Trends in presurgical evaluation and surgical treatment of epilepsy at one centre from 1988-2009.

BACKGROUND: Presurgical epilepsy diagnostics and surgical treatment have become standard procedures of neurology. Here, we report on presurgical patients grouped according to their underlying pathology by giving results of presurgical evaluation, surgical therapy and long-term follow-up between 1989-2009 and describe trends over this period. PATIENTS AND METHODS: Data of prospectively documented presurgical patients were retrospectively analysed. Trends were evaluated by a year-by-year analysis.
RESULTS: 2684 presurgical patients underwent presurgical work-up, 1721 of whom (64.1%) went on to resective surgery. The largest presurgical/surgical group was mediotemporal lobe epilepsy with hippocampal sclerosis (29.5%/35.4%). Of all operated patients, 1160 (67.4%) had a follow-up of ≥ 2 years. A total of 586 were continuously seizure-free without auras (50.5%; benign tumours: 61.0%; focal cortical dysplasia: 57.6%; mediotemporal lobe epilepsy with hippocampal sclerosis: 49.4%; non-lesional: 27.6%). Based on the number of the presurgically studied patients, we calculated as a novel measure of the effect of a presurgical/surgical programme an 'intention-to treat seizure-freedom' rate of 32.4%. Over time, the number of patients undergoing evaluation, but also of those not suitable or agreeable for invasive measures increased. Annual numbers of resective procedures remained stable. Average epilepsy duration of patients admitted for presurgical assessment increased. The proportion of patients with benign tumours declined. Intracranial studies and MRI-histopathology discrepancies decreased. Seizure-freedom rates remained constant.
CONCLUSIONS: Epilepsy surgery is highly effective, especially in patients with clearly defined focal pathologies. At this specialised centre, there is a trend towards growing numbers of difficult patients and increasing epilepsy duration prior to referral for presurgical assessment.