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 upperextremity 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.

Trans-Spinal Direct Current Stimulation in Spasticity: A Literature Mini-Review

“…Interestingly, patients did not receive any intervention and/or treatment during the trial duration, indicating that the observed clinical results were mostly associated to the intervention itself. The authors of this study used standardized spasticity measurements and stroke-specific, performance-based impairment index to assess improvement, thus, showing the applicability of this technique in the clinical setting (Paget-Blanc et al, 2019).…”

Non-Invasive Transcutaneous Spinal DC Stimulation as a Neurorehabilitation ALS Therapy in Awake G93A Mice: The First Step to Clinical Translation

“…Despite the mouse’s small size, tsDCS stimulation can be successfully delivered in normal mice [ 47 ] and in spastic mice after spinal cord injury [ 48 ], which inspired successful tsDCS stimulation testing in spastic human patients [ 49 ]. Because truly non-invasive spinal electrical stimulation had never been performed on awake ALS mice, we anticipated many technical challenges.…”

Transcutaneous Auricular Vagus Nerve Stimulation (tAVNS) Delivered During Upper Limb Interactive Robotic Training Demonstrates Novel Antagonist Control for Reaching Movements Following Stroke

“…Given that robotic intervention targeted more than one joint of the upper limb, the MTS was evaluated both as a summed score across 11 joints of the upper extremity, MTS total, and at the individual joint complexes for the shoulder, MTS shoulder (summed across 3 joints: horizontal adductors, vertical adductors, internal rotators), the elbow, MTS elbow (summed across 4 joints: elbow flexors, elbow extensors, pronators, supinators), and the wrist, MTS wrist (summed across 4 joints: wrist flexors, wrist extensors, fingers, palmer interrossei/flexor digitorum superficilias). For studies involving whole-limb intervention, summed scores are advantageous as they may more sensitively detect changes across trained muscles groups ( Pundik et al, 2014 ; Paget-Blanc et al, 2019 ). We selected to use the MTS instead of the Modified Ashworth Scale (MAS) as the MTS has been shown to be more sensitive to changes in spasticity ( Mehrholz et al, 2005 ; Haugh et al, 2006 ).…”

“…We have previously shown that robotic therapy provides clinically significant benefits to upper limb motor recovery after stroke ( Volpe et al, 2009 ; Lo et al, 2010 ; Chang et al, 2017 ; Edwards et al, 2019 ), and can specifically reduce upper limb flexor synergy patterns through shoulder/elbow robotic training ( Dipietro et al, 2007 ). We have also demonstrated that treatment aimed at passively elicited spasticity reduction can unmask latent motor potential ( Paget-Blanc et al, 2019 ). In this study, we tested whether maximal and optimized current delivered to the auricular branch of the vagus nerve during pre-motor activity for robot-trained extensor movements would reduce spasticity and generate additional motor recovery of arm function after stroke.…”