Multiphasic disseminated encephalomyelitis mimicking multiple sclerosis.

We report a case of multiphasic disseminated encephalomyelitis (MDEM) following viral illness presenting as multiple sclerosis (MS) in a 7-year-old boy. The patients had two episodes of alternating hemiparesis and other neurologic symptoms following viral infection, which were separated by 3 years. Neuroimaging studies demonstrated multiple, discrete, small nodules and large globular lesions in the cerebral white matter, basal ganglia, brainstem and cerebellar areas. Based on typical appearance of magnetic resonance imaging (MRI) and clinical manifestations including systemic symptoms such as fever, nausea, vomiting, headache and seizures followed by consciousness disturbance and other multifocal neurologic signs, the diagnosis of MDEM rather than that of MS was made. Because it is difficult to differentiate between MDEM and MS on the basis of the clinical history, the cerebrospinal fluid examination and evoked potential studies, this report emphasizes that the MRI study of the brain may provide an important clue for the diagnosis.