Two clinical tests assessing long thoracic nerve function to determine C5 and C6 root graft eligibility in patients with brachial plexus injury

Identifying roots available for grafting is of paramount importance prior to reconstructing complex injuries involving the brachial plexus. This is traditionally achieved by combining input from both clinical examinations and imaging studies. In this paper, the authors describe and evaluate two new clinical tests to study long thoracic nerve function and, consequently, to predict the status of the C5 and C6 roots after global brachial plexus injuries. From March 2020 to December 2020, in 41 patients undergoing brachial plexus repair, preoperative clinical assessments were performed using modified C5 and C6 protraction tests, C5 and C6 Tinel's signs, and MRI findings to predict whether graft-eligible C5 and C6 roots would be identified intraoperatively. Findings from these three assessments were then combined in a logistic regression model to predict graft eligibility, with overall predictive accuracies calculated as areas under receiver operating characteristic curves. In the 41 patients, the pretest probability of C5 root availability for grafting was 85% but increased to 92% with a positive C5 protraction test and to 100% when that finding was combined with a positive C5 Tinel's sign and favorable MRI findings. The pretest probability of C6 root availability was 40%, which increased to 84% after a positive C6 protraction test and to 93% when the protraction test result concurred with Tinel's test and MRI findings. Combining observations of the protraction tests with Tinel's sign and MRI findings accurately predicts C5 and C6 root graft eligibility.