The classic triad of diffuse axonal injury is that of diffuse damage to axons located at the gray-white matter interface of the cerebral hemispheres, the dorsolateral aspect of the rostral brainstem, and the corpus callosum. Injury to the corpus callosum occurs commonly with head trauma, being detected on MR imaging in 47% of patients with nonfatal head injuries. In the subacute and chronic forms, the lesions involve the central part of the body most commonly and are hypointense on T1-weighted images and hyper- or hypointense (hemosiderin deposits) on T2-weighted images (Fig. The corpus callosum is of low signal on T1-weighted images and high signal on T2-weighted images and often enhances. In the acute form, the central corpus callosum enlarges, presumably because of edema. The acute form affects the genu and splenium, whereas the chronic form most commonly affects the body. The disease can follow one of three clinical courses, a fulminate acute form or subacute and chronic forms. The central layers of the corpus callosum are affected, with sparing of the dorsal and ventral layers (sandwich sign). It was first described in Italian wine drinkers and is thought to be due to chronic and massive alcohol use. Marchiafava-Bignami disease is a rare demyelinating neurologic disorder, primarily affecting the corpus callosum. Differentiation should be made from ischemia, trauma, and other demyelinating processes on the basis of morphology, location, and the presence of concurrent multiple sclerosis plaques in the periventricular region (Fig. Enhancement is common in the acute stage. The lesions are hyperintense on long-TR sequences and can best be seen with proton-density and fluid-attenuated inversion recovery (FLAIR) sequences.
Atrophy of the corpus callosum can coexist in long-standing multiple sclerosis, making the diagnosis of corpus callosum lesions difficult. On MR imaging, the prevalence of lesions in the corpus callosum has been reported to be up to 93% in the radiology literature. The lesions of the corpus callosum can be focal or confluent nodular lesions and tend to affect the callosal-septal interface, which is the central inferior aspect of the corpus callosum. Lesions characteristically involve the periventricular white matter, internal capsule, corpus callosum, and pons, although plaques can be found anywhere in the white matter and less commonly even in gray matter.
Multiple sclerosis is a demyelinating disease of unknown cause that more commonly affects young women.
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