Relationships Between Objective Sleep Indices and Symptoms in a Community Sample of People With Tetraplegia

Berlowitz DJ, Spong J, Gordon I, Howard ME, Brown DJ. Relationships between objective sleep indices and symptoms in a community sample of people with tetraplegia. Arch Phys Med Rehabil 2012;93:1246-52. Objective: To examine the relationships between injury severity, quality of life, sleep symptoms, objectively measured sleep, and sleep disorders in chronic tetraplegia. Design: Cross-sectional survey. Setting: Community. Participants: People with tetraplegia (N=78; 59 men, 35 with motor and sensory complete tetraplegia; mean age +/- SD, 43 +/- 12.1; age range 18-70y), living in the state of Victoria, Australia, who were not currently being treated for sleep disorders and who completed both questionnaires and sleep studies comprised the study cohort. Intervention: Questionnaire battery mailed to potential participants. Returned questionnaires were followed with full, home-based polysomnography. Main Outcome Measures: Demographics and questionnaire responses. Results: Quality of life (Assessment of Quality of Life instrument) was worse in the group with complete lesions compared with incomplete lesions (P=.001; median=16; interquartile range, 9 vs 12 [12]), and the Apnea-Hypopnea Index was higher (P=.002; interquartile range, 32.0 [25.2] vs 13.2 [24.8]). Ninety-one percent of those with complete lesions had obstructive sleep apnea (Apnea-Hypopnea Index >10) versus 55.8% of those with incomplete tetraplegia. No effect of lesion level on the Apnea-Hypopnea Index was observed (r=-.04, P=.73). In the complete group, the time taken from sleep onset until the first rapid eye movement sleep period was significantly delayed at over 2 hours. Multiple regression analyses showed substantially stronger relationships between daytime sleep complaints and abnormalities observed in the sleep study in those with complete lesions. Conclusions: Obstructive sleep apnea is a major problem, particularly in those with complete tetraplegia, and this single comorbidity is associated with reduced quality of life. In those with incomplete cervical lesions, the relationships between sleepiness, other sleep symptoms, and polysomnography indices are less precise.