Concentric needle electrode for neuromuscular jitter analysis

We used a concentric needle electrode (CNE) with 2 kHz low-cut filter and a single fiber electrode (SFE) in the same subjects for neuromuscular jitter measurement in the extensor digitorum communis (EDC) and orbicularis oculi (OOc) muscles. At the same session, 20 jitter values were obtained from ea ch subject with each electrode. For EDC (during voluntary contraction), mea n jitter values with SFE and CNE were 23.4 +/- 8 mu s and 23.3 +/- 8 us in 10 normals; and 56.8 +/- 28 us and 57.4 +/- 33 mu s in 10 myasthenics. For OOc (during electrical stimulation), mean jitter values with SFE and CNE we re 17.9 +/- 5 mu s and 16.3 +/- 4 mu s in 11 normal subjects, and 41.2 +/- 29 mu s and 36.7 +/- 27 mu s in 10 myasthenics. For both muscles, the numbe rs of individual abnormal jitter values with SFE and CNE were highly compar able. Both needles labeled the same patients as having "normal" or "abnorma l" neuromuscular transmission. CNE may be an alternative to SFE in neuromus cular jitter analysis. (C) 2000 John Wiley & Sons, Inc.