Sleep Medicine — MCQs

Q: What is the minimum number of apnea episodes required for the diagnosis of obstructive sleep apnea?

AHI ≥ 5 events/hour. ***AHI ≥ 5 events/hour*** - An **apnea-hypopnea index (AHI)** of 5 or more events per hour of sleep, accompanied by symptoms such as **daytime sleepiness**, snoring, or witnessed apneas, is the diagnostic criterion for obstructive sleep apnea (OSA) [1]. - This threshold signifies a clinically significant frequency of **breathing disturbances** during sleep [1]. *AHI ≥ 2 events/hour* - An AHI of 2 events/hour is generally considered within the **normal range** or indicates very mild, non-pathological sleep disordered breathing. - It is **insufficient** to diagnose OSA in adults, even with associated symptoms. *AHI ≥ 10 events/hour* - An AHI of 10 events/hour would indicate at least **mild to moderate OSA**, well above the minimum diagnostic threshold. - While diagnostic, it is not the *minimum* number required for initial diagnosis. *AHI ≥ 4 events/hour* - An AHI of 4 events/hour is close to the diagnostic threshold but still **below the minimum** required for a formal diagnosis of OSA. - It would typically be considered **mild sleep-disordered breathing** that may not meet diagnostic criteria without other significant factors.

Q: What is the most common cause of restless leg syndrome?

Iron deficiency anemia. ***Iron deficiency anemia*** - **Iron deficiency** is a well-established and the most common reversible secondary cause of **restless leg syndrome (RLS)**, affecting dopamine synthesis and function in the brain [1]. - Correcting iron levels, often with oral iron supplements, can significantly improve RLS symptoms. *Chronic kidney disease* - While **chronic kidney disease (CKD)** is a known cause of secondary RLS, it is less common than iron deficiency anemia. [1] - RLS in CKD is often associated with **uremia** and electrolyte imbalances [1]. *Hyperthyroidism* - **Hyperthyroidism** is not typically associated with restless leg syndrome. - Symptoms of hyperthyroidism usually include **tremor**, anxiety, weight loss, and heat intolerance. *Peripheral neuropathy* - **Peripheral neuropathy** can cause leg discomfort and sensory symptoms, but these are generally described as burning, tingling, or numbness rather than the irresistible urge to move associated with RLS [1]. - While some neuropathies may coexist with RLS, it is not the most common direct cause of RLS itself [1].

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Normal Sleep Physiology

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Sleep-Disordered Breathing

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Insomnia

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Hypersomnias

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Circadian Rhythm Disorders

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Parasomnias

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Sleep-Related Movement Disorders

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Sleep in Medical Disorders

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Sleep in Psychiatric Disorders

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Sleep Diagnostics

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Pharmacologic Management of Sleep Disorders

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Non-pharmacologic Sleep Interventions

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