms vary. The name of the disease comes from the fact that these symptoms are also frequently observed in patients with brain tumor, and the elevated pressure of the CSF on the optic nerves creates papilledema, which also occurs with brain tumors. Risk factors are overweight, use of the oral contraceptive pill and various types of medication (including tetracycline antibiotics and vitamin A).

Diagnosis

The diagnosis of BIH is one of exclusion. Due to the possibility of causing a brain herniation if an actual lesion is present, a lumbar puncture (spinal tap) should only be performed after a negative MRI or CT scan. Abnormal high pressure with exclusion of other causation is considered a defintive diagnosis.

Treatment

The main concern in treatment is preventing visual loss. Elevated CSF levels put pressure on the optic nerves, which causes visual disruptions, and can cause blindness. Prevention of vision loss is a primary concern in treatment.

The treatment of pseudotumor cerebri is primarily symptomatic. Causation is unknown and there is no cure. Psuedotumor cerebri may resolve after initial treatment, may not resolve for years, or may resolve and return chronically.

Pressure may be decreased by repeated spinal taps (to remove excessive cerebrospinal fluid), drugs that reduce cerebrospinal fluid production (acetazolamide, Diamox®) or diuretics. Diamox is the most common CSF inhibitor used in treatment; it can cause drowsiness and hypokalemia. Papilledema is a very common sign of BIH. Depending on severity there are other treatment options available, such as optic nerve fenestration, and shunts to remove excess CSF from the brain.

Shunting is a neurosurgical procedure to facilitate the draining of excess CSF to the normal circulation. There are various types of shunting operations; lumboperitoneal shunts drain from the lumbar spine to the peritoneal cavity, while ventriculoatrial shunts run from the cerebral ventricles to the heart. Although shunts can dysfunction due to occlusion or compression, they are very effective in normalizing CSF pressures.

External links

• Intracranial Hypertension Research Foundation (http://www.ihrfoundation.org/)