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How Do I Use the Periodic Leg Movement (PLM) tool?

Last Updated: Jul 26, 2016 06:01PM CDT
The Periodic Leg Movement (PLM) tool allows users to detect and score periodic leg movements in patients with PLM disorder or restless leg syndrome.  Note: The PLM tool is only compatible with data collected from the legacy ActiSleep or the new ActiSleep+ monitor devices
 
Initializing Devices
To use the tool, initialize an ActiSleep monitor through the devices tab to start collecting data at the desired time.  (Info about ActiSleep battery life) ActiSleep+ devices only have one option for initialization (30Hz).  Legacy ActiSleep devices should be initialized to collect data at 1s epochs.  During initialization, ActiLife gives users the option to print a sleep diary.  The sleep diary can be used by patients who choose to wear the devices for several nights in their own homes or for doctors who are logging multiple patients' sleep behaviors.   Patients should be instructed to use the sleep diary to keep track of the time in bed (TIB) and time out of bed (TOB) for purposes of analysis.
 
Attach the ActiSleep monitor to the top interior of the patient’s left and right feet around the ball of the foot as shown in the image below.  This can be accomplished with bandage wrapping or with the straps provided with the ActiSleep monitoring package.  Patients should wear the device during the entire duration of their total time in bed.
 
 
Downloading Devices
After patients have worn the devices for the desired number of sleep periods, collect the devices and download them using the Devices tab.  Legacy ActiSleep monitors will produce an *.agd file on download.  This file can be used for scoring PLM in the PLM tab.  ActiSleep+ devices will create a *.gt3x file on download.  This file contains the raw acceleration data collected by the devices and needs to be post-processed (i.e., converted to *.agd format) prior to PLM scoring.  This can be accomplished by choosing “Create AGD File” from the download dialog as shown in the figure below.  Select 1s epoch and 3 axes.  The other options are optional, but “Low Frequency Extension” should not be selected.
 
 
After download, an AGD file will be created in the download folder which is also selected at the time of download.
 
Scoring the PLM Data
To score periodic leg movements, open the PLM tab and select the left and right leg *.agd files.  Click the “Add Sleep Periods” button and select the entry method. 
  • Add Period Using Bed Times– Use this option to manually enter in times as recorded by the doctor or patient on the sleep diary.
  • Import from Separate AGD File– Use this option to import sleep times from another AGD file that already contains the same sleep times.
  • Enter Period Graphically- coming soon)
Select which axis or axes to use to score the PLM data.  The Vector Magnitude option combines all three axes using the vector magnitude formula SQRT( (Axis 1^2) + (Axis 2)^2 + (Axis 3)^2).
 
Select the thresholds for detecting legitimate “movement”.  Note: these thresholds only set the level at which PLM activity occurs.  ActiLife’s built-in algorithm determines whether or not the movement qualifies as PLM.
 
  • Onset Threshold: The threshold (in counts-per-epoch) at which PLM movement detection starts
  • Decay Threshold: The threshold (in counts-per-epoch) at which PLM movement detection ends.
 
An onset and decay threshold are available to introduce hysteresis into the movement detection.
 
See What is a Count? for more info.
 
Selecting the different sleep periods in on the left-hand side will populate the graphs and results for that corresponding period for both left and right side files.  See “How Do I Interpret the PLM Output?” for further information.
 

If you need any further assistance, please visit our support portal at https://help.theactigraph.com/home. From there, you can view many helpful FAQ's and Troubleshooting Articles; log in to check any existing Support Requests; or create a new Support Ticket if you are unable to find a solution. You can also email us at support@theactigraph.com or give us a call at (877) 497-6996, Monday through Friday, 8 am to 5 pm CST.

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