Cross-sectional Study of the Anatomic Variation of Brachial Plexus’ Nerve Roots Origin in Jordan: Prefixed and Postfixed

Background: Anatomical variations in the origin of brachial plexusand the nerve roots contributing to it exist. Based on literature review, thesevariations are not uncommon and may even be the rule rather than the exception.However, data regarding these variations in the Jordanian population is absent,and assessment of such variations is important in both clinical evaluation andsurgical procedures. Such anatomical variations may increase the likelihood ofspecific pathologies, like thoracic outlet syndrome, and can influence the surgicalstrategies employed for the brachial plexus. This study aimed to explore theanatomy and variations of the brachial plexus’s origin in normal healthyJordanian subjects using magnetic resonance imaging (MRI), particularlyprefixed and postfixed variants.Methods: This was a cross-sectional study. Random selection of50 subjects undergoing cervical spine MRI, for which a 3D NerveVIEW sequenceof the brachial plexus nerve roots was performed in both coronal and axial planes.For each subject, identification of the nerve root levels contributing to theformation of the brachial plexus on each side was performed andprefixed/postfixed variations were identified. Other measurements, diameter andlength of nerve roots, were identified, and a comparison of these measurementsbetween males and females in the studied population was performed.Results: Out of the 94 brachial plexuses analyzed, 25 were prefixed (26.6%) andnone were postfixed. Those 25 prefixed plexuses were identified in 15 subjects;10 subjects having the prefixed variant bilaterally (66.7% of all prefixedplexuses), 4 subjects were left prefixed plexus (26.7%) and only one was a rightprefixed plexus (6.7%). Data analysis of the lengths and diameters of all nerveroots contributing to the formation of the brachial plexuses in all subjects (n=94)showed that the mean diameter and length of the left-sided roots weresignificantly thicker and longer than their right-sided counterparts (p-values were0.0178 and 0.0014, respectively). In addition, nerve roots contributing to brachialplexuses formation were longer and wider in males than those in females.Conclusions: This study concluded that anatomical variation of the nerve rootscontributing to brachial plexus is common among the Jordanian population,particularly the pre-fixed variant.