Article
Usefulness of optic-tract fibre-tracking for mesial temporal surgery
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Published: | May 20, 2009 |
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Objective: Visual field deficits are a common complication of mesial temporal surgery. About 50% of cases suffer from postoperative upper quadranopia after transsylvian approaches. We attempted to minimize trauma to the optic tract by using a temporo-basal approach guided by navigated DTI fibre tracking of Meyer’s loop.
Methods: Ten patients with amygdalohippocampectomy to treat mesial temporal lobe epilepsy were prospectively included. Every patient underwent preoperative MRI (Neuronavigation and DTI sequences). Meyer’s loop was reconstructed using DTI fibre tracking with the BrainLab Vector Vision System. Preoperatively, the approach was planned strictly avoiding any compromise of the optic tract. Intraoperative visualisation via the navigation-bound microscope was provided.
Results: A temporo-basal approach was the only possible route in all cases to access the temporal horn without interfering with any parts of the optic tract. Two patients were operated using a basal transcortical approach and eight with a subtemporal trans-fusiform-gyrus approach. Eight patients (80%) did not show any visual field defects. One patient with a transcortical approach had a minimal scotoma, and one patient with a subtemporal approach suffered an incomplete contralateral quadranopia.
Conclusions: Meyer’s loop can be sufficiently reconstructed using this DTI fibre tracking algorithm. Preoperative approach planning proved to be useful to avoid any relevant damage to the optic tract. The use of basal approaches seems to be beneficial regarding post-operative visual field deficits.