Usefulness of latero-orbital electrodes in detecting interictal epileptiform activity - a study of 60 patients with complex partial seizures

OBJECTIVES: The use of latero-orbital (Lo) electrodes is a routine practice in any EEG laboratory to evaluate eye motion, but there are no data about their usefulness in revealing interictal epileptiform abnormalities. METHODS: In 60 consecutive patients (27 men, 33 women, mean age 36.8 years, range 17-72) with complex partial seizures, we prospectively evaluated the utility of Lo electrodes in comparison with anterior temporal (AT) electrodes, for the detection of interictal epileptiform discharges (SW). RESULTS: No epileptiform abnormality was seen in 4/60 patients. Both AT and Lo electrodes were significantly superior to 10-20 electrodes for detection of both patients and foci. Indeed, the standard 10-20 system alone allowed the detection of only 39 independent epileptiform foci in 35/56 (63%) patients, while AT and Lo electrodes were necessary for detection of 23 epileptiform foci in the remaining 21/56 (37%) patients. Importantly, there was no statistically significant difference in detection between AT and Lo electrodes. CONCLUSIONS: Recordings from Lo electrodes are comparable to those from AT electrodes and are useful for localizing interictal temporal spiking activity. Lo electrodes may be substituted for basal electrodes in the day-to-day evaluation of patients with complex partial seizures.