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  • Homonymous Hemianopsia as a Complication From Laser Interstitial Thermal Therapy for Mesiotemporal Epilepsy

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    Walter J Jermakowicz MD PhD; Michael E. Ivan MD MBS; Ramses Ribot MD; Bruno Wieckowski; Naymee Velez-Ruiz MD; Enrique Serrano MD; Andres Kanner MD; Jonathan R. Jagid MD

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    Subject Category:

    Meeting: 2016 ASSFN Biennial Meeting

    Introduction: Laser interstitial thermal therapy (LITT) is a novel tool that is quickly emerging as a mainstream therapy for temporal lobe epilepsy (TLE). We present the case of a 24-year-old male who developed homonymous hemianopsia as a result of LITT for TLE. Detailed anatomical comparisons are provided between this patient and 17 prior TLE patients treated with LITT at our institution in an attempt to better-understand this complication.

    Methods: This is a retrospective chart review of all patients that have undergone LITT for TLE at our institution. Detailed volumetric tracings of mesial temporal lobe structures were performed for all patients using high-resolution pre- and post-op MRI scans. For all patients, volumes of hippocampus, amygdala, ablation zone and CSF dorsal to the hippocampus were calculated.

    Results: The 24-year old male woke up with a complete right-sided homonymous hemianopsia after LITT of left mesial temporal structures. By five months post-op he had partial recovery of vision in the central superior quadrant. MRI suggested inadvertent ablation of the lateral geniculate nucleus. Comparison of intra-op images suggests the patient’s laser catheter was not positioned significantly higher on the cranio-caudal axis than in the prior patients. Similarly, ablation number, energy delivered and size were not significantly greater for this patient compared to the prior patients. However, the subject did have significantly smaller CSF spaces dorsal to the hippocampus, compared to the prior patients.

    Conclusions: Homonymous hemianopsia is a complication of LITT for TLE that patients with small CSF spaces dorsal to the hippocampus may be susceptible to. Our data suggest that inspection of these structures on pre-op MRI scans may help identify this subset of patients. When such anatomy is identified we recommend lowering laser catheter trajectory and decreasing ablation power through the hippocampal body and using additional temperature set points at the lower thalamic border.

    Patient Care: This research will help identify patients vulnerable to visual deficits during LITT for epilepsy and provide suggestions for avoiding the complication.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the relevance of surrounding CSF spaces during LITT 2) Know which patients are susceptible to visual deficits after LITT 3) Describe precautions that can be taken to avoid visual deficits


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