Acute disseminating encephalomyelitis in neuromyelitis optica: closing the floodgates.

OBJECTIVE: To report the clinical and radiological features of 2 patients with neuromyelitis optica (NMO) associated with severe acute disseminating encephalomyelitis. The first patient had anti-aquaporin 4 antibodies (NMO-IgG) but no lesion enhancement, in contrast to the second patient who was seronegative for NMO-IgG but had clear lesion enhancement on magnetic resonance imaging.

DESIGN: Clinical, laboratory, and radiological analysis of 10 patients presenting with features compatible with an NMO-spectrum disorder, 2 of whom developed acute disseminating encephalomyelitis.

SETTING: Inpatient ward at the Department of Neurology, Hadassah University.

PATIENTS: Patients admitted during a 1-year period with features compatible with an NMO-spectrum disorder.

INTERVENTIONS: Medical histories and imaging data were reviewed and serum samples were analyzed for the presence of NMO-IgG.

MAIN OUTCOME MEASURES: Clinical and paraclinical evidence of brain involvement.

RESULTS: Of 10 patients tested, 5 were positive for NMO-IgG. One seropositive and 1 seronegative patient had an acute disseminating encephalomyelitis-like episode. In both cases, the clinical, laboratory, and electroencephalographic findings supported a diagnosis of acute disseminating encephalomyelitis. Magnetic resonance imaging demonstrated extensive bilateral white matter lesions in both patients. Lesions in the seropositive patient were notably lacking in enhancement following gadolinium injection, whereas robust lesion enhancement was observed in the seronegative patient.

CONCLUSIONS: Acute disseminating encephalomyelitis without lesion enhancement on magnetic resonance imaging may represent a childhood manifestation of seropositive NMO. The lack of enhancement suggests an intact blood-brain barrier and supports a unique mechanism of edema induction due to dysfunction of water channels.