Abstracts

Epileptic nystagmus is defined as quick repetitive eye movement, which is secondary to epileptic activity. The few reports within the literature describe epileptic nystagmus with the fast phase of the nystagmus directed contralateral from the epileptic activity. The literature describes epileptic activity arising from the posterior temporo-parietal-occipital region. The purpose of this study was to estimate the incidence of epileptic nystagmus in patients with epilepsy and confirm its lateralizing value.
All consecutive admissions to the Epilepsy Monitoring Unit at the Cleveland Clinic Foundation between 1999 and 2002 were reviewed for ictal epileptic nystagmus. The side of the epileptic nystagmus was determined by the fast phase of the nystagmus.
Nine patients (average age: 12 years, range 10 months [ndash] 34 years of age; 7 females, 2 males) with ictal epileptic nystagmus were identified among1838 (991 adult, 847 pediatric) consecutive admissions. The epileptogenic zone was within the left hemisphere in 3 and the right hemisphere in 6. The epileptogenic zone was further localized to the temporal region in 3, temporo-parietal region in 3, and hemispheric in 3. The epileptogenic zone was determined by epilepsy surgery with seizure freedom for at least 6 months in 3, and by concordant EEG and imaging data in 6. Four patients had eye version ipsiversive to the epileptic nystagmus, 2 contraversive to the epileptic nystagmus, and 3 patients had no eye version. The etiologies as determined by imaging or pathology were 2 mesial temporal sclerosis, 2 malformations of cortical development, 2 areas of encephalomalacia, 1 cortical dysplasia, and 1 Rasmussen[rsquo]s encephalitis.
Ictal epileptic nystagmus was present in 0.5% of patients evaluated in the Epilepsy Monitoring Unit at the Cleveland Clinic Foundation, and was predominantly seen within pediatric patients. All 9 cases involved epileptic nystagmus, which was always directed contralateral to the epileptogenic zone. Ictal epileptic nystagmus is a helpful semiological feature lateralizing seizure onset to the contralateral hemisphere. This is in contrast to eye version, which appears to be a less reliable lateralizing sign. Localization of the epileptogenic zone was temporo-parietal in 6 and more diffuse in 3, consistent with previous reports.
[Supported by: Author TL was supported by Innovative Medizinische Forschung, WWU Münster, Germany (FoeKz. LO 610101)]