Abstract WP224: Etiology of Lesions with Restricted Diffusion in the Corpus Callosum
Background: Infarction of the corpus callosum (CC) is a rare event that has been poorly described in the literature. Multiple non-vascular lesions may also cause restricted diffusion in the CC on MRI, leading to diagnostic uncertainty. We sought to identify the etiology of lesions with diffusion restriction in the CC, hypothesizing they were often due to a non-vascular etiology and, in cases of infarct, that the mechanism of stroke would often be atypical.
Methods: CC lesions with diffusion restriction on MRI were identified in the radiology database at our institution over a 10 year period using the search terms “callosum,” “diffusion,” and “restricted/restriction”. Known trauma, brain tumor, and/or post-surgical cases were excluded. Radiographic and clinical features were independently reviewed by two investigators to determine the etiology of the lesion and the underlying mechanism. Vascular and non-vascular cases were compared.
Results: One hundred and twenty one cases were reviewed. Of these, 67% were stroke and 33% were non-vascular. Lesions were present in the genu in 26%, body in 30%, and splenium in 63% of cases; 17% had lesions in multiple territories and 5% in all territories. Additional lesions with restricted diffusion were found outside of the CC in 80% of cases. Atypical mechanisms of stroke such as vasculitis or hypercoaguable state were most common (37% of stroke cases), followed by cardioembolic (28%), cryptogenic (22%), large vessel (7%), and multiple causes (5%). The most common non-vascular etiology was demyelination (35%). Patients with a non-vascular lesion were younger, (46 years vs 56 years, p=0.0036), more often had lesions in multiple CC segments, 25% vs 12% (p=0.078), less often had additional lesions outside the CC (68% vs 86%, p=0.014) and were less likely to have vascular risk factors including hypertension (24% vs 76%, p=0.02), diabetes (19% vs 81%, p=0.06), and atrial fibrillation (7% vs 93%, p=0.03).
Conclusions: Diffusion restriction in the CC is due to a non-vascular cause in one third of cases. In cases of stroke, atypical etiologies are common. Clinical and imaging characteristics can help distinguish stroke from non-vascular lesions in the CC.
- © 2012 by American Heart Association, Inc.