Affection of the cerebral circulation following the extraaxial transsylvian approach has been reported. This study aims at the comparison of the risk for the development of vasospasm in the transparenchymal transcortical versus the transsylvian approach for selective amygdalohippocampectomy in patients with Ammon's horn sclerosis. n = 80 consecutive patients (13-58 years) were randomized and allotted to either the transsylvian (TS) or transcortical (TC) group. Bilateral middle cerebral arteries (MCA) and internal carotid arteries (ICA) were examined with transcranial Doppler pre-operatively, and from post-operative day 1 to 7. Blood flow velocities (BFV) were compared via ANOVA. Post-operatively, ipsilateral (= side of operative approach) mean BFV increased significantly in both groups with a mean ipsilateral increase of 79.2% in the TS group, and 48.8% in the TC group. This intergroup difference was also statistically significant. In addition, contralateral BFV increased significantly to a maximum mean of 26.3% in the TS group with no significant increase in the TC group. The results in the TS group are interpreted as vasospasm and not hyperemia - due to dissection of the sylvian vessels and the breakdown of blood within the basal cisterns. Factors such as the extent of visual field cuts and results from neuropsychological testing must be taken into account before drawing a conclusion leading to a fundamental change in surgical strategy.
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