[Computer-assisted analysis of the electromyogram for routine clinical use].

A computerized EMG analysis system implemented on an MS-DOS computer was developed explicitly for clinical routine usage. It incorporates analysis of interference pattern as well as of motor unit action potentials (MUAPs). Key features of MUAP analysis are the automatic segmentation and parameterization of the EMG signal and the automatic assignment of MUAPs to motor units. Determination of muscle activity is based on threshold detection of the signal's first derivative, leading to the definition of a MUAPs central component. Its parameters (length, amplitude, maximal steepness, area between curve and base-line, area between first derivative and base-line, number of turns etc.) are used when comparing MUAPs. The automatic assignment of MUAPs to motor units was implemented as an iterative procedure. MUAPs are compared to a reference MUAP and eventually assigned to it if their parameters are sufficiently similar. For such a group of MUAPs the most representative MUAP is determined which is then used as new reference MUAP in the next iteration step. Most important for clinical routine usage are simple handling, speed and the clearly arranged presentation of results. The system allows for interactive modification of MUAP assignment as well as start and end points of every MUAP. Analysis results may be displayed on the screen and printed, giving the user a quick impression of the muscle under study. Thus this method meets basic requirements for computer assisted decision making in differential diagnosis.