Unraveling the neuroimaging predictors for motor dysfunction in long-standing multiple sclerosis.

Abstract

To find the strongest neuroimaging predictors for motor dysfunction using conventional and quantitative imaging measures focusing on the corticospinal tract (CST) in a large cohort of patients with long-standing multiple sclerosis (MS). In this cross-sectional study, a wide spectrum of neuroimaging measures at the whole-brain, cervical, and CST level were analyzed in 195 patients with MS and 54 healthy controls. Motor function was assessed using the Expanded Disability Status Scale (EDSS), 9-Hole Peg Test, Timed 25-Foot Walk Test, and Multiple Sclerosis Walking Scale. Associations between damage in different parts of the motor system and motor functioning were assessed using stepwise linear regression. Patients had an average disease duration of 19.98 (±6.99) years and a median EDSS score of 4 (range: 1.0-8.0). EDSS score was associated with number of infratentorial and cervical cord lesions, lesion volume in the CST, and mean upper cervical cord area (adjusted R(2) = 0.403). Timed 25-Foot Walk Test score was associated with number of infratentorial lesions and cerebellar volume (adjusted R(2) = 0.150), 9-Hole Peg Test score with number of infratentorial lesions and thickness of the cortex connected to the CST (adjusted R(2) = 0.245), and Multiple Sclerosis Walking Scale with number of infratentorial and cervical lesions, thickness of the cortex connected to the CST, and mean upper cervical cord area (adjusted R(2) = 0.354). Motor dysfunction in MS has a complex substrate that cannot be ascribed to a single neuroimaging finding, but is the consequence of infratentorial and spinal cord damage, as well as damage in the CST.