Concentric needle jitter on stimulated Orbicularis Oculi in 50 healthy subjects

doi:10.1016/j.clinph.2010.07.012

Clinical Neurophysiology

Volume 122, Issue 3, March 2011, Pages 617-622

https://doi.org/10.1016/j.clinph.2010.07.012 Get rights and content

Abstract

Objectives

The aim of this study was to estimate the jitter parameters in healthy controls in stimulated Orbicularis Oculi (OOc) muscle using concentric needle electrode (CNE).

Methods

Fifty healthy subjects, 13 males and 37 females (21–56 years, mean age of 38 ± 9.2 years) were studied. The zygomatic branch of facial nerve was stimulated with a bar electrode. Jitter was expressed as the mean consecutive difference (MCD). Filter settings 1000 Hz–10 kHz.

Results

The mean MCD from individual studies (n = 50, Gaussian distribution) was 21.5 ± 1.99 μs (median = 21 μs), ranging from 17.8 to 26 μs (upper limit, 97.5%, 25.5 μs). The mean and median MCD from all potentials (n = 1500, non-Gaussian distribution) were 21.6 and 21 μs, ranging from 7.1 to 39 μs (upper limit, 97.5%, 33.4 μs).

Conclusions

Suggested practical limits in the OOc for mean MCD was 26 μs and for outliers 34 μs.

Significance

Stimulation jitter recordings with CNE could be used in practice but borderline findings should be judged with great caution until larger database obtained with uniform setting available.

Introduction

Single fiber electromyography (SFEMG) was developed in the early 1960s by Erik Stålberg and Jan Ekstedt in Sweden (Ekstedt, 1964, Stålberg and Trontelj, 1994, Sanders and Stålberg, 1996) to study the propagation velocity of individual muscle fibers, the distribution of muscle fibers within individual motor units, and the neuromuscular jitter (Stålberg and Sanders, 2009). A recent summary is given in Stålberg et al. (2010).

For jitter measurement, the SFEMG needle electrode has a small recording surface allowing for the recording of single fiber action potentials (SFAPs) from individual muscle fibers. Neuromuscular jitter represents the variation in time intervals between pairs of SFAPs in voluntarily activated technique (v-jitter) or the variation in time measured between stimulus and evoked SFAPs in stimulation technique (s-jitter).

Due to the increasing concern for the transmission of infections (Benatar et al., 2006, Sarrigiannis et al., 2006) an inexpensive disposable electrode is desirable for jitter analysis. In the past two decades attempts have been made to measure jitter by filtering the motor unit potential recorded with disposable monopolar (Clarke and Eisen, 1985, Wiechers, 1985), and, more recently, with concentric needle electrodes (CNE) (Benatar et al., 2006, Ertaş et al., 2000, Kouyoumdjian and Stålberg, 2007, Kouyoumdjian and Stålberg, 2008a, Kouyoumdjian and Stålberg, 2008b, Sarrigiannis et al., 2006, Farrugia et al., 2009, Stålberg and Sanders, 2009) instead of the SFEMG needle electrode.

To successfully use the CNE for the measurement of jitter, the low-frequency filter (high pass) should typically be raised from 500 to 1 kHz, to suppress activity from distant muscle fibers (Stålberg and Trontelj, 1994, Benatar et al., 2006, Sarrigiannis et al., 2006). Payan (1978) used even stronger filtering (3 kHz) in his “blanket principle” to detect shape variability in motor unit potentials. Filtering of 2 kHz and above is disadvantageous. The original shape characteristics are lost and summation of many SFAPs may be very difficult to detect visually. We have found a practical limit to be 1 kHz high pass filter, rather than higher. This gives sufficient suppression of low frequencies, with still preserved signal shape so that presence of irregularities can be detected. As the signals obtained with CNE recording do not often represent a single fiber action potential, but rather a summation of many, the term SFEMG will not be used for these recordings. Earlier the term “jiggle” has been introduced to describe the variability in a motor unit potential obtained with a CNE (Stålberg and Sonoo, 1994). To avoid confusion at this moment, the term “jitter recording with CNE” or “CNE jitter” has been used. The recorded spike components may well represent SFAP, but may represent summation, sometimes difficult to detect. We therefore call the CNE spikes apparent single fiber action potentials (ASFAPs) a term introduced by Ertaş et al. (2000).

The aim of this study was to study normal jitter parameters in the Orbicularis Oculis (OOc) muscle by using CNE in stimulation technique.

Section snippets

Subjects

Fifty healthy subjects recruited from Medical School (FAMERP, Brazil) employees were prospectively studied for jitter measurement using CNE in stimulated OOc. There were 13 men and 37 women with the mean age of 38 ± 9.2 years (range, 21–56). None of them were diagnosed with a neuromuscular disorder, an unrelated medical condition or were taking medication that reasonably could have interfered with the study, e.g., calcium blockers (Ozkul, 2007).

Recording

For all studies, either portable Keypoint or

Results

The mean jitter was analyzed according to a previously used method, i.e., a calculation of the mean MCD of 30 isolated potentials for s-jitter (Stålberg and Trontelj, 1994). There was no correlation to age in this material (p > 0.5). There were no recordings with impulse blocking.

The mean of the 50 mean MCD (s-jitter) values in each subject was 21.5 ± 1.99 μs ranging from 17.8 to 26 μs; median was 21 μs; the distribution was Gaussian (Anderson–Darling, p-value = 0.119). The upper 97.5% confidence limit

Discussion

For SFEMG, reference jitter values for various muscles have been collected in individual laboratories and in a multicenter study. For CNE jitter, a few laboratories have reported reference values. The present study has measured the jitter values obtained after facial zygomatic branch stimulation in the OOc muscle. Often, the spikes obtained with CNE are not obtained from single muscle fibers (Stålberg and Daube, 2003, Stålberg and Sanders, 2009) but represent summation of more than one SFAP.

Financial support

FAPESP, Fundação de Amparo à Pesquisa do Estado de São Paulo, Brazil.

References (24)

J.A. Kouyoumdjian et al.
Concentric needle single fiber electromyography: comparative jitter on voluntary-activated and stimulated Extensor Digitorum Communis. Concentric needle single fiber electromyography
Clin Neurophysiol
(2008)
Y. Ozkul
Influence of calcium blocker drugs in neuromuscular transmission
J Clin Neurophys
(2007)
E. Stålberg et al.
Electromyographic methods
J.V. Trontelj et al.
Jitter measurement by axonal micro-stimulation. Guidelines and technical notes
Electroencephalogr Clin Neurophysiol
(1992)
M. Benatar et al.
Concentric-needle single-fiber electromyography for the diagnosis of myasthenia gravis
Muscle Nerve
(2006)
S. Clarke et al.
Electromyographic jitter measured using a monopolar electrode
Neurology
(1985)
J. Ekstedt
Human single muscle fiber action potentials
Acta Neurol. Scand.
(1964)
M. Ertaş et al.
Concentric needle electrode for neuromuscular jitter analysis
Muscle Nerve
(2000)
M. Ertaş et al.
Surface stimulation single-fiber electromyography
Muscle Nerve
(1998)
M.E. Farrugia et al.
Concentric and single fiber needle electrodes yield comparable jitter results in Myasthenia Gravis
Muscle Nerve
(2009)

J.M. Gilchrist et al.

Single fiber EMG reference values: a collaborative effort. Ad Hoc Committee of the AAEM interest group on single fiber EMG

Muscle Nerve

(1992)

J.A. Kouyoumdjian et al.

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

Arq Neuropsiquiatr

(2007)

Cited by (37)

Concentric or monopolar electrode for jitter determination in orbicularis oculi
2018, Clinical Neurophysiology
Citation Excerpt :
Hence, it is important to find a suitable alternative for routine clinical use. Disposable conventional electrodes, such as monopolar (MN) and concentric (CN) needles have been increasingly used in patients with suspected MG (Buchman and Garratt, 1992; Ertas et al., 2000; Tutkavul et al., 2006; Farrugia et al., 2009; Kouyoumdjian and Stålberg, 2011). These electrodes have larger recording areas than SFEMG electrodes, so the registered waveforms also contain low-frequency components that arise in more distant muscle fibers or from different motor units (Buchman and Garratt, 1992; Tutkavul, et al., 2006; Stålberg and Sanders, 2009).
To investigate if monopolar (MN) and concentric (CN) electrodes are equivalent for volitional contraction jitter estimation in orbicularis oculi (OO), and to study the effect of selecting a specific high-pass filter.
We studied neuromuscular jitter in OO on both sides in 100 consecutive patients with a clinical diagnosis of ocular myasthenia gravis (MG). We used either MN (50 patients) or CN (50 patients) electrodes in individual patients, according to a randomised protocol, with a 1kH high pass filter on one side and a 3kH filter on the other. Ten or more potential pairs were studied on each side.
48 patients had a definite clinical diagnosis of ocular MG, and 52 of mimicking-disorders, who were analysed as controls. In controls, jitter (MCD) showed a normal distribution independent of the electrode type or filter settings. The mean jitter value and the number of abnormal pairs (>10%) was similar in MN and CN recordings, with both 1 kHz and 3 kHz filters. Sensitivity was 73% for mean jitter and 94% for number of abnormal pairs. Specificity was 100%.
The jitter in OO using MN or CN was similar in controls and the diagnostic sensitivity was similar using either electrode in patients with ocular MG. The use of high-pass filters of 1 or 3 kHz did not influence these results.
MN and CN are both suitable for determining volitional jitter in OO.
The problem of lack of normative data in paediatric EMG and possible solutions
2018, Clinical Neurophysiology
Pitfalls and errors in measuring jitter
2017, Clinical Neurophysiology
Citation Excerpt :
Reference values have been obtained in multicenter studies for SFEMG (Gilchrist et al., 1992; Bromberg and Scott, 1994) and for jitter studies with CN electrodes (CNE) (Kokubun et al., 2012; Stålberg et al., 2015). Other CN jitter reference value studies from single laboratories have also been published (Ertas et al., 2000; Kouyoumdjian and Stålberg, 2008, 2011, 2012, 2013). CN jitter has, as for SFEMG, been assessed in myasthenia gravis (Benatar et al., 2006; Sarrigiannis et al., 2006; Farrugia et al., 2009; Kouyoumdjian et al., 2011; Orhan et al., 2013) and in other conditions (Liu, 2015).
The safety factor of neuromuscular transmission can be assessed by measuring the neuromuscular jitter, which reflects the time variability of processes in the motor end-plate. Jitter is increased in any condition with disturbed end-plate function, such as myasthenic conditions and ongoing reinnervation. Jitter is increasingly being measured with concentric needle (CN) electrodes, which are more prone to artefacts than single fiber EMG recordings.
The objective of this review is to identify and demonstrate pitfalls that can be seen with CN jitter measurements, made with both voluntary activation and electrical stimulation.
With voluntary activation, errors are caused by poor signal quality; inappropriate time reference points on the signal; an irregular firing rate; and signals with dual latencies, i.e., “flip-flop.” With electrical stimulation, additional errors result from insufficient stimulation intensity; from abrupt change in firing rate; and from axon reflexes.
Many pitfalls cannot be avoided during recording and can only be detected during post-processing.
It is critical to be aware of these artefacts when measuring jitter with CN electrodes.
Assessing neuromuscular junction stability from stimulated EMG in children
2017, Clinical Neurophysiology
We present our 9-year experience of stimulated EMG potential analysis using concentric electrodes (SPACE) to evaluate neuromuscular junction (NMJ) disorders in awake children. The technique uses high frequency filtration of stimulated motor unit potentials and applies peak detection software to estimate mean consecutive difference (MCD).
SPACE was carried out in orbicularis oculi of 878 children (377 girls; median age 47 months) between 2007 and 2015, stimulating the facial nerve with a monopolar cathode. Mean MCD-index (MCD-I) was expressed as a ratio of the measured MCD to the upper normal limit. Diagnostic accuracy was calculated for primary NMJ disorders based on the 660 cases with clinical follow-up data.
Primary NMJ disorders were present in 106 children, including 46 with genetically confirmed congenital myasthenic syndrome (CMS). Mean MCD-I was two times higher in children with primary NMJ disorders compared to others (205 ± 108 μs vs 94 ± 38 μs, p < 0.005). After excluding children with neuronopathies, an MCD-I >100% had 84% sensitivity and 74% specificity for the primary NMJ disorders. Receiver operating characteristics (ROC) curve identified an MCD-I >115% as providing best diagnostic accuracy with sensitivity of 77% and specificity of 84%.
SPACE is practicable and safe in unsedated children.
In combination with routine EMG, it has high diagnostic accuracy and can facilitate recognition of paediatric NMJ transmission disorders.
Electromyography in Pediatrics
2015, Neuromuscular Disorders of Infancy, Childhood, and Adolescence: A Clinician's Approach
This chapter discusses the use of electromyography (EMG), which includes needle EMG and nerve conduction studies, in the pediatric population. It deals first with some of the misconceptions that surround this technique: that it is too painful, too difficult, and in any case redundant in the era of molecular genetics. As with any technique, the need for normative data is stressed, but the difficulties obtaining these in children are highlighted. Technical aspects covered include the choices of electrodes and of nerve that are likely to improve chances of a successful investigation. Investigative strategies used to delineate the underlying pathological abnormalities are grouped anatomically into those relevant to anterior horn cell disease, peripheral neuropathy, neuromuscular junction disorders, and myopathy. This technique may evolve and be practiced differently in the future, but it will likely remain an important contribution to the investigation of neuromuscular disease.
Single-Fiber EMG
2014, Encyclopedia of the Neurological Sciences
Single-fiber electromyography (SFEMG) is a selective electromyography (EMG) recording technique that uniquely identifies action potentials (APs) from individual muscle fibers, thus allowing measurement of fiber density (FD) and neuromuscular jitter. FD quantifies the local concentration of muscle fibers within a motor unit and is a sensitive measure of reinnervation. Jitter is the most sensitive in vivo measurement of transmission across the neuromuscular junction and is particularly useful in demonstrating abnormalities associated with myasthenia gravis (MG) and related conditions.

View all citing articles on Scopus

View full text

Concentric needle jitter on stimulated Orbicularis Oculi in 50 healthy subjects

Abstract

Objectives

Methods

Results

Conclusions

Significance

Introduction

Section snippets

Subjects

Recording

Results

Discussion

Financial support

Clin Neurophysiol

J Clin Neurophys

Electroencephalogr Clin Neurophysiol

Concentric-needle single-fiber electromyography for the diagnosis of myasthenia gravis

Muscle Nerve

Electromyographic jitter measured using a monopolar electrode

Neurology

Human single muscle fiber action potentials

Acta Neurol. Scand.

Concentric needle electrode for neuromuscular jitter analysis

Muscle Nerve

Surface stimulation single-fiber electromyography

Muscle Nerve

Concentric and single fiber needle electrodes yield comparable jitter results in Myasthenia Gravis

Muscle Nerve

Single fiber EMG reference values: a collaborative effort. Ad Hoc Committee of the AAEM interest group on single fiber EMG

Muscle Nerve

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

Arq Neuropsiquiatr