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P0582 - High resolution functional mapping of upper and lower limb sensorimotor function in minimally disabled people with multiple sclerosis using 7T MRI (ID 1050)
In multiple sclerosis (MS) upper and lower limbs can be affected, but impairments only moderately relate to each other. Previous motor task studies have focussed predominantly on imaging hand function at clinical field strengths, preventing the detection of subtle changes and differentiation of mechanisms underlying subtle motor impairment.
To investigate functional brain changes related to upper and/or lower limb motor task performance in minimally disabled MS patients using ultra-high field MRI.
Twenty-eight MS patients and seventeen healthy controls underwent visually-guided force-matching fMRI tasks using either hand or foot. Task performance (force error and lag) and activation level during upper and lower limb movements were compared between groups. Correlations were assessed between task activation and behavioural performance.
During lower limb force tracking, MS patients showed significantly (p<0.01) longer lag, higher force error, higher primary motor and premotor cortex activation and lower cerebellar Crus I/II activation, compared to controls. No differences were seen in upper limb performance or activation. Upper and lower limb task performance was related to the level of activation in cerebellar, visual and motor areas in MS patients.
Altered lower limb movements and brain activation with preserved upper limb function and activation in minimally disabled patients suggests partially divergent functional mechanisms underlying upper and lower limb disability.