Low-frequency electrical stimulation effective for stimulation of the wrist extensors in patients after stroke

1. Low-frequency electrical stimulation yields greater stimulation efficiency than kilohertz-frequency stimulation in stroke patients with arm paresis, though both modalities produce similar force, discomfort, and fatigue profiles.

Evidence Rating Level: 2 (Good) 

Stroke frequently results in upper limb paresis, severely impacting daily functioning. Electrical stimulation (ES) is a standard therapeutic intervention, but the optimal stimulation frequency for improving wrist extensor function in stroke patients remains unclear. This randomized crossover trial compared the acute effects of 1.0 kilohertz (kHz) versus low-frequency ES on stimulation efficiency, force production, discomfort, and fatigue in 20 stroke patients with arm paresis. Participants received both ES types in randomized order across two sessions, each including a stepwise intensity protocol and a muscle fatigue protocol. The primary outcome, stimulation efficiency (force per stimulation intensity), was significantly greater with low-frequency stimulation (mean difference 0.14 N/mA, p = .031). However, no significant differences were observed between current types for secondary outcomes including electrically induced force, perceived discomfort, or muscle fatigue. Force and discomfort increased with stimulation intensity regardless of frequency, while fatigue showed a consistent decline in force over repetitions for both conditions. Notably, large interindividual variability was present, emphasizing the importance of personalized treatment settings. Although both ES types are viable, low-frequency stimulation demonstrated superior efficiency at submaximal intensities, while kilohertz stimulation may offer advantages in early neuroactivation stages post-stroke.

Click to read the study in PMRJ

Image: PD

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