Childhood Adenotonsillectomy Trial

6.8.4 Scoring Periodic Leg Movements

Prior scoring defined Period Limb Movement in Sleep as: "PLMS is a series of four or more consecutive movements lasting 0.5 to 5.0 seconds with an inter-movement interval of 4 to 90 seconds."( Coleman RM: Periodic movements in sleep (nocturnal myoclonus) and restless legs syndrome. In Guilleminault C (ed) Sleeping and Waking Disorders: Indications and Techniques. Menio Park, CA, Addison-Wesley, 1982, pp265-295.)

The new AASM rules for scoring Periodic Limb Movements in Sleep (PLMS) used are as follows:

• A. The following rules define a significant leg movement (LM) event:
  • 1. The minimum duration of a LM event is 0.5 seconds
  • 2. The maximum duration of a LM event is 10 seconds
  • 3. The minimum amplitude of a LM event is an 8 microV-increase in EMG voltage above resting EMG
  • 4. The timing of the onset of a LM event is defined as the point at which there is an 8 microV- increase in EMG voltage above the resting EMG
  • 5. The timing of the ending of a LM event is defined as the start of a period lasting at least 0.5 seconds during which the EMG does not exceed 2 microV above resting EMG
• B. The following rules define a PLM series:
  • 1. The minimum number of consecutive LM events needed to define a PLM series is 4 LMs
  • 2. The minimum period length between LMs (defined as the time between onsets of consecutive LMs) to include them as part of a PLM series is 5 seconds
  • 3. The maximum period length between LMs (defined as the time between onsets of consecutive LMs) to include them as part of the PLM series is 90 seconds
  • 4. Leg movements of 2 different legs separated by less than 5 seconds between movements onsets are counted as a single leg movement

Compumedics ProfusionPSG 3 software defines the interval between limb movements as the duration measured between the end of the previous limb movement event and the commencement of the next limb movement event. Leg movements that are exclusively associated with the termination of respiratory events will not be considered in the PLMI. (Will be deleted if occurring in clusters.) The AASM rule states: a LM should not be scored if it occurs during a period from 0.5 seconds preceding an apnea or hypopnea to 0.5 seconds following an apnea or hypopnea.

Delete all the PLMs in awake.