Extratemporal Electroencephalographic Activity in Temporal Lobe Epilepsy: Associated or Not to the Etiology?
Abstract number :
3.136
Submission category :
Year :
2000
Submission ID :
1087
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Kette D R Valente, Carmen L Jorge, Rosi M Grosmann, Luis Hm Castro, Sueli K N Marie, Univ of Sao Paulo, Sao Paulo, Brazil.
RATIONALE: We analyzed the relevance of ictal and interictal electroencephalographic (EEG) findings in distinguishing patients with mesial temporal sclerosis (MTS) from patients with unilateral temporal lobe lesions of other etiologies. METHODS: Of 90 consecutive patients with TLE who underwent surgical treatment for refractory epilepsy, 70 patients in Engel class I were selected. These patients were divided in groups according to etiology: group I (GI) consisted of 50 patients with MTS, and group II (GII) of 20 patients with other lesions (18 patients with low-grade tumors, 1 with tuberculous granuloma and 1 with gliosis). Of the latter, 10(50%) patients presented a localized lesion, exclusively in the mesial portion of the TL, and 10(50%) had a lateral neocortical lesion, with or without extension to the mesial structures. Epileptiform EEG activity (ictal and interictal) was classified as unilateral temporal, bilateral temporal and extratemporal. RESULTS: GI patients had a mean age of 30.9 years, mean age of epilepsy onset of 9 years and epilepsy duration of 21.6 years. Post-surgical follow-up ranged from 1 to 91 months (mean 43 months). In GII, mean age, mean age of onset and epilepsy duration was 20.3, 11.2 and 9.1 years, respectively. Post-surgical follow-up in GII ranged from 1 to 88 months (mean 40.3 months). Unilateral temporal lobe interictal EEG activity, ipsilateral to MRI findings, was found in 76% in GI and 40% in GII. Localizing and lateralizing ictal temporal lobe activity was observed in 90% in GI and 69% in GII. Bilateral interictal TL discharges were seen in 20% of GI and 30% in GII; bilateral ictal TL involvement was seen in 8% of GI and 15.4% of GII. Extratemporal epileptiform activity (EEA) was significantly more frequent in GII (2% of GI and 20% of GII; p=0.03). None of the ictal EEG in GI showed EEA whereas it was observed in 15,4% of EEG in GII (p=0.05). CONCLUSIONS: This study suggests that, in patients with TLE, presence of interictal and ictal extratemporal epileptiform activity is more frequent in patients with etiologies other than MTS.