A novel intraoperative classification for brachial plexus birth injury based on operative findings in 162 patients

Introduction: The Narakas classification of brachial plexus birth injuries has been widely used but its validity for intraoperative classification of lower root injuries (C8–T1) is debated. This study introduces a new intraoperative classification and assesses its correlation with muscle function before and after operative repair of the brachial plexus. Methods: The study reviewed 162 primary brachial plexus explorations over 19 years. Based on intraoperative findings, patients were categorized by injury patterns, A (C5–C6), B (C5–C7), C (C5–C8) and D (C5–T1), followed by the number of root avulsions. Preoperative and postoperative active movement scale scores, along with intraoperative findings, were compared in assessing lower root involvement. Results: Ten cases were classified as injury type A, 42 as type B, 14 as type C, and 96 as D. Of 682 injured nerve roots, 189 were avulsed. With a mean follow-up of 5.4 years, the median preoperative total active movement scale score was 39 (IQR 24 to 54) and improved to 55 (IQR 44.25 to 70) at final postoperative follow-up. There was a decline in pre- and postoperative scores with increasing injury severity from A to D. Significant differences were observed between injury subtypes based on number of avulsions, notably in the injury D subgroup ( p < 0.001). Horner’s syndrome did not significantly impact final postoperative active movement scale scores after adjusting for injury types. Conclusions: An intraoperative classification that specifies roots involved may better capture variability of brachial plexus birth injuries than the established Narakas system and align more closely with functional recovery. These findings emphasize the importance of intraoperative assessment to guide surgical decision-making. Level of Evidence: IV