Inspiratory muscle reflex control after incomplete cervical spinal cord injury.
| Title: | Inspiratory muscle reflex control after incomplete cervical spinal cord injury. |
|---|---|
| Authors: | McNaughton KMD; Neuroscience Research Australia, Randwick, New South Wales, Australia.; Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia.; Witherow JL; Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia.; Dupuche CB; Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia.; Peebles KC; Department of Health Sciences, Macquarie University, Macquarie Park, New South Wales, Australia.; Elphick TG; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.; Hudson AL; Neuroscience Research Australia, Randwick, New South Wales, Australia.; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.; College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.; McCaughey EJ; Neuroscience Research Australia, Randwick, New South Wales, Australia.; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.; Queen Elizabeth National Spinal Injuries Unit, Glasgow, United Kingdom.; Boswell-Ruys CL; Neuroscience Research Australia, Randwick, New South Wales, Australia.; Department of Physiotherapy, Prince of Wales Hospital, Randwick, New South Wales, Australia.; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia.; Butler JE; School of Medical Sciences, University of New South Wales, Kensington, New South Wales, Australia. |
| Source: | Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2022 Dec 01; Vol. 133 (6), pp. 1318-1326. Date of Electronic Publication: 2022 Nov 10. |
| Publication Type: | Journal Article |
| Language: | English |
| Journal Info: | Publisher: American Physiological Society Country of Publication: United States NLM ID: 8502536 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1522-1601 (Electronic) Linking ISSN: 01617567 NLM ISO Abbreviation: J Appl Physiol (1985) Subsets: MEDLINE |
| Imprint Name(s): | Original Publication: Bethesda, MD : American Physiological Society, c1985- |
| MeSH Terms: | Cervical Cord*; Humans ; Reflex ; Muscles |
| Abstract: | In healthy individuals, loading inspiratory muscles by brief inspiratory occlusion produces a short-latency inhibitory reflex (IR) in the electromyographic (EMG) activity of scalene and diaphragm muscles. This IR may play a protective role to prevent aspiration and airway collapse during sleep. In people with motor and sensory complete cervical spinal cord injury (cSCI), who were able to breathe independently, this IR was predominantly absent. Here, we investigated the reflex response to brief airway occlusion in 16 participants with sensory incomplete cSCI [American spinal injury association impairment scale (AIS) score B or C]. Surface EMG was recorded from scalene muscles and the lateral chest wall (overlying diaphragm). The airway occlusion evoked a small change in mouth pressure resembling a physiological occlusion. The short-latency IR was present in 10 (63%) sensory incomplete cSCI participants; significantly higher than the IR incidence observed in complete cSCI participants in our previous study (14%; P = 0.003). When present, mean IR latency across all muscles was 58 ms (range 29-79 ms), and mean rectified EMG amplitude decreased to 37% preocclusion levels. Participants without an IR had untreated severe obstructive sleep apnea (OSA), in contrast to those with an IR, who had either had no, mild, or treated OSA (P = 0.002). Insufficient power did not allow statistical comparison between IR presence or absence and participant clinical characteristics. In conclusion, spared sensory connections or intersegmental connections may be necessary to generate the IR. Future studies to establish whether IR presence is related to respiratory morbidity in the tetraplegic population are required.NEW & NOTEWORTHY Individuals with incomplete cSCI were tested for the presence of a short latency reflex inhibition of inspiratory muscles, by brief airway occlusion. The reflex was 4.5 times more prevalent in this group compared with those with complete cSCI and is similar to the incidence in able-bodied people. Participants without this reflex all had untreated severe OSA, in contrast to those with an IR, who either had no, mild, or treated OSA. This work reveals novel differences in the reflex control of inspiratory muscles across the cSCI population. |
| Contributed Indexing: | Keywords: aspiration; diaphragm; reflex; scalene; spinal cord injury |
| Entry Date(s): | Date Created: 20221110 Date Completed: 20221215 Latest Revision: 20221220 |
| Update Code: | 20260130 |
| DOI: | 10.1152/japplphysiol.00113.2022 |
| PMID: | 36356259 |
| Database: | MEDLINE |
Journal Article