INTRODUCTION
Insomnia has been reported to coexist with various musculoskeletal disorders. Although lumbar spinal stenosis (LSS) is the most frequently operated on spinal disease, the causal relationship between LSS and the development of sleep disorders remains unclear due to a lack of longitudinal studies. This study aimed to determine whether LSS was a risk factor for developing new sleep disorders, primarily insomnia, using a prospective cohort of community residents.
METHODS
This study was a prospective cohort study. Participants aged ≥65 years from the "Locomotive Syndrome and Health Outcomes in Aizu Cohort Study (LOHAS)” conducted in 2008 formed our study population. LSS was diagnosed using the self-administered, self-reported history questionnaire (SSHQ), a validated diagnostic support tool for LSS. Sleep disorder was investigated using a questionnaire during the 2-year follow-up. The impact of LSS on sleep disorder onset was analyzed after adjusting for potential confounders, such as age, sex, obesity, hypertension, diabetes, depression, and smoking habits, using propensity score matching.
RESULTS
Of the 489 participants who were followed up for two years, 38 (7.8%) had newly developed a sleep disorder in 2010. After adjusting for confounding factors, a comparison of 133 participants each in the control and LSS groups showed a significantly higher frequency of new-onset sleep disorders (19 [14.3%] in the LSS group versus 6 [4.5%] in the control group).
DISCUSSION
This study clarified that LSS independently increases the risk of sleep disorders, even after adjusting for confounding factors with propensity score matching.
The mechanisms by which LSS might cause sleep disorders include the effects of pain, numbness, and cauda equina syndrome. Actually, surgical interventions for LSS have been reported to improve sleep more effectively than non-surgical treatments. However, further research is needed to determine how LSS develops sleep disorders.
Clinically, this result implies orthopedic surgeons should assess LSS patients for sleep disorders. On the other hand, The general physician should consider LSS in patients with sleep disorders and, if present, should treat them in conjunction with an orthopedic surgeon. The SSHQ is a useful screening tool in this process. Management of LSS can also reduce dependence on sleep medications.
The research, a large-scale cohort study with two years of follow-up, utilized an SSHQ and intimated a causal relationship between LSS and sleep disorders. Limitations include a restricted sleep disorder definition, possible misdiagnosis with SSHQ, and unconsidered variables such as medication and daily activity.
In conclusion, LSS can cause sleep disorders and should be evaluated during treatment. Future research should validate these outcomes and explore the benefits of integrative treatment strategies.