Journal of Neurological Sciences (Turkish) 2017 , Vol 34 , Num 3
Jitter Measurement using a Concentric Needle in 133 Patients with Myasthenia Gravis: A Retrospective Analysis
Nermin Görkem ŞİRİN1,Elif Kocasoy ORHAN2,Hacer DURMUŞ2,Piraye OFLAZER2,Yeşim PARMAN2,Ali Emre ÖGE2,Feza DEYMEER2,Mehmet Barış BASLO2
1Istanbul University, Department of Neuroscience, Institute of Experimental Medicine.
2Istanbul University, Istanbul Faculty of Medicine, Department of Neurology
DOI : 10.24165/jns.10168.17 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. Keywords : Jitter, concentric needle electrode, myasthenia gravis, single-fiber electromyography