NEUROPSYCHOLOGICAL CONSEQUENCES OF EPILEPSY SURGERY IN FRONTAL-LOBE EPILEPSY

The present study investigated the effect of frontal lobe surgery on ' 'cognitive functions'', which have previously been shown to be discrim inative in the evaluation of non-resected patients with frontal lobe e pilepsy (FLE). The cognitive outcome was evaluated with particular con sideration of the side (left/right), the site(lateral, orbital, mesial , premotor/SMA), the type of surgery (resections vs resections plus Mu ltiple Subpial Transactions), and seizure outcome. The evaluation is b ased on 33 patients with left (n = 17) or right (n = 16) frontal surge ry. Forty-five patients who underwent successful left (n = 21) or righ t (n = 24) temporal lobectomy served as controls. The neuropsychologic al examination covered speed/attention, motor sequencing/coordination, response maintenance/inhibition, short-term memory, and language. Wit h the exception of short term memory, the chosen tests were discrimina tive in determining preoperative frontal lobe dysfunctions but they di d not differentiate patients with a different lateralization or locali zation of the frontal focus. At the three month follow-up examination, patients with temporal lobectomy had improved frontal functions, whil e patients with frontal lobe surgery showed a mild deterioration. With in the frontally resected group, completely seizure free patients had significantly improved short-term memory. Further consideration of the side, site and the type of the frontal resection indicated that patie nts with premotor/SMA surgery and patients with precentral/central MST had additional impairment after surgery. Premotor/SMA resections led to a deterioration in response maintenance/inhibition and if performed left sided also to deteriorated language functions. The latter impair ment could be clearly related to transient aphasia directly after surg ery. Irrespective of pareses observed immediately after surgery, patie nts with MST's of precentral/central areas displayed additional proble ms in motor coordination at the follow-up examination. In this group t he seizure outcome was also less favorable. In summing up, frontal lob e surgery does not cause any considerable additional impairment in the short term follow-up. However, caution is recommended when surgery or MST affect functional relevant cortex (here the prefrontal/SMA and pr ecentral/central area). Finally, a release of functions associated to frontal areas not affected by surgery is suggested, when seizures are successfully controlled by surgery. (C) 1998 Published by Elsevier Sci ence Ltd. All rights reserved.