Long term follow-up (>10 years) in a single Epilepsy Surgery Centre: a series of 420 consecutive patients operated on for drug-resistant epilepsy at the “Claudio Munari” Centre

epilepsy patients; nonetheless few studies assess the very long-term post-operative outcome of epilepsy surgery.Aim of this study is presenting the long-term outcome of a series of patients who underwent a tailored cortical resection from May 1996 to December 2003. Method: Assessment of the clinical outcome and of the potentially associated anatomo-electroclinical variables. Results: We identified 420 patients (46% females) with at least 10 years follow-up (range: 10-17.6, mean: 13.4 years); 81% of subjects had a seizure onset < 14 years of age, 42% < 6 years. Surgery was realized in adult age in 80.2%, at a mean age of 27.5 years and a mean duration of 18.7 years.MRI was normal in 10.2% of cases; 41.6% of subjects underwent a pre-surgical Stereo-EEG evaluation.Surgery was performed in the left hemisphere in 44.5% of cases; a lesionectomy was realized in 34 patients, in the remaining a corticectomy, including the eventual lesion, was performed.Surgery was: temporal (58.6%), frontal (19.4%), parietal (4%), occipital and central (0.7% each), multilobar (16.6%).Malformative pathologies represented the commonest histological finding (43.6%).Seizure freedom was achieved by 70 % of subjects (Engel class Ia: 42.8%, Ib: 9%, Ic: 12.4%, Id: 5.4%), 10.7% are in class II, 9% in class III and 10.3% in class IV. AEDs were stopped in 35.7% and tapered in further 18% of cases. A relapse was observed in 10 cases.An MRI-identifiable discrete lesion represented a statisticallysignificant favourable predictor, whereas early epilepsy onset (< 5 years), the necessity to perform Stereo-EEG, an extratemporal resection and FCDI at histology statistically correlated with a negative outcome. Conclusion: A very long-term seizure control following individually-tailored epilepsy surgery can be achieved in 70% of the patients, allowing a drug discontinuation in around 50%