Effects of intramuscular needle position on motor unit action potential metrics

Abstract

It is unclear whether there are clinically significant differences in amplitude, duration, and numbers of turns and phases if an electromyographic (EMG) study is performed near to, or far from, the end-plate zone. The effects of temporal dispersion of arriving muscle-fiber action potentials on quantitative motor unit action potential (MUAP) metrics were assessed in simulated and biologic muscles. Two muscle simulation models were studied with electrode recording positions near the motor end-plate zone and 50-75 mm away. When the electrode was moved away from the end-plate zone, averages of 20 MUAPs significantly decreased in amplitude and area, and increased in numbers of turns and phases, but there was no significant change in duration. In biologic muscles (both normal and pathologic), similar changes in average metrics were observed, but to lesser degrees; few were statistically significant. Zones of innervation in biologic muscles are broadly distributed and, during routine electrode studies, distances between random electrode placements and end-plate zones are therefore relatively short, leading to clinically insignificant changes in quantitative MUAP metrics with distance from the end-plate zone. Thus, electrode position within a muscle is unlikely to affect clinical MUAP interpretation.

Development of a nerve conduction technique for the recurrent laryngeal nerve

“…In this study, we did not investigate the amplitude of the evoked potentials elicited by electrical stimulation of the recurrent laryngeal nerve because we recorded the evoked potentials from the thyroarytenoid muscle using the monopolar needle, and this caused a dramatic variation in the response, with slight changes in the position of electrodes relative to each motor unit distribution within a muscle, especially near the endplate zones . Therefore, the amplitude of the evoked potentials in the recurrent laryngeal nerve, as assessed by the monopolar needle, does not represent the characteristics of the evoked potentials in the recurrent laryngeal nerve.…”

Investigation of the effect of fiber diameter variability via recording from tendon via of single fiber electromyography

“…Biri 90 µm'lik sabit çap değerine diğeri de 20 µm ile 85 µm arasında çap değerleri değişen 2 kas lifinden kas sinir kavşağının yakınından ve tendonun yakınından kaydedilen sinyallere ait olan ilk ve son minimum genliklerinin süreleri ve bu sürelerle ilişkili zamansal yayılım değerleri Tablo [13]. Günlük EMG pratiğinde kullanılan konsantrik iğne elektrot aracılı bu çalışmalar, MÜAP parametrelerinin kavşaktan uzaklaştıkça değiştiğini ortaya koymuşlardır.…”

Métodos de procesamiento y análisis de señales electromiográficas

“…Los parámetros definidos para cuantificar dichas dimensiones deberían mostrarse robustos y ofrecer estimaciones fiables aunque varíen las condiciones de registro. La amplitud y el área están relacionadas con el número de FMs de la UM presentes en el radio de captación del electrodo, pero muestran una amplia variabilidad dependiendo de la distancia del electrodo a las FMs 42 . Para superar esta limitación se intenta formular parámetros e índices que expresen el número de FMs de la UM con independencia de la distancia entre el electrodo y las FMs y que tengan, por tanto, mayor capacidad discriminativa entre la normalidad y la patología.…”