Pseudo-subarachnoid hemorrhage: a CT-finding in spontaneous intracranial hypotension.

Increased attenuation in the basilar cisterns or along the tentorium cerebelli resembling subarachnoid hemorrhage (SAH) may be found on CT in the absence of blood (pseudo-SAH). The authors found pseudo-SAH on CT in four of 40 patients with spontaneous intracranial hypotension. All four patients had brain sagging with obliteration of the cisterns and pachymeningeal enhancement along the tentorium cerebelli. Spontaneous intracranial hypotension should be included in the differential diagnosis of pseudo-SAH.