Long-term memory performance after surgical treatment of unilateral temporal lobe epilepsy (TLE)

• Long-term memory performance after TLE surgery was evaluated.
• Verbal learning and memory declined in both left and right TLE groups.
• Individual postoperative long-term memory performance was variable.
• Risk factors for decline in verbal memory were left side of surgery, better baseline performance and older age at surgery.

SummaryLong-term cognitive and memory performance after surgical treatment of unilateral temporal lobe epilepsy (TLE) was investigated in a series of 98 patients. Neuropsychological evaluation was performed preoperatively and after one and three years postoperatively. Fifty-eight patients (59%) became seizure-free (Engel's class I). Verbal learning and memory declined in long-term follow-up in both left and right TLE groups. Visual memory remained stable. Ongoing postoperative seizures were related to decline in the immediate recall of logical prose, and postoperative seizure-freedom to improvement in verbal fluency in patients with left TLE. There was significant variability in the individual postoperative long-term memory performance. Left side of surgery, better baseline performance and older age at surgery were identified as risk factors for individual decline in delayed verbal memory. Selected patients undergoing surgery for drug-resistant TLE are at risk for significant postoperative memory decline especially after left temporal lobe surgery. Preoperative counseling and long-term follow-up of cognitive performance in individual patients is recommended. Additionally, more accurate predictors of individual postoperative memory performance would be needed.