Microanatomical and immunohistochemical study of the human radial nerve at the antecubital fossa

Background: Poor prognosis of radial nerve repair in elderly patients may be due to changes in intraneural anatomy with age. Also, chances of Complex Regional Pain Syndrome-Type I (CRPS-I) following radial nerve injury are comparatively high. The present study is to find the fascicular pattern of radial nerve (at antecubital fossa), microanatomic morphometric characteristics of its connective tissue components and changes with age and study of intraneural sympathetic fiber content. Methods: Twenty human (21-87 years) cadaveric radial nerves have been collected from antecubital fossa and the study has been performed at magnifications (10×, 20× and 40× objective) after routine histological (hematoxylin & eosin stain) processing was done for morphometric analysis (total cross-sectional, fascicular and non-fascicular area) and immunohistochemical (tyrosine hydroxylase) processing for sympathetic fibers. Results: The radial nerve is of a polyfascicular type with a grouped pattern of nerve fascicular distribution. The number of fascicles range from 9 to 17, whereas the number of fascicles per square millimeter of a cross-sectional area is 1.95. In elderly cases, there is significant increase in total radial nerve cross-sectional area due to an increase in its non-fascicular connective tissue area and excessive adipose tissue deposition in interfascicular domains. The average sympathetic fiber area is 0.046 mm² without definite relationship to age. Conclusion: There is an increase in total nerve cross-sectional area of the radial nerve in elderly cases. There is no relationship of sympathetic content to age. Our study makes an attempt to build a normal data base for radial nerve which might be helpful during the application of diagnostic procedures.