Cognitive consequences of coexisting temporal lobe developmental malformations and hippocampal sclerosis

Objective: To characterize patterns of cognitive functioning in a well-defi ned group of patients with MRI-identified coexisting left temporal lobe dev elopmental malformations (TLDM) and mesial temporal sclerosis (MTS), and to examine neuropsychological outcome in this dual-pathology group following epilepsy surgery. Methods: Cognitive functioning in patients with left TLDM and MTS (n = 15) was compared with patients with isolated left MTS (n = 40 ). TLDM and MTS were identified by high-quality MRI protocol. Patients were administered a battery of neuropsychology tests as part of their presurgic al workup for possible epilepsy surgery. Unilateral temporal lobe resection was performed on 10 of the dual-pathology patients and 34 of the isolated MTS patients. Postoperative cognitive performance was also assessed. Result s: Both groups displayed impairments in verbal and visual memory, language, and academic achievement. Performance on measures of psychometric intellig ence, executive function, and attention were not impaired and were similar between groups. Presence of dual pathology was associated with a significan tly less efficient verbal encoding strategy on the word list learning task. Postoperatively, declines were noted for both groups across tasks of verba l memory and language. Groups were not different significantly in terms of neuropsychological outcome after surgery. Conclusion: Patients with coexist ing TLDM and MTS have impaired cognitive functioning similar to MTS patient s-in particular, with regard to episodic memory and language deficits. Temp oral lobe resection produces similar cognitive changes in both groups.