trans-spinal Electrical Stimulation (tsES)

Stimulation will be achieved with two self-adhesive stimulation electrodes attached to the dorsal aspect of the neck overlying the cervical vertebrae and two self-adhesive rectangular return electrodes placed over the shoulders. Spinal motor evoked potentials (sMEP) induced by trans-spinal electrical stimulation (parameters, 1 Hz with a 0.1-1 ms pulse width and monophasic waveform) to determine recruitment profiles of proximal and distal motor pools with increasing stimulation intensity ranging from 10 to 200 milliampere. Stimulation parameters for the therapeutic stimulation will be ranged from 5-40 Hz and 20-100 milliampere.

Fugl-Meyer Assessment for upper extremity will be used for the measurement of upper limb motor functional recovery. We will adobe the version of the University of Gothenburg approved by Fugl-Meyer AR. In a cumulative numerical scoring to evaluate the physical performance including coordination and speed of the upper extremities, functions of hand and wrist will be assessed separately. The test is constructed with different stages of motor recovery: 1) reflexes reoccur; 2) stereotyped volitional movement can be imitated within flexor and extensor synergies; 3) movements can be performed that deviate from primitive synergies; and 4) reflexes are normalized. A 3-point ordinal scale will be applied to each item: 0=the detail cannot be performed, 1=the detail can be partially performed; 2=the detail can be fully performed. The maximum motor score for the upper extremity can be 66 points where higher score will indicate better function.

Modified Ashworth Scale is a measurement tool for muscle tone which can be used to measure upper-limb spasticity at different upper extremity segments. It is a 6-point numerical scoring system: 0=no increase in muscle tone, 1=slight increase in muscle tone; 1+=slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder; 2=more marked increase in muscle tone through most of the ROM, but affected part move easily; 3=considerable increase in muscle tone, passive movement difficult; 4=affected part rigid. Lower scores after the treatment will indicate the decrease of muscle spasticity around the specific upper extremity joints, on contrary, higher scores will indicated the aggravation of the muscle spasticity of the segment.The test will be carried out before and after each of the three experimental phases (Phase 1-3).

Action Research Arm Test is also a cumulative numerical rating scale for the measurement of upper extremity performance,which is frequently used in research and clinical practice. The reliability of this test has been evaluated in several studies using reliability coefficients such as Spearman's rank correlation coefficient and intra-class correlation coefficient. This test focuses more on the hand functions with 4 basic movements: grasp, grip, pinch and gross movement, and is assessed on a 4-category ordinal scale (i.e., 0,1,2, and 3) with totally 19 items.The ordinal scale is not only related to the degree of completion of an action, but also related to the time cost:0=the motion task cannot be performed, 1=the motion task can be partially performed, 2=the motion task can be fully performed, but clunky or slow, 3=the motion task can be fully performed normally.

In addition to assessing patients' post-injury functional status, the Functional Independence Measure will also be monitored once a month and in follow-up. The Functional Independence Measure is an 18-items,7-level questionnaire assessment designed to evaluate the amount of assistance required by the disabled individual to perform basic life activities safely and effectively.

Muscular physiological activity will be collected via surface electromyography, mechanomyography and sonomyography of upper-limb muscles including flexor digitorum, extensor digitorum, brachioradialis, biceps brachii, and triceps brachii. Forelectromyography: Four pairs of Ag/Agl electrodes (Bluesensor, Ambu Inc. America) will be attached on to the skin surface of the muscle bellies, with a 2-cm center separation. A single reference electrode will be attached on the skin surface of olecranon. For mechanomyography and sonomyography, custom sensors form the laboratory of the Department of Biomedical Engineering, The Hong Kong Polytechnic University will be used.