EEG Sleep Staging and Sleep EEG 3 — Questions and Answers
Question 1: An EEG epoch scored as REM typically shows all of the following EXCEPT:
- Sleep spindles (Correct answer)
- Low-amplitude mixed-frequency background
- REMs on EOG channels
- Reduced chin EMG tone
Correct answer: Sleep spindles
Sleep spindles are a feature of NREM (N2) sleep and are absent during REM sleep; REM is defined by low-voltage mixed EEG, rapid eye movements, and muscle atonia.
Question 2: Alpha intrusion into NREM sleep (alpha-delta sleep) is associated with:
- Non-restorative sleep and fibromyalgia (Correct answer)
- Normal aging in patients over 60
- Enhanced slow-wave sleep recovery
- Increased REM density
Correct answer: Non-restorative sleep and fibromyalgia
Alpha-delta sleep, where alpha activity intrudes into slow-wave sleep, is linked to non-restorative sleep and is commonly described in fibromyalgia patients.
Question 3: In polysomnography scoring, an arousal is defined as an abrupt EEG frequency shift lasting at least:
- 3 seconds (Correct answer)
- 10 seconds
- 15 seconds
- 1 second
Correct answer: 3 seconds
AASM defines an arousal as an abrupt shift to higher EEG frequencies (alpha, theta, or >16 Hz) lasting ≥3 seconds, preceded by ≥10 seconds of sleep.
Question 4: Which normal EEG variant appearing at sleep onset consists of brief 4–6 Hz runs with a positive polarity at the vertex?
- Hypnic jerks with associated vertex potentials (Correct answer)
- POSTS
- 6 Hz spike-and-wave (phantom spike)
- Wicket spikes
Correct answer: Hypnic jerks with associated vertex potentials
Hypnic jerks are sudden body twitches at sleep onset that correlate with brief vertex-maximal EEG potentials and are a normal physiologic phenomenon.
Question 5: The EEG technologist notes the patient's EEG shows continuous delta slowing only in the posterior head regions during deeper NREM sleep. This is most consistent with:
- Normal occipital delta of sleep (Correct answer)
- Structural posterior lesion
- Lennox-Gastaut syndrome
- Nonconvulsive status epilepticus
Correct answer: Normal occipital delta of sleep
Occipital delta waves during deep NREM sleep are a normal finding and should not be interpreted as pathological posterior slowing.
Question 6: Sleep onset REM (SOREMP) within 15 minutes of sleep onset on a PSG is most suggestive of:
- Narcolepsy (Correct answer)
- Idiopathic hypersomnia
- Obstructive sleep apnea
- Restless legs syndrome
Correct answer: Narcolepsy
SOREMPs are a key diagnostic finding in narcolepsy, where the loss of orexin/hypocretin neurons disrupts normal sleep architecture and causes premature REM onset.
EEG Sleep Staging and Sleep EEG 3
An EEG epoch scored as REM typically shows all of the following EXCEPT: