We reported serial clinical, radiological, and neurophysiological findings of a patient with PEHO (progressive encephalopathy with edema, hypsarrhythmia and optic atrophy) syndrome. The case was a 4-year-and-8-month-old boy. He had no apparent problems during pregnancy, but after his birth severe hypotonia and developmental delay were evident. Infantile spasms appeared at 3 months of age, and progressive opisthotonic posture and loss of his visual acuity at 8 months. Eye fixation was lost, and optic atrophy was observed. Seizures and progressive atrophy of the cerebellum and brainstem developed during the same period. These findings of our case support the hypothesis that brainstem lesions are related to infantile spasms.