The lower subscapular nerve conduction studies and utilisation in brachial plexopathy evaluation

Abstract

Objective To define the optimal nerve conduction study (NCS) method of lower subscapular nerve and evaluate its clinical utility. Methods Thirty healthy adults (8 males) with a mean age of 45.2 ± 16.5 (range, 21–75) years were recruited in this study. A total of sixty nerves were studied using the Dantec Counterpoint EMG machine (Dantec, Skovlunde, Denmark). 6 patients with clinical and electrodiagnostic evidence of brachial plexopathy were also evaluated. Results The mean ± 2 standard deviation values of the distal latencies, base-to-peak amplitudes and inter-side amplitude ratio were 2.38 ± 0.52 (range, 1.80–2.90) ms, 13.10 ± 5.10 (range, 8.70–21.10) mV and 0.93 ± 0.12 (range, 0.67–1.00), respectively. There was a significant correlation between the subject age and the base-to-peak amplitudes. All 6 patients with brachial plexopathy had reduced base-to-peak amplitudes as well as inter-side amplitude ratio of less than 0.67 (the normal limits for control). Conclusion The lower subscapular NCS were satisfactorily recordable and well tolerated. It was useful in evaluation of patients with brachial plexopathy.