Evaluation of MRI-Assisted Diagnosis of C5 Root Quality and Long-term Functional Outcomes After Nerve Grafting in Traumatic Brachial Plexus Injuries

Chang Gung Memorial Hospital, Linkou Branch, Taoyuan, Taiwan

YH Lee, YP Lin, YC Lin, TNC Chang, DCC Chuang

INTRODUCTION: For brachial plexus injury (BPI), a C5 ruptured stump can be used to graft to vital target nerves. Classic preoperative signs include Tinel sign in the neck or a viable rhomboid muscle. Newer sequence modalities of the MRI have improved the visualization of the rootlets quality. The aim of this study was to compare MRI to classic preoperative signs and the compatibility rate of these factors with long-term functional outcomes after nerve grafting.

MATERIALS AND METHODS: This study was a retrospective analysis of BPI patients who had used the C5 root for nerve grafting between the years 2010 and 2020 at a tertiary medical center. Preoperative factors to evaluate a viable C5 root stump were Tinel sign in the neck and rhomboid EMG. MRI of the brachial plexus was used to differentiate intradural dorsal and ventral rootlets into normal (grade A), partial (grade B), severe or complete avulsions (grade C). The sensitivity, specificity, and area under the curve (AUC) of the three tests were compared with intra-operative findings. Patients with follow up more than 2 years were graded by their outcomes into good, equivocal and poor. The compatibility rate of the long-term functional outcome with MRI diagnosis was calculated.

RESULTS: Sensitivity, specificity and AUC, in predicting ruptured C5 root stumps eligible for grafting were 84%, 96%, AUC 0.90 for MRI; 56%, 60% and AUC 0.59 for Tinel test; and 85%, 21% and AUC 0.53 for rhomboid EMG. The compatibility rate of the MRI diagnosis and long-term functional outcome was 62.1% for panplexus injuries and 70.6% for non-panplexus injuries, with no significant difference.

CONCLUSION: MRI-assisted evaluation of the brachial plexus improves the evaluation of C5 roots that can benefit brachial plexus reconstruction, especially for grafting. Evaluating the long-term outcomes is important in assessing the true value of these predictive factors.