Morphologic and morphometric bilateral analysis and sexual dimorphism in sciatic nerves of adults: an anatomic investigation of cadaveric specimens in Uganda with implications on sciatic nerve neuropathologies

Abstract

Background The Sciatic nerve (SN) depicts sex and side-associated dimorphic features that are of clinical relevancy. The study investigated the sex and side-related morphologic and morphometric variations of the nerve using cadavers. Methods A cross-sectional cadaveric study on 62 Ugandan cadavers were used. Continuous variables were reported using descriptive statistics and discrete variables were reported as percentages. Ordinary two-way ANOVA was used to compare the dimensions and percentages of patterns of the SN. Results The study identified six categories of exit patterns of the SN, type A (“Below and undivided”) occurred in a majority of cases (62.9%), a penta furcate branching pattern dominated the whole population, “Bifurcate” termination pattern was found in most SNs (90.3% and 87.1% for right and left limbs respectively) while the rest have the trifurcate termination pattern, with no side or sex-related variations. The average dimensions of SN were within normal ranges, and show no side-related differences but with a sex effect (are significantly higher in males than females), mean length of the SN in centimeters (length A: Males, right limbs = 30.58 ± 9.00; left limbs = 31.30 ± 6.20; Females, right = 26.07 ± 6.58; left = 26.30 ± 5.56), the mean level of termination of SN in centimeters (length B: Males, right = 8.5 ± 4; left = 8.2 ± 3.9; Females, right = 7.76 ± 3.8; left = 7.82 ± 3.5), mean SN diameters in millimeters: mean exit diameter (Males: right = 11.69 ± 1.92; left = 11.67 ± 2.16; Females, right = 8.41 ± 2.24; left = 9.28 ± 1.99), mean midthigh diameter (Males: right = 8.86 ± 1.56; left = 9.64 ± 1.88; Females, right = 7.12 ± 1.46; left = 8.28 ± 1.89), mean terminal end diameter (Males, right = 9.47 ± 2.07; left = 9.86 ± 2.32; Females, right = 7.5 ± 1.62; left = 8.4 ± 2.24). Conclusions Most SNs show normal anatomical characteristics with rare cases of sex-related dimorphism in the termination level and morphometry (length and diameter) of the nerve. The observed sexual dimorphisms in sciatic nerves are of great clinical and surgical interest and a warranty for more investigations in different populations, especially through the use of advanced techniques such as ultrasonographic anatomy techniques.