Modern high resolution ultrasound machines are capable of imaging the individual nerves of the brachial plexus. The aim of this study was to map the spatial orientation of the brachial plexus in relation to the carotid and subclavian arteries and the first rib using high resolution 3D ultrasound.
METHOD AND MATERIALS
A freehand optically tracked 3D ultrasound system was used with a 12MHz transducer. Ten healthy volunteers underwent 3D ultrasound of both sides of their neck. From the 3D ultrasound data-sets, the outlines of the brachial plexus, carotid and subclavian artery and the first rib were manually segmented and a surface interpolated.
Eighteen data-sets were recorded. The resolution of the ultrasound data allowed clear depiction of the brachial plexus from its extra-foraminal orgins to its disappearance under the lateral third of the clavicle. The nerves of the plexus were segmented and reconstructed in all 18 cases. Anatomical variations existed that have not been previously described. A deviant course of the C5 nerve root was observed in 2/18 cases. In 6/18 cases, the plexus remained clumped together over the first rib rather than horizontally aligned as was observed in the majority.
The technique used to reconstruct the brachial plexus illustrated in this study could be used to map plexus injuries and aid the radiotherapist planning supraclavicular radiotherapy to reduce the plexus dose. The anatomical variations observed have implications for selective anaesthesia and explain why ultrasound guided brachial plexus blocks are quicker to perform and achieve more effective pain control.