Automatic measurement of random interpotenial intervals in single fibre electromyography

The paper describes computer-aided measurement of interpotential intervals in single fibre eletromyography (SFEMG), a diagnostic and research method in clinical medicine. The method is based on analysis of consecutive intervals in pairs of single muscle fibre action potentials. The most important parameter obtained is the mean value of absolute differences of consecutive interpotential intervals, which reflects the reliability of impulse conduction along the terminal branches of motor axons and across the neuromuscular junction. The interface units, in combination with amplifers, binary counters and pulse amplitude-to-pulse width converters, allow not only direct analogue-to-digital conversion but also recognition of potentials. This enables the computer system to make decisions. The results are computed in less than 1 sec after analysis, and are immediately displayed in a graphic and alpha-numberical form on a screen at the measurement site. This provides an immediate visual feedback for the investigator thus both increasing the diagnostic efficacy and reducing the discomfort to the patient. Simultaneous printout by a teletype is used for documentation. The computer system consists of an HP 2116C computer with standard periphery and the program has been written in FORTRAN IV language with subroutines in FORTRAN IV and ASSEMBLER languages.