Epileptic nystagmus: a case study video-EEG correlation

Epileptic nystagmus (EN) is an uncommon phenomenon characterized by repetitive and rapid saccades, in association with epileptic discharges. We present a critical video-EEG recording in a patient with occipital seizures that appeared clinically as EN. The subject, male, 70 years-old, was examined because of generalized tonic-clonic seizures, preceded by left cephalic version. These were controlled using i.v. PHT, but partial seizures persisted, which we recorded using video-EEG. Clinically, we observed episodes of left conjugate deviation of the eyes, accompanied by horizontal nystagmoid movements, with a rapid leftward component and visual hallucinations. The patient did not lose consciousness. Ictal EEG: spike rhythm in the posterior right occipito-temporal region extending to adjacent and contralateral regions, followed by post-discharge of slow waves. The video-EEG was interpreted as partial oculo-clonic status epilepticus of right temporo-occipital origin. Cranial MRI: old, bilateral hemorrhaging occipital contusions associated with previous cranial injury. The picture persisted for two days, and disappeared with administration of CBZ 600 mg/d. Our patient's nystagmus seemed to be related to the critical activity recorded in the right occipito-temporal region. The co-existence of visual hallucinations and the video-EEG correlation support this possibility. This phenomenon is probably due to epileptic activation of the cortical center of saccadic movements, with a rapid phase of nystagmus, contralateral to the focus, and a slow ipsilateral phase in association with a defect in the gaze-fixing system ("leaky neural integrator") [published with videosequences].