Assessing visually guided reaching in people with multiple sclerosis with and without self-reported upper limb impairment

Metabolic costs of walking and arm reaching in persons with mild multiple sclerosis

Movement slowness is a common and disruptive symptom of multiple sclerosis (MS). A potential cause is that individuals with MS slow down to conserve energy as a behavioral adjustment to heightened metabolic costs of movement. To investigate this prospect, we measured the metabolic costs of both walking and seated arm reaching at five speeds in persons with mild MS (pwMS; n = 13; 46.0 ± 7.7 yr) and sex- and age-matched controls (HCs; n = 13; 45.8 ± 7.8 yr). Notably, the cohort of pwMS was highly mobile and no individuals required a cane or aid when walking. We found that the net metabolic power of walking was approximately 20% higher for pwMS across all speeds (P = 0.0185). In contrast, we found no differences in the gross power of reaching between pwMS and HCs (P = 0.492). Collectively, our results suggest that abnormal slowness of movement in MS-particularly reaching-is not the consequence of heightened effort costs and that other sensorimotor mechanisms are playing a considerable role in slowing.NEW & NOTEWORTHY Individuals with multiple sclerosis (MS) often move more slowly than those without the disease. A possible cause is that movements in MS are more energetically expensive and slowing is an adaptation to conserve metabolic resources. Here, we find that while walking is more costly for persons with MS, arm-reaching movements are not. These results bring into question the driving force of movement slowness in MS and implicate other motor-related networks contributing to slowing.

Assessing proprioceptive acuity in people with multiple sclerosis

Background

Proprioceptive acuity and impairments in proprioceptively guided reaches have not been comprehensively examined in people with multiple sclerosis (MS).

Objective

To examine proprioceptive acuity in people with MS who self-report and who do not self-report upper limb (UL) impairment, and to determine how people with MS reach proprioceptive targets.

Methods

Twenty-four participants with MS were recruited into two groups based on self-reported UL impairment: MS-R (i.e. report UL impairment; n  =  12) vs. MS-NR (i.e. do not report UL impairment; n  =  12). Proprioception was assessed using ipsilateral and contralateral robotic proprioceptive matching tasks.

Results

Participants in the MS-R group demonstrated worse proprioceptive acuity compared to the MS-NR group on the ipsilateral and contralateral robotic matching tasks. Analyses of reaches to proprioceptive targets further revealed that participants in the MS-R group exhibited deficits in movement planning, as demonstrated by greater errors at peak velocity in the contralateral matching task in comparison to the MS-NR group.

Conclusion

Our findings suggest that people with MS who self-report UL impairment demonstrate worse proprioceptive acuity, as well as poorer movement planning in comparison to people with MS who do not report UL impairment.