Sleep Apnea in Patients With Fibromyalgia: A Growing Concern
Fibromyalgia (FM) is a widespread pain and fatigue syndrome without a known cause. The prevalence of FM ranges from 2% to 3% of the general population, with women affected six to nine times more frequently than men.1 It is estimated that the prevalence increases in women as they age, from 4% at age 20 to 8% by age 70.1-3
Most patients with FM complain of hurting all over—from head to toe. The neck, back, hips, and shoulders are typically prominent sites of pain. Patients also will frequently complain of poor sleep, burning and numb sensations, dry eyes and mouth, temperature sensitivity (feeling cold), headaches, fatigue, dizziness, abdominal and bladder problems, sensitivities to medications, restless leg syndrome, jaw discomfort, and difficulties with mood and memory.
From its earliest description in the literature, FM has been recognized as more than a pain syndrome. Researchers’ understanding that FM involves central nervous system sensitization and deep sleep dysregulation have changed the focus of FM diagnosis and treatment. Revised diagnostic criteria are illustrated in Table 1. As such, clinicians have begun to recognize that the treatment of sleep and fatigue comorbitities should be a major focus in the management of FM patients. The objective of this article is to review current diagnosis and treatment options for sleep-related problems in patients with FM, including a case presentation representative of a common FM patient.
According to a recent article, sleep and fatigue symptoms have surpassed pain as the most prominent complaints in FM patients.4 It is now known that FM patients suffer from a litany of sleep issues including nonrestorative sleep with alpha-wave intrusions, insomnia, restless leg syndrome, hypersomnia such as narcolepsy, and obstructive sleep apnea (OAS).
Perhaps the most common sleep problem seen in patients with FM is nonrestorative sleep. The majority of patients with FM will have alpha-wave intrusions during deep sleep. It is thought that this phenomenon contributes to sleep complaints among patients with FM. In the past, the diagnosis of alpha-wave intrusions could be very time consuming, with researchers counting the intrusions by hand over many hours. Today, diagnostic approaches, including the use of quantitative electroencephalography (qEEG), can easily demonstrate alpha-wave intrusions in deep sleep (see Figure 1).5
Figure 2 shows alpha-wave intrusion during delta waves on a sleep hypnogram from an overnight sleep study using polysomnography (PSG) in a patient with FM. More than 90% of patients with FM will have alpha-wave intrusions during their sleep and it is thought that this phenomenon contributes to pathology and complaints in patients with FM. Recent therapeutic approaches that target this phenomenon, such as the γ-aminobutyric acid (GABA)-type B agonist, sodium oxybate (Xyrem), has been shown to reduce alpha-wave intrusions, as well as improve symptoms of pain and fatigue.6,7
In addition to alpha-wave intrusions that may impair the restorative aspect of sleep, FM patients usually have diminishment of the overall amount of deep sleep. In the normal population, slow-wave sleep (SWS) should account for 20% to 25% of sleep, but in the FM population it is typically much less. In Figure 3, a normal sleep hypnogram demonstrates normal deep sleep predominantly in the first 5 hours of sleep as compared to a FM patient who does not enter deep sleep for any significant period of time and has multiple unexplained arousals.
Patients with sleep disordered breathing (SDB) also can present with a number of complaints, including drowsiness, inability to sleep, cognitive dysfunction, fatigue, mood complaints, and decreased libido. A small case study demonstrated that treatment of SDB could improve symptoms in patients with FM.8 We also know that disruption of deep sleep in healthy individuals can predispose them to increases in pain perception and cognitive difficulties. A number of smaller trials have shown that when deprived of SWS, healthy volunteers developed pain and cognitive dysfunction similar to that seen in the FM population; findings that support the association between dysfunctional sleep and FM.9
Given the plethora of complaints common in both patients with FM and SDB, there has been new interest in ruling out SDB in patients with FM. Since we know that patients with FM can have poor quality sleep, the identification of a treatable sleep disorder such as SDB is something that can greatly benefit this patient population.
Patients with FM and SDB have added risk factors—prescription of sedative or narcotic agents, which can cause or worsen SDB. With the airway blocked, air cannot reach the lungs and oxygen levels drop. This causes the brain to slightly wake up; this is referred to as a microarousal. These brief repeated arousals cause sleep to be nonrestorative and put stress on the heart and other organs.
One of the more serious SDBs is OSA. The condition is characterized by loud, frequent snoring and involves the partial or complete collapse of the airway during sleep. With OSA, muscles in the throat start to relax during sleep, which makes it more likely for the airway to collapse. An apnea is described as a cessation of airflow >10 seconds. A hypopnea is typically defined as a decrease in airflow of at least 30% associated with a decrease in oxygen saturation of >4%. Episodes can occur hundreds of times in one night. A large neck (greater than 18 inches in men or 16 inches in women), body mass index (BMI) >35 kg/m2, a retrusive jaw, or large tonsils in children can predispose patients to OSA.
Obstructive sleep apnea can cause excessive daytime drowsiness, which can affect performance at work and quality of life. When oxygen levels drop, numerous physiologic changes occur, including elevated cortisol levels, hyperglycemia, insulin resistance, and increase in sympathetic tone with increased heart rate and blood pressure. Because of this, OSA has been linked to a number of medical conditions, including high blood pressure, stroke, heart attack, atrial fibrillation, gastroesophageal reflux, diabetes, and glaucoma. Problems controlling weight, mood and memory problems, as well as diminished libido, also are common symptoms associated with OSA.
The incidence of moderate and severe OSA in the general population is estimated to range from 5% to 7% in men and 2% to 4% in women.10 However, in women who have been diagnosed with OSA, the incidence of FM is tenfold higher than in the normal population, indicating a profound association between SDB and FM.11