The syndrome of spontaneous intracranial hypotension.

The authors report four cases of headache and other symptomatology related to the syndrome of intracranial hypotension. They were seen in a routine clinical practice over the past 3 years. The clinical features, magnetic resonance imaging (MRI) findings, and follow-up of these patients are described. Review of the prior literature on the topic is also included. All four patients presented with orthostatic headache syndrome. Three of the four demonstrated diffuse leptomeningeal thickening and enhancement on MRI studies. One subsequently developed a subdural effusion. One patient demonstrated downward displacement of the posterior fossa initially, which resolved on follow-up MRI scanning. Possible pathophysiologies of the syndrome are discussed.