Introduction: Mesial temporal lobe epilepsy is the most common cause of refractory epilepsy in adults. In these patients selective or non-selective amygdalohippocampectomy can lead to seizure-freedom in 62-70% of cases. However, the prognostic factors determining seizure outcome are still debatable.

Objectives: To identify the pre and post-operative factors that are independent predictors of seizure outcome of patients who underwentnon-selective amygdalohippocampectomy in Epilepsy Surgery Group from Centro Hospitalar de Lisboa Ocidental.

Material and methods: Case-control study of the patients who underwent non-selective amygdalohippocampectomy, in our centre, between 1997 and 2015. Patients were divided in two groups according to Engel classification: seizure-free (Engel class I) and non seizure-free (Engel Classes II- IV). Univariate analysis was performed to analyse the potential prognostic predictors, including demographic characteristics, early insults, imaging findings, pathology results and post-surgical data.

Results: During this period 119 patients underwent non-selective amygdalohippocampectomy. After an average 9 years follow-up (range 1-18 years) 91 patients (76%) are in the seizure-free group and 28 patients (24%) in the non seizure-free group. Four factors were associated with non seizure-free outcome: date of surgery before 2005 (p = 0.02), negative MRi (p = 0.02), major surgical complications (p = 0.0001) and seizures in the early post-operative period (p = 0.032). No significant differences were found in gender, age at time of surgery, duration of epilepsy, side, early insults or pathology result.

Conclusions: In our series, negative pre-operative MRi, lack of experience of the epilepsy group, major surgical complications and seizures in early post-operative period were associated with higher risk of non seizure-freedom after non-selective amygdalohippocampectomy.