Validation of corpus callosotomy after laser interstitial thermal therapy: a multimodal approach

Abstract

ObjectiveDisconnection of the cerebral hemispheres by corpus callosotomy (CC) is an established means to palliate refractory generalized epilepsy. Laser interstitial thermal therapy (LITT) is gaining acceptance as a minimally invasive approach to treating epilepsy, but this method has not been evaluated in clinical series using established methodologies to assess connectivity. The goal in this study was to demonstrate the safety and feasibility of MRI-guided LITT for CC and to assess disconnection by using electrophysiology- and imaging-based methods.MethodsRetrospective chart and imaging review was performed in 5 patients undergoing LITT callosotomy at a single center. Diffusion tensor imaging and resting functional MRI were performed in all patients to assess anatomical and functional connectivity. In 3 patients undergoing simultaneous intracranial electroencephalography monitoring, corticocortical evoked potentials and resting electrocorticography were used to assess electrophysiological correlates.ResultsAll patients had generalized or multifocal seizure onsets. Three patients with preoperative evidence for possible lateralization underwent stereoelectroencephalography depth electrode implantation during the perioperative period. LITT ablation of the anterior corpus callosum was completed in a single procedure in 4 patients. One complication involving misplaced devices required a second procedure. Adequacy of the anterior callosotomy was confirmed using contrast-enhanced MRI and diffusion tensor imaging. Resting functional MRI, corticocortical evoked potentials, and resting electrocorticography demonstrated functional disconnection of the hemispheres. Postcallosotomy monitoring revealed lateralization of the seizures in all 3 patients with preoperatively suspected occult lateralization. Four of 5 patients experienced > 80% reduction in generalized seizure frequency. Two patients undergoing subsequent focal resection are free of clinical seizures at 2 years. One patient developed a 9-mm intraparenchymal hematoma at the site of entry and continued to have seizures after the procedure.ConclusionsMRI-guided LITT provides an effective minimally invasive alternative method for CC in the treatment of seizures associated with drop attacks, bilaterally synchronous onset, and rapid secondary generalization. The disconnection is confirmed using anatomical and functional neuroimaging and electrophysiological measures.

Recent advances in the neurosurgical treatment of pediatric epilepsy

“…33 In a 2018 study, Lehner et al report on 5 adult patients who underwent LITT for anterior corpus callosotomy. 40 Effective disconnection with LITT was validated by evaluating diffusion tensor imaging (DTI), resting-state functional MRI (r-fMRI), and cortico-cortical evoked potentials (CCEPs) in select patients undergoing concomitant SEEG. DTI revealed decreased fractional anisotropy in the region of the ablated corpus callosum relative to the remainder of the nonablated corpus callosum.…”

“…Collectively, these data provide strong support in a small number of adult patients studied before and after LITT callosotomy. 40…”

Letter to the Editor. Resting-state functional MRI for functional neurosurgery: seeing the light?

“…We read with great interest the recent article by Lehner 5 et al, discussing the corpus callosotomy performed by laser interstitial thermal therapy (LITT), in a small cohort of 5 patients, in the context of a multimodal approach. The authors additionally used resting-state functional MRI (rs-fMRI) to assess the outcome of this functional neurosurgery intervention.…”

How technology is driving the landscape of epilepsy surgery

“…These advantages have led to the proliferation of LITT to treat a broad range of epileptic conditions, many of which have yet to generate sufficient evidence to determine efficacy. This includes hemispheric disconnections such as corpus callosotomy using multiple lasers, 36 lesional and nonlesional focal epilepsy in deep and functionally eloquent anatomic locations such as the insula, 37 and focal and multifocal epilepsy in patients with cavernous malformation 38 or tuberous sclerosis complex 24 …”