Optic Radiation Tractography and Visual Field Deficits in Laser Interstitial Thermal Therapy for Amygdalohippocampectomy in Patients with Mesial Temporal Lobe Epilepsy

Abstract

Background/Aims: Laser interstitial thermal therapy (LITT) has become an alternative to open-resective surgery for refractory mesial temporal lobe epilepsy (MTLE). Occurrence of visual field defects (VFDs) following open surgery for MTLE is reported at 52-100%. We examined the rate of VFDs following LITT for amygdalohippocampectomy (AHE) and correlated the occurrence of VFDs with damage to the optic radiations, assessed by diffusion tensor tractography (DTI). Methods: We performed a retrospective analysis of 5 patients who underwent LITT-AHE for medically refractory MTLE. We examined the association between VFDs and optic radiation damage by correlating postprocedural visual field testing with qualitative assessment of optic radiation fiber tracts. Results: Postoperative assessments showed that 4 patients had normal visual field testing, and 1 had a right superior quadrantanopsia (20%). We performed 3-dimensional reconstruction of the optic radiation, laser probe trajectory, and ablation volume. Damage to Meyer's loop was determined consistent with the VFD. Conclusions: Short-term follow-up in our series suggests that laser ablation AHE may be associated with a lower rate of VFD than has been reported for open AHE. Our results suggest that incorporating optic radiation mapping through DTI may preoperatively help to minimize the risk of VFD following laser ablation AHE.

Effects of surgical targeting in laser interstitial thermal therapy for mesial temporal lobe epilepsy: A multicenter study of 234 patients

“…Further examination of the maps highlights the importance of targeting the mesial hippocampus, parahippocampal gyrus, entorhinal cortex, and perirhinal cortex-as missing these structures frequently resulted in persistent seizures. 31 The lack of significant benefit with ablation of the hippocampal tail posteriorly may be related to the negative relationship between hippocampal ablation volumes and seizure outcome-as ablation of the hippocampal tail with a straight laser catheter necessitates a compromise of hippocampal head coverage. 4 Extending the ablation beyond the coronal plane in line with the lateral mesencephalic sulcus yields diminishing F I G U R E 6 Theoretical favorable (green) and unfavorable (red) ablation locations based on the PPV and NPV maps.…”

“…More importantly, ablations that extend further posteriorly have been associated with damage to the optic radiations with resultant visual field deficits. 31 The lack of significant benefit with ablation of the hippocampal tail posteriorly may be related to the negative relationship between hippocampal ablation volumes and seizure outcome-as ablation of the hippocampal tail with a straight laser catheter necessitates a compromise of hippocampal head coverage.…”

Postoperative Outcomes of Magnetic Resonance Imaging (MRI)-Guided Laser Interstitial Thermal Therapy (LITT) in the Treatment of Drug-Resistant Epilepsy: A Meta-Analysis

“…Estimates for Engel Class II (a rare occurrence of disabling seizures or almost seizure-free), included 34 out of 135 patients who were evaluated, was reported in seven studies [14,20,22–25]. Estimates ranged from 3–65% with a pooled prevalence of 12% (95% CI, 0.07–0.16), but there was evidence to suggest significant study heterogeneity (I 2 =86.8%; P=0.000).…”

Automated Steerable Path Planning for Deep Brain Stimulation Safeguarding Fiber Tracts and Deep Gray Matter Nuclei

“…However, this tool may be useful when different surgical approaches are exploited in order to cure diverse pathologies, such as in occipital access for the amygdalohippocampectomy for epilepsy (Jermakowicz et al, 2017;Yin et al, 2017), or if the skull surface is bumpy or less easily accessible, such as in experimental approaches for reaching the hippocampus through the foramen ovale (Comber et al, 2017). Further validations are needed on real patients in order to understand if the aforementioned advantages can be gained even in actual clinical cases, but, globally, it can be stated that the new functions integrated in our algorithm allow the computing of extremely precise CTs for DBS, safer than ordinary RTs.…”