Abstracts

RATIONALE: This study sought to determine cognitive outcome in a sample of medically intractable epilepsy patients who underwent either left frontal topectomy (LFT) or left temporal lobectomy (LTL) in combination with multiple subpial transection (MST). Postsurgical neuropsychological (NP) performance was compared to a sample of patients who underwent focal resective surgery alone. The objective of this study was to assess the cognitive risk of MST to cortical speech areas.
METHODS: The sample consisted of 11 patients who underwent either LFT (n = 8) or LTL (n = 3) and MST of speech and in some case, motor areas as determined by intraoperative mapping. The control sample consisted of eight patients who had only LFT (n = 5) or LTL (n = 3). All patients in this study were left speech dominant as determined by Wada procedure. Demographic, seizure, medical, and surgical data were retrospectively collected for both the presurgical and postsurgical periods. The two groups were compared on both verbal and nonverbal measures of NP function. Desciptive, parametric, and nonparametric statistical analyses were utilized to assess group differences and NP outcome following surgery.
RESULTS: There were no significant differences between the two groups in terms of gender, age of seizure onset, age at surgery, education, number of presurgical and postsurgical antiepileptic drugs, postsurgical interval, and presurgical and postsurgical seizure frequency. Ninety-percent or greater improvement in postsurgical seizure control was achieved by 63% and 75% of the MST and focal resection-only groups, respectively. Presurgical neuropsychological performance was comparable between the two groups, except for the MST group performing significantly worse on a measure of visuospatial construction. Postsurgical NP outcome for the MST group revealed moderate to substantial (10-30%) declines on measures of verbal fluency (p [lt] .05), verbal reasoning, and vocabulary. All other measures of verbal and nonverbal cognitive function showed either no change or modest improvements. In contrast, the focal resection-only group demonstrated no change or improved performance on all verbal and nonverbal cognitive measures. On postsurgical neurologic exam, 64% of the MST group showed clinical language deficits, 71% of which were judged to be persistant.
CONCLUSIONS: These preliminary data support previous findings of adverse cognitive risk, especially to langauge, associated with MST plus additional resective surgery to the frontal or temporal lobe of the speech-dominant hemisphere. These findings should be considered when counseling patients regarding postoperative risk. There is a need to replicate this study with a larger series of patients.