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077. Multi-Institutional Study on MRI-guided Laser Interstitial Thermal Therapy for Corpus Callosotomy (MRIgLITT-CC): Technique Variation, Ablation Coverage, and Need for Additional Surgery

Authors: Jonathan A. Pindrik, MD, FAANS

Introduction:
Corpus callosotomy (CC) offers palliation of intractable atonic, tonic, and generalized tonic-clonic seizures. Representing an alternative to open surgery, MRI-guided laser interstitial thermal therapy for CC (MRIgLITT-CC) is used at various centers with differing techniques that may impact performance measures, as investigated in this multi-institutional study.Methods: Pediatric patients undergoing MRIgLITT-CC at 3 institutions were reviewed retrospectively. Percent coverages of intended callosal ablation zones were estimated from MRI. Operative, imaging, and outcomes data were investigated for technical variations, extent of ablation, and need for additional surgery.
Results:
Twenty-seven subjects (18 males, 9 females; mean age 13 years +/- 5 years [4 years, 21 years]) underwent planned complete (13, 48%), anterior (11, 41%), or posterior (3, 11%) MRIgLITT-CC. Complete MRIgLITT-CC entailed 2 (1/13, 8%), 3 (6/13, 46%), or 4 (6/13, 46%) trajectories with 100% (8/13, 62%) or 95-99% (5/13, 38%) coverage. Anterior MRIgLITT-CC cases included 1 (1/11, 9%), 2 (8/11, 73%), or 3 (1/11, 9%) trajectories to achieve 100% (7/11, 64%), 95-99% (2/11, 18%), 90-94% (1/11, 9%), or < 90% (1/11, 9%) coverage. There were no significant differences in percent coverage of intended ablation zone as a function of trajectory number. Three (11%) and four (15%) subjects required repeat callosal surgery or underwent vagus nerve stimulator (VNS) insertion, respectively, during clinic follow-up (mean 11.7 months +/-10.6 months; [0.4 months, 37.1 months]). The need for repeat callosal surgery differed based on percent coverage of intended ablation zone (100%, 0/16; < 100%, 3/11; p = 0.03).
Conclusion:
MRIgLITT-CC yielded 100% or 95-99% coverage of the intended callosal ablation zone in most subjects, integral to evaluating surgical success of CC, regardless of technical or trajectory variation between centers. Few subjects required repeat callosal surgery or additional VNS insertion. This study serves as a precursor to future comparative studies between MRIgLITT-CC and standard open surgical CC.