High spatial resolution EMG
The single motor unit is the smallest unit of the muscle which can be innervated by the central nervous system independently. In neurology it is well known that from activation of a single motor unit detailed information about its structural and functional properties can be gained. This is why the information about the single motor unity activity contributes essentially to the diagnosis of neuromuscular disorders.
However, up to now only invasive EMG methods provide a spatial resolution which is high enough to detect the single motor unit activity. These invasive methods cause pain and discomfort to the patient. The Department of Rehabilitation and Prevention engineering has developed the methodology of High Spatial Resolution Electromyography (HSR-EMG), which for the first time allows the non-invasive and therefore painless acquisition of the single motor unit activity. Herewith, the HSR-EMG provides useful information for diagnostics and therapy control of neuromuscular illnesses.
The HSR-EMG is based on the use of a multi-electrode array in combination with a Laplace-Filter. The electrode array consist of pin-electrodes arrange 2dimensionally with an interelectrode-distance in the millimeter range. The applied Laplace-Filter suppresses the activities of motor units located more distantly from the skin surface and amplifies contributions of motor units located close to the array. As a consequence the activity of single motor units can be detected as isolated peaks within the HER-EMG signal course.