Correlation between the width of the facial nerve trunk and greater auricular nerve

Abstract

Introduction. Surgical repair of the facial nerve trunk (FNT) after iatrogenic injures, trauma or tumor removal is one of the primary goals in head and neck surgery. As grafts for facial nerve repair in large nerve defects the sural, the greater auricular nerve (GAN), and anastomosis with the hypoglossal and masseteric nerves are used. Considering the proximity of the GAN to FNT and the fact that harvesting of GAN is comfortable for both surgeons and patients, the goal of our study was to determine the correlation between the widths of the FNT and GAN depending on sex, laterality and cephalometric type. Materials and Methods. The study was carried out on 70 dissected formalized adult hemiheads at the Department of Anatomy and Clinical Anatomy of Nicolae Testemitanu State University of Medicine and Pharmacy. The measurements of the FNT and GAN widths were done by a caliper. For statistical analysis, Pearson correlation coefficient was applied. Results. The mean value of the FNT width was 2.7±0.47 mm, and that of the GAN – 2.9±0.51 mm. A strong and positive correlation (r=+0.86), statistically significant (p<0.001), between the FNT and GAN widths was established. A positive and very strong correlation between the widths of both nerves was characteristic depending on sex. In males the correlation was positive (r=+0.78), p<0.001, while in females it was positive and stronger (r=+0.98), p<0.001. A strong bilateral correlation between the FNT and GAN widths was found. On the right hemiheads Pearson correlation coefficient was (r=+0.93) and on the left samples it was (r=+0.81), p<0.001. The correlation was higher on the right side, p=0.05. Depending on the cephalometric type, the lowest correlation was characteristic of mesocephalic type (r=+0.84), followed by the brachycephalic type (r=+0.91) and the highest value was determined in dolichocephalic type (r=+0.94). The correlation coefficient was statistically significant for all cephalometric types: for mesocephalic type (p<0.001) and for each of the brachycephalic and dolichocephalic types (p=0.002). Conclusions. The facial nerve trunk was thinner to 0.2 mm compared to the width of the greater auricular nerve. A strong and statistically significant correlation between the FNT and GAN widths depending on sex, laterality and cephalometric type was established.