Abstracts

Rationale: Epileptic nystagmus is a rare but potentially useful lateralizing manifestation of epileptic seizures. The direction of the fast component of the nystagmus is regarded as reliably pointing away from the seizure onset zone (Kaplan and Tusa, Neurology 1993, 43, 2508-14; Kellinghaus et al., Epilepsy Behav 2008, 13, 700-2). Methods: A 13 year-old boy with static encephalopathy, quadriplegia, cortical blindness, severe mental retardation and epilepsy as consequence of a battered child syndrome with bilateral encephalomalacia worse on the left hemisphere (figure 1) presented with episodes of eye-flutter and occasional elevation of the arms up to 25-times per month lasting several minutes with a tendency to cluster and thus was admitted to a Video-EEG-monitoring.Results: Aside of asymmetric bilateral tonic seizures of the upper extremities mainly, the patient s most frequent seizure type during the monitoring consisted in an epileptic nystagmus along with impaired reactivity to external stimuli. The fast part of the nystagmus pointed to the right side with a moderate upward component, variable amplitude but constant frequency close to 2 Hertz. While localization of the seizure onset remained difficult the EEG showed epochs of highly regular discharges matching the frequency of the nystagmus. The initial discharge of each cycle of nystagmus lateralized to the right hemisphere, primarily parieto-central (figure 2).Conclusions: The direction of the fast component of epileptic nystagmus may under circumstances be preceded by or associated with a predominant ipsilateral seizure pattern. This may be related to widespread contralateral brain lesions (Choi et al., J Neuroophthalmol 2012, 32, 135-8). Additionally, this case demonstrates an example of an ictal semiology time-locked to the frequency of its seizure pattern.