In Reply to “Corpus Callosotomy for Drug-Resistant Schizophrenia; Novel Treatment Based on Pathophysiology” W e read with great interest the comments made by Taghipour and Ghaffarpasand 1 concerning the poor clinical response to psychosurgery of patients with schizophrenia. On the basis of Julian Jaynes’ controversial theory of the bicameral mind and a number of pathophysiologic findings, they postulate that anterior corpus callosotomy in patients with refractory schizophrenia could interfere with transmission and conductance of aberrant stimulation from right brain language areas to the left brain. To our knowledge, a few cases of anterior corpus callosotomy have actually been reported by the Finnish neurosurgeon Laitinen, 2-5 although he referred to the operation as anterior mesoloviotomy, which is derived from the Greek word mesolovion for corpus callosum (for review see 6 ). Interestingly, and in contrast to most other psychosurgical procedures at this time, stimulation or lesions in this region were reportedly most effective in patients with schizophrenia, while there was little or no effect in patients suffering from depression or obsessive-compulsive disorders. In addition, psychologic assessments after anterior mesoloviotomy revealed no evident deficits (compared with preoperative tests) but maintained improvements in memory function and intelligence. 2 With this in mind, we certainly agree with Taghipour and Ghaffarpas that the anterior corpus callosum could be a promising target for psychosurgery in patients with treatment-resistant schizophrenia. With regard to the scientific basis, we think it is important to keep in mind that most mechanisms involved in the effects of psychosurgery are not well established. Jaynes’ theory, while innovative and thought provoking, was founded on neurobiologic knowledge available around 1970. Even though the debate it provoked appears to support some contemporary approaches to deconstruct the concept of a unitary self as a coherent center of consciousness, neurophysiologic data provide only weak support for the theory. 7 Given that the original prefrontal leucotomy was also proposed as a treatment for schizophrenia that prevents spread of abnormal activity to other areas of the brain, it remains imperative to be vigilant about any ambiguous scientific rationale for psychosurgery. After all, the clinical utility of psychosurgery is still based more on pragmatic analysis of case reports than understanding of the scientific basis of the diseases. While callosotomy has been in continuous use for treating severe cases of treatment-resistant epilepsy 8 and previous reports about this operation in patients with schizophrenia are promising, they remain at best anecdotal. 2-5 Well-designed controlled trials, possibly with “reversible” approaches like deep brain stimulation, will therefore be necessary to establish the effectiveness of anterior callosotomy in patients with schizophrenia. Felix Neumaier 1 , Mario Paterno 2 , Serdar Alpdogan 1 , Etienne E. Tevoufouet 1 , Toni Schneider 1 , Ju ¨ rgen Hescheler 1 , Walid Albanna 3 From the 1 Institute for Neurophysiology, University of Cologne, Cologne; 2 Institute of Neuroscience and Medicine, Jülich; and 3 Department of Neurosurgery, RWTH Aachen University, Aachen, Germany To whom correspondence should be addressed: Felix Neumaier [E-mail: felix@neumaier-net.de] https://doi.org/10.1016/j.wneu.2018.04.206. REFERENCES 1. Taghipour M, Ghaffarpasand F. Corpus callosotomy for drug-resistant schizo- phrenia: a novel treatment based on the pathophysiology. World Neurosurg. 2018; 116:483-484. 2. Laitinen LV. Stereotactic lesions in the knee of the corpus callosum in the treatment of emotional disorders. Lancet. 1972;299:472-475. 3. Laitinen LV, Vilkki J. Observations on the transcallosal emotional connections. In: Laitinen L, Livingston K, eds. Surgical Approaches in Psychiatry. Baltimore, MD: University Park Press; 1973:74-80. 4. Vilkki J. Late psychological and clinical effects of subrostral cingulotomy and anterior mesoloviotomy in psychiatric illness. In: Sweet WH, Obrador S, Martin- Rodriguez JG, eds. Neurosurgical Treatment in Psychiatry, Pain, and Epilepsy. Baltimore, MD: University Park Press; 1977. 5. Neumaier F, Paterno M, Alpdogan S, Tevofouet EE, Schneider T, Hescheier J, et al. Surgical approaches in psychiatry: a survey of the world literature on psychosurgery. World Neurosurg. 2017;97:603-634. 6. Salminen V. The history of stereotactic psychosurgery in Finland. Psychiatr Fenn. 2014;45:85-106. 7. Cavanna AE, Trimble M, Cinti F, Monaco F. The “bicameral mind” 30 years on: a critical reappraisal of Julian Jaynes’ hypothesis. Funct Neurol. 2007;22:11-15. 8. Malmgren K, Rydenhag B, Hallböök T. Reappraisal of corpus callosotomy. Curr Opin Neurol. 2015;28:175-181. WORLD NEUROSURGERY 116: 485, AUGUST 2018 www.WORLDNEUROSURGERY.org 485 Letter to the Editor