Distribution of sympathetic fiber areas of radial nerve in the forearm: an immunohistochemical study in cadavers.

PURPOSE: Secondary to peripheral nerve injuries, involvement of sympathetic fibers complications such as complex regional pain syndrome (CRPS) have been reported. There are limited studies on the sympathetic fibers and their distribution in the upper limb nerves. There are no reports available in the distribution of the sympathetic fibers/areas of radial nerve in the forearm. The aim of the present study was an attempt to find the distribution of sympathetic fibers in the radial nerve just above cubital fossa (RN), superficial branch of radial nerve at cubital fossa (SBRN-1) and above wrist (SBRN-2).

METHODS

We have studied on 19 fresh human cadaveric RN, SBRN-1, and SBRN-2 samples. Frozen sections of these nerves were processed by immunohistochemical (tyrosine hydroxylase) method for sympathetic fibers.

RESULTS

The sympathetic fibers area (Asym) was found to be more in RN when compared to SBRN-1 and SBRN-2. The comparison of the sympathetic index (SI = sympathetic fibers area/total fascicular area of the nerve) between RN and SBRN-1 (p < 0.001), RN and SBRN-2 (p < 0.001), and SBRN-1 and SBRN-2 (p = 0.016) were statistically significant. The sympathetic index (SI) for SBRN-1 was more when compared to RN and SBRN-2.

CONCLUSIONS

Sympathetic fibers area (Asym) was found to be more in RN when compared to SBRN-1 and SBRN-2. The sympathetic ratio (SI) and percentage of sympathetic fibers area (Asym %) was more in SBRN-1 when compared to RN and SBRN-2. These results of the study might help to explain sympathetic system-related diseases in the area of distribution of RN and SBRN.