Validation of the Root Analysis Score for C5 Viability in Pan-brachial Plexus Injury Patients
Kitty Wu, MD, MSc, FRCSC1, Ellen Y Lee, MD2, Michelle F. Kirchner, MD3, Allen T Bishop, MD4, Robert J. Spinner, MD5 and Alexander Y Shin, MD6, 1Mayo Clinic, Rochester, MN, 2National University Health System, Kent Ridge, Singapore, 3Department of Orthopaedic Surgery, Division of Hand Surgery, Mayo Clinic, Rochester, MN, 4Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, 5Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 6Orthopedics, Mayo Clinic, Rochester, MN
Introduction: Patients with pan-brachial plexus injuries present a reconstructive challenge given the paucity of available donor sources. The Root Analysis Score was developed from parsimonious multivariate modelling of 311 pan-brachial plexus injury patients, with the purpose of determining the probability of having a viable C5 nerve for grafting. The score included four factors: positive C5 Tinel’s sign, intact C5 nerve on CT myelogram, lack of hemi-diaphragmatic elevation, and absence of mid-cervical paraspinal fibrillations. We hypothesize that patients with higher Root Analysis Scores (range 0 – 100 based on the sum of points in four categories) have a higher probability of an intact C5 nerve.
Materials & Methods: A different cohort of pan-brachial plexus injury patients, who underwent surgical reconstruction were identified. We retrospectively reviewed their data and calculated their Root Analysis Score. The Root Analysis Scores were validated by the presence or absence of a graftable C5 root, determined during supraclavicular exploration and intra-operative electrophysiologic testing. The receiver operating characteristic (ROC) curve, accuracy, and concordance statistic (c-statistic) were determined. Patients were divided into three cohorts based on their Root Analysis Score: less than 50 (Low), 50 – 75 (Average), and 75 – 100 points (High) (Figure A, B). The probability, sensitivity, and specificity of each cohort having an available C5 nerve for grafting was ascertained.
Results: 80 patients (mean age 33.1 years; 15 females, 65 males) were included. Thirty-one patients (39%) had an available C5 nerve for grafting. The Root Analysis calculator had an overall accuracy of 82.5%, ROC of 0.873, and c-statistic of 0.87, demonstrating high overall predictive value. Within this cohort, 6.5% of patients with a score of less than 50 (94% sensitivity, 43% specificity), 16.1% of patients with a score of 50 – 75 (94% sensitivity, 67% specificity), and 77.4% of patients with a score of 75 – 100 (77% sensitivity, 90% specificity) had a graftable C5 nerve.
Conclusions: The Root Analysis Score demonstrated high accuracy and predictive power for a viable C5 nerve. The ability to pre-operatively predict patients with a graftable C5 nerve facilitates both reconstructive planning and patient counselling. In patients with a score of less than 50, the necessity of supraclavicular root exploration should be carefully considered, balancing patient factors including the timing of presentation and concomitant injuries.
Back to 2024 Abstracts