Effects of dual pathology on cognitive outcome following left anterior temporal lobectomy for treatment of epilepsy

- Dual pathology may be more prevalent in temporal lobe epilepsy than previously reported.
- Dual pathology may mitigate risk for cognitive decline following dominant temporal lobectomy.
- Findings may reflect limited functional adequacy of resected tissue or reorganization of function.

The objective of this retrospective study was to determine if dual pathology [DUAL - focal cortical dysplasia (FCD) and mesial temporal sclerosis (MTS)] in patients with left temporal lobe epilepsy is associated with greater risk for cognitive decline following temporal lobectomy than single pathology (MTS only). Sixty-three adults (Mage = 36.5 years, female: 52.4%) who underwent left anterior temporal lobectomy for treatment of epilepsy (MTS = 28; DUAL = 35) completed preoperative and postoperative neuropsychological evaluations. The base rate of dual pathology was 55.5%. Repeated measures ANOVAs yielded significant 2-way interactions (group × time) on most measures of language and memory with generally moderate effect sizes. Specifically, patients with MTS only demonstrated postoperative declines, while those with dual pathology remained unchanged or improved. Results suggest that dual pathology may be associated with better cognitive outcome following epilepsy surgery than MTS alone, possibly reflecting limited functionality of the resected tissue or intrahemispheric reorganization of function in the context of a developmental lesion.