Multichannel surface EMG for the non-invasive assessment of the anal sphincter muscle.

BACKGROUND/AIMS This work focuses on recording, processing and interpretation of multichannel surface EMG detected from the external anal sphincter muscle. The aim is to describe the information that can be extracted from signals recorded with such a technique. METHODS The recording of many signals from different locations on a muscle allows the extraction of additional information on muscle physiology and anatomy with respect to that obtained by classic bipolar recordings. Multichannel EMG methods have been recently developed for the assessment of the external anal sphincter. An anal probe was used in this study to record signals at different depths within the anal canal during contractions at different effort levels. The plug is 150 mm in length and 14 mm in diameter, holding a circumferential array of 16 equally spaced silver bar electrodes, located at a distance of 20 mm from the probe tip and aligned with the probe axis. RESULTS Information about localization of the innervation zone, fiber length, EMG amplitude, muscle fiber conduction velocity and single motor unit analysis can be obtained from the signals recorded with the circumferential array by means of innovative signal processing techniques. CONCLUSIONS The type of information extracted from multichannel surface EMG signals cannot be obtained with other currently available techniques. The technological innovation described in this work is promising for a further insight into the investigation of pelvic floor pathologies and rehabilitation treatments.