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The Effects on Cognitive Performance of Tailored Resection in Surgery for Nonlesional Mesiotemporal Lobe Epilepsy
Author(s) -
Leijten Frans S. S.,
Alpherts Willem C. J.,
Van Huffelen Alexander C.,
Vermeulen Jan,
Van Rijen Peter C.
Publication year - 2005
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.0013-9580.2005.33604.x
Subject(s) - neocortex , temporal lobe , epilepsy , hippocampal sclerosis , epilepsy surgery , cognition , medicine , effects of sleep deprivation on cognitive performance , hippocampal formation , anesthesia , psychology , audiology , neuroscience
Summary: Purpose: Mesiotemporal lobe epilepsy (MTLE) can be treated with different surgical approaches. In tailored resections, neocortex is removed beyond “standard” margins when spikes are present in the electrocorticogram. We hypothesized that these larger resections are justified because spiking neocortex is dysfunctional. This would imply that in patients with spikes (a) postoperative cognitive performance is not affected, and (b) preoperative performance is worse than without spikes. Methods: We studied 80 operated‐on MTLE patients with pathologically confirmed nonlesional hippocampal sclerosis. All patients were left‐sided language dominant and underwent cognitive tests 6 months pre‐ and postoperatively. A repeated measures analysis of variance (ANOVA) was performed, looking for within‐ and between‐subjects interactions with presence of intraoperative neocortical spikes. Results: Intraoperatively, neocortical spikes were present in 61% of patients. Improved postoperative cognitive outcome was seen only in left‐sided patients with spikes. Their performance IQ (PIQ) increased by 8.1 points (95% confidence interval, 3.8–12.3; p = 0.02), and visual naming latency by 12.8 s (95% CI, 2.1–23.5; p = 0.07). Conversely, in left‐sided patients without spikes, naming latency declined by 7.5 s (95% CI, −2.3–17.2; p = 0.07). Preoperative scores were comparable except for a 15.3‐point (95% CI, 0.1–30.5; p = 0.02) lower VIQ in left‐sided patients without spikes. Conclusions: Tailoring does not harm cognitive performance and is, in left‐sided MTLE, associated with postoperative improvement. Left‐sided MTLE without neocortical spikes has lower verbal scores, which tend to decline after standard resection and may represent a special pathophysiologic entity.