Promoting Respiratory Motor Plasticity After Spinal Cord Injury Through High Frequency Stimulation (HF‐SCS)

Abstract

More than 50% of the spinal cord injury (SCI) population have injuries at the cervical level. Located at this level are the respiratory bulbospinal pathways which mediate breathing. Therefore, injuries at the cervical level can leave many of these patients unable to breath. One promising intervention to restore breathing is HF‐SCS (300Hz). In previous investigations, we demonstrated that HF‐SCS applied at the T2 level after an experimental complete C2 spinal cord section leads to evoked inspiratory diaphragmatic EMG activity that can enable survival of the animal. However, the extent to which HF‐SCS can promote spinal respiratory motor plasticity in order to promote restoration of breathing function is still unknown. To address this question, we performed a HF‐SCS at the T2 level in six anesthetized rats while recording bilateral diaphragmatic EMG activity one week after C2 hemisection. As expected, C2 hemisection abolished activity in the hemidiaphragm ipsilateral to the hemisection, while spontaneous activity contralateral to the C2 hemisection still remained. HF‐SCS resulted in robust inspiratory activity bilaterally in the diaphragm. Following discontinuation of HF‐SCS bilateral spontaneous activity persisted. Moreover, EMG activity on the hemisected side was synchronized with the contralateral side. Taken together, these results suggest that HF‐SCS after a C2 hemisection can enhance activity and promote plasticity of the crossed phrenic pathways which still remain. Further studies are planned to explore the mechanisms of these observations with the ultimate goal to restore function in patients following SCI.Support or Funding InformationFunded by University of Kentucky College of Medicine Funds & The MetroHeath Foundation.Disclosure: Dr. DiMarco has a significant financial interest in Synapse BioMedical, Inc, a manufacturer of diaphragm pacing systems.