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To examine whether psychiatric comorbidity is a predictor of long-term seizure outcome following temporal lobe epilepsy surgery.

A sample of 434 adult patients who received temporal lobe resection to treat epilepsy between 1991 and 2009 and were psychiatrically assessed before surgery were followed for 2 years to assess seizure outcome. Stepwise multivariate logistic regression analyses were used to assess the impact of psychiatric variables on complete seizure freedom (Engel class IA), and freedom from disabling seizures (Engel class I). Lifetime histories of three psychiatric syndromes (PS: psychosis; depression; other) and five personality disorders (PD: DSM-IV Clusters A, B, and C; organic personality disorder; other) were considered as predictors, complemented by age at onset, duration of epilepsy, type of lesion (mesiotemporal sclerosis vs. other), and year of surgery.

Seizure-freedom rates were significantly higher (p < 0.001) in patients with no history of PS or PD (N = 138; Engel class IA: 61.6%; Engel class I: 87.7%) than in those with any PS or PD (N = 296; Engel class IA: 39.5%; Engel class I: 58.8%). Particularly low seizure-freedom rates were found in patients with a diagnosis of psychosis (N = 32, Engel class IA: 21.9%; Engel class I: 40.6%), organic PD (N = 48, Engel class IA: 25.0%; Engel class I: 35.4%) or a double diagnosis of PS plus PD (N = 97; Engel class IA: 27.8%; Engel class I: 45.5%). No other variables emerged as significant risk factors in multivariate logistic regression analyses.

Patients with and without psychiatric comorbidities can benefit from temporal lobe epilepsy surgery; however, psychiatric comorbidities are negatively associated with postoperative seizure-freedom rates. Surgical outcome is related to the type and extent of preoperative psychiatric morbidity, which underscores the prognostic value of presurgical psychiatric evaluation. The data support the argument that there are common pathogenetic mechanisms underlying both epilepsy and psychiatric conditions.