Upper Limb Rehabilitation Using Non-invasive Spinal Cord Stimulation

Upper Extremity Motor Score (UEMS)

This will be used for assessing the motor function, that is, the strength and functionality of the muscles involved in movement. It helps determine the severity of motor impairments in patients with cervical lesions and is used to track recovery and assess outcome during inpatient rehabilitation. It has high inter-rater and intra-rater reliability. It also has high validity as an impairment measure and has moderate validity for predicting real-world functional independence. The test evaluates five movements of each arm, namely, elbow flexion, wrist extension, elbow extension, middle finger flexion, and little finger abduction. The participant is asked to perform these movements either actively or passively, depending on their ability. These are scored on a scale from 0 (no movement) to 5 (full function). Thus, the higher score reflects improvement in the motor function across the three time frames.

The Prehension subtest of the Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP- version 2)

This test will be used to assess the hand function in participants, particularly their grasping ability and object manipulation. This includes two components: prehension ability (PA) and prehension performance (PP). PA evaluates the capacity to perform different grasp patterns, including cylindrical, lateral pinch, and tip pinch grasps. Each hand is assessed separately and scored on a scale from 0 to 4, with 4 being the normal voluntary control of the wrist and fingers during grasp execution. PP assesses the ability to complete functional tasks requiring grasp, manipulation, and release of objects of various shapes and sizes. Each hand is evaluated separately, and task performance is scored from 0 to 5, with 5 being the most successful task completion using the intended grasp pattern. Higher total scores indicate better hand function and prehension ability. The subtest has excellent test-retest reliability (ICC = 0.93-0.98) and excellent inter-rater reliability (ICC = 0.95-0.96).

Upper-limb sensory score of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI)

This will be used to assess the sensory level of the participant by evaluating the ability to feel stimuli and to differentiate between sharp and dull sensations (pinprick test) on specific regions of the skin corresponding to spinal nerve segments. The summed sensory scores (light touch + pinprick) have good to excellent inter- and intra-rater reliability. So, we will use the summed scores. The test has good validity for classifying lesion level and severity, moderate for predicting function, and has limited sensitivity (not sensitive to subtle changes) compared to electrophysiological or quantitative tests. Light touch and pinprick sensation are first demonstrated on the participant's cheek. The participant, seated with eyes closed, is tested using light touch with tissue or cotton (assessing large A fibers) and pinprick with a pin or toothpick (assessing smaller A-delta and C fibers for superficial pain) at six test sites. The sensation is reported by them.

Monofilament test

This will be used to quantify and to assess the sensory function, particularly for detecting areas of sensory loss or abnormal sensation (neuropathic pain). This test has high validity and inter-and intra tester reliability in participants with chronic cervical spinal cord injury. The test is conducted using Semmes-Weinstein monofilaments. With eyes closed, the participant is asked to report whether they can feel the pressure when a monofilament is applied to different regions of the upper limb. The threshold at which the stimulus is perceived is recorded (5.88, 5.07, 4.56, 4.08, 3.22). Specific regions are assessed depending on the nerve: the pulp of the middle finger for the median nerve, the pulp of the little finger for the ulnar nerve, the first dorsal space of the hand between the thumb and index finger and the lateral epicondyle at the extensor compartment for the radial nerve, and the deltoid region for the axillary nerve.

Force (Grip and Pinch Strength) test

This will be used to assess grip and pinch strength which are used in daily tasks involving hand function. The Pinch strength test has good to excellent reliability for neurological conditions and has strong to very strong correlations with grip strength. It has a good validity. The Grip strength has an excellent test-retest reliability in SCI. It shows a very high intra- and inter-rater reliability if standardized protocols (same dynamometer, position, instructions) are followed. It has a good validity. Grip strength is measured using a dynamometer, with the participant seated and the elbow flexed at 90 degrees. The participant must squeeze the device as hard as possible for 3 trials; the average of these trials is calculated. Pinch strength is measured using a pinch gauge, where the participant pinches an object between the thumb and index finger with maximum effort. Again, the average of 3 trials is taken.