RPSGT RPSGT Sleep Disorders & Pathophysiology 4 — Questions and Answers
Question 1: Which polysomnographic finding is most characteristic of REM sleep behavior disorder (RBD)?
- Increased slow-wave activity during NREM
- REM sleep without atonia (RSWA) (Correct answer)
- Cyclic alternating pattern in NREM
- Alpha intrusion into delta sleep
Correct answer: REM sleep without atonia (RSWA)
RBD is defined by the loss of normal REM muscle atonia, resulting in REM sleep without atonia on chin EMG.
Question 2: In a patient with suspected upper airway resistance syndrome (UARS), which finding differentiates it from simple snoring?
- AHI greater than 5
- Esophageal pressure swings with EEG arousals but no apneas (Correct answer)
- Oxygen desaturation below 88%
- Presence of hypopneas lasting over 30 seconds
Correct answer: Esophageal pressure swings with EEG arousals but no apneas
UARS is characterized by increased respiratory effort detected via esophageal manometry causing arousals without discrete apneas or significant desaturations.
Question 3: A patient with Cheyne-Stokes respiration most commonly has which underlying condition?
- Obstructive sleep apnea
- Congestive heart failure (Correct answer)
- Chronic obstructive pulmonary disease
- Hypothyroidism
Correct answer: Congestive heart failure
Cheyne-Stokes respiration is most commonly associated with congestive heart failure due to prolonged circulation time causing oscillating ventilatory drive.
Question 4: Which sleep disorder is associated with the HLA-DQB1*06:02 allele in over 90% of cases?
- Idiopathic hypersomnia
- Fatal familial insomnia
- Narcolepsy type 1 (Correct answer)
- Kleine-Levin syndrome
Correct answer: Narcolepsy type 1
Narcolepsy type 1 (with cataplexy) shows a strong HLA-DQB1*06:02 association, reflecting its autoimmune destruction of hypocretin neurons.
Question 5: During a PSG, a patient's airflow signal shows a crescendo-decrescendo pattern lasting 60 seconds cycling every 90 seconds. What is the most likely scoring?
- Obstructive apnea cluster
- Central sleep apnea with Cheyne-Stokes breathing pattern (Correct answer)
- Mixed apnea series
- Hypopnea with periodic limb movements
Correct answer: Central sleep apnea with Cheyne-Stokes breathing pattern
The waxing-and-waning crescendo-decrescendo breathing with a cycle length typically 45–90 seconds is the hallmark of Cheyne-Stokes breathing.
Question 6: Which neurotransmitter system is primarily implicated in the pathophysiology of narcolepsy type 1?
- Dopaminergic neurons in the ventral tegmental area
- Hypocretin/orexin neurons in the lateral hypothalamus (Correct answer)
- Serotonergic neurons in the dorsal raphe nucleus
- Histaminergic neurons in the tuberomammillary nucleus
Correct answer: Hypocretin/orexin neurons in the lateral hypothalamus
Narcolepsy type 1 results from autoimmune loss of hypocretin (orexin)-producing neurons in the lateral hypothalamus, causing CSF hypocretin-1 levels below 110 pg/mL.
Question 7: A patient is diagnosed with sleep-related hypoventilation. Which PSG parameter is most directly used to confirm this diagnosis?
- Apnea-hypopnea index above 15
- End-tidal or transcutaneous CO2 exceeding 55 mmHg for more than 10 minutes (Correct answer)
- SpO2 below 88% for more than 5 minutes total
- Arousal index above 30 per hour
Correct answer: End-tidal or transcutaneous CO2 exceeding 55 mmHg for more than 10 minutes
Sleep-related hypoventilation is confirmed by CO2 monitoring showing PaCO2 or surrogate (ETCO2/TcCO2) >55 mmHg for ≥10 minutes during sleep.
RPSGT RPSGT Sleep Disorders & Pathophysiology 4
Which polysomnographic finding is most characteristic of REM sleep behavior disorder (RBD)?