[Acute disseminated encephalomyelitis in a 3-month-old infant].

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease showing multifocal central nervous system lesions due to an autoimmune disorder. We reported a 3-month-old girl with ADEM. One week after having a cold, she presented with somnolence, poor feeding and vomiting. When she was admitted three days after the onset, she could neither fix or follow objects with her eyes nor respond to sound. Her muscle tone was decreased. Cerebrospinal fluid examination revealed pleocytosis, elevated protein concentration and positive myelin basic protein. No oligoclonal band was detected. Diffuse monomorphic slow wave activity was noted on the electroencephalogram. Only wave I was present bilaterally on the auditory brainstem response. T2 weighted images of magnetic resonance imaging revealed multiple areas of high signal in the right posterior limb of the internal capsule, white matter of the cerebellum and brainstem. She was diagnosed as having ADEM, and underwent high dose gamma-globulin therapy. Corticosteroids were not given because of her high blood pressure. The clinical symptoms improved continuously before and after the administration. Two years after the onset, she showed normal growth and development without reoccurrence. The age at onset of childhood ADEM is usually 3 or 4 years. ADEM before one year of age is very rare. The demyelinating lesions of this case corresponded to the regions which normally become myelinated by 3 months. Although ADEM is usually treated with corticosteroids, high dose gamma 1-globulin therapy can be considered if patients are very young or have a high risk for corticosteroid, or respond poorly to corticosteroids.