Callosal lesion patterns differentiate multiple sclerosis (MS) from neuromyelitis optica spectrum disorders (NMOSD) and acute disseminated encephalomyelitis (ADEM), according to study data published in Multiple Sclerosis and Related Disorders.

The study investigators conducted a retrospective cohort study of Chinese individuals with MS (n=33), NMOSD (n=31), and ADEM (n=18). Brain and spinal cord magnetic resonance imaging (MRI) scans were obtained of all participants. Subsequently, 2 neurologists examined the MRI scans independently to determine lesion characteristics. In the study, the rostrum and genu were described together as the callosum “forepart”; the isthmus was considered part of the body.

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Lesion distribution, shape, and spreading shape was established. All quantitative data were assessed with the chi-squared test.

Lesions in the forepart of the corpus callosum were more common in patients with MS (69.7%) than patients with NMOSD (51.6%) or ADEM (22.2%). Patients with NMOSD (77.4%) more often had lesions in the callosal body compared with patients with MS (60.6%) or ADEM (55.6%). Splenial lesions were observed with similar frequency in patients with MS (54.5%) and NMOSD (54.8%), although less often in patients with ADEM (33.3%).

Compared with MS and NMOSD, ADEM lesions occurred less frequently in the rostrum and genu (P =.002). According to mid-sagittal images, ovoid lesion shapes were most common in MS (45.5%), radial lesions were more frequent in NMOSD (41.9%), and lesions with other shapes were most likely to be associated with ADEM (61.1%).

NMOSD and ADEM lesions were more likely to have a diffuse distribution (P =.006; P =.033) and blurred margins (P <.001; P =.017) compared with MS. Lesions with heterogeneous intensity occurred more often in NMOSD than MS (P =.016) and ADEM (P =.001).

Callosal lesions in MS tended to have a focal distribution and clear margins compared with NMOSD and ADEM lesions. Such characteristics may facilitate correct diagnosis with MRI scans, according to the investigators.

Reference

Cai M-T, Zhang Y-X, Zheng Y, Fang W, Ding M-P. Callosal lesions on magnetic resonance imaging with multiple sclerosis, neuromyelitis optica spectrum disorder and acute disseminated encephalomyelitis [published online April 16, 2019]. Mult Scler Relat Disord. doi:10.1016/j.msard.2019.04.019