S-3-08-01
ELECTROPHYSIOLOGICAL EVALUATION OF NEUROMUSCULAR FUNCTION
Akio Kimura, Naoichi Chino (Dept. of Rehab. Medicine, Keio University School of Medicine) Yasutomo Okajima (Dept. of Rehab. Mledicine, Keio University Tsukigase Rehab. Center)
Rehabilitation medicine deals with neuromuscular dysfunctioning. For this reason, electrophysiological evaluation, such as electromyography, takes an important part in daily practice of rehabilitation medicine. Therefore, every physiatrist has to be familiar with electrodiagnostics. In this symposium, I would like to make clear the role of electrophysiological evaluation as a diagnostic tool of neuromuscular function.
I would like to focus on two aspects of electrophysiological evaluation. First, I will present the MUP (motor unit action potential) automatic analysis using a microcomputer. Secondly, clinical use of muscle fiber conduction velocity measured by a surface electrode array will be discussed.
S-3-08-02
CONDUCTION BLOCK AND SLOWING IN NERVE CONDUCTION STUDIES
Yasutomo Okajima (Dept. of Rehabilitation Medicine, Keio University Tsukigase Rehabilitation Center) Akio Kimura, Naoichi Chino (Dept. of Rehabilitation Medicine, Keio University School of Medicine)
Nerve fibers may recover quickly from demyelinating pathology while once they suffer axonal degeneration, it takes time for the fibers to regenerate. Conduction block characterized by amplitude reduction of electrically-evoked potentials at a distance is a sign of demyelination while conduction slowing is seen both in demyelination and degeneration-regeneration process. In this study, waveform changes caused by conduction block and slowing were analyzed by computer simulation. In sensory studies, amplitude reduction reflects either widening of conduction velocity distribution or conduction slowing of both faster and slower fibers, either of which can be determined by checking the maximum velocity calculated from onset latencies. Amplitude reduction by conduction block should be considered in cases duration of the potential at a distance is not markedly increased. In motor studies, marked amplitude reduction always reflects conduction block. However, mild reduction is seen in the tibial M wave of the normal subjects that is ascribed to shorter duration of the component motor units. Multiphasic long-duration M waves often indicate mixture of severe conduction block and slowing due to demyelination.
