Transcranial Direct Current Stimulation Combined Sensory Modulation Intervention in Chronic Stroke Patients

Background and purpose:

About 30% of people with stroke suffered from severe long-term upper extremity （UE） motor impairment. Severe UE impairment, especially dysfunction of hand, can greatly impact stroke patients' daily living independence and quality of life. However, treatment effect of current interventions is still limited. Nick Ward and Leonardo Cohen suggested 5 intervention strategies for stroke motor recovery: （1） reduction of somatosensory input from the intact; （2） increase in somatosensory input from the paretic; （3） anesthesia of a body part proximal to the paretic hand; （4） activity within the affected motor cortex may be up-regulated; （5） activity within the intact motor cortex may be down-regulated. Recent studies have shown each strategy to be effective in stroke patients with mild or moderate UE impairment. However, evidence for people with severe UE impairment after stroke remains unclear. Since research has found a greater effect for combined strategies than a single strategy, this proposal develops a combined intervention with the above 5 strategies, named "transcranial direct current stimulation （tDCS） combined sensory modulation intervention". This intervention is expected to be most effective for people with severe UE impairment after stroke.

In addition, neuroimaging can provide in vivo information about the brain plasticity which underpinning the motor recovery after stroke. However, image indexes that can be used in stroke patients with severe UE impairment remained examined. Therefore, this proposal has 3 aims: （1） to examine the treatment effect of the "tDCS combined sensory modulation intervention" in stroke patients with severe UE impairment; （2） to examine the underline mechanism of the efficacy of "tDCS combined sensory modulation intervention" using neuroimaging technology.

Methods:

This study is a double-blinded randomized controlled trial which will recruit 60 people who have had stroke onset more than 6 months and have severe UE motor impairment. All participants will be randomly assigned into 2 groups. The experimental group will be given the "tDCS combined sensory modulation intervention", combining bilateral tDCS stimulation, anesthesia techniques and repetitive passive motor training. The control group is given sham tDCS, sham anesthesia and repetitive passive motor training. Each group will be evaluated for outcomes at 4 time points （i.e. baseline, post-intervention, 3 months and 6months post-intervention）. The immediate and long-term effect of the interventions will be examined.

Primary outcome indicators include upper extremity impairment measures. Secondary outcome measures include upper extremity function, activities of daily living function, functional Magnetic Resonance Imaging （fMRI）, and corticospinal tract structural integrity using diffusion spectrum imaging （DSI）. Fifteen subjects of each group will be assessed 2 times （i.e., prior to the intervention and after the intervention） for fMRI and DSI scan.

Anticipatory results and contributions:

The results of the studies are expected to present a potentially effective intervention for stroke patients with severe impaired UE motor. Imaging evidence of brain plasticity for this particular intervention is also provided. The results will contribute to our understanding of brain plasticity for UE motor recovery after stroke. Findings from this proposal may help researchers and clinicians choose or develop interventions that are optimal to their clients individually.


Eligibility Criteria:
Inclusion Criteria:

1. first ever ischemic or hemorrhagic stroke patients identified by computed tomography (CT) or magnetic resonance imaging (MRI)
2. age between 40 and 80 years old
3. have a stroke over 6 months
4. unilateral hemiplegia
5. Fugl-Meyer assessment-upper extremity (FMA-UE) score≦29 when selection
6. poststroke elbow flexor spasticity less than 2 using modified Ashworth scale (MAS)
7. no severe anesthesia (FMA sensory test, upper extremity score≧10 )
8. no wrist and finger joint pain
9. clear consciousness, can understand simple sentences and spoken orders, and co-operate manipulation
10. can accept motor training in the sitting position for approximately 30 minutes.

Exclusion Criteria:

1. Suffer from other orthopedic diseases (such as severe arthritis), nerve damage (such as peripheral nerve damage), or severe pain, which influences upper extremity motor
2. have a medical history or family history of epilepsy
3. regularly take central nervous system drugs (such as sedatives), or the Class III antiarrhythmic drugs (such as amiodarone)
4. have atopic dermatitis or skin disorders of the scalp
5. have allergy to anesthetic medicines of the acyl amine
6. have a metal implant in the head or neck, or serious arrhythmia (the heartbeat is less than 50 beats per minute or higher than 100 beats per minute); or use a pacemaker or atrial defibrillator
7. suffer from congenital or idiopathic methemoglobinemia. Aphasia is not an exclusion criterion, but the patients should understand simple spoken orders.