Prevalence and Risk Factors
Breathing disorders including sleep apnea appear to have a higher prevalence in people after SCI than those without with some researchers estimating it is present in 60% of motor complete persons with tetraplegia (Prosperio et al. 2015; Chiodo et al. 2016). In general, the studies that examined the prevalence of OSA were limited by small sample sizes and by an experimental design that lacked a non-SCI control group that could be directly compared to the patients with SCI. Both overnight oximetry and full polysomnography (PSG) were used to diagnose disease. The prevalence rate ranged from 9.1-83% (Short et al. 1992; Burns et al. 2000; Burns et al. 2001; Stockhammer et al. 2002; Berlowitz et al. 2005). Obesity was identified as a risk factor for sleep apnea in most studies. The use of muscle relaxants was identified as a potential risk factor for SDB in some but not all studies (Short et al. 1992; Ayas et al. 2001; Burns et al. 2001; Berlowitz et al. 2005).
Discussion
SDB is common in people with SCI; obesity appears to be a consistent risk factor. The prospective observational study of Proserpio et al. (2015) with 35 patients with acute SCI found that SDB in the first year following injury was more frequent in tetraplegic than in paraplegic patients, and periodic leg movements during sleep (PLMS) were more frequent in participants with an incomplete motor lesion than in those with complete motor lesions. Moreover, they showed that level and completeness of the spinal cord lesion were the main factors associated with an early development of SDB and PLMS.
There are few studies that have assessed the impact of sleep apnea therapy in patients with SCI. Berlowitz et al. (2019) showed in an RCT that CPAP plus usual care reduced sleepiness when patients with acute SCI were adherent to the therapy during the 3-month study period. Graco et al. (2019) showed that greater usage of CPAP was associated with higher abdominal girth, increased age, and more severe OSA. A limited number of studies have examined the impact of sleep apnea therapy on health and quality of life outcomes in SCI; future investigations should examine these and other questions with larger sample sizes to determine more accurate effects of CPAP therapy.
Conclusion
There is level 1b (from one RCT: Berlowitz et al. 2019) to support CPAP therapy therapies to treat SDB in people with acute SCI.
