Anterior versus Posterior: Evolving Evidence in Callosotomy for Drug-Resistant Epilepsy

Dear Editor,We thank Prof. Martins et al. [1] for their thoughtful and articulate comments on our recent review and clinical decision-making framework on contemporary neurosurgical approaches for generalized drug-resistant epilepsy [2]. Their perspective in support of selective posterior corpus callosotomy (CC) is well received, and we agree that mounting evidence supports its potential role as a safe and effective option for controlling drop attacks.Historically, selective anterior CC was preferred based on the hypothesis that sectioning posterior callosal fibers might cause greater disruption of interhemispheric motor and sensory integration, leading to disconnection syndromes [3, 4]. As discussed in our review and reiterated by Prof Martins and colleagues, recent decades have seen the emergence of posterior callosotomy, targeting the splenium, isthmus, and posterior body of the corpus callosum in select patients with generalized DRE [5‒7]. Multiple large series have demonstrated significant reductions in drop attacks following selective posterior CC, with minimal cognitive morbidity [5, 7]. These benefits may reflect complete disruption of transcallosal fibers connecting sensorimotor regions compared to selective anterior CC [7]. We fully agree with our colleagues that comparative studies would be useful to delineate the relative efficacy and safety profiles of selective anterior versus posterior CC for the treatment of generalized DRE.We also suspect that a “one size fits all” – anterior versus posterior – approach may leave little room for nuance in surgical decision-making. Certain patients may benefit from one approach over another (or often from a complete callostomy). Advances in functional brain mapping may inform individualized risk profiles and guide personalized treatment decisions. To this end, tractography and functional MRI have shown early promise in mapping functionally significant connections within the corpus callosum on an individualized basis [8‒12]. Such technological advances may facilitate more tailored, patient-specific intervention that could minimize neurocognitive risk.In conclusion, we welcome the insightful additions of Prof. Martins and colleagues, which highlight the growing recognition of selective posterior callosotomy as an important addition to the surgical armamentarium for generalized drug-resistant epilepsy. We anticipate that ongoing comparative studies, combined with advanced brain mapping technologies, will prove effective in determining ideal surgical treatments for individual patients.K.M. has no conflicts of interest to disclose. G.M.I. receives consulting fees from Medtronic Inc. and also reports a relationship with Synergia Inc. and LivaNova Inc. that includes consulting and advisory fees and investigator-initiated funding. These organizations played no role in any part of the current work.The authors declare no funding was obtained or used for this study.K.M. and G.M.I. drafted and revised the manuscript.