Enhancement of subarachnoid space during magnetic resonance imaging of endolymphatic hydrops: a case report.

Enhancement of the subarachnoid space after intravenous administration of gadolinium contrast agent is not common. Enhancement usually occurs in pathological conditions that increase the permeability of the blood-cerebrospinal fluid barrier, most notably in meningitis. We herein describe possible subarachnoid enhancement in patients with no apparent effect on the meninges. These patients had clinical signs of Meniere's disease and underwent specific magnetic resonance imaging of the inner ear to possibly visualize endolymphatic hydrops. The endolymphatic space can be noninvasively imaged by intravenous administration of contrast agent, usually at a double dose, 4 hours before the scanning process. During this time, the contrast agent penetrates not only the perilymph but also the subarachnoid space, where the highest concentration occurs after 4 hours according to some studies.