Two possible cases of Alexander disease. Multimodal evoked potentials and MRI.

We describe two unrelated girls with slowly progressive leukodystrophy with macrocephaly. On MRI, both patients exhibited diffuse involvement of the cerebral white matter, excluding the internal capsule and optic radiation. Their visual-evoked potentials were normal. Short-latency somatosensory-evoked potentials exhibited the absence of early scalp components. Auditory brainstem responses in both patients showed intramedullary conduction disturbance. These MRI and electrophysiological findings are similar to those in infantile Alexander disease.