Differentials
Central sleep apnea and Cheyne-Stokes respiration (CSB)
SIGNS / SYMPTOMS
Recurrent episodes of apnea with absence of respiratory effort.
CSB associated with congestive heart failure, renal failure, or cerebrovascular disease, which is not necessarily present with OSA.
INVESTIGATIONS
Polysomnogram: in OSA there is evidence of thoracoabdominal effort, whereas episodes of central apnea are devoid of effort signal on thoracoabdominal sensors. In CSB, a crescendo-decrescendo change in breathing amplitude interspersed by episodes of central apnea or hypopnea would be seen. Some portable devices with a central plus sensor can also detect central sleep apnea.
Narcolepsy
SIGNS / SYMPTOMS
Level of sleepiness in narcolepsy may be higher on the Epworth Sleep Scale. Epworth Sleepiness Scale Opens in new window
Some patients with narcolepsy have cataplexy, hypnagogic hallucinations, and sleep paralysis.
INVESTIGATIONS
OSA needs to be excluded or evidenced to be sufficiently treated. After OSA is excluded using polysomnography, a multiple sleep latency test may be performed to assess for narcolepsy.
Insufficient sleep
SIGNS / SYMPTOMS
May be difficult to differentiate clinically.
INVESTIGATIONS
Sleep diary and/or actigraphy should be used. However, total sleep time may still be under- or overestimated. Polysomnography is performed to rule out OSA if there are additional risk factors.
Inadequate sleep hygiene
SIGNS / SYMPTOMS
Improper sleep schedule with frequent napping. Routine use of alcohol, nicotine, caffeine, and engaging in stimulating activities close to bedtime. Poor bedroom environment.
INVESTIGATIONS
Diagnosis is usually clinical; however, actigraphy may be used to help diagnose irregularities in the sleep cycle.
Periodic limb movement disorder
SIGNS / SYMPTOMS
If restless leg syndrome is present, patients may describe an urge to move legs due to discomfort during periods of inactivity (usually in evening), which is relieved by motion.
INVESTIGATIONS
OSA is excluded by polysomnography or sufficiently treated to ascribe the excessive sleepiness to the limb movements on a polysomnogram.
Hypersomnia due to drug or substance use
SIGNS / SYMPTOMS
May be difficult to differentiate clinically.
INVESTIGATIONS
Urine or blood toxicological analysis may be performed for suspected substance. If the patient is no longer dependent on the drug and symptoms persist, a polysomnogram is performed.
Hypothyroidism
SIGNS / SYMPTOMS
Patient may have cold intolerance, constipation, coarse hair, puffiness, and coarse skin.
Although these symptoms are not exclusive to hypothyroidism, they are not associated with OSA in absence of hypothyroidism.
INVESTIGATIONS
Thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels are measured. In patients with primary hypothyroidism, TSH will be elevated and T4 will be low.
Laryngospasm related to gastroesophageal reflux
SIGNS / SYMPTOMS
May be associated with more exaggerated choking symptom.
INVESTIGATIONS
Differentiated using polysomnography.
Sleep-related hypoventilation
SIGNS / SYMPTOMS
Caused by neuromuscular or chest wall disorders, lower airway obstruction, pulmonary parenchymal or vascular pathology, or medullary lesions.
May also coexist with OSA.
INVESTIGATIONS
Differentiated using polysomnography and clinical criteria/diagnoses. Polysomnogram will show greater duration of oxygen desaturations.
Patient will develop hypercapnia.
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