EDITORIAL

Idiopathic intracranial hypertension: any light on the mechanism of the raised pressure? Everyone knows that no one knows the mechanism of the increase of intracranial pressure in idiopathic intracranial hypertension (IIH; also called pseudotumour cerebri; see table 1 for diagnostic criteria). Does it much matter? After all, for most aVected people IIH is a benign, self limiting condition. However, sometimes it is not,1 and current therapies are unsatisfactory. Medical treatment is poor and of unproved benefit.2 3 Surgical interventions (optic nerve sheath fenestration, lumboperitoneal shunting) have ap-preciable hazards and failure rates.4–10 Moreover, the mechanism of increase in intracranial pressure in IIH might have relevance to raised intracranial pressure and its management in other situations such as meningitis an