Corpus Callosotomy Using Laser Interstitial Thermal Therapy Kurt R Lehner BS; Erin Yeagle BS; Miklos Argyelan MD; Victor Du MD; Sean Hwang MD; Ashesh Mehta MD, PhD Hofstra-Northwell School of Medicine, Hempstead, NY North Shore University Hospital, Manhasset, NY Feinstein Institute for Medical Research, Manhasset, NY

Methods Results Figure 1 Figure 3 Retrospective chart and MRI review • sEEG electrode or scalp EEG recording was performed on all cases prior to surgery showed either bilaterally synchronous onsets undergoing LITT callosotomy at one or rapid bisynchronous secondary center. Seizure outcomes were generalization. followed for 18 months. Diffusion • Ablation of the anterior corpus tensor imaging (DTI), resting callosum was successfully complete functional magnetic resonance as a single procedure in three imaging (rfMRI) and patients. Patient 1 required a second electrophysiological connectivity LITT procedure due to a misplaced analysis including corticocortical device. (Figure 1) evoked potential (CCEP) and resting • Diffusion tensor imaging showed anatomical disconnection of the electrocorticogram (ECoG) were Sagittal MRI images of patients 1-4. (a) Pre anterior (Figure 2) performed. -callosotomy T1-weighted MRI. (b) Intra- • Functional separation of the cerebral hemispheres was characterized using operative MRI with placement of probes Introduction resting state fMRI (rs-fMRI) and within the corpus callosum demonstrated Corpus callosotomy is a palliative cortico-cortical evoked potentials and by red dotted lines. The green dotted line procedure for the treatment of resting electrocorticographyic represents the deflected fiber of patient 1. which is particularly effective for drop connectivity. (Figure 3) (c) Post-callosotomy contrast-enhanced T1 attacks and generalized [1,2]. • sEEG monitoring post-callosotomy MRI. (a) Representative rs-fMRI pre- and post- Seizure lateralization after callosotomy has revealed lateralized seizure foci in 3 callosotomy demonstrating decreased also been described[3,4]. Callosotomies patients. Two elected for resection of Figure 2 resting state interhemispheric connectivity. have been successfully performed using epileptic focus and are seizure free at (b) Sample electrode contact for CCEP traditional, endoscopic, CO2-laser, and 18 months. The remaining patients (red dot) (c) High gamma power correlation radiosurgical approaches. Magnetic experienced an 83% and 100% of rsECoG recorded in left hemisphere pre- resonance imaging (MRI)-guided laser decrease in generalized seizure interstitial thermal therapy (LITT) is a frequency. and post-callosotomy showing decrease in minimally invasive procedure that is • No neurological morbidity HGP correlation in diffuse fronto-parietal gaining increasing use to treat a variety of encountered. locations (d) Representative mean cortico- brain abnormalities associated with tumor cortical evoked potential showing loss of and epilepsy[5]. Here we report corpus Conclusions the characteristic shape implying direct callosotomy performed in four patients MRI-guided LITT provides a viable Representative DTI demonstrating large functional connectivity between the two using LITT. minimally-invasive alternative approach to decrease in fractional anisotropy (FA) regions was disrupted. corpus callosotomy in the treatment of within the corpus callosum post- References medically intractable epilepsy. Functional Clinical characteristics and seizure callosotomy. 1. Tanriverdi T, et al. JNS 110(2):332-342. 2. connectivity measurements may aid in outcomes of patients undergoing MRI- Bower RS, et al. 73(6):993-1000. demonstrating the extent of callosotomy. 3. Clarke DF, et al. Seizure 16(6):545-553. 4. guided LITT corpus callosotomy Matsuzaka T, et al. Epilepsia 40(9):1269-1278. 5. Medvid R, et al. AJNR 36(11):1998-2006.