Rhythmic interlimb coordination of the lower limbs in multiple sclerosis during auditory pacing to three different frequencies

Abstract

Background: Multiple sclerosis (MS) is a demyelinating disorder of the central nervous system with heterogeneous symptoms. Persons with MS (PwMS) show reduced walking capacity with changes in their gait pattern. It is unknown to which extent coordination deficits are present in PwMS, which can be measured by seated lower leg interlimb coordination tasks, and to which extent they are related to motor and cognitive function. Research question: How is the control of interlimb coordination of the lower limbs characterized in PwMS compared to healthy controls (HC) during a seated rhythmical coordination task and what is the relationship between interlimb coordination, motor or cognitive function? Methods: Rhythmical interlimb coordination was assessed during a single session in 38 PwMS and 13 HC, using a seated rhythmical coordination task, comprising of antiphase flexion-extension of the lower limbs, to metronomes at 0.75 Hz, 1.00 Hz, 1.50 Hz. Outcomes were phase coordination index (PCI), movement amplitude and movement frequency. Correlations between interlimb coordination, motor, and cognitive function were examined. Results: PwMS showed impaired walking capacity but preserved cognitive function. Mixed model analysis revealed a significant effect of group and metronome frequency for PCI, attenuated by the variability in generating knee (antiphase flexion-extension) movements. Movement amplitude was highest at metronome frequency 1.00 Hz. In PwMS significant correlations were found between PCI and cognitive function when performing the task at metronome frequencies 0.75 Hz and 1.50 Hz, as well as motor function at 1.50 Hz. Significance: PwMS had a higher variability in interlimb coordination compared to HC. The most stable interlimb antiphase coordination mode was performed at 1.00 Hz. Significant correlations support the existence of a relationship between information processing speed, as well as walking impairment, with interlimb coordination. While cognitive and motor control are always needed for interlimb coordination movements, associations are strongest in the deviant higher and lower metronome rhythms.