Epidemiologic Associations of Carpal Tunnel Syndrome and Sleep Position: Is There a Case for Causation?

Abstract Introduction Carpal tunnel syndrome (CTS) is thought to be due to compression of the median nerve in the carpal tunnel. It is known that carpal tunnel pressures are elevated in wrist postures of flexion and extension and in those patients with CTS. Classic symptoms of CTS include night waking with pain, tingling, and numbness. These classic symptoms stimulated our interest in the relationship of sleep to the development of CTS. Method We reviewed the literature surrounding the epidemiology of CTS and the literature regarding sleep disturbances. Through careful distillation of these studies and a process of reasoning, we have developed a hypothesis for a causal mechanism of CTS. Results Epidemiologically, it has been shown that CTS is associated with age, gender, increased body mass index (BMI), diabetes, pregnancy, and is more common in some populations. The same associations noted above for CTS are strongly associated with sleep disturbances. Sleep disturbances due to age, gender, BMI, pregnancy, and population variations are all associated with sleeping in the lateral position supporting the hypothesis that a common causative mechanism of CTS is sleeping in a lateral position. Discussion We believe that the epidemiologic associations with CTS act through a common causative mechanism, increased sleeping in the lateral position which puts the wrist at increased risk of flexion or extension, compressing the median nerve in the carpal tunnel. This hypothesis is simple and explains the connection between a previously unconnected group of epidemiologic associations. This realization has real clinical significance in that it focuses our attention on the early disorder when it is completely reversible. It clarifies previously confused clinical circumstances, creates research questions that can be tested, and it invites us to change our clinical perspective in this most common form of nerve compression

Characteristics of Japanese Patients with Complex Sleep Apnea Syndrome: A Retrospective Comparison with Obstructive Sleep Apnea Syndrome

Objective The prevalence of complex sleep apnea syndrome (CompSAS) among Asian patients with obstructive sleep apnea syndrome (OSAS) has not yet been reported. Distinguishing CompSAS from pure OSAS is difficult using only diagnostic polysomnography (PSG). We examined the prevalence of CompSAS in Japanese patients with OSAS and the possibility to distinguish CompSAS from pure OSAS by analyzing the severity of respiratory events based on either sleep body position or sleep stage using a diagnostic PSG. Patients and Methods A retrospective chart review of 297 consecutive Japanese patients who were 15 years of age or older with a primary diagnosis of OSAS who were referred for CPAP titration (AHI. 20 events/hr). Results Seventeen patients (5.7%) out of the 297 patients who had an obstructive apnea hypopnea index (AHI) of 20 or higher showed adverse increases in central apnea index (CAI) by the treatment with CPAP whereas obstructive apnea index (OAI) and mixed apnea index (MAI) were significantly decreased. In the results, the AHI on the PSG for CPAP titration reached only approximately half of the values on the diagnostic PSG. In these CompSAS patients, both the total CAI and the CAI in the supine position during NREM sleep on the diagnostic PSG were significantly higher than those in the OSAS group. The sleep body position did not so strongly affect the AHI, OAI and MAI in the CompSAS group. Multiple, stepwise, and logistic regression analyses revealed that the CAI in the supine position during NREM (p=0.026) was a significant variable to distinguish CompSAS from OSAS statistically although the variables were within the normal range. Conclusion The prevalence of CompSAS in Japanese OSAS patients may be lower when compared with Caucasian patients. The increase of CAI in the supine position during NREM sleep on diagnostic PSG may be a characteristic feature in CompSAS.ArticleINTERNAL MEDICINE. 48(6):427-432 (2009)journal articl

Sleep-Disordered Breathing and Caffeine Consumption

BACKGROUND: Sleepiness is one of the most burdensome symptoms of sleep-disordered breathing (SDB). While caffeine is frequently used to avert sleepiness, the association between SDB and caffeine use has not been thoroughly explored. The current study examined whether SDB is associated with caffeine consumption and if factors such as sex, age, and daytime sleepiness explain or modify the association. METHODS: Data from the Sleep Heart Health Study, a community-based study on the consequences of SDB, were used to characterize the association between SDB and caffeine intake. SDB was assessed with full-montage polysomnography. Caffeine use was quantified as the number of cans of soda or the cups of coffee or tea consumed daily. The Epworth Sleepiness Scale was used to assess daytime sleepiness. Multivariable negative binomial regression models were used to characterize the independent association between SDB and caffeine use. RESULTS: Caffeinated soda, but not tea or coffee, intake was independently associated with SDB severity. Compared with participants without SDB, the relative ratios for caffeinated soda consumption in women with mild, moderate, and severe SDB were 1.20 (CI, 1.03-1.41), 1.46 (CI, 1.14-1.87), and 1.73 (CI, 1.23-2.42), respectively. For men, an association was only noted with severe SDB and caffeinated soda use. Age did not modify the SDB-caffeine association, and sleepiness could not explain the observed associations. CONCLUSIONS: SDB is independently associated with caffeinated soda use in the general community. Identifying excessive caffeine used in SDB has potential significance given the cardiovascular effects of caffeine and untreated SDB