Estimating the probability of OSA in the spinal cord injury population: specific tools are still needed

Patients with high spinal cord injury (SCI) and tetraplegia have a remarkably high prevalence of sleep-disordered breathing (SDB). Most reports describe obstructive sleep apnoeas (OSAs) and hypopnoeas in this population.1 2 OSA impairs health-related quality of life (HRQL) in tetraplegic subjects and is associated with cognitive dysfunction, with repercussions mainly on attention, concentration, memory and learning skills.3 4 Changes in upper airways (UA) in SCI may increase the risk of OSA syndrome (OSAS): increased passive UA collapsibility,5 greater volume of soft palate and lateral pharyngeal walls, increased nasal resistance and nasal congestion.6 7 Breathing at lower volumes may also contribute to the higher prevalence of OSAS in this population.2 8 Coexistent traumatic brain injury, sleep position and medication (opioids, baclofen and benzodiazepines) can affect breathing during sleep with an additional burden of central events9 or nocturnal hypoventilation. It is quite possible that central events are underestimated in available publications because hypopnoeas are most often not specified as being central or obstructive as proposed by the American Academy of Sleep Medicine (AASM) 2012 guidelines. 10 Despite the high prevalence of SDB and SDB-related symptoms in SCI, adherence to Continuous Positive Airways Pressure (CPAP) is poor: symptomatic patients treated with SDB by CPAP have a long-term adherence to treatment of 50%–63%.