The Periodic Leg Movement tool in ActiLife utilizes some algorithms to yield several output parameters related to the detection of Periodic Leg Movement or PLM. The following outline describes those terms and the references we used to develop the algorithm related to those terms.
- Kicks - Kicks are simply movement of the foot indicative of typical peridoic leg movements detected by PSG. The device is worn on the dorsum of each foot at the base of the big toe and hence is more sensitive to "kicks" as might be detected by electromyograph (EMG) with electrodes placed on the tibialis anterior muscles. The decision to place ActiSleep devices on the to area was based on the research performed by Kemlink, et., al. in A comparison of polysomnographic and actigraphic evaluation of periodic limb movements in sleep. The concept of kicks and their relation to EMG were derived from M. King, et.al in The validation of a new actigraphy system for the measurement of periodic leg movements in sleep and from E. Sforza, et.al. in The PAM-RL ambulatory device for detection of periodic leg movements: a validation study. Click on the paper to read the abstracts.
- PLMS - Periodic Leg Movement during Sleep. The definition of periodic leg movement used in ActiLife is the same as the definition found in the research paper by Gschliesser, et.al., PLM detection by actigraphy compared to polysomnography: A validation and comparison of two actigraphs. Accordingly, PLM are defined as "a sequence of four or more leg movements separated by at least 5 (and not more than 90) seconds with a duration between 0.5 and 5 seconds." Since the minimum epoch allowed in ActiLife is 1s, our criteria for defining a PLM is a duration between 1 and 5 seconds. A minimum of four "kicks" (or, leg movements) are required to start a PLM bout (or PLMS).
- PLMS Bouts - PLMS bouts are simply the consecutive bout time representing unbroken PLM. A PLM is disqualfiied when the separation between kicks exceeds 90 seconds or does not reach 5 seconds. This information was also gathered from the research paper by Gschliesser, et.al., PLM detection by actigraphy compared to polysomnography: A validation and comparison of two actigraphs