Effect of Transcutaneous Cervical Spinal Cord Stimulation on Trunk Function in Subjects with Cervical Spinal Cord Injury

Author(s): Hatice Kumru, Yolanda Castillo-Escario, Raimon Jane, Joan Vidal, Loreto García Alén

This study aimed to examine how cervical transcutaneous spinal cord stimulation (tSCS) influences trunk muscle activity and movement patterns while individuals with SCI perform a reaching task. Trunk stability is crucial for daily activities, and spinal cord injury (SCI) often impairs this stability. By evaluating muscle activity and movement patterns during a specific task, the researchers seek to understand whether tSCS has an impact on enhancing trunk muscle control and movement.

Methods:

Nineteen subjects with cervical or high thoracic SCI participated in the randomized mix of parallel group and crossover clinical trial, consisting of an intervention group (n=13; tSCS) and control group (n=10), and four of them participated in both groups. We used the American Spinal Injury Association Impairment Scale (AIS) scale to evaluate clinical motor and sensory deficits, and the clinical trunk impairment control test (static and dynamic equilibrium and static equilibrium with upper limbs). In addition, data from electromyography (EMG) and smartphone accelerometers were recorded during a reaching task that required trunk tilting. Outcome measures included response time (RespT) until pressing a target button, EMG onset latencies and amplitudes, and trunk tilt, lateral deviation, and other movement features from accelerometry. Patients were evaluated before and after eight sessions of tSCS applied at C3-4 and C6-7 at 30 Hz during upper extremity rehabilitation.

Result:

The results showed in tSCS group significant improvement in total motor strength, while trunk control evaluated by clinical scales did not show significant changes in any group. Additionally, there were no significant changes in any EMG or smartphone variables, except response time (RespT), which was faster in the controls after last session. Changes as absolute or percentage values were similar in both groups in all parameters.

Significance:

tSCS applied at two cervical segments showed significant improvement in total motor score but not in trunk control in SCI individuals. This is a crucial finding, suggesting that while tSCS at cervical segments positively affected certain aspects of motor function, this did not translate into improvements in trunk stability.