Abstracts

Rationale: Extra-temporal resection is becoming increasingly common as a procedure for treatment of refractory epilepsy. One of the issues in assessment of seizure outcome after surgery is whether early/acute post-operative seizures have any prognostic significance in terms of eventual outcome. This remains a matter for debate in the assessment of outcome after other types of epilepsy surgery (i.e. temporal lobectomy). Currently, there is little data about the risk associated with early seizures amongst patients who have had an extra-temporal resection. We aimed to examine this issue in a cohort of patients who have undergone extra-temporal resection at Austin Health, Melbourne, Australia.Methods: Early seizures were defined as complex partial or secondarily generalised seizures in the first 28 days post-surgery. Recurrence was denoted as seizures between 29 days and 1 year post-surgery. We also measured outcome during the third post-surgery year. Incidence rate ratios (IRR) calculated the risk of recurrence.Results: Extra-temporal resections were performed on 75 patients. Surgery was frontal (n=46) parietal (n=16) occipital (n=7) or multi-lobar (n=6). Fifty-six percent (n=42) had early seizures. Of those who had early seizures, 93% had a recurrence within 12 months compared to 37% of those who did not have an early seizure (IRR 13.5, 95%CI 6.9-28.3, p=0.00). Patients who experienced an early seizure in the first week after surgery (n=25) had 8 times the risk of recurrence (IRR 8.5, 95%CI 4.2-17.1, p=0.00) compared to those with no early seizures. Those who experienced a seizure in the first two days after surgery (n=8) had 10 times the risk of recurrence (IRR 10.3, 95%CI 4.0-26.0, p=0.00). When outcome in the third post-operative year was measured, 81% of the group who had early seizures experienced seizures during the third post-operative year. This was similar to outcome for those (n=12) who had their first seizure 2-12 months post-surgery (75% experienced seizures, p=0.6).Conclusions: Seizures that occur soon after extra-temporal resection are not benign and are associated with a high risk of recurrence. This information may be of use in classification of post-operative outcome and patient counselling. (Sources of finding: Austin Health Medical Research Foundation, the University of Melbourne, National Health and Medical Research Council Australia)