Objective
To establish the posterior cutaneous nerve of arm (PCNA) conduction technique and set up the reference values.

Method
A PCNA conduction study was performed in 80 nerves of 40 neurologically healthy adult subjects with a mean age of 38 years (range, 20 to 56). Dantec Counterpoint MK2 machine was used. The recording bar electrodes were placed 10 cm distal to the axillary fold on a line connecting the posterior axillary fold and the olecranon. Supramaximal stimulation was applied to the axilla posterior to the brachial artery. Onset latency, baseline to peak amplitude and negative spike duration of sensory nerve action potentials were obtained. Skin temperature was measured in the posterior arm and maintained at 34^oC or above.

Results
Compound sensory action potential for the PCNA was recordable in all the subjects. The results were as follows: onset latency, 1.7⁑0.1 msec; baseline to peak amplitude, 4.6⁑1.4μV; negative spike duration, 1.1⁑0.2 msec.

Conclusion
PCNA response is readily obtainable. This study may help to assess the pain or paresthesia in the posterior aspect of the arm, although more studies are required for clinical application.