Low cerebrospinal fluid pressure may not be necessary in the diagnosis of spontaneous intracranial hypotension: A report of four cases

We presented four patients with sub-acute onset orthostatic headache in occipital and sub-occipital regions and neck pain. No loss of consciousness, neurologic deficit, trauma or cranial/spinal surgery history was noted. They had normal cerebrospinal fluid (CSF) opening pressure, normal laboratory studies, and diffuse pachymeningeal enhancement or sagging of brain on gadolinium-enhanced magnetic resonance imaging (MRI). Their symptoms resolved with intravenous large isotonic fluid or epidural blood patch. The diagnosis of spontaneous intracranial hypotension requires history of orthostatic headache, demonstration of lower CSF pressure, and abnormal findings on MRI. But these patients may have normal CSF opening pressure. CSF hypovolemia rather than CSF hypotension has been proposed as the underlying cause. Therefore, the CSF pressure may not be necessary for diagnosis in such patients with typical radiographic features. Thus, in the presence of convincing clinical symptoms and imaging abnormalities, a normal CSF pressure should not discourage the clinician from searching for a source of CSF leak.