Persons with Multiple Sclerosis Exhibit Strength Asymmetries in both Upper and Lower Extremities

Abstract

Objective: To characterize strength asymmetries in the upper and lower extremities in persons with multiple sclerosis (PwMS) with severe disability, and examine associations between asymmetries and functional, symptomatic, and participatory outcomes.

Design: Cross-sectional.

Setting: University research laboratory.

Participants: 25 PwMS with Expanded Disability Status Scale scores between 6.0-8.0.

Main outcome measures: Bilateral strength and asymmetry scores for muscle groups at the ankle, knee, and shoulder joints in addition to grip strength.

Results: Significant differences were observed between all contralateral strength measures, with asymmetry scores ranging between 20-32%. A high prevalence of asymmetry (i.e., score>10%) was observed for all strength measures, with 92% of participants having four or more affected measures. Significant associations were observed between dorsiflexion asymmetry and physical health-related quality of life (ρ= -0.69; p<0.001), and between shoulder flexion asymmetry and lower extremity function (ρ= -0.62; p=0.001). Plantarflexion (ρ= 0.61; p=0.003) and knee flexion (ρ= 0.63; p=0.002) asymmetry were significantly associated with lower extremity functional asymmetry.

Conclusions: A high prevalence of asymmetry in the upper and lower extremities was observed, with asymmetry scores exceeding those previously reported in PwMS with mild-to-moderate disability. Rehabilitation strategies should consider a full body approach to address strength asymmetries.

Keywords: asymmetry; multiple sclerosis; muscle strength; muscle weakness.