PRINCIPLES OF HIGH-SPATIAL-RESOLUTION SURFACE EMG (HSR-EMG) - SINGLE MOTOR UNIT DETECTION AND APPLICATION IN THE DIAGNOSIS OF NEUROMUSCULARDISORDERS

The most detailed information about the structural and functional char acteristics of the muscle can be gained from the single motor unit (MU ) action potential. In addition, information about the activity of a s ingle MU is essential for the diagnosis of neuromuscular disorders. Du e to the low spatial resolution of conventional bipolar surface electr omyography (EMG), the resulting signal is a superposition of a large n umber of simultaneous active MUs. The difficulty is in separating the activity of a single MU from simultaneous active adjacent MUs. In cont rast to other non-invasive EMG procedures, the high-spatial-resolution -EMG (HSR-EMG), which is based on the use of a multi-electrode array i n combination with a spatial filter procedure, allows the detection of single MU activity in a non-invasive way. It opens access to the exci tation spread and enables the determination of the conduction velocity in single MUs, and the localization of the endplate region. In additi on, HSR-EMG detects changes in the electrical activities of the MUs wh ich are typical in neuromuscular disorders. Using HSR-EMG it was possi ble to identify 97% of all investigated volunteers and patients with m uscular or neuronal disorders. Therefore, HSR-EMG is suitable as a too l for the non-invasive diagnosis of neuromuscular disorders. (C) 1997 Elsevier Science Ltd. All rights reserved.