Pseudotumor cerebri: LP effect


Pseudotumor cerebri (aka Idiopathic Intracranial Hypertension) commonly causes headache, papilledema, and visual symptoms (and enlarged blind spot) in the setting of isolated elevations in ICP.

Several mechanisms have been considered as possible explanations for the pathophysiology of IIH. These include an increased rate of CSF formation, a sustained increase in intracranial venous pressure, or a decreased rate of CSF absorption by arachnoid villi apart from venous occlusive disease.

Females have 8 to 10 times the likelihood of males (esp. if overweight and of childbearing age). Frequently, the women are moderately or markedly overweight. IIH has a complex relationship to adrenal hormones. Rarely, IIH is a complication of Addison disease or Cushing disease. Improvement occurs after restoration of a normal adrenal state. Intracranial hypertension also occurs secondarily to occlusion of the intracranial venous sinuses.

Diagnosis is made by lumbar puncture (CSF pressure > 25 mmHg with normal CSF composition) but requires exclusion of a mass lesion. Spontaneous recovery is possible however most practitioners advise treatment in order to prevent visual loss. Daily lumbar puncture was used in the past to lower CSF pressure to normal levels by removing sufficient fluid; 15 mL to 30 mL of fluid may be removed, but the value of this procedure is dubious. A CSF-shunt procedure, such as a lumboperitoneal shunt, is useful in patients with intractable headache and progressive visual impairment. It may dramatically relieve symptoms. Optic nerve decompression has its advocates as the procedure of choice to preserve vision. Weight reduction may help, acetazolamide and furosemide reduce CSF production. Repeated lumbar puncture may be of use.

Surgical options include optic nerve fenestration and ventricular-peritoneal shunting.

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