Non-invasive treatment of patients with upper extremity spasticity following stroke using paired trans-spinal and peripheral direct current stimulation

Abstract

Background: Muscle spasticity is a common impediment to motor recovery in patients with chronic stroke. Standard-of-care treatments such as botulinum toxin injections can temporarily relieve muscle stiffness and pain associated with spasticity, but often at the expense of increased muscle weakness. Recent preclinical investigations of a non-invasive treatment that pairs trans-spinal direct current stimulation and peripheral nerve direct current stimulation (tsDCS+pDCS) provided promising data for a novel approach based on bioelectronic medicine for the treatment of patients with post-stroke spasticity.

Methods: Twenty-six patients with upper limb hemiparesis and wrist spasticity at least 6 months after their initial stroke participated in this single-blind crossover design study to test whether tsDCS+pDCS reduces chronic upper-extremity spasticity. Subjects received five consecutive daily sessions (20 min of stimulation or sham) of anodal tsDCS+pDCS, separated by a one-week washout period. The sham condition always preceded the active condition. Clinical and objective measures of spasticity and motor function were collected before and after each condition, and for five weeks after the completion of the active intervention.

Results: Subjects treated with active tsDCS+pDCS demonstrated significant reductions in both Modified Tardieu Scale scores (summed across the upper limb, P < 0.05), and in objective torque measures (Nm) of the spastic catch response at the wrist flexor (P < 0.05), compared to the sham condition. Motor function also improved significantly (measured by the Fugl-Meyer and Wolf Motor Function Test; P < 0.05 for both tests) after active treatment.

Conclusions: tsDCS+pDCS intervention alone significantly reduced upper limb spasticity in participants with stroke. Decreased spasticity was persistent for five weeks after treatment, and was accompanied by improved motor function even though patients were unsupervised and there was no prescribed activity or training during that interval.

Trial registration: NCT03080454, March 15, 2017.

Keywords: CVA; Hemiparesis; Motor rehabilitation; Paired spinal and peripheral stimulation; Spasticity; Stroke; Trans-spinal direct current stimulation; Upper motor neuron syndrome; tsDCS+ pDCS.

Conflict of interest statement

Competing interestsDr. Zaghloul Ahmed is the scientific founder of Pathmaker, LLC., which manufacturers the device that delivers the double stimulation. All other authors declare that they have no competing interests.

© The Author(s) 2019.

Figures

Fig. 1

tsDCS+pDCS treatment delivered by the MyoRegulator®paired trans-spinal direct current stimulation with peripheral direct current stimulation. a PathMaker MyoRegulator® control panel with two pairs of 2x2in sponge-electrodes. b Anode electrode placed on the spine at C6 level for spinal stimulation (4 mA); and cathode electrode placed on the abdomen. c Second set of electrodes, anode and cathode positioned on the median nerve. d Subject receiving tsDCS+pDCS treatment: 4 mA for spinal stimulation and 1 mA for peripheral nerve stimulation

Fig. 2

tsDCS+pDCS acutely and chronically reduced clinically measured spasticity. a MTS score change (mean +/− SEM) immediately following 5 days of sham treatment and one week later (visits 5,6); 5 days of active treatment and one week later (visits 11,12; *P < 0.05, ANOVA). b MTS score change (mean+/− SEM) after active treatment measured weekly for five follow up visits (11–16; *P < 0.05, ANOVA, visit 6 control)

Fig. 3

tsDCS+pDCS acutely and chronically reduced objectively measured spasticity. a Change in torque resistance (mean percent +/− SEM) immediately following 5 days of sham treatment and one week later (visits 5,6); 5 days of active treatment and one week later (visits 11,12; *P < 0.05, ANOVA). b Change in torque resistance (mean percent +/− SEM) after active treatment measured weekly for five follow-up visits (11–16; *P < 0.05, ANOVA, visit 6 control)

Fig. 4

tsDCS+pDCS significantly improved Upper-Extremity Fugl-Meyer and Wolf Motor Function Test. a UE-FM score change (mean +/− SEM) immediately following 5 days of sham or treatment (visit 5 and 11; **P < 0.00625, Wilcoxon); and one week later (visits 6,12; **P < 0.00625, Wilcoxon). For the follow-up, UE-FM (mean+/−SEM) scores improved significantly from visits 12–16 (*P < 0.00625, Wilcoxon, visit 6 control). b WMFT-FAS score and WMFT Time score change (mean +/− SEM) immediately following 5 days of sham or treatment (visit 5 and 11; NS, Wilcoxon); and one week later (visits 6,12; NS, Wilcoxon). For the follow-up, WMFT Time scores (mean+/−SEM) improved significantly from visits 13–16 (*P < 0.00625, Wilcoxon, visit 6 control); WMFT-FAS scores one to five weeks later (NS, Wilcoxon)