Reversible encephalopathy with focal brain edema in patients with neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease is a heterogeneous neurodegenerative disease defined, pathologically, by the presence of round eosinophilic intranuclear inclusions. The adult-onset form usually shows slowly progressive dementia with leukoencephalopathy. In the study of 57 cases of adult-onset neuronal intranuclear inclusion disease, Sone et. al. reported two cases with encephalitic episodes with focal brain edema, although encephalitic episodes had not been reported as a symptom of the disease. We here describe two additional cases presenting as reversible encephalopathy with focal brain edema. In both patients, repetitive cerebrospinal fluid examinations showed no pleocytosis, although cortical involvement was evident. The diagnosis was made based on characteristic brain magnetic resonance imaging findings and skin biopsy in the absence of other known conditions related to encephalopathy. These findings suggest that neuronal intranuclear inclusion disease should be considered as a differential diagnosis in patients with encephalopathy of unknown etiology. This article is protected by copyright. All rights reserved.