Location of brain lesions predicts conversion of clinically isolated syndromes to multiple sclerosis

From the Department of Neurological and Behavioral Sciences (A.G., M.B., A.D.L, N.D.S.), University of Siena, Siena
Neurology (Impact Factor: 8.29). 12/2012; 80(3). DOI: 10.1212/WNL.0b013e31827debeb
Source: PubMed


To assess in a large population of patients with clinically isolated syndrome (CIS) the relevance of brain lesion location and frequency in predicting 1-year conversion to multiple sclerosis (MS).

In this multicenter, retrospective study, clinical and MRI data at onset and clinical follow-up at 1 year were collected for 1,165 patients with CIS. On T2-weighted MRI, we generated lesion probability maps of white matter (WM) lesion location and frequency. Voxelwise analyses were performed with a nonparametric permutation-based approach (p < 0.05, cluster-corrected).

In CIS patients with hemispheric, multifocal, and brainstem/cerebellar onset, lesion probability map clusters were seen in clinically eloquent brain regions. Significant lesion clusters were not found in CIS patients with optic nerve and spinal cord onset. At 1 year, clinically definite MS developed in 26% of patients. The converting group, despite a greater baseline lesion load compared with the nonconverting group (7 ± 8.1 cm3 vs. 4.6 ± 6.7 cm3, p < 0.001), showed less widespread lesion distribution (18% vs. 25% of brain voxels occupied by lesions). High lesion frequency was found in the converting group in projection, association, and commissural WM tracts, with larger clusters being in the corpus callosum, corona radiata, and cingulum.

Higher frequency of lesion occurrence in clinically eloquent WM tracts can characterize CIS subjects with different types of onset. The involvement of specific WM tracts, in particular those traversed by fibers involved in motor function and near the corpus callosum, seems to be associated with a higher risk of clinical conversion to MS in the short term.

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    ABSTRACT: Clinically isolated syndrome (CIS) describes a first symptomatic neurologic episode that is consistent with multiple sclerosis (MS), lasts at least 24 hours, occurs in the absence of fever or infection, and presents without encephalopathy.(1) Its cause is inflammation or demyelination in one (i.e., monofocal episode) or multiple areas (i.e., multifocal episode) of the CNS. Symptoms are those commonly found in MS and include, for example, optic neuritis, sensory or motor signs, partial myelitis, and bladder or bowel dysfunction.(1).
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