Unilateral alpha subharmonics: a case report.

Occipital alpha subharmonics are a normal EEG variant. Unilateral occipital slowing, however, is associated with focal dysfunction of that particular side. We report a 10-year-old girl with the incidental EEG finding of unilateral occipital slowing. MRI of her brain was completely normal and on long-term follow up she remained healthy. Based on her clinical history, normal MRI of brain, and the character of the slow posterior rhythms, we conclude that unilateral slow alpha rhythm can be a normal variant akin to alpha subharmonics.