periodic limb movement index
Also written as: PLMI
A quantitative measure from polysomnographic studies expressing the number of periodic limb movements per hour of sleep, used to assess sleep-related movement disorders.
Full Definition
Periodic Limb Movement Index (PLMI) is a standardized parameter calculated from polysomnographic recordings that quantifies the frequency of periodic limb movements during sleep. The index is calculated by dividing the total number of periodic limb movements by the total sleep time in hours. Movements are typically detected through EMG electrodes placed on the anterior tibialis muscles and must meet specific criteria for duration, amplitude, and periodicity to be scored as periodic limb movements. A PLMI greater than 15 per hour is generally considered abnormal in adults, though the clinical significance depends on associated sleep fragmentation and symptoms. The PLMI is essential for diagnosing periodic limb movement disorder and assessing treatment efficacy in patients with restless legs syndrome or other sleep-related movement disorders.
Usage
Usage note: Always express as number per hour; PLMI acceptable abbreviation
In Context
- "The patient's periodic limb movement index of 45 per hour indicated severe periodic limb movement disorder." — Sleep study report
- "Following treatment with pramipexole, the PLMI decreased from 38 to 8 movements per hour." — Treatment follow-up assessment