Cranial Nerve Neuromodulation to Improve Arm Function and Brain Plasticity in Stroke

Condition(s) studied

Investigational drug(s) / intervention(s)

Strength training: The strength training program will last 4 weeks (3 X/week, 60 minutes). Using dead weights, the 1RM (i.e. the maximal load that an individual can lift once) will be estimated by the 10RM for the wrist extensors and the elbow and shoulder flexors. The grip muscles of the affected hand will also be trained with a JAMAR® dynamometer. Depending on each participant's intensity training group, training will start at 35%, 50% or 70% of 1RM and will be increased by 5% each week to reach, by week 4, 50%, 65% and 85%, for the low, moderate, and high-intensity group, respectively.

Cranial nerve non-invasive neuromodulation: For the first 20 minutes of each training session, CN-NINM will be applied (50 μsec at 150 Hz), using a portable stimulator (Cthulhu Shield, USA) with a network of 18 electrodes, directly on the participants' tongue. The participants will hold the device in place by pressing their tongue upwards and the intensity of the stimulus will be set by each participant to a comfortable level of sensation (experimental group) or set by a trainer to a non-perceivable stimulus (control group).

Study summary

Following a stroke, persistent residual muscle weakness in the upper limb (UL) drastically impacts the individuals' quality of life and level of independence. Training interventions are recommended to promote UL motor recovery, and recent studies have shown that training must be tailored to each individual's recovery potential to maximise training gains. Complementary to training interventions, non-invasive brain stimulation devices (NIBS) can help support the provision of post-stroke care by modulating brain excitability and enhancing recovery. Among NIBS, cranial nerve non-invasive neuromodulation (CN-NINM) is gaining increasing attention in rehabilitation since it can directly and non-invasively stimulate the tongue's cranial nerves. The impulses generated can then reach the motor cortex, induce neuroplastic changes and support recovery. Promising results in various neurological populations have been observed, but in stroke, the efficacy of CN-NINM at improving arm motor recovery and brain plasticity is yet to be determined. This is what the present project intends to address, using a stratified randomized controlled trial, where participants in the chronic phase of a stroke will take part in a 4-week individualized training program of their affected UL in combination with real or sham CN-NINM. Before and after the intervention, participants will undergo clinical and neurophysiological evaluations to thoroughly evaluate CN-NINM-induced changes in UL motor function and associated neuroplastic changes. The proposed study will allow an in-depth evaluation of the effects of CN-NINM for an eventual implementation in clinics and at home to support optimal post-stroke recovery.

Eligibility

Primary outcome measure(s)

• Change in UL motor function on the Fugl-Meyer Stroke Assessment Scale — The assessments will be done at the baseline and in the week after completion of the training program and CN-NINM
  Change in motor function of the affected UL will be assessed using the Fugl-Meyer Stroke Assessment. The score of this scale range from 0 (no motor recovery) to 66 (full motor recovery).
• Change in UL functional performance on the Wolf Motor Function Test — The assessments will be done at the baseline and in the week after completion of the training program and CN-NINM.
  Change in functional performance of the affected UL will be assessed with the timed score of the Wolf Motor Function Test; comprising 17 tasks. The maximal time allocated to each task is 120 seconds.
• Change in motor cortex excitability by means of resting MEP amplitudes elicited by TMS over both hemispheres. — The assessments will be done at the baseline and in the week after completion of the training program and CN-NINM.
  Change in motor cortex excitability will be assessed by resting peak-to-peak MEP amplitudes of the affected and unaffected first dorsal interosseous muscles (FDI) at 130% of the FDI resting motor threshold over 20 trials

Trial sites (3)

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