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 rando m motor restlessness. The definition of PLM follows the generally acce pted 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 h our spent in bed between the two methods. Furthermore, the actigraph r ecords PLM specifically. An index of random motor restlessness is not sufficient for a reliable PLM recording. In addition, periodic movemen ts 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 whe n sleep efficiency is reduced. This method is an ambulatory assessment tool that can also be used for screening purposes.