The effects on cognitive performance of tailored resection in surgery for nonlesional mesiotemporal lobe epilepsy.
OBJECTIVE
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.
Leijten
Frans S S
FS
Rudolf Magnus Institute of Neuroscience, Department of Clinical Neurophysiology, University Medical Center Utrecht, Utrecht, The Netherlands. fleijten@neuro.azu.nl
Alpherts
Willem C J
WC
Van Huffelen
Alexander C
AC
Vermeulen
Jan
J
Van Rijen
Peter C
PC
D000328:Adult; D001927:Brain Diseases / Q000601:surgery; D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D007839:Functional Laterality; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D019579:Neocortex / Q000503:physiopathology / Q000601:surgery*; D009483:Neuropsychological Tests; D019635:Neurosurgical Procedures / Q000379:methods; D011183:Postoperative Complications / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D011300:Preoperative Care; D012598:Sclerosis / Q000601:surgery; D013702:Temporal Lobe / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D014743:Videotape Recording; D014888:Wechsler Scales / Q000706:statistics & numerical data