Suprascapular nerve conduction: a comparative analysis in normal subjects

An electromyographic examination is often utilized to confirm the diagnosis of suprascapular neuropathy in patients with shoulder pain and dysfunction. The purpose of this study was to compare three compound motor action potential (CMAP) recording methods (surface electrode, monopolar needle, concentric needle) for evaluating suprascapular nerve conduction. Twenty-two normal, healthy subjects were tested with each method. Differences between the recording methods were noted for CMAP latencies and amplitudes with the monopolar needle recordings having the shortest mean latency and greatest mean amplitude. The monopolar needle recordings also appeared to give a more reproducible measurement of CMAP latency and evoked amplitude to the supraspinatus and infraspinatus. Therefore, it may be more accurate to use a monopolar needle to record suprascapular nerve conduction and determine abnormalities with a side-to-side latency difference of 0.4 ms being acceptable. Considering the diverse branching of the suprascapular nerve, and the monopolar needle's relatively small sampling area of motor fibers, it may be prudent to test conduction to multiple sites within these muscles for the most accurate assessment.