Introduction: To map the fascicular topography in the roots of brachial plexus.
Methods: The right-sided brachial plexus of 25 adult male cadavers was dissected. The whole of the plexus was then taken out, including roots from 5 mm distal to their exit from the intervertebral foramen, to proximal 1 cm of the distal branches. All roots were tagged on ventral aspects by 10-0 nylon, about 5 mm distal to their exit from foramen. The fixed specimens were then dissected and interfascicular longitudinal dissection performed under magnification. The dissection was conducted proximally to the level of the nylon stitch and distally till the plexal branches. The area occupied by different nerve fascicles was then expressed as percentage of the total cross-sectional area of the roots.
Results: Fascicular branching is fortuitous, but microdissection is possible. Localization of fascicular groups is consistent in roots. Overall, 10.4% plexus supplies shoulder (Axillary and SS). 11% supplies Musculocutaneous N. 19.6% supplies the Median N. 14% supplies the Ulnar N. 38% plexus supplies the radial nerve- which is the main innervator of antigravity muscles. Thus, the antigravity muscles receive more representation in the plexus than the gravity muscles, supplied by median and ulnar nerves (33.6%).
Conclusions: Fascicular branching is common, especially in the C8-T1. Fascicular microdissection is possible with careful dissection. Definite anatomical localization of fascicular groups is feasible in plexal elements. Exact fascicular location is translatable to the operating room and this knowledge can be used to anastomose related fascicles in plexal surgery, thereby avoiding axonal misrouting and possibly improving the results of nerve grafting.
Patient Care: The study aimed to devise the topographical maps of the roots of brachial plexus, wherein it would be possible to localize the respective nerve fascicular elements with a fair accuracy in future. This finding can then be translated into the operating room, where the nerve anastomosis can be made specifically to the already identified areas of those nerve fascicles. Therefore, the axonal misrouting could be avoided potentially, which in most of the cases, is responsible for the poor outcome of nerve transfers.
We have already started employing the findings of our research in to the surgical treatment of our patients and are in practice of anastomosing the related fascicular groups only, with the aim to improve the surgical outcome of these patients.
Learning Objectives: by the end of this session, the participants should be able to identify the location of corresponding nerve fascicles in the roots of the brachial plexus