Brain and cervical spinal cord MRI correlates of sensorimotor impairment in patients with multiple sclerosis

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Spinal cord (SC) involvement, particularly cervical SC (cSC) atrophy and lesions, is increasingly recognized as a key determinant of disability in multiple sclerosis (MS), yet its role in specific sensorimotor impairments remains underexplored. This cross-sectional multiparametric MRI study aimed to assess the relative contribution of brain and cSC lesion burden and atrophy to global disability and specific sensorimotor functions in MS. A total of 151 MS patients and 69 age- and sex-matched healthy controls underwent 3T brain and cSC MRI and clinical evaluations including Expanded Disability Status Scale (EDSS), pyramidal and sensory functional system (P-FS, S-FS) scores, motor performance tests (9-hole peg test [9-HPT], finger tapping test [FTT], timed 25-foot walk test [T25FWT]), and vibration detection threshold (VDT). Random forest models identified MRI features most predictive of disability milestones (EDSS ≥3.0, ≥4.0, and ≥6.0), functional system impairments, and motor/sensory test performance. Across all outcomes, cSC gray matter cross-sectional area (GM CSA) emerged as the most informative variable, outperforming brain volumetric and lesion metrics. GM CSA was the strongest predictor of progressive MS phenotype and higher EDSS scores (AUC up to 0.900). It also best explained impairments in lower limb motor function (T25FWT), upper limb repetitive motor performance (FTT), and vibratory sensation (VDT). In contrast, 9-HPT impairment, a more complex dexterity task, was associated with a broader combination of cSC and brain abnormalities, including lesion burden and cortical and deep gray matter atrophy. VDT impairment was linked to volume loss in both cSC GM and white matter (WM), supporting the role of dorsal columns and posterior horns in somatosensory processing. Brain metrics, particularly thalamic volume, also contributed to VDT variability. The findings highlight the predominant role of cSC GM atrophy as a structural correlate of sensorimotor impairment and disability in MS, especially at higher levels of functional decline. These results support integrating spinal cord MRI, particularly quantification of GM damage, into routine clinical assessments to enhance prognostic accuracy and guide personalized interventions in MS management.

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