EPILEPSY SURGERY IN BELGIUM, THE FLEMISH EXPERIENCE

Between January 1992 and June 1995, 160 patients were presurgically ev aluated for medically refractory epilepsy by the Epilepsy Monitoring a nd Surgery Team at the University Hospital of Gent. All these patients underwent a comprehensive presurgical evaluation, including extensive neurological history and examination, video-EEG monitoring of intel i ctal EEG and habitual seizures, CT and optimum MR. In a large subgroup of these patients a comprehensive neuropsychological examination and interictal (18)FDG-PET were pet-formed. After the non-invasive phase o f the presurgical evaluation, a bilateral carotid angiography and intr acarotid amytal procedure was planned in 27 patients to establish hemi spheric language dominance and bilateral memory function. After proper selection, 14 patients underwent invasive video-EEG monitoring with i ntracranial implantation of parenchymal and/or subdural electrodes to further document the area of seizure onset. From the initial group of 160 potential surgical candidates, 40 patients (20 M, 20 F) with mean age of 31 years (range : 2 months - 55 years) and mean duration of unc ontrolled seizures of 16 years (range : 2 months-47 years) eventually underwent a surgical procedure. 30/40 patients were on high dose anti- epileptic polytherapy. Optimum MR detected structural abnormalities, c onfined to a limited brain area, in 39 patients. These abnormalities w ere of space-occupying nature in 21 cases; an atrophic lesion was susp ected in 17 patients. Structural abnormalities were most frequently lo cated in the temporal lobe (n = 26) and the frontal lobe (n = 7). Vide o-EEG monitoring documented complex partial seizures in 32 patients wi th occasional secondary generalisation in 14. In most of these patient s, seizures could be subclassified as being of temporal lobe origin ba sed on clinical and EEG criteria. Two patients had only simple partial seizures. One patient with Sturge-Weber syndrome and a strictly unila teral angioma had hemiconvulsions. A mentally retarded patient with Le nnox-Gastaut syndrome had different types of seizures. After non-invas ive and invasive exploration, the area of seizure onset could be deter mined in all patients. Standard or modified temporal lobectomy +/- hip pocampectomy were the most commonly performed procedures (n = 26). In 5 patients complete lesionectomies were performed for epileptogenic st ructural lesions in and outside the temporal lobe. In 2 patients only partial lesionectomies were possible; in 5 patients only biopsies coul d be performed. Anterior 2/3 callosotomy and hemispherectomy were each performed in one patient. Postsurgical seizure control, after average follow-up of 20 months (range : 6-40 months), was excellent in 27 pat ients who became seizure-free. In these patients antiepileptic therapy was tapered 2 years after surgery. An additional 4 patients continue to experience non-disabling simple partial seizures only. Patients in whom only biopsies ol partial lesionectomies were performed have poor seizure control. Three patients died as a result of the intrinsic mali gnancy of their space-occupying lesion. Two patients who are seizure f ree experienced a moderate postoperative hemiparesis with subtotal rec overy. Overall quality of life was substantially improved both in pati ents who became entirely seizure free or who experienced a very signif icant reduction in seizure frequency. Presurgical evaluation and epile psy surgery are a labour intensive but rewarding therapeutic alternati ve for patients with medically refractory epilepsy. Besides providing therapeutic efficacy, comprehensive presurgical evaluation and epileps y surgery allow for fruitful clinical neurological research.