RST Sleep Stage and Event Scoring Questions and Answers

Question 1

A 30-second epoch of sleep contains a clear K-complex in the first 10 seconds. The remainder of the epoch is characterized by low-amplitude, mixed-frequency EEG, a sustained low chin EMG tone, and intermittent rapid eye movements. How should this epoch be scored?

Accepted Answer

Stage R

Answer

According to the AASM Manual, if the criteria for Stage R (low-amplitude, mixed-frequency EEG; low chin EMG; and rapid eye movements) are met for more than half of an epoch, the epoch is scored as Stage R. This rule takes precedence even if hallmark features of other stages, such as a K-complex from Stage N2, are also present within the same epoch.

Question 2

According to the AASM Manual for the Scoring of Sleep and Associated Events, which of the following criteria must be met to score an epoch as Stage N3?

Accepted Answer

At least 20% of the epoch contains EEG activity of 2 Hz or less with peak-to-peak amplitudes of at least 75 µV.

Answer

The AASM defines Stage N3 (slow-wave sleep) as an epoch in which 20% or more (i.e., 6 seconds or more) of the epoch consists of slow-wave activity. Slow-wave activity is defined as waves with a frequency of 2 Hz or less and a peak-to-peak amplitude of 75 µV or greater, measured over the frontal EEG derivations.

Question 3

A technologist is scoring a respiratory event and observes a >30% drop in the nasal pressure signal for 12 seconds. This event is associated with a 4% oxygen desaturation from the pre-event baseline. According to the AASM's acceptable scoring criteria, how should this event be scored?

Accepted Answer

Hypopnea

Answer

The AASM's acceptable criteria for scoring a hypopnea include a drop in the nasal pressure signal by ≥30% of the pre-event baseline for a duration of ≥10 seconds, associated with a ≥4% oxygen desaturation. Since this event has a >30% signal drop for >10 seconds and is associated with a 4% desaturation, it meets the criteria for a hypopnea.

Question 4

Which of the following is a required criterion for scoring a series of events as Periodic Limb Movements in Sleep (PLMS)?

Accepted Answer

The duration of each limb movement must be between 0.5 and 10 seconds.

Answer

According to AASM scoring rules, a PLMS series requires a minimum of 4 consecutive limb movements. Each individual limb movement must have a duration of 0.5 to 10 seconds. The period between the onsets of consecutive movements must be between 5 and 90 seconds. There is no requirement for an associated oxygen desaturation.

Question 5

During Stage N2 sleep, a technologist observes an abrupt shift in EEG frequency to alpha activity lasting for 4 seconds. This shift is preceded by at least 10 seconds of stable sleep. How should this 4-second event be scored?

Accepted Answer

Arousal

Answer

The AASM defines an arousal during NREM sleep as an abrupt shift in EEG frequency (including alpha, theta, and/or frequencies greater than 16 Hz) that lasts for at least 3 seconds and is preceded by at least 10 seconds of stable sleep. This 4-second event meets these criteria perfectly.

RST - Registered Sleep Technologist Practice Test

RST - Registered Sleep Technologist Practice Test

RST Sleep Stage and Event Scoring Questions and Answers