[Ictal nystagmus: acquired nystagmus of infrequent cause in pediatrics]. / Nistagmo ictal: causa infrecuente de nistagmo adquirido en pediatría.

Ictal nystagmus is a rare phenomenon secondary to an epileptic seizure, usually in the temporo- occipital region. For its characterization, we must rely on clinical history, examination, and ideally observation of the episodes. OBJECTIVES: To describe a case of this unusual entity and highlight the characteristics that should increase diagnostic suspicion in order to avoid treatment delay. CLINICAL CASE: An 8-year-old schoolboy, with no relevant history, consulted due to 5-6 episodes a day in the last year of conjugate horizontal eye movements with rapid jerks and associated slight miosis, lasting 5-10 seconds, with doubtful disconnection from the environment or consciousness impairment in some of the episodes, with no other accompanying signs or symptoms. Neurological examination between episodes was normal. He was evaluated by ophthalmology and otolaryngology, which ruled out pathology in these areas. Video-electroencephalogram showed electro-clinical correlations, with epileptiform activity in the left temporal and occipital region, which subsequently generalized during episodes. Brain MRI showed no pathological findings. After initiation of carbamazepine treatment, the patient had a good evolution, without recurrence of the episodes at 2 years of follow-up. CONCLUSIONS: When faced with a case of acquired nystagmus, epileptic etiology should be included in the differential diagnosis, especially if the frequency of episodes is high, of short duration, and associated with consciousness impairment. The diagnosis is based on a video-electroencephalogram with electro-clinical correlations and a good response to treatment with antiepileptic drugs is expected.