MAGNETIC RESONANCE IMAGING STUDY ON RELATIONSHIP OF BRACHIAL PLEXUS TO CORACOID IN VARIOUS SHOULDER POSITIONS

Abstract

Scientific Background The Coracoid process of scapula is a principal landmark in shoulder surgery. Brachial plexus is at risk of injury during surgery around the coracoid, e.g. Weaver-Dunn procedure. Magnetic resonance imaging is the method of choice for evaluating the anatomy and pathology of the brachial plexus and has good resolution compared to Computed tomography or Ultrasound (Ref: 1).

Aim The aim was to study the proximity of brachial plexus to coracoid process in various Shoulder positions. The objective was to define the position of safety for operating around the coracoid.

Methods With Ethics Committee approval, twelve healthy volunteers (men with average age of thirtyfive years) were recruited. Exclusion criteria included previous shoulder injury or operations, known contra-indication for MRI examination and children. An open Magnetic Resonance Scanner (1.5 Teslar) was used to facilitate shoulder positioning. Consent was obtained prior to scanning after information was given to subjects. They were placed under the scanner and images were obtained in axial, coronal and sagittal plane with shoulder in neutral, 45 degrees and 90 degrees of abduction. The images taken are T1, T2 axial spin-echo sequences with 2-mm cuts and coronal echo of a T1-3D gradient with 2 mm cuts, together with a T1 coronal spin-echo, with cuts 2 mm in width. Distance from coracoid process to the Brachial plexus bundle is measured in millimetre on the PACS system which has software to eliminate magnification.

Results The brachial plexus consistently moved away medially from the coracoid in all the subjects at 45 degrees abduction of the shoulder. It returned to the closer position to coracoid in 90Degree abduction. The statistical analysis showed that on an average the distance the brachial plexus moved away towards medial side by 4.37 mm with Standard deviation 3.57 (p= 0.014).

Conclusion The brachial plexus move medially away from coracoid process at 45 degrees shoulder abduction. This position reduces the risk of injury to the brachial plexus during surgery around the coracoid process.