Abstracts

Rationale: Approximately 20-55% of people with epilepsy suffer from significant mood problems. Resective epilepsy surgery has been associated with improvement in depressive symptoms up to two years post resection. Longer-term results of depression outcomes have not been studied, prospectively. The depression literature, in patients without epilepsy, shows the five-year risk of depressive relapse is up to 80%. This study explores five-year outcomes using linear mixed effects model, which accounts for time effect adjusting for co-variables. Methods: Analysis was performed in a sample of 379 adult subjects who were enrolled between 1996 and 2001 in a multi-center prospective study to evaluate outcomes of resective epilepsy surgery. A standardized protocol to record history, neurological evaluation, MRI, video-EEG monitoring, and neuropsychiatric assessments was administered. As part of the standardized protocol, assessment of depression symptoms using Beck Depression Inventory (BDI) was conducted at preoperatively as well as 3, 12, 24, 48, and 60 months postoperatively. Epilepsy control was classified into one of four categories: excellent (completely seizure free during the 5-year follow up, good (>=2 consecutive years of being seizure free and one or more seizures during the 5-year follow up period), fair (seizure free <2 but >= 1 year) and poor (never had a one full year of seizure freedom through out the 5 year follow up). A mixed-model repeated-measures analysis was performed, which adjusted for co-variates of seizure location, pathology, gender, age, race, education, and seizure control. Results: Out of total 379 patient, 256 patients had both presurgical and 5 year depression evaluations. Of the 256 subjects who were evaluated presurgically, 164 (64.1%) were not depressed, 34 (13.3%) were mildly depressed, and 58 (22.7%) had moderate to severe depression. After five years, out of the 256 subjects who were re-evaluated 198 (77.3%) were not depressed, 20 (7.8%) were mildly depressed, and 38 (14.8%) were moderately to severely depressed (See Figure 1). Of the subjects that had missing data at 5 years: 13 had moderate to severe depression while 94 were not depressed at their last visit, respectively. Subjects who completed 5-year BDI were not significantly different from those who dropped out during follow up in terms of their baseline BDI score, depression status, seizure control, age, gender, education and seizure location. Five years after surgery, mixed model demonstrated that reduction in mean change from baseline in BDI was greater in excellent seizure control than in fair and poor group (p=.0006 and p=.02 respectively). People with good seizure control had greater reduction in BDI than poor seizure control group (p=0.02), and borderline significance than fair seizure control group (p=0.055). See Figure 2. No significant difference was found among other group comparisons. Conclusions: While all patients have initial improvement in depressive symptoms post respective surgery, only patients with good or excellent seizure control have sustained long term improvement.