The Cortical Motor Effects of PNS and AO on Motor Training in Chronic Stroke

Study Overview
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Brief Summary
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This study aimed to investigate if peripheral nerve stimulation (PNS) paired with action observation (AO) would augment motor training in promoting corticomotor excitability for the paretic hand in people with stroke. Twenty subjects in chronic stage of stroke were exposed to 3 different interventions involving one-hour PNS or sham PNS paired with 30 minutes of AO or sham AO, all followed by 30 minutes of finger abduction training in 3 separate sessions.

Detailed Description
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The investigator's previous study (Liu & Au-Yeung, 2017; PMID: 28383292) has demonstrated that 1-hour peripheral nerve stimulation (PNS) applied to the radial and ulnar nerves of the paretic UL of people with chronic stroke can increase transcranial magnetic stimulation (TMS)-evoked excitability of corticomotor pathways in both hemispheres projected to the contralateral first dorsal interosseous (FDI) hand muscle, and also improve dexterity in the paretic hand. This bi-hemispheric effect of PNS suggests that certain additional therapies such as action observation (AO) and motor training should be incorporated to strengthen the plastic corticomotor adaptation specifically for paretic UL control. The hypothesis of this study is that PNS paired with AO would augment task training of the paretic hand by increasing the corticomotor excitability in the lesioned hemisphere for the trained hand muscle in people with stroke, with associated dexterity function improvement. Twenty subjects were recruited by convenience in the community. They then attended an assessment session to evaluate the baseline sensorimotor status of their paretic upper limb. After the clinical tests，the subjects were introduced the assessment procedure for measuring corticomotor excitability with transcranial magnetic stimulation (TMS). After 1-week intermission, the subjects returned for 3 intervention sessions with different protocols including (1)PNS+AO+Training; (2)PNS+AOsham+Training; and (3)PNSsham+AOsham+Training. These 3 intervention sessions were arranged in random sequence for subjects. For PNS+AO+Training session, electrical stimulation was applied to the radial and ulnar nerve (PNS) of the paretic arm for 60 minutes. During the last 30 minutes of PNS, action observation (AO) was introduced in which subjects were required to watch a series of video clips. After one hour's PNS+AO, the subjects then proceeded to a 30-minute period of motor training of paretic hand. During PNS+AOsham+Training session, PNS was given as described before. During the last 30 minutes of the PNS, subjects were shown different photos illustrating a letter, a number or a hand as AOsham. The protocol of motor training was the same as described before. In the session of PNSsham+AOsham+Training, The 1-hour PNSsham was conducted with the electrical stimulation unit turned on but without current output. The protocols for AOsham and motor training were the same as those described before.

Official Title
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The Motor Effects of Combined Peripheral Nerve Electrical Stimulation and Action Observation on the Affected Hand in People With Stroke

Conditions
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Stroke

Intervention / Treatment
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* Genetic: PNS+AO+Training
* Genetic: PNS+AOsham+Training
* Genetic: PNSsham+AOsham+Training


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age between 40 and 80 years; has history of first hemispheric stroke of 6or more months; presence of electromyographic signals in first dorsal interosseous (FDI) during active abduction of the index finger contralateral to the lesioned hemisphere; medically stable; able to comprehend instructions. Exclusion Criteria: past history of musculoskeletal or neurological impairment in the paretic upper limb; recurrent stroke; cognitive impairment (Mini-mental state examination (MMSE) < 24); visual impairment not correctable by optical lens; presence of metal in the head region or a cardiac pacemaker as contraindications for TMS (Rossi et al., 2009).

Ages Eligible for Study
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Minimum Age: 43 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Single-blind randomized cross-over study
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: PNS+AO+Training<br>adopted PNS+AO+Training as the intervention | Genetic: PNS+AO+Training<br>* Electrical stimulation was applied to the radial and ulnar nerve (PNS) of the paretic arm for 60 minutes. During the last 30 minutes of PNS, action observation (AO) was introduced in which subjects were required to watch a series of video clips. After one hour's PNS+AO, the subjects then proceeded to a 30-minute period of motor training of paretic hand.<br>|
| Experimental: PNS+AOsham+Training<br>adopted PNS+AOsham+Training as the intervention | Genetic: PNS+AOsham+Training<br>* PNS was given as described before. During the last 30 minutes of the PNS, subjects were shown different photos illustrating a letter, a number or a hand as AOsham. The protocol of motor training was the same as described before.<br>|
| Placebo Comparator: PNSsham+AOsham+Training<br>adopted PNSsham+AOsham+Training as the intervention | Genetic: PNSsham+AOsham+Training<br>* The 1-hour PNSsham was conducted with the electrical stimulation unit turned on but without current output. The protocols for AOsham and motor training were the same as those described before.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Corticomotor excitability evoked by Transcranial magnetic stimulation (TMS) | Corticomotor excitability in terms of the slope of the MEP recruitment curve and peak MEP amplitude captured for the contralateral FDI hand muscle in both hemispheres were assessed. | 90 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Hand dexterity of paretic hand evaluated with Purdue Pegboard | The score was the total number of pins inserted into the holes with paretic hand in 30 seconds. | 24 hours | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Electrical Stimulation, Cortical Excitability, Transcranial Magnetic Stimulation