[Lesions of the corpus callosum and syndromes of interhemispheric disconnection of traumatic origin]

Abstract

We review the different kinds of injury to the corpus callosum in closed head trauma, as well as their different mechanisms. Most frequent lesions are either diffuse and at the microscopic level, secondary to disruption of axons at the time of the trauma, or focal and at macroscopic level, also due to torsion or shearing strains on the corpus callosum. They are associated with diffuse axonal injury of hemispheric and brainstem white matter. Focal macroscopic lesions, sometimes extensive, are encountered in 16-40% of autopsies after fatal head injury. Likewise, MRI allows nowadays to show them in 22-49% of nonfatal head injuries. Such lesions can produce an interhemispheric disconnection syndrome. However, clinical observation of an interhemispheric disconnection after head trauma has been only rarely reported in the literature, as it is showed by a brief overview of those cases, which suggests that this pathology is probably often overlooked. Focal damage to the corpus callosum seems to be a marker of severe injury, with often long-lasting coma and sometimes transitory vegetative state or mutism. Extension of posterior callosal lesions towards adjacent midline structures, such as the fornix, could contribute to the important memory impairment which is particularly frequently associated with posttraumatic interhemispheric disconnection syndromes.