A 16-month-old girl was admitted because of bilateral ophthalmoplegia, left blepharoptosis, and disturbance of consciousness. Her symptoms resolved spontaneously within a week after admission, but mild left abducens palsy remained. The cranial computed tomography showed a mild non-specific brain atrophy. The auditory brain stem response was normal. Visual evoked potentials (VEPs) to flash stimuli were repeated serially after the onset. No significative patterns of VEP were evoked during the acute stage. However, three months after the onset, an asymmetrical pattern, namely left-sided abnormalities (not-identified P 100 wave, etc.), was observed. The asymmetrical pattern of VEP diminished six months after. And a bilaterally normal VEP pattern was found twelve months after.