Transorbital laser surgery for epilepsy: Anatomic-radiological feasibility of transorbital magnetic resonance imaging-guided laser interstitial thermal therapy (MRIgLITT) for amygdalohippocampectomy in refractory epilepsy

Objective: to study the anatomical feasibility of laser fiber insertion for interstitial thermal therapy via transorbital approach to the temporo-mesial structures (amygdala-hippocampus-parahippocampus complex).

Methods: Anatomical dissections were performed bilaterally on two human cadaveric heads via a transorbital approach, in which screws and laser fibers were used for magnetic resonance imaging-guided laser interstitial thermal therapy (MRIgLITT) assisted by neuronavigation. In addition, eight transorbital trajectories were simulated using the transorbital entry points obtained from a cadaveric radiological study of four patients previously operated on for mesial temporal lobe epilepsy.

Results: Successful placement of all four laser fibers was achieved in the anatomical specimens according to the predetermined plan, with an average vector error of 1.3 ± 0.2 mm, ensuring complete coverage of the amygdala-hippocampus-parahippocampus complex. Furthermore, simulations of patient trajectories confirmed safe vascular pathways. An optimal transorbital entry point was identified in the inferolateral quadrant of the orbit, specifically on the lateral wall above the greater wing of the sphenoid. However, the small size of the laser fiber-anchoring screw currently limits its clinical application. This technique may serve as a potential alternative to occipital access in laser surgery for epilepsy, in very specific situations.

Conclusions: The placement of a transorbital laser fiber for MRIgLITT targeting the temporomesial structures in epilepsy is anatomically feasible; however, the small size of the anchoring screw presently precludes its clinical use.