E-ISSN 2636-865X
Research Article
Jitter Measurement using a Concentric Needle in 133 Patients with Myasthenia Gravis: A Retrospective Analysis
1 Istanbul University, Department of Neuroscience, Institute of Experimental Medicine.  
2 Istanbul University, Istanbul Faculty of Medicine, Department of Neurology  
Neurol Sci Neurophysiol 2017; 34: 207-214
DOI: 10.24165/jns.10168.17
Key Words: Jitter, concentric needle electrode, myasthenia gravis, single-fiber electromyography
Abstract

Objectives: Single-fiber electromyography is being used in the diagnosis of patients with myasthenia gravis (MG) and is more sensitive, although less specific, than repetitive nerve stimulation (RNS). For the past two decades, concentric needle electrodes (CN) have been used in calculating jitter. In this retrospective study, we aimed to reveal the sensitivity of CN-jitter in patients with MG.

 

Methods: Patients with MG who were followed up in our neuromuscular clinic were recruited to the study. Clinical findings and CN-jitter analyses were reviewed retrospectively.

 

Results: Among the 401 patients with MG who were admitted to our neuromuscular clinic, 155 patients were investigated electrophysiologically. Among them, 136 patients underwent CN-jitter analysis. Eighty-four percent of the patients had high jitter. The sensitivity of CN-jitter was 80% when only one muscle was studied, whereas the sensitivity rose to 90% when two muscles were studied. The sensitivity of CN-jitter in ocular MG (OMG) and generalized MG (GMG) was 81% and 86%, respectively. MuSK-ab positive patients tended to have the highest positivity in CN-jitter (92%), followed by AChR-ab positive (86%) and seronegative patients (75%). Twenty-five of 26 patients with GMG had positive CN-jitter in the extensor digitorum communis (ED) muscle.

 

Conclusion: CN-jitter is a sensitive method in patients with MG. Sensitivity improved when two muscles were studied. 

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