Treatment of upper extremity paresis using transcutaneous electrical stimulation during acute stroke

Abstract

Introduction: Previous randomized controlled trials on people with stroke showed that transcutaneous electrical stimulation (TES) of muscles, nerves or acupuncture points (acupoints) could reduce spasticity and improve muscle strength of lower extremities. Such effects have not been systematically demonstrated in the paretic upper extremities (UE), especially during the acute stage. Methods: A longitudinal cohort of 57 patients recruited at acute stroke units and receiving conventional rehabilitation (CR) was studied. The course and extent of recovery in the paretic UE in terms of (1) tactile sensation of pressure and two-point discrimination in the index finger, (2) muscle tone measured with the Composite Spasticity Score, (3) muscle strength of shoulder and elbow measured with the Motricity Index, (4) power grip and index pinch strength measured with a dynamometer, and (5) functional ability measured with the Action Research Arm Test, was documented over the first 6 months of stroke. Early clinical characteristics that predicted the recovery of functional dexterity at 6 months were delineated. A double-blind, randomized, placebo-controlled trial then investigated the effectiveness of TES applied to 6 acupoints for promoting recovery in the paretic UE. Patients recruited within 46 hours after stroke onset were randomized to receiving CR alone as controls (n=18), or to the TES (n=28) or placebo-TES (n=20) groups whose subjects were respectively given TES and placebo stimulation in addition to CR. Such treatment was started within 2 days of stroke, given 60 minutes per day, 5 days per week for 4 weeks. Including 19 subjects recruited within 60 hours of stroke and who had been receiving CR as controls, the 3 groups were compared their UE recovery. All subjects were reassessed weekly for the first 4 weeks and then at 1, 2, 3 and 5 months afterwards. Statistics used were descriptive analyses, logistic regressions and mixed model ANCOVA. Results: The sensory, motor and functional recovery was rapid in the first 1 to 2 months of stroke. UE muscle strength consistently predicted the recovery of functional dexterity at 6 months post-stroke. The strongest prediction was found at 4 weeks post-stroke, with power grip and index pinch strength being stronger predictors than the shoulder and elbow muscle strength. The TES programme induced better recovery in grip and pinch strength than CR alone when the 1-month treatment ended (P <0.01), and better UE functional ability 3 months afterwards (P <=0.01). These effects persisted beyond the end of the programme for at least 5 months. Differences between the placebo-TES and the TES or control groups could not be demonstrated in the present study. Conclusions: (1) The initial 4 weeks of stroke was the time window when rapid motor recovery occurred. (2) Muscle strength in the paretic UE, especially grip and pinch strength 4 weeks after stroke, strongly predicted the return of functional dexterity at 6 months. (3) Adding an early intensive TES programme to CR was effective in promoting greater grip and pinch strength than CR alone as early as 4 weeks after stroke, with carry-over effects lasting for at least 5 months after the programme ended. TES treatment given during acute stroke could be a promising adjunct to CR in promoting motor and functional recovery of a paretic UE.