Additional clinical history: The patient is an alcoholic.
Findings
CT shows mild prominence of the ventricles and sulci consistent with mild generalized cerebral volume loss. There is hypodensity involving the entire anterior and posterior corpus callosum. There are no intra or extra-axial fluid collections, midline shift, or mass effect. The basilar cisterns are patent. MRI shows abnormal T2 prolongation involving the entire genu and splenium of the corpus callosum. On T1, there is low signal intensity in the corpus callosum. On other images (not shown) there was no abnormal enhancement of the corpus callosum, and there was increased signal in the corpus callosum on diffusion weighted imaging.
Differential diagnosis for corpus callosum lesions:
- Ischemia
- Lymphoma
- Gliobastoma multiforme
- Metastasis
- Demyelinating disorders (MS, ADEM, PML)
- Marchiafava-Bignami syndrome
- Trauma shearing injury
- Toxoplasmosis
Diagnosis: Marchiafava-Bignami
Key points
Alcoholic patients and others with nutritional deficiencies may sustain demyelination of the corpus callosum, which may be considered a variant of extrapontine myelinolysis. It may also be more extensive and involve other brain regions. In an alcoholic patient with sudden onset of encephalopathy, this diagnosis should be considered. Marchiafava-Bignami syndrome is characterized by demyelination and central necrosis of the corpus callosum, often presenting with seizures, neurologic dysfunction, and coma. This is a rare syndrome with approximately 150 reported cases in the literature. There is a high incidence of mortality with this disorder. There is a subacute form which displays sudden onset of dementia progressing to the chronic vegetative state and a chronic form characterized by progressive dementia and a disconnection syndrome. The genu and splenium are often involved in the acute form and the body in the chronic form. Treatment is largely supportive and IV thiamine may be of some benefit.
Radiological overview
On non-contrast head CT, there will be hypodensity involving corpus callosum.
On MRI, there will be low T1 signal intensity in the corpus callosum due to edema and cystic change. There will be high signal predominantly in the genu and splenium on T2 weighted images. Diffuse weighted images are positive in the acute form signifying restricted diffusion and ischemic injury.
