Epileptic nystagmus: electroclinical study of a case.

Epileptic nystagmus (EN) is a rare form of nystagmus that occurs only during epileptic seizures. We report a case in which EN was first noted in an 8 year-old boy. Neuro-imaging was normal. Sharp waves from the left occipital lobe characterised the interictal EEG. Ictal video-EEG showed the aspects of electric seizures during clinical manifestations e.g. nystagmus. Ambulatory EEG displayed numerous diurnal and nocturnal seizures, but exclusively in REM sleep. After two weeks of sodium valproate treatment, the seizures, EEG focus spikes and nystagmus, as well as the squint, disappeared. During a two-year follow-up the child had no further seizures, EEG was normal and the school performance was unaffected. This case has the main features of benign epilepsy, although there are unusual features such as epileptic nystagmus, permanent squint, reduction of EEG paroxysmal abnormalities during NREM, and the presence of seizures during REM sleep. The observation and the significance of EN are discussed with reference to the literature.