Brain Involvement in Neuromyelitis Optica Spectrum Disorders

Background: Neuromyelitis optica spectrum disorders (NMOSDs) are severe inflammatory demyelinating disorders of the central nervous system. Brain involvement is increasingly recognized. Objective: To study brain involvement in NMOSDs among Hong Kong Chinese patients. Design: Retrospective study of patients with NMOSDs. Setting: Tertiary medical center in Hong Kong. Patients: Thirty-four Hong Kong Chinese patients with NMOSDs of 2 years or longer were recruited. Interventions: Brain and spinal cord magnetic resonance imaging was performed during NMOSD attacks and was repeated yearly for the first 3 years. Main Outcome Measures: We evaluated clinical features of NMOSDs associated with brain involvement and brain lesions on magnetic resonance imaging. Results: Among 34 patients with NMOSDs of 2 years or longer, 20 (59%) had brain involvement. The mean age at onset among these 20 patients was 45.6 years (age range, 19-67 years); 18 were women. Eleven patients (32% of all the patients with NMOSDs) had clinical manifestation of brain involvement, 19 patients (56%) had brain abnormalities on magnetic resonance imaging consistent with inflammatory demyelination, and 2 patients (6%) fulfilled criteria for multiple sclerosis. Clinical manifestation of brain involvement included the following: trigeminal neuralgia; vomiting, vertigo, ataxia, dysphagia, and tetraparesis from lesions around the third and fourth ventricles and aqueduct; homonymous hemianopia, aphasia, hemiparesis, and cognitive impairment from extensive hemispheric white matter lesions; and ataxia, diplopia, hiccups, facial sensory loss, internuclear ophthalmoplegia, hemisensory loss, and hemiparesis from other lesions in the midbrain, pons, cerebellar peduncles, and medulla. Eight patients (24%) developed brainstem encephalitis clinically, and brainstem encephalitis was the initial clinical manifestation in 6 patients (18%). Brain abnormalities on magnetic resonance imaging were detected in brainstem in 15 patients (44%), hemispheric periventricular white matter in 7 patients (21%), deep white matter in 7 patients (21%), corpus callosum in 4 patients (12%), subcortical white matter in 3 patients (9%), thalamus in 2 patients (6%), hypothalamus in 1 patient (3%), basal ganglia in 1 patient (3%), internal capsule in 1 patient (3%), periaqueductal gray matter in 1 patient (3%), and around the third and fourth ventricles in 1 patient (3%); large confluent lesions were detected in 2 patients (6%). Conclusion: Brain involvement manifesting clinically as brainstem encephalitis is common among Hong Kong Chinese patients with NMOSDs.