Corpus Callosotomy: Indications and Techniques

In 1940, William P. van Wagenen and R. Yorke Herren described a small series of patients with various disruptive lesions of the corpus callosum. Their report highlighted the phenomenologic distinction between generalized convulsive seizures in individuals with tumors near the intact callosum and only partial seizures following insidious invasion of the corpus callosum months to years later. The hypothesis that interruption of the corpus callosum could alter the bihemispheric spread of seizure activity in epileptic individuals led to the simple yet elegant conclusion that surgical division of the corpus callosum might confine epileptogenic foci to a single hemisphere and thus ameliorate secondary seizure generalization. At the time of their writing, the practice of excising regions of brain tissue to eliminate seizures had been firmly established, although with varying rates of success. Nevertheless, the historical significance of van Wagenen and Herren’s careful observations cannot be overstated. They set the stage for the first corpus callosotomy lesions performed with the intent of stopping seizure propagation to the contralateral hemisphere in individuals with intractable epilepsy, marking a critical advancement in the field of modern epilepsy surgery.

In the 10 cases of corpus callosotomy that constituted van Wagenen and Herren’s landmark report, there was significant reduction in seizure frequency, with few permanent adverse effects. Curiously, however, the practice of corpus callosotomy for treatment of epilepsy was rarely used until more than 20 years later, when the next case reports of corpus callosotomy in humans appeared and the procedure began to gain acceptance within the neurosurgical community. The procedure itself has undergone various technical modifications, including total versus partial callosotomy, anterior versus posterior approaches, single versus multistaged operations and even radiosurgical callosotomy. ^, Furthermore, 21st-century technology for less invasive neurosurgical approaches, such as vagal nerve stimulation, and the advent of novel antiepileptics have led to reconsideration of the role of surgical corpus callosotomy for patients having intractable seizures without a focally resectable lesion. However, the safety and efficacy of this procedure have been substantiated in more than 60 years of empiric and retrospective studies in humans and experimental studies in animals. ^{, , ,} Van Wagenen and Herren’s seminal work directly contributed to the first theoretical interpretation of “split-brain” syndromes by Andrew J. Akelaitis and eventually culminated in the awarding of a Nobel Prize to the neuropsychologist Roger Sperry for his innovative tachistoscopic experiments on disconnected patients. Sperry’s insights subsequently led to more detailed anatomic and physiologic studies of callosal function, which have helped shape our contemporary understanding of the functional lateralization of the cerebral hemispheres.