Abstracts

RATIONALE: Surgery is a safe and efficient treatment of temporal drug-resistant epilepsies. However, a percentage varying among centers from 10 to 30% of patients are not cured. Only few authors reported changes in semioloy after surgery.
METHODS: Among the 107 patients operated on between 1989 and July 1997 in our center for anterior temporal epilepsy and having a complete follow-up, we identified a group of 27 patients whose semiology changed after surgery. All patient had preoperative video-electroencephalographic (EEG) recordings of seizures. 16 had stereoelectroencephalography (SEEG). In all cases cortectomy spared the temporal superior gyrus (STG). Post-operatively, seizure semiology was established by description of the patient and his family, in 4 cases by video-EEG recordings of seizures, associated in 3 cases with ictal single photon emission computed tomography (SPECT).
RESULTS: We classified the patients with new seizure types in 4 groups : misunderstanding of epilepsy (2 cases), patients having rare tonic-clonic nocturnal generalized seizures (8 cases), persistence of a part of epileptogenic zone located in eloquent cortex (9 cases). In the third group, 6 patients are now seizures-free for more than 2 years. The most homogenous group is the 4th one consisting of 8 patients having electroclinical features strongly suggestive of an epileptogenic zone located in the STG with auditive hallucinations or illusions, vertigo, usually associated with vague autonomic features. Seizures usually last several minutes, often ending with tonic-clonic generalization. The origin of seizures was confirmed in 2 patients by SEEG ; they were reoperated. We suspect some tonic-clonic nocturnal generalized seizures to have the same origin. In most patients retrospectively some preoperative features suggested involvement of STG (singing or voice modifications) but it was considered as secondary epileptogenic zone. In others neoepileptogenesis cannot be excluded.
CONCLUSIONS: In some temporal epilepsies with bipolar epileptogenic zones located in the internal and external cortices, ablation of the internal cortex only can modify and sometimes worsen epilepsy allowing a new network to be expressed.