CLINICAL SEIZURE LATERALIZATION IN MESIAL TEMPORAL-LOBE EPILEPSY - DIFFERENCES BETWEEN PATIENTS WITH UNITEMPORAL AND BITEMPORAL INTERICTAL SPIKES

Objective: To compare the reliability of clinical seizure lateralizati on in temporal lobe epilepsy patients with unitemporal and bitemporal independent interictal spikes and unilateral hippocampal atrophy or sc lerosis (HAMS) on MRI scan. Patients and methods: We studied 11 patien ts with unitemporal and 10 patients with bitemporal interictal spikes. We calculated a spike ratio by dividing the number of spikes ipsilate ral to the side of HAMS by those occurring contralaterally. Results: C linical seizure lateralization was correct, i.e., ipsilateral to the s ide of HAMS, significantly more often in the unitemporal group. Spike ratios were significantly higher in seizures that were lateralized cor rectly as compared with both incorrectly and nonlateralized seizures. Within the individual patients, a significant positive correlation bet ween spike ratios and the proportion of correctly lateralized seizures was found. We identified three categories of symptoms according to la teralization accuracy. Category 1 symptoms (version, postictal paresis , and early ictal vomiting/retching) lateralized to the side of HAMS i n 100% of patients in the uni- and bitemporal groups. Category 2 sympt oms (dystonic posturing, mouth deviation, postictal dysnomia/dysphasia , and ictal speech) provided a 100% correct lateralization in the unit emporal but not in the bitemporal patients. Category 3 symptoms (nonve rsive early head turning and unilateral upper extremity automatisms) y ielded erroneous lateralization in both patient groups. Conclusions: W e conclude that reliable clinical seizure lateralization in mesial tem poral lobe epilepsy can only be achieved in patients with unitemporal interictal spikes, whereas clinical lateralization in patients with bi temporal spikes must be viewed cautiously.