Magnetic Resonance Imaging for Detecting Root Avulsions in Traumatic Adult Brachial Plexus Injuries: A Systematic Review and Meta-Analysis of Diagnostic Accuracy

Abstract

Background: Traumatic brachial plexus injuries (BPI) affect 1% of patients involved in major trauma. Magnetic resonance imaging (MRI) is the best indicator of traumatic BPIs although its ability to differentiate root avulsions (which require urgent reconstructive surgery) from other types of nerve injury remains unknown. Methods: Medline and Embase were searched from inception to August 20th 2018, with no restrictions. Studies of adults with traumatic non-penetrating unilateral brachial plexus injuries were included. The target condition was root avulsion. The index test was pre-operative MRI and the reference standard was operative exploration of the roots of the brachial plexus. Results: Eleven studies of 275 adults were included. Most patients were males (94%) injured in motorcycle collisions (84%). The majority of studies were at unclear or high risk of bias and there were high applicability concerns for the index test (MRI) given the lack of diagnostic criteria for root avulsion, inadequate descriptions of pulse sequences and multiplicity of reporting radiologists. At least one root of the brachial plexus was avulsed in 72% of patients (IQR 53%, 86%) but meta-analysis of patient-level data was not performed due to sparse and heterogeneous data. With the nerve as the unit of analysis, 583 out of 918 roots were avulsed (median 55%; IQR 38%, 71%); the mean sensitivity of MRI for root avulsion was 93% (95% CI 77%, 98%) with a mean specificity of 72% (95% CI 42%, 90%). Conclusions: Based on the limited data, MRI has modest accuracy for diagnosing root avulsions following traumatic BPI and operative exploration should remain the diagnostic option. Funding Statement: Ryckie Wade is a Doctoral Research Fellow funded by the National Institute for Health Research (NIHR, DRF-2018-11-ST2-028). This research is supported by NIHR infrastructure at Leeds, Oxford and Birmingham. The views expressed are those of the author(s) and not necessarily those of the United Kingdom’s National Health Service, NIHR or Department of Health. Declaration of Interests: The authors state: none. Ethics Approval Statement: The authors state: Not required.