Quantitative motor unit potential analysis in the diaphragm: A normative study

Abstract

Although quantitative motor unit potential (MUP) analysis has an established role in other skeletal muscles, it has not been performed in the diaphragm. The aim of the present study was to test whether such studies are possible and to establish normative data. Twenty-nine healthy volunteers (15 men), aged 21-65 years (median, 33 years), were studied using standard concentric needle electrodes, and equipment with the facility for template-operated multi-MUP analysis. Needle electrodes were inserted into the right medial recess of the seventh to ninth intercostal spaces. During MUP sampling, subjects were asked to hold their breath in partial inspiration for 5 s. At least 20 MUPs were obtained in 28 subjects. Diaphragmatic MUPs were confirmed to be much smaller than those of limb muscles. We found diaphragmatic quantitative MUP analysis to be possible in healthy volunteers. However, further studies in patient groups are needed to establish the feasibility and clinical value of such studies.

Electrical stimulation of the pudendal nerve promotes neuroregeneration and functional recovery from stress urinary incontinence in a rat model

“…To maintain urinary continence, a guarding-like reflex exists in which the EUS contracts to prevent urine leakage and counteract increased abdominal pressure upon the bladder, such as during LPP testing (27,46). Increased contractile force generated by striated muscle, such as that comprising the EUS, involves the recruitment of additional motor units, which translates into both increased firing rate and increased amplitude of EUS EMG (39,45). This increase in firing rate and amplitude of EUS EMG has been noted during LPP testing in uninjured rats but was impaired 2 wk after simulated birth injury by VD ϩ PNC (25,26) and has been confirmed in this study regardless of electrical stimulation or sham stimulation.…”

Diaphragm quantitative electromyography in difficult-to-treat asthmatic patients

“…Podnar and Resman-Gaspersic 6 , in their normative study, asked normal individuals to hold a 5-second partial inspiration breath to achieve MUAP stability during these 5 seconds; otherwise the software wasn't able to identify a MUAP. But this was not feasible in some patients 6 . Although it is difficult or impossible to maintain a moderate sustained contraction, it is feasible to analyze 30 seconds of normal breathing, to achieve at least 20 MUAPs.…”

Size and Proportions of Slow-Twitch and Fast-Twitch Muscle Fibers in Human Costal Diaphragm

“…Moreover the discrepancy might be partly due to the small number of subjects enrolled in the biopsy study which may be critical because of the interindividual variability. Since muscle fiber size is one of the variables which contributes to the amplitude of MUPs [2], circumstantial evidence for the smaller size of the diaphragmatic fibers comes also from MUP analysis of costal diaphragm which demonstrated smaller amplitude of diaphragmatic MUPs compared to those of limb muscles [1]. The relation between MUPs amplitude and muscle fiber diameter is valid for slow fibers only as the first recruited MUPs recorded by EMG arise from slow conducting motor units while later recruited, fast motor units, are not possible of being analyzed by EMG [18].…”

“…Quantitative motor unit potential (MUP) analysis in healthy volunteers has established that amplitude, area, and size index of MUPs are much smaller in costal diaphragm than in limb muscles [1]. Muscle fiber size is one of the variables which contribute to the amplitude of MUPs [2], suggesting that muscle fibers of costal diaphragm, being the generators of MUPs, might also be smaller than those of limb muscles.…”