Detection of periodic leg movements with a static-charge-sensitive bed.

We evaluated the performance of the static-charge-sensitive bed (SCSB), a non-invasive movement sensor, in detecting nocturnal periodic movement activity using simultaneous bilateral anterior tibialis electromyography (EMGat) as a reference. Two different study setups were used, one with 500 random record extracts, another with 10 continuous recordings. The inter-rater reliability between two independent scorers was 0.92 in scoring EMGat and 0.91 in scoring SCSB. In an epoch based analysis, depending on the study setup and scorer, the sensitivity of the SCSB to detect periodic leg movements was 0.81-0.94 whereas the specificity was 0.84-0.89. In a movement-by-movement analysis, despite incomplete concordance between the two methods the total number of movements per hour were comparable. Our findings support the use of the SCSB as a non-invasive alternative to anterior tibialis EMG recordings to reveal the presence of nocturnal periodic movement activity and estimate its frequency.