Spontaneous intracranial hypotension presenting as pseudo-subarachnoid hemorrhage on CT scan.

We report a 20-year-old man who suffered from severe headache. A brain CT scan revealed that he had diffuse brain swelling and increased attenuation of the basal cisterns and Sylvian fissure. Subarachnoid hemorrhage (SAH) was diagnosed but the results of CT angiography and conventional arterioangiography were negative. His headache relapsed and remitted several times during the following months. Brain MRI demonstrated brain sagging with a crowded foramen magnum. Spontaneous intracranial hypotension (SIH) was finally diagnosed and his headache subsided after application of an epidural blood patch. Pseudo-SAH on CT scan is an unusual manifestation of SIH that often results in delay of diagnosis and adequate treatment.