NEW ACTIGRAPHIC ASSESSMENT METHOD FOR PERIODIC LEG MOVEMENTS (PLM)

A new actigraphic method by which periodic leg movements (PLM) can be measured is presented. Data acquisition and analysis were brought into line to distinguish short-lasting repetitive leg movements from random motor restlessness. The definition of PLM follows the generally accepted criteria for PLM scoring. Thirty restless legs patients, all also suffering from PLM, were investigated three times by polysomnography, including tibialis anterior surface electromyography and actigraphy. A high correlation (reliability) was found for the number of PLM per hour spent in bed between the two methods. Furthermore, the actigraph records PLM specifically. An index of random motor restlessness is not sufficient for a reliable PLM recording. In addition, periodic movements in sleep (PMS) and PLM show comparable variability in general. The actigraphic assessment of PLM, however, gives a better measure because PMS recordings may result in a substantial underestimation of PLM when sleep efficiency is reduced. This method is an ambulatory assessment tool that can also be used for screening purposes.