Diaphragm Pacing in Individuals With Spinal Cord Injuries

Diaphragm Stimulation After Human Spinal Cord Injury: Effects on Respiratory Neural Drive and Function

This project will evaluate the effects of intramuscular diaphragm stimulation (pacing) and test the hypothesis that diaphragm pacing enhances neuromuscular diaphragm activation and respiratory function in adults with cervical spinal cord injuries (C-SCIs). The investigators will test the hypothesis by recording activity of the diaphragm from intramuscular pacing electrodes and conduct respiratory assessments in adults with intramuscular diaphragm pacing electrodes following acute, traumatic C-SCIs.

Respiratory dysfunction is a leading cause of death in individuals with spinal cord injuries (SCIs). Nearly one-quarter of all SCI cases involve injury to the upper spinal cord segments which impairs neural activation of the diaphragm muscle and compromises breathing. Although mechanical ventilation can be life-saving after cervical SCI (C-SCI), it also triggers rapid and profound diaphragm muscle atrophy, thereby complicating (or even preventing) ventilator weaning. Intramuscular diaphragm stimulation, or diaphragm pacing, was developed to replace long-term ventilator support and is now used acutely post C-SCI (<4 months following injury) to promote ventilator weaning. This study will assess the effects of diaphragm stimulation on respiratory neural drive and breathing function in individuals with acute, traumatic C-SCI. Recording from these surgically implanted electrodes allows comparisons of electromyogram (EMG) recordings, in association with respiratory assessments, before and after short periods of diaphragm pacing to isolate the unique contribution of diaphragm pacing on neuromuscular diaphragm activation.

Inclusion Criteria:

• Acute, traumatic cervical spinal cord injuries (C-SCIs), classified according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS) as A-C
• Scheduled to undergo implantation of a diaphragm pacer, or who have recently received (in past 5-days) implantation of intramuscular diaphragm pacing electrodes due to severe respiratory impairments and dependence on mechanical ventilation

Exclusion Criteria:

• Progressive neuromuscular diseases such as multiple sclerosis and myasthenia gravis
• History of neurologic injuries such as stroke or prior SCI
• Chest wall injuries or deformities likely to influence breathing
• Pregnancy
• Cognitive impairments limiting study participation