Concentric needle single fiber electromyography: normative jitter values on voluntary activated Extensor Digitorum Communis

Abstract

Single fiber electromyography (SFEMG) is the most sensitive clinical neurophysiological test for neuromuscular junction disorders, particularly myasthenia gravis. Normal values for jitter obtained with SFEMG electrode have been published, but there are few publications for concentric needle electrode (CNE). The aim of this study was to discuss the possibilities to analyse the jitter in CNE recordings and to get normal values of jitter for voluntary activated Extensor Digitorum Communis using disposable CNE. Fifty normal subjects were studied, 16 male and 34 female with a mean age of 37.1±10.3 years (19-55). The jitter values of action potentials pairs of isolated muscular fibers were expressed as the mean consecutive difference (MCD) after 20 analysed potential pairs. The mean MCD (n=50) obtained was 24.2±2.8 µs (range of mean values in each subject was 18-31). Upper 95% confidence limit is 29.8 µs. The mean jitter of all potential pairs (n=1000) obtained was 24.07±7.30 µs (range 9-57). A practical upper limit for individual data is set to 46 µs. The mean interpotential interval (MIPI) was 779±177 µs (range of individual mean values was 530-1412); there were no potentials with impulse blocking. The present study confirms that CNE is suitable for jitter analysis although certain precautions must be mentioned. Our findings of jitter values with CNE were similar to some other few reports in literature.

Stimulated jitter with concentric needle in 42 myasthenia gravis patients

“…We have done it in some previous reports for ED and OOc muscles, both for voluntary and stimulated techniques and FR stimulated 10,[20][21][22][23][24] . A few studies that have compared jitter values from SFEMG and from CNE in healthy controls and patients with MG reported a good correlation between results [6][7][8] .…”

“…Some papers have presented normative data and diagnostic value of the test in MG [7][8][9][10][11][12][13] . Farrugia et al 14 found no differences in mean jitter values for extensor digitorum (ED) and OOc muscles in 24 MG patients using both SFE and CNE.…”

Análise do jitter com agulha concêntrica em pacientes com miastenia gravis autoimune adquirida

“…Recentemente, com a necessidade crescente de utilização de material descartável em procedimentos médicos, incluindo os eletrodos de agulha utilizados em eletroneuromiografia (ENMG), iniciou-se uma série de estudos usando eletrodos de agulha convencionais descartáveis, por exemplo, a agulha monopolar (Wiechers, 1985;Buchman, Garratt, 1992;Tutkavul, Baslo, 2010) e a agulha concêntrica (AC) (Ertaş et al, 2000;Benatar et al, 2006;Sarrigiannis et al, 2006;Kouyoumdjian, Stålberg, 2007;2008a;2008b;2013a). Em comparação com as agulhas monopolar e concêntrica, a AFU possui área de registro muito mais seletiva (King et al, 1997).…”

“…Adicionalmente à filtragem de sinais, são necessários cuidados técnicos na aceitação dos PAs obtidos com AC para análise do jitter (Sanders, Stålberg, 1996;Ertaş et al, 2000;Benatar et al, 2006;Sarrigiannis et al, 2006;Kouyoumdjian, Stålberg, 2007;Stålberg, Sanders, 2009 (Stålberg, Sanders, 2009;Stålberg et al, 2010). Além da velocidade de propagação nas fibras musculares individuais (Stålberg, 1966) e do jitter neuromuscular (Stålberg et al, 1971;Ekstedt et al, 1974), a EMGFU também permite o estudo da distribuição das fibras musculares nas unidades motoras individuais, denominado densidade de fibras (Gath, Stålberg, 1976).…”

“…Os primeiros valores normativos de jitter obtidos com AC são procedentes de centros independentes, a maioria com poucos sujeitos analisados, para os músculos seguintes: Frontalis (Kouyoumdjian, Stålberg, 2012, 2013a, Extensor Digitorum e OOc (Ertaş et al, 2000;Sarrigiannis et al, 2006;Kouyoumdjian, Stålberg, 2007, 2008bFarrugia et al, 2009;, e recentemente para o Masseter (Orhan et al, 2013). Alguns autores destacam a necessidade de cuidados técnicos para obtenção de resultados confiáveis com a utilização da AC, e também enfatizam que os valores de referência podem ser válidos em outros laboratórios, se for adotada uma metodologia igual ou similar (Kouyoumdjian, Stålberg, 2008b).…”