title: Corpus callosum and epilepsies.
abstract: OBJECTIVE
  Corpus callosum (CC) is the largest forebrain commissure. This review focuses on the significance of CC for seizure disorders, the role of CC in seizure spread and the surgical disruption of callosal fibers (callosotomy) for treatment of patients with drug-resistant epilepsy.
  
  
  METHODS
  Personal experience/extensive literature review.
  
  
  RESULTS
  Structural CC pathologies comprise developmental abnormalities, callosal involvement in identified disorders, transient imaging findings and microstructural changes. Epilepsies are reported in up to two thirds of patients with complete or partial CC agenesis (AgCC). However, AgCC per se is not indicative for seizure disorders. Moreover, additional malformations of cortical development (MCD) are causal. Microstructural CC abnormalities are detected by advanced imaging techniques, are part of diffuse white matter disturbances and are related to cognitive deficits. The etiological significance remains unexplained. However, they are also found in non-epileptic benign and transient disorders. In drug-resistant epilepsies with violent drops to the floor ("drop seizures") callosotomy may be beneficial in seizure reduction. Since the EEG after callosotomy exhibits a single seizure focus in up to 50% of patients, consecutive resective surgical methods might be successful.
  
  
  CONCLUSIONS
  CC is part of cerebral white matter and anomalies cannot act per se as seizure onset zone. Imaging techniques demonstrate additional lesions in patients with epilepsies. CC is the major pathway for seizure generalization. Therefore, callosotomy is used to prevent generalized drop seizures.
authors.affiliation: Department of Neurology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria. Electronic address: iris.unterberger@tirol-kliniken.at.
authors.forename: Iris
authors.initials: I
authors.lastname: Unterberger
authors.affiliation: Department of Neurosurgery, Landeskrankenhaus Feldkirch, Carinagasse 47, 6800 Feldkirch, Austria.
authors.forename: Richard
authors.initials: R
authors.lastname: Bauer
authors.affiliation: Department of Neurology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
authors.forename: Gerald
authors.initials: G
authors.lastname: Walser
authors.affiliation: Department of Neurology, Innsbruck Medical University, Anichstrasse 35, A-6020 Innsbruck, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bauer
mesh_terms: D061085:Agenesis of Corpus Callosum / Q000175:diagnosis / Q000601:surgery*; D003337:Corpus Callosum / Q000503:physiopathology* / Q000601:surgery*; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D012640:Seizures / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome
keywords: Callosotomy; Corpus callosum; Drop seizures; Epilepsy