Untreated Moderate-to-severe Sleep Apnea Is Associated with More Severe Spasticity in Individuals Living with Spinal Cord Injury: A Cross-sectional Prospective Study.
Julio Furlan1, Eldon Loh2, Mark Boulos3
1KITE Research Institute and Toronto Rehabilitation Institute; University of Toronto, 2University of Western Ontario, 3Sunnybrook Health Sciences; University of Toronto Centre
Objective:
To study the potential association between the severity of spasticity and the degree of sleep-related breathing disorders (SRBDs) in individuals living with subacute/chronic spinal cord injury (SCI).
Background:
SCI has been linked to increased frequencies of SRBDs (up to 50% after paraplegia, up to 90% following tetraplegia) and spasticity (up to 60% after tetraplegia).
Design/Methods:
This cross-sectional prospective study examined the potential association between moderate-to-severe SRBD and more severe spasticity among adults with subacute/chronic (≥1 month since SCI), cervical/high-thoracic, complete/incomplete SCI. The diagnosis of SRBD was established using a home-based sleep apnea test that quantifies the apnea-hypopnea index (AHI). Spasticity was assessed using the modified Ashworth scale (MAS), and adjusted MAS based on the use of antispasmodic drugs. C-reactive protein (CRP) level was also measured.
Results:
By September/2023, we recruited 57 individuals (17 females, 40 males; ages: 20-84 years, mean age: 67.4 years) with motor complete (n=20) or incomplete SCI at cervical (n=48) or thoracic levels. Time from SCI onset varied from 1 month to 52 years (mean time: 34.4 months). Mean AHI was 19.2 events/hour (range: 0.8-66.2 events/hour). Total MAS varied from 0-12 (mean MAS: 5.3); adjusted MAS varied from 0-12 (mean adjusted-MAS: 5.5). A higher total MAS was associated with a greater AHI (P=0.0458, Rsqr=0.0701); there was also an association between a higher adjusted MAS and a greater AHI (P=0.0434, Rsqr=0.0721). Moreover, individuals with no/mild SRBD had less severe spasticity (lower adjusted MAS) than individuals with moderate-to-severe SRBD (P=0.0149). CRP levels varied from 0.5-101.2 mg/L; there were no significant differences between individuals with no/mild SRBDs and individuals with moderate-to-severe SRBDs regarding their CRP levels (P=0.9498).
Conclusions:
Our preliminary results suggest that more severe SRBD is associated with a greater degree of spasticity following SCI. Treatment of SRBDs may have the potential to be a novel treatment target for managing spasticity in SCI.