C5 Palsy after Cervical Spine Decompression: Topographic Correlation with C6 Chassaignac Tubercle?: A Fresh-Cadaveric Study of the Cervical Spine and Rediscussion of Etiological Hypotheses

Abstract

Study Design.Cadaveric study on fresh unprocessed, nonpreserved, undyed specimens, which has not previously been reported.Objective.Our aim was to explore the possible topographic correlation of the C5 nerve root with regards to its course and regional relation to C6 Chassaignac tubercle.Summary of Background Data.C5 palsy is reported amongst the most frequent postoperative complications of cervical spinal procedures. We hypothesized that etiologic mechanisms proposed thus far in the current literature, although with some plausible explanation, still cannot explain why the C5 nerve root and not any other level suffer a postoperative palsy.Methods.Six fresh cadavers had extensive layer by layer dissection performed by two surgeons (one of whom has experience as an anatomy demonstrator and dissector). Roots of brachial plexus were exposed in relation to cervical transverse processes. Photographs were taken at each stage of the exposure.Results.We observed a close relation of the path of the C5 nerve root with the C6 tubercle bilaterally. Moreover, we noted a steeper descent of C5 in comparison with the other adjacent roots.Conclusion.Steeper angle of the C5 nerve root and close proximity to C6 Chassaignac tubercle may play a role in predisposing it to neuropraxia. Detailed anatomical photographs on fresh unprocessed cadaveric specimens are novel. Peculiar anatomical features and recent experimental evidence discussed do highlight a postganglionic extraforaminal etiology corresponding well to the demographic meta-analysis data on clinical features of postoperative C5 palsy. Exploring an alternative unified "neurophysiologic stress and critical tipping point" etiological model that encompasses current theories and correlates known metanalyses observations, we believe further studies would be prudent to ascertain/refute these findings.Level of Evidence: 3.