Anatomical variations in morphology of the brachial plexus among black African population; a cadaveric study in western Kenya

Abstract

Brachial plexus (Bp) is a network of nerve bundle in the spinal cord around neck and axillar formed by union of ventral primary rami of C5 - C8 and T1. Bp may be affected by trauma, irradiation, neoplasm, infection, and autoimmune inflammatory disease. Aim was to identify anatomical variations in morphology of Bp among black African population in western Kenya. The specific objectives were to find out variation differences in demographic characteristics (male and female); determine variation differences of right and left, investigate anatomical variations in origin, course, and distribution. Descriptive Cross-sectional design adopted. The sample population of 86 cadavers (Maseno 43, Uzima 23 and Masinde Muliro 20) calculated based on Yamane taro formula giving sample size of (35,19,16) 70 respectively. Descriptive statistics used to determine mean, mode, median and standard deviation. Chi- square test used to find statistical significance between variables with p–value of (α = 0.05). Pearson’s correlation test used to analyze statistical evidence for a linear relationship among variables. Ethical consideration observed. Posterior neck & axillar incisions made exposing and identifying variations at roots, trunks, divisions, cords, and terminal branches. Gender variable, 50% (35) female and 50% (35) male. Most frequent variation was the pre-fixed 20.9% least at division 2.2%. Highest variation in branching was musculocutaneous at 18.6% whilst lowest was radial 5%. The total 17.8% variations in the origin and segments of Bps, majority were from left whilst 7.9% from the right. Highest frequency occurred at pre-fixed root with 8.6% left and 12.1% right. The lowest was division with anterior division of the medial trunk connecting with medial nerve. Females had highest variations of terminal branches at 37.8% followed by males at 32%. There was statistical significance difference (p=0.008) in variation distribution of median nerve in relation to the sexes. No statistical significance variation observed in all the branching patterns. Levine’s test didn’t show any strong variation from the normal anatomical standards. Musculocutaneous nerve variations were most common and occurred on right-side affecting females hence gender specific variations should be considered for further studies. Study has prospective to enhance clinical correlation and medical research diversity.