Motor Activated Auricular Vagus Nerve Stimulation as a Potential Neuromodulation Approach for Post-Stroke Motor Rehabilitation: A Pilot Study.

BACKGROUND: Implanted vagus nerve stimulation (VNS), when synchronized with post-stroke motor rehabilitation improves conventional motor rehabilitation training. A non-invasive VNS method known as transcutaneous auricular vagus nerves stimulation (taVNS) has emerged, which may mimic the effects of implanted VNS. OBJECTIVE: To determine whether taVNS paired with motor rehabilitation improves post-stroke motor function, and whether synchronization with movement and amount of stimulation is critical to outcomes. METHODS: We developed a closed-loop taVNS system for motor rehabilitation called motor activated auricular vagus nerve stimulation (MAAVNS) and conducted a randomized, double-blind, pilot trial investigating the use of MAAVNS to improve upper limb function in 20 stroke survivors. Participants attended 12 rehabilitation sessions over 4-weeks, and were assigned to a group that received either MAAVNS or active unpaired taVNS concurrently with task-specific training. Motor assessments were conducted at baseline, and weekly during rehabilitation training. Stimulation pulses were counted for both groups. RESULTS: A total of 16 individuals completed the trial, and both MAAVNS (n = 9) and unpaired taVNS (n = 7) demonstrated improved Fugl-Meyer Assessment upper extremity scores (Mean ± SEM, MAAVNS: 5.00 ± 1.02, unpaired taVNS: 3.14 ± 0.63). MAAVNS demonstrated greater effect size (Cohen's d = 0.63) compared to unpaired taVNS (Cohen's d = 0.30). Furthermore, MAAVNS participants received significantly fewer stimulation pulses (Mean ± SEM, MAAVNS: 36 070 ± 3205) than the fixed 45 000 pulses unpaired taVNS participants received (P < .05). CONCLUSION: This trial suggests stimulation timing likely matters, and that pairing taVNS with movements may be superior to an unpaired approach. Additionally, MAAVNS effect size is comparable to that of the implanted VNS approach.

Phase I Safety Trial: Extended Daily Peripheral Sensory Stimulation Using a Wrist-Worn Vibrator in Stroke Survivors.

Peripheral sensory stimulation augments post-stroke upper extremity rehabilitation outcomes. Most sensory stimulations interfere with natural hand tasks and the stimulation duration is limited. We developed TheraBracelet, low-level random-frequency vibration applied via a wristwatch, to enable stimulation during hand tasks and potentially extend stimulation durations. To determine safety of prolonged exposure to TheraBracelet. Single-site double-blind crossover randomized controlled trial. Chronic stroke survivors were instructed to wear a device on the affected wrist for > 8 h/day everyday for 2 months while coming to the laboratory weekly for evaluations, with a 2-week break between each month. The device applied vibration at 60% and 1% of the sensory threshold for the real and sham month, respectively. The order of the real and sham months was randomized/balanced. Adverse events (AEs) were assessed weekly, including worsening of hand sensation, dexterity, grip strength, pain, or spasticity and occurrence of skin irritation or swelling. Device-related AE rates were compared between the real and sham month. Twenty-five participants completed the study. Six participants (24%) experienced mild AEs involving worsened sensory scores that may be related to the intervention with reasonable possibility. Two experienced them in the real stimulation month only, 3 in the sham month only, and 1 in both months. Therefore, less participants experienced device-related AEs in the real than sham month. Daily stimulation using the device for a month is safe for chronic stroke survivors. Future studies examining the efficacy of pairing TheraBracelet with therapy for increasing neurorehabilitation outcomes are a logical next step. Trial registration: NCT03318341.

Matching Task Difficulty to Patient Ability During Task Practice Improves Upper Extremity Motor Skill After Stroke: A Proof-of-Concept Study.

OBJECTIVE: To test the feasibility of the Fugl-Meyer Assessment of the Upper Extremity "keyform," derived from Rasch analysis, as a method for systematically planning and progressing rehabilitation. DESIGN: Feasibility study, single group design. SETTING: University rehabilitation research laboratory. PARTICIPANTS: Participants (N=10; mean age, 59.70±9.96y; 24.1±30.54mo poststroke) with ischemic or hemorrhagic stroke >3 months prior, voluntarily shoulder flexion ≥30°, and simultaneous elbow extension ≥20°. INTERVENTIONS: The keyform method defined initial rehabilitation targets (goals) and progressed the rehabilitation program after every third session. Targets were repetitively practiced within the context of client-selected functional tasks not in isolation. MAIN OUTCOME MEASURES: Feasibility was defined by subject's pain or fatigue, upper extremity motor function (Wolf Motor Function Test), and movement patterns (kinematics). Assessments were administered pre- and posttreatment and compared using paired t tests. Task-difficulty and patient-ability measures were calculated using Rasch analysis and compared using paired t tests (P<.05). RESULTS: Ten participants completed 9 sessions, 200 movement repetitions per session in <2 hours without pain or fatigue. Participants gained upper extremity motor function (Wolf Motor Function Test: pretreatment, 22.23±24.26s; posttreatment, 15.46±22.12s; P=.01), improved shoulder-elbow coordination (index of curvature: pretreatment, 1.30±0.15; posttreatment, 1.21±0.11; P=.01), and exhibited reduced trunk compensatory movement (trunk displacement: pretreatment, 133.97±74.15mm; posttreatment, 108.08±64.73mm; P=.02). Task-difficulty and patient-ability measures were not statistically different throughout the program (person-ability measures of 1.01±0.05, 1.64±0.45, and 2.22±0.65 logits and item-difficulty measures of 0.93±0.37, 1.70±0.20, and 2.06±0.24 logits at the 3 testing time points, respectively; P>.05). CONCLUSIONS: The Fugl-Meyer Assessment of the Upper Extremity keyform is a feasible method to ensure that the difficulty of tasks practiced were well matched to initial and evolving levels of upper extremity motor ability.