Magnetic resonance imaging of intracranial hypotension syndrome with pathophysiological correlation.

OBJECTIVE: To correlate the pathophysiology of intracranial hypotension syndrome with abnormalities in the brain and spine found through magnetic resonance imaging.
METHODS: In a series of 11 patients with intracranial hypotension syndrome, brain magnetic resonance scans were evaluated for the thickness, distribution, morphology, and pattern of meningeal enhancement coincident with subdural fluid collections and the descent of the brain toward the skull base. Spinal magnetic resonance studies were reviewed for extra-arachnoid fluid collections, meningeal enhancement, and distended epidural veins.
RESULTS: Diffuse, continuous dural-arachnoid enhancement was present in all patients with abnormal brain studies. The dura was thickest in patients with very low intracranial pressures. Subdural fluid collections and descent of the brain were seen in patients with the thickest meninges and were not present in the absence of meningeal enhancement. Extra-arachnoid or paraspinal fluid collections were found in all patients who had spinal magnetic resonance scans.
CONCLUSIONS: In the brain, diffuse dural-arachnoid enhancement is the most common imaging abnormality and is probably the earliest magnetic resonance manifestation of intracranial hypotension syndrome, while subdural fluid collections and descent of the brain are indicators of a more severe hypotensive state. Extra-arachnoid fluid collections are common spinal imaging abnormalities.