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Rise time or rise rate: which should be a criterion for analysing motor unit action potentials?
Y Masakado1, K Akaboshi, A Kimura
1Department of Rehabilitation Medicine, Keio University School of Medicine, Tokyo, Japan.
Electromyography and Clinical Neurophysiology
|October 20, 2000
Summary
The study found that the rise rate (RR) of motor unit action potentials (MUAPs) is a more reliable measure than rise time (RT) in clinical electromyography (EMG). RR provides a better indicator for accepting MUAPs, especially when sharp sounds are used as stimuli.
Area of Science:
- Neurology
- Physiology
- Biomedical Engineering
Background:
- Motor unit action potentials (MUAPs) are crucial in electromyography (EMG) for diagnosing neuromuscular disorders.
- Assessing MUAP characteristics like rise time (RT) and rise rate (RR) aids in accurate signal interpretation.
- Auditory stimuli, such as sharp sounds, can influence MUAP parameters.
Purpose of the Study:
- To compare the reliability of MUAP rise time (RT) and rise rate (RR) in clinical EMG.
- To investigate the impact of sharp sound stimuli on MUAP RT and RR in different muscles.
- To determine the optimal parameter for MUAP acceptance in automated EMG analysis.
Main Methods:
- Concentric EMG recordings were performed on the first dorsal interosseus (FDI) and biceps brachii (BIC) muscles of healthy subjects.
- MUAPs were analyzed for their rise time (RT) and rise rate (RR) under auditory stimulation.
- Statistical distributions of RT and RR were calculated for both muscles.
Main Results:
- FDI muscle showed 85% of MUAPs with RT < 500 microseconds, while BIC muscle had 65%.
- FDI muscle exhibited 98.3% of MUAPs with RR > 0.3 mV/ms, and BIC muscle had 93%.
- A significant portion of MUAPs in BIC muscle exceeded the 500-microsecond RT threshold.
Conclusions:
- Rise rate (RR) is a more consistent and reliable parameter than rise time (RT) for MUAP acceptance in clinical EMG.
- The use of RT alone for MUAP characterization may be reconsidered, especially with auditory stimuli.
- Implementing RR in automated EMG programs is recommended for improved diagnostic accuracy.