Pulse Width Does Not Influence the Gains Achieved With Neuromuscular Electrical Stimulation in People With Multiple Sclerosis: Double-Blind, Randomized Trial

Abstract

Background: Multiple sclerosis (MS) eventually compromises the walking ability of most individuals burdened with the disease. Treatment with neuromuscular electrical stimulation (NMES) can restore some functional abilities in persons with MS, but its effectiveness may depend on stimulus-pulse duration.

Objective: To compare the effects of a 6-week intervention with narrow- or wide-pulse NMES on walking performance, neuromuscular function, and disability status of persons with relapsing-remitting MS.

Methods: Individuals with MS (52.6 ± 7.4 years) were randomly assigned to either the narrow-pulse (n = 13) or wide-pulse (n = 14) group. The NMES intervention was performed on the dorsiflexor and plantar flexor muscles of both legs (10 minutes each muscle, 4 s on and 12 s off) at a tolerable level for 18 sessions across 6 weeks. Outcomes were obtained before (week 0) and after (week 7) the intervention and 4 weeks later (week 11).

Results: There was no influence of stimulus-pulse duration on the outcomes ( P > .05); thus, the data were collapsed across groups. The NMES intervention improved ( P < .05) gait speed and walking endurance, dorsiflexor strength in the more-affected leg, plantar flexor strength in the less-affected leg, force control for plantar flexors in the less-affected leg, and self-reported levels of fatigue and walking limitations.

Conclusion: There was no influence of stimulus-pulse duration on the primary outcomes (gait speed and walking endurance). The 6-week NMES intervention applied to the lower leg muscles of persons with mild to moderate levels of disability can improve their walking performance and provide some symptom relief.

Keywords: force steadiness; multiple sclerosis; muscle strength; neuromuscular electrical stimulation; walking endurance; wide pulse.

Conflict of interest statement

Declaration of Conflicting Interests

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1

The intervention setup showing the stimulation pads locations over the plantar flexor (A) and dorsiflexor (D) muscles, the standing positions when stimulation was applied to the plantar flexor (B) and dorsiflexor (E) muscles, and the sitting position when stimulation was applied to the plantar flexor (B) and dorsiflexor (E) muscles.

Figure 2

The relative (%) improvement in the distance walked in 6-min and time taken to walk 25 ft immediately at Weeks 7 and 11.

CONSORT 2010 Flow Diagram