Non-Invasive Cervical Spinal Stimulation and Respiratory Recovery After Spinal Cord Injury: A Randomized Controlled Trial with a Partial Crossover Design

Background/Objectives: Respiratory impairment is the leading cause of morbidity and mortality in participants with spinal cord injury (SCI). Cervical SCI (cSCI) severely compromises respiratory function due to paralysis and weakness of the respiratory muscles. Recent evidence suggests that transcutaneous electrical spinal cord stimulation (tSCS) may enhance motor strength and promote functional recovery. Therefore, cervical tSCS, applied at cervical segments, holds potential as a therapeutic strategy to improve respiratory function in participants with cervical SCI. Methods: This randomized controlled trial with a partial crossover design included participants with both complete and incomplete cSCI. Neurological assessments were used, as well as tests to evaluate pulmonary function maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), and spirometric measurements. These assessments were conducted at baseline and after the last session. The experimental group received tSCS at the C3–C4 and C6–C7 cervical spinal levels, delivered at a frequency of 30 Hz during occupational therapy. The control group underwent identical occupational therapy sessions without stimulation. Each session lasted 30 min and was conducted over eight days. Results: Fifteen participants with cSCI received tSCS, while 11 cSCI participants were included in the control group. Seven participants took part in both groups. Only the tSCS group showed significant improvements in MIP, MEP, and forced vital capacity (p < 0.05), while no significant changes were observed in the control group. Conclusions: tSCS applied at the cervical segments can promote respiratory function following cervical SCI. This approach may support neuroplasticity and help reduce long-term respiratory complications in participants with cervical SCI. However, to confirm these effects, long-term stimulation protocols and follow-up studies in larger SCI populations are required.