Scoring Movement Rules

LEARNING OBJECTIVES

On completion of this chapter, the reader should be able to:

1. Describe movement events and movement event scoring rules according to the standards of the American Academy of Sleep Medicine.
2. Identify the common artifact that occurs in leg movement channels.

In polysomnography (PSG), scoring movements is necessary but can be tricky. The AASM Manual for the Scoring of Sleep and Associated Events has outlined the scoring rules for scoring movements in both adults and pediatrics. Review the current sections Parameters to Be Recorded as well as the Technical Specifications for Movement Rules in the AASM Manual for the Scoring of Sleep and Associated Events to verify you are using the most updated recording parameters for collection of data. In this chapter, we will review the movement scoring rules as well as provide examples to illustrate how these events should be scored.

When scoring movements, it is important that we are recording the proper channels and using appropriate sensors. To assess movement activity in the lower limbs, both legs should be monitored. Surface electrodes are placed on the belly of the tibialis anterior muscle of each leg, about 2 to 3 cm apart (1). If upper limb movements are being assessed, both arms should be monitored. Surface electrodes should be placed on either the extensor digitorum communis or flexor digitorum superficialis muscles, or both (1).

Surface electrodes are placed on the neck over the paraspinal muscles (1) to record movement activity typical of rhythmic movement disorder (RMD). To record the electromyographic (EMG) activity seen with bruxism, surface electrodes are placed on the masseter muscle (1). For exact placements of the electrodes used for these EMG recordings, see the chapter on Movement Rules in the current version of the AASM Manual for the Scoring of Sleep and Associated Events.

PERIODIC LIMB MOVEMENTS IN SLEEP

Periodic limb movements in sleep (PLMS) are defined as leg movements with a duration between 0.5 and 10 seconds.
The maximum amplitude of the event must be an 8 µV increase from the baseline limb EMG signal.
PLMS events may cause arousals. Arousals are scored as long as they occur within 0.5 seconds of the movement.

See Figure 41-1 for an example of a periodic limb movement that resulted in an arousal.

PERIODIC LIMB MOVEMENT SERIES

A periodic limb movement series is defined as four leg movements (see Fig. 41-2) with a duration between 5 and 90 seconds.
The maximum amplitude of the event must be at minimum an 8 µV increase from the baseline limb EMG signal.
Events may cause arousals. Arousals are scored as long as they occur within 0.5 seconds of the movement.

Figure 41-1 There is a greater than 8 µV increase in the leg electromyogram channels from baseline. The event duration is between 0.5 and 10 seconds. At the end of the movement event, there is an arousal.

Figure 41-2 There is a greater than 8 µV increase from baseline. There are four leg movements. The period length is between 5 and 90 seconds. At the end of each movement event, there is an arousal.

Figure 41-3 This epoch shows movements consistent with rhythmic movement disorder. There are more than four clustered movements. The activity is twice the amplitude of the baseline electromyogram activity.

Only gold members can continue reading. Log In or Register to continue