The AASM Scoring Manual four years later

Abstract

Purpose of review: Review published studies and critiques which evaluate the impact and effects of the American Academy of Sleep Medicine (AASM) Sleep Scoring Manual in the four years since its publication.

Findings: USING THE AASM MANUAL RULES TO SCORE SLEEP AND EVENTS IN A POLYSOMNOGRAM (PSG) RESULTS IN: (1) very large differences in apnea-hypopnea indexes (AHI) when using the recommended and alternative rule for scoring hypopneas in adults; (2) increases in NREM 1 and sleep stage shifts with compensatory decreases in NREM 2 in children and adults when following rule 5.C.b. for ending NREM 2 sleep; (3) increases in NREM 3 in adults scoring slow wave activity in the frontal EEG derivations; (4) improved interscorer reliability; and (5) successfully identified fragmented sleep in children with obstructive sleep apnea (OSA) from primary snorers or normal controls because they had more NREM 1 and stage shifts using rule 5.C.b. Criticism of the Manual most often cited: (1) two rules for scoring hypopneas; (2) alternative EEG montage cancellation effects; (3) scoring stages 3 and 4 as NREM 3; and (4) too few rules for scoring arousals and REM sleep without atonia.

Summary: Four years have passed since the AASM Scoring Manual was published with far less criticism than those who developed it feared. The AASM Manual provides a foundation upon which we all can build rules and methods which identify the complexity of sleep and its disorders.

Keywords: AASM standard; Sleep scoring parameters; polysomnography/classification/standards; practice guidelines as topic sleep apnea; practice guidelines as topic sleep scoring.

Figure 1. NREM 1 sleep time and sleep stage shifts increase when scoring sleep studies using AASM sleep scoring rule 5.C.b.

Figure showing a 60-sec epoch from a polysomnogram done on one of my patients. In the first 30-sec epoch, he is in NREM 2 sleep, then has an arousal (arrow). Because no sleep spindles or K-complexes recur following the arousal, the second epoch is scored as NREM 1 because of AASM scoring rule 5.C.b (p. 26 of the AASM Manual). Rule 5.C.b. has proved useful, increasing the amount and percent time of NREM 1 sleep and sleep stage shifts scored, providing a clinically useful marker of sleep fragmentation. This figure is from my laboratory, no permission needed.

Figure 2. Sleep spindles in a 3-month-old infant

Note well-developed sleep spindles in this 30-sec epoch from a PSG recorded on a 3-month-old infant. Sleep spindles between 3-4 months of age often last 5-8 sec and are maximal over Cz. Sensitivity 500 μV peak-to-peak, LFF 0.3 Hz, HFF 35 Hz.

Figure 3. Cancellation effects of the bipolar linkage Fz-Cz on slow wave activity of NREM 3 sleep

Note how much lower the amplitude is in the Fz-Cz and Cz-Oz channels compared to F3-M2, C3-M2, and O1-M2 due to cancellation effects of bipolar linkages over frontocentral regions where slow wave activity is often synchronous and of each amplitude.

Figure 4. Advantages and disadvantages of recommended and alternative EOG montages

Figure 5. The alternative EOG montage better identifies eye movements

Note how the alternative EOG montage better demonstrates the direction of eye movements and subtle eye blinks compared with the recommended EOG montage (Figure provided by Michael Silber, M.D.)

Figure 6. An EEG arousal from NREM 3 sleep in a 13-year-old

An arousal from NREM 3 sleep in a 13 year old. Pediatric electroencephalographers would score this EEG delta shift as NREM 1 sleep.