Obstructive sleep apnea
Matthew L. Ho, Steven D. Brass UC Davis Department of Neurology, Davis Medical Center, University of California, California, USA
Obstructive sleep apnea (OSA) affects millions of Americans and is estimated to be as prevalent as asthma and diabetes. Given the fact that obesity is a major risk factor for OSA, andgiven the current global rise in obesity, the prevalence of OSA will increase in the future. Individuals with sleep apnea are often unaware of their sleep disorder. It is usually first recognized as a problem by family members who witness the apneic episodes or is suspected by their primary care doctor because of the individual’s risk factors and symptoms. The vast majority remain undiagnosed anduntreated, despite the fact that this serious disorder can have significant consequences. Individuals with untreated OSA can stop breathing hundreds of times a night during their sleep. These apneic events can lead to fragmented sleep that is of poor quality, as the brain arouses briefly in order for the body to resume breathing. Untreated, sleep apnea can have dire health consequences and canincrease the risk of hypertension, diabetes, heart disease, and heart failure. OSA management has also become important in a number of comorbid neurological conditions, including epilepsy, stroke, multiple sclerosis, and headache. Diagnosis typically involves use of screening questionnaires, physical exam, and an overnight polysomnography or a portable home study. Treatment options include changes inlifestyle, positive airway pressure, surgery, and dental appliances.
The Greek word apnea means breathless or loss of breath.1 Sleep-disordered breathing (SDB) encompasses a heterogeneous group of sleep-related disorders that are characterized by abnormal pauses in breathing during sleep. There are two major types of SDB: obstructive sleep apnea (OSA) and central sleep apnea (CSA).Despite the difference in the actual cause of each type, in both cases, people with untreated sleep apnea stop breathing repeatedly during their sleep. Of the two types of sleep apneas characterized, OSA is the most common type, constituting greater than 85% of all cases of SBD; CSA is far less common.2 [page 60]
OSA affects more than twelve million Americans.5 An epidemiological review byYoung et al. estimates that 1 in 5 adults has at least mild OSA and 1 in 15 adults has at least moderate OSA.6 Sleep apnea can affect anyone at any age, even children.7,8 OSA is becoming increasingly prevalent. However, because of the lack of awareness by the public and healthcare professionals, the vast majority remain undiagnosed and untreated. Data from the Wisconsin sleep cohort study of patientsestimate that 93% of women and 82% of men with moderate-to-severe sleep apnea were undiagnosed.9 A follow-up publication from the Wisconsin Cohort Study five years later indicated that the prevalence of OSA in people aged 30-60 years was 9-24% for men and 4-9% for women.10,11 Primary risk factors for OSA include the male gender, those over age 40, overweight persons or recent weight gain, andpersons with a large neck size or small chin/jaw (Table 1).12 Epidemiological studies have consistently shown that body weight, and in particular BMI, is the strongest risk factor for OSA. It is estimated that about 70% of those with OSA are obese and that the prevalence of OSA in obese men and women is about 40%.13,14 Twenty-six percent of patients with a BMI greater than 30 and 33% of those with aBMI greater than 40 have moderate OSA.15 A large neck circumference is also associated with an increased risk of OSA. In fact, neck circumference of 15.7 in (40 cm) or greater may have a greater sensitivity and specificity than BMI in predicting OSA, regardless of the person’s sex.16,17 [Neurology International 2011; 3:e15]