Recent developments in idiopathic intracranial hypertension (IIH)

Abstract

Idiopathic intracranial hypertension is a disease with a predilection for young obese women. The most common symptoms are headache, transient visual obscuration and pulsatile tinnitus. The only focal neurologic finding is false-localizing 6th cranial nerve palsy. Papilledema is usually present and this can lead to optic atrophy with progressive permanent visual loss. The earliest visual loss is constriction of peripheral visual field, usually starting with the inferior nasal quadrant. Numerous theories have been entertained as to the pathogenesis but this still remains an open controversy. The most prevalent current theories involve increased resistance to cerebrospinal fluid reabsorption at the arachnoid granulations, either from intrinsic disease in the granulations or secondary to elevated pressure in the dural venous sinuses into which the cerebrospinal fluid is absorbed across the granulations. The syndrome of idiopathic intracranial hypertension was long ago recognized as a complication of recurrent otitis media with resultant thrombosis of the transverse and sigmoid dural venous sinuses. Cases secondary to dural venous sinus thrombosis are seldom encountered today because the incidence of chronic otitis is much less than in the past. The prevalent concept has been that the idiopathic cases in obese young women were not associated with pathology in the dural venous sinuses. A recent study using ATECO MR venography, which the authors claim to be more reliable than even conventional catheter venography, has demonstrated stenosis of the transverse and sigmoid dural venous sinuses distinguishes cases of idiopathic intracranial hypertension from controls with a high degree of sensitivity and specificity. The authors believe the stenosis is secondary to intracranial hypertension but that it may further aggravate the hypertension when it occurs.