Magnetic resonance imaging of the upper airway in patients with quadriplegia and obstructive sleep apnea

Abstract

The aim of this study was to investigate upper airway anatomy in quadriplegics with obstructive sleep apnea. Fifty subjects were recruited from three hospitals in Australia: people with quadriplegia due to spinal cord injury and obstructive sleep apnea (n = 11), able-bodied people with obstructive sleep apnea (n = 18), and healthy, able-bodied controls (n = 19). All underwent 3-Tesla magnetic resonance imaging of their upper airway. A subgroup (n = 34) received a topical vasoconstrictor, phenylephrine and post-phenylephrine magnetic resonance imaging. Mixed-model analysis indicated no significant differences in total airway lumen volume between the three groups (P = 0.086). Spinal cord injury-obstructive sleep apnea subjects had a significantly larger volume of soft palate (P = 0.020) and retroglossal lateral pharyngeal walls (P = 0.043) than able-bodied controls. Able-bodied-obstructive sleep apnea subjects had a smaller mandible volume than spinal cord injury-obstructive sleep apnea subjects and able-bodied control subjects (P = 0.036). No differences were seen in airway length between groups when controlling for height (P = 0.055). There was a marginal increase in velopharyngeal volume across groups post-phenylephrine (P = 0.050), and post hoc testing indicated the difference was confined to the able-bodied-obstructive sleep apnea group (P < 0.001). No other upper airway structures showed significant changes with phenylephrine administration. In conclusion, people with obstructive sleep apnea and quadriplegia do not have a structurally smaller airway than able-bodied subjects. They did, however, have greater volumes of soft palate and lateral pharyngeal walls, possibly due to greater neck fat deposition. The acute response to upper airway topical vasoconstriction was not enhanced in those with obstructive sleep apnea and quadriplegia. Changes in upper airway anatomy likely contribute to the high incidence in obstructive sleep apnea in quadriplegic subjects.

<p>Impact Of Spinal Cord Injury On Sleep: Current Perspectives</p>

“…These include obesity (as indicated by increased specific measures of body habitus such as weight, body mass index (BMI), waist, abdominal, and neck girth) which is associated with OSA in both SCI24 and the general population 33. Obesity leads to narrowing of the upper airway by deposition in pharyngeal tissues including the tongue in both the general population and in SCI,22,34 in addition to the effect of reducing lung volume on decreased upper airway caliber during sleep 35. In chronic SCI, most authors have observed associations between OSA prevalence and increasing age, BMI and neck circumference,24,25,27,36 but these relationships appear weaker in the acute, post-injury period 23.…”

A randomised controlled trial of nasal decongestant to treat obstructive sleep apnoea in people with cervical spinal cord injury

“…The pathogenesis of OSA results from a combination of anatomical and non-anatomical physiological traits including high upper airway collapsibility, low arousal threshold, high loop gain and low muscle responsiveness [9]. While the relative contributions of these factors are likely to be different in tetraplegia [10], anatomical and physiological changes associated with injury, such as altered autonomic [11], neuromuscular [12] and respiratory control [13], increased adipose tissue and neck circumference [2,14], and increased nasal resistance [15,16], may increase the risk of OSA in people with tetraplegia.…”

Positive airway pressure for sleep-disordered breathing in acute quadriplegia: a randomised controlled trial

“…SDB, predominantly obstructive sleep apnoea (OSA), can be caused acutely by cervical spinal cord injury4–6 and is up to five times more prevalent in chronic quadriplegia7–16 compared with the general population 17 18. The pathophysiological basis for SDB remain unclear in quadriplegia,19 although both ‘spinal specific’ issues such as a higher nasal resistance,20 21 ventilatory control instability,22 23 altered upper airway reflex responses24 and an increased upper airway lateral wall size,25 coupled with a high rate of ‘general population’ risks in chronic quadriplegia such as obesity, ageing and a male predominance all contribute 14…”