Epileptic ictal strabismus: a case report and review of the literature

Ictal strabismus, sometimes associated with epileptic nystagmus, is an extremely rare epileptic phenomenon, suggestive of cortical involvement in monocular eye movement control. We describe a patient with ictal disconjugate contraversive horizontal eye deviation of cortical origin as the main clinical feature of a focal seizure. A 17-year-old, previously healthy woman had a seizure characterized by initial rightward conjugate eye deviation, followed by convergent strabismus due to adduction of the right eye towards the nose without conjugate left eye abduction (esotropia), forced leftward head deviation with impaired awareness, and subsequent evolution into a bilateral tonic-clonic seizure. Postictal and interictal neurological status were unremarkable; more specifically, neuro-ophthalmological examination revealed no nystagmus or altered eye motility. Ictal EEG showed a rhythmic theta activity over the right posterior temporal region, involving fronto-central regions when strabismus appeared. MRI showed cortical dysplasia in the right temporal lobe. Due to the low spatial resolution of scalp EEG, we could not identify with precision the symptomatogenic zone underlying ictal strabismus. However, the concomitant appearance of rhythmic theta activity over the right fronto-central region and the leftward head version with MRI perfusion sequences, showing cerebral blood flow increase in the right frontal eye field area, suggest involvement of the right frontal lobe.