March 2019, Volume XXXII, No 12

Neurology

Obstructive sleep apnea

Examining the adverse consequences

bstructive sleep apnea (OSA) is a common sleep disorder affecting at least 25 million adults in the U.S. Those at increased risk for OSA include males; post-menopausal women; overweight/obese individuals; and patients with larger neck circumference and crowded oropharynx, positive family history of OSA, and use of sedative hypnotics. Associated chronic medical conditions (e.g., atrial fibrillation, heart failure, diabetes mellitus, stroke, or obesity) also increase risk for OSA. There has been a rise in numbers over the last few decades in association with the obesity epidemic.

Untreated OSA is associated with adverse consequences, including cardiovascular and cerebrovascular complications such as hypertension, coronary artery disease, heart failure, arrhythmias, and stroke. Individuals often suffer from impairments in vigilance, concentration, and cognitive function. Evidence shows that there are higher rates of job-related and motor vehicle accidents due to excessive daytime sleepiness related to untreated OSA. People often experience a decline in their mental health, resulting in increased mood disorders such as depression, which are often more refractory to treatments with untreated OSA. There is also evidence that OSA is associated with metabolic dysregulation, affecting glucose control and risk for diabetes.

Obstructive sleep apnea is characterized by repetitive episodes with cessation of breathing (apneas) or partial upper airway obstructions (hypopneas). This narrowing of the upper airway results in increased breathing effort and impaired normal ventilation during sleep. These events are often associated with reduced blood oxygen saturation. Five or more respiratory events (apneas, hypopneas, or respiratory effort-related arousals/RERAs) per hour of sleep are required for diagnosis of OSA. The severity of the apnea is determined by the frequency of airway obstructions per hour (<5=normal, 5–15=mild, 15–30=moderate, >30=severe).

Patients who report sleep-related concerns—excessive snoring, frequent insomnia, or fatigue during the day—to their primary care doctor are often referred to a specialist in sleep medicine. These specialists may include neurologists, otolaryngologists, pulmonologists, dentists, and other physicians with additional training in the field. Neurologists can identify neurological issues that may affect sleep, as well as long-term risk of dementia and other conditions. Primary care doctors should follow up with these patients to ensure compliance with treatment regimens.

Diagnostic testing for OSA should be performed with a comprehensive sleep evaluation and adequate follow-up with a sleep specialist. The clinical evaluation for OSA should include a thorough sleep history and a physical examination that includes the respiratory, cardiovascular, and neurologic systems. Sleep specialists should inquire about snoring, witnessed apneas, nocturnal choking or gasping, restlessness, insomnia, waking unrefreshed, and/or excessive sleepiness. A complete sleep history is essential, since many patients suffer from more than one sleep disorder or present with atypical sleep apnea symptoms.

Sleep specialists should screen for medical conditions associated with increased risk for OSA, such as obesity, atrial fibrillation, hypertension, stroke, and congestive heart failure. The evaluation should serve to establish a differential diagnosis, which can then be used to ensure that the appropriate diagnostic testing is performed to address OSA, as well as other comorbid sleep complaints such as insomnia, REM behavior disorder, parasomnias, restless limbs syndrome and periodic limb movement disorder, nocturnal seizures, and/or pathologic hypersomnia. Follow-up under the supervision of a board-certified sleep medicine physician ensures that study findings and recommendations are relayed appropriately, and that appropriate therapy is made available to the patient.

Many patients suffer from more than one sleep disorder.

Sleep apnea-focused questionnaires lack diagnostic accuracy, making direct measurement of patient sleep patterns necessary to establish a diagnosis of OSA. This may take two forms:

Home sleep testing (HST) is performed in the patient’s residence with a portable monitor that records sleep patterns for subsequent review by a physician specializing in sleep medicine. Some insurance companies require an HST as an initial sleep test. While the home equipment is considered an alternative initial method to diagnose OSA in adults, it cannot diagnose the majority of sleep disorders, and should be followed with an in-lab sleep study when home studies have not adequately confirmed or ruled out OSA.

Polysomnogram (PSG), performed overnight in a sleep study lab with an attendant on hand, is the gold standard for diagnostic testing of OSA. In-lab PSGs can also identify co-existing sleep disorders.

Another benefit of doing in-lab PSG monitoring is that positive airway pressure (PAP) therapy (described below) may be initiated during the test. This allows for more precise treatment and potentially better compliance, by determining appropriate follow-up therapy (e.g., selecting a PAP machine and masks, identifying individualized airflow pressure settings, and addressing challenges encountered in using PAP therapy). It also allows patients to determine if PAP therapy is a desired treatment or whether other options should be pursued early on.

Disadvantages of PSG include the cost associated with evaluating all patients suspected of having OSA with PSG, limitations with insurance coverage, and potentially restricted access to in-laboratory testing in some regions. HST may be less costly and more efficient for some populations.

There are a variety of treatment options available for OSA, including both surgical and nonsurgical options.

Nonsurgical treatment options

The most widely used nonsurgical treatment for moderate and severe OSA in adults is positive airway pressure (PAP) machines, which deliver gently pressurized room air or oxygen through a mask attached to the patient’s nose and/or mouth, ensuring that airways remain open during sleep. Modern technology offers PAP machines that are compact and quiet. New models include modem capability, allowing the provider and patient to continue close monitoring without the need to transport the machine back to the clinic.

The mandibular advancement device (MAD), an oral appliance that increases airway diameter, is another nonsurgical treatment option employed both as primary or as adjunctive treatment for OSA. MAD is beneficial in that it is compact and portable, making it easy to travel with. This therapy is more discreet and allows individuals to be more intimate with their bed partner (no machine in the way). No electricity is needed, which can be ideal for camping, cabins, and travel. Consequences of MAD that need to be monitored include TMJ (temporomandibular joint disorders) arthritis or arthralgia (pain); bite changes or teeth shifting; and hypersalivation, mouth dryness, and/or tooth discomfort.

If clinically indicated, patients should be encouraged to lose weight. Positional therapy (promoting lateral sleep and/or elevating the head of the bed) should also be considered for certain populations.

Untreated OSA results in significant cardiovascular and cerebrovascular complications.

Surgical treatment options

Surgical options for  treating OSA include UPPP (uvulopalatopharyngoplasty) —removal of the uvula, part of the soft palate, and tonsils—which can help reduce the severity of the OSA. Mandibular advancement surgery or other surgical procedures may be explored as well. These surgical options may be a useful adjunctive treatment option for patients with OSA.

Another new technology for treating OSA involves upper airway stimulation using a hypoglossal nerve stimulator (Inspire device), which activates the hypoglossal nerve to tighten the muscles of the tongue and upper airway during sleep, improving airflow. The hypoglossal nerve stimulator is a treatment option for adult patients (age 22 or older) with moderate to severe OSA (AHI 15–65) who have failed or are unable to tolerate PAP therapy and have a BMI of 32 or less. Patients who meet these criteria will be referred to the implanting surgeon, who performs endoscopy to determine if they are an appropriate candidate.

Neurological sleep disorders

Several sleep disorders can be associated with different neurological conditions. Abnormal nocturnal behaviors, for example, can be easily distinguished by clinical presentation. REM sleep behavior disorder (RBD) may present as an early manifestation of an evolving neurodegenerative disorder with alpha-synucleinopathy (Parkinson’s disease, dementia with Lewy bodies, and multiple systems atrophy). RBD typically manifests during the second half of the night, when REM sleep is typically observed, and consists of dream enactment behavior. Often, the patient is redirectable, is able to recall the dream content, and was observed or aware of acting out the dream.

Parasomnias, on the other hand, typically occur during the first half of the night out of slow wave sleep and consist of complex motor behaviors (e.g., sleep walking, sleep eating, sleep texting, sleep sex). The patient will have no recollection of the event and is not redirectable. Nocturnal seizures are unique in that they are stereotyped (repeat the same pattern), are short lived, and occur out of sleep. Patients may or may not be aware of having them. It is also important to recognize sleep disorders in our patients with dementia. It is now thought that chronic sleep deprivation may increase the risk for dementia due to the accumulation of beta-amyloid protein in the brain. Patients with dementia can also have reversal of their sleep patterns, or advanced sleep phase syndrome, resulting in earlier bedtimes and awakenings. This can be disruptive to families and is the leading cause of institutionalization for patients with dementia.

Summary

There is a high prevalence of OSA in major chronic diseases, and untreated OSA results in significant cardiovascular and cerebrovascular complications. It is critical that sleep specialists monitor for symptoms of OSA, and screen those at risk for it. Undiagnosed OSA can result in a significant burden on the health care system, with increased health care utilization and cost due to chronic health consequences.

It is therefore important that our patients be appropriately evaluated and treated for their underlying sleep disorder. Diagnostic testing for OSA should be performed with a comprehensive sleep evaluation. PSG or HST can be used for the diagnosis of OSA in patients at increased risk of OSA. If a single HST is negative, inconclusive, or technically inadequate, PSG should be performed for the diagnosis of OSA. The gold standard for diagnostic testing continues to be the in-lab PSG, however. Many treatment options are available to individuals with OSA. Providers should consider using alternative treatments early on if indicated to help increase compliance to therapies.

It is important for us to remember that the best brain is the rested brain.

Tacjana K.E. Friday, MD, practices at the Minneapolis and Blaine offices of Noran Neurological Clinic. She is board-certified in neurology, sleep medicine, and epilepsy. 

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Tacjana K.E. Friday, MD, practices at the Minneapolis and Blaine offices of Noran Neurological Clinic. She is board-certified in neurology, sleep medicine, and epilepsy.