Brachial plexus injuries: diagnosis performance and reliability of everyday tools

Determining the patterns of brachial plexus injuries is challenging. Diagnostic methods have been used to facilitate diagnosis, but there is no consensus regarding which tool best complements physical examination (PE). Magnetic resonance imaging (MRI) and nerve conduction studies (NCSs) are instruments with widespread use and feasibility for everyday assessment. In this study, we evaluated the diagnostic performance of these diagnostic instruments and PE. We also assessed the agreement in the PE and diagnostic instrument findings of two experienced and certified hand surgeons.

We reviewed data gathered from medical records and compared these data with the results of operative findings. We divided data according to the site of injury and the root injury patterns for all three diagnostic instruments (PE, MRI, and NCSs).

We considered 102 assessments. We found poor inter-observer agreement for the PE assessments and poor agreement among the PE, NCS, and MRI assessments. Diagnostic performance was higher for PE: sensitivity = 97.8 [95% confidence interval (C.I.) = 92.1-99.7]; specificity = 30.8 [95% C.I. = 9.1-61.4], and NCSs (sensitivity = 98.9 [95% C.I. = 93.9-100]; specificity = 23.1 [95% C.I. = 5-53.8]. MRI had inferior performance for all measurements. Separate analysis using pre- and post-ganglionic injuries revealed that PE had the lowest sensitivity, 46.7 (95% C.I. = 21.3-73.4) despite having the highest specificity, 81.6 (95% C.I. = 71.9-89.1).

Low agreement among the findings using different diagnostic instruments demonstrated that PE is the most specific tool, despite its low sensitivity. Detailed PE is cornerstone for evaluating brachial plexus injuries and NCSs are better than MRI for scrutinizing injuries not found in PE.

In our study, NCSs exhibited superior performance to MRI, and should be considered a more reliable supporting tool after detailed PE.