Alexander disease: clinical, electrodiagnostic and radiographic studies.

A 10-month-old boy with Alexander disease is described. He was clinically characterized by early onset of megalencephaly, psychomotor retardation, spasticity and recurrent seizure attacks. Pathological examination of the biopsied cerebrum revealed a large number of Rosenthal fibers in the white matter and beneath the pia in association with advanced demyelination. The motor nerve conduction velocity was remarkably delayed, suggesting a possible change of the peripheral nerve. The computerized tomography demonstrated megalencephaly and bilateral symmetrical low density areas in the cerebral white matter, particularly in the frontal region. The preferential involvement of frontal lobes was also confirmed by electroencephalogram and brain scan. The preferential damage of the frontal region in the early stage of the disease may be an important clue to a diagnosis of Alexander disease by computerized tomography, brain scan and electroencephalogram.