title: Cerebral blood flow reactivity in patients undergoing selective amygdalohippocampectomy for epilepsy of mesial temporal origin. A prospective randomized comparison of the trans-Sylvian and the transcortical approach.
abstract: OBJECTIVE
  The aim of this study was to assess (1) whether vasoreactivity is altered in patients with epilepsy and (2) whether the two most commonly used approaches, the trans-Sylvian (TS) and the trans-cortical (TC) route, differ in their impact on cortical blood flow.
  
  
  METHODS
  Patients were randomized to undergo selective amygdalohippocampectomy (selAH) through a TC or TS route. Before and after selAH, we recorded microcirculation parameters on the superficial cortex surrounding the surgical corridor. Blood flow and velocity were measured using laser Doppler flowmetry and micro-Doppler, respectively. Cortical oxygen saturation (SO2) was measured using remission spectrophotometry under hypocapnic and normocapnic conditions.
  
  
  RESULTS
  Ten patients were operated using the TS approach, and eight were operated via the TC approach. Vasomotor reactivity patterns measured with micro-Doppler were physiologically prior to selAH in both groups. After completion of surgery, a significant increase in SO2-values occurred in the TS group (before: 56.7 ± 2.2, after: 65.5 ± 3.0%SO2), but not in the TC group (before: 52.9 ± 5.2, after: 53.0 ± 3.7%SO2). The rate of critical SO2 values below 25% was significantly higher after the TC approach (12.3%) compared to the TS approach (5.2%; p < 0.05).
  
  
  CONCLUSIONS
  Our findings provide the first invasively measured evidence that patients with mesial temporal lobe epilepsy have preserved cerebral blood flow responses to alterations in CO2. In addition, local cortical SO2 was higher in the TS group than in the TC group after selAH. This may be a sign of reactive cortical vessel dilation after proximal vessel manipulation associated with the TS approach. In contrast, the lower values of SO2 after the TC approach indicate tissue ischaemia surrounding the surgical corridor surrounding the corticotomy.
authors.affiliation: 1 Faculty of Medicine, Department of Neurosurgery, Geneva University Hospital , Geneva, Switzerland.
authors.forename: Bawarjan
authors.initials: B
authors.lastname: Schatlo
authors.forename: Max
authors.initials: M
authors.lastname: Jägersberg
authors.forename: Gerhard
authors.initials: G
authors.lastname: Paass
authors.forename: Rupert
authors.initials: R
authors.lastname: Faltermeier
authors.forename: Jörg
authors.initials: J
authors.lastname: Streich
authors.forename: Bernhard
authors.initials: B
authors.lastname: Meyer
authors.forename: Karl
authors.initials: K
authors.lastname: Schaller
mesh_terms: D000328:Adult; D000368:Aged; D000679:Amygdala / Q000601:surgery*; D000704:Analysis of Variance; D002536:Cerebral Arteries / Q000502:physiology; D002540:Cerebral Cortex / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000601:surgery*; D005260:Female; D006624:Hippocampus / Q000601:surgery*; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D017063:Outcome Assessment, Health Care; D010101:Oxygen Consumption / Q000502:physiology; D011086:Polycythemia; D011446:Prospective Studies; D013053:Spectrophotometry; D055815:Young Adult
keywords: Cerebral blood flow; Cerebrovascular reactivity; Epilepsy surgery; Intraoperative monitoring; Microcirculation; Selective amygdalohippocampectomy