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Science News: Degree of Agreement between Electrodiagnostic Testing and Magnetic Resonance Imaging in the Evaluation of Brachial Plexopathy

Submitted by Rebecca O'Bryan, MD
Edited by Clark Pinyan, MD

Degree of Agreement between Electrodiagnostic Testing and Magnetic Resonance Imaging in the Evaluation of Brachial Plexopathy
Kang, Seok MD; Yoon, Joon Shik MD, PhD; Hong, Suk-Joo MD, PhD; Yang, Seung Nam MD, PhD
American Journal of Physical Medicine & Rehabilitation: July 2019 - Volume 98 - Issue 7 - p 545–548

This article reports the findings of a retrospective analysis of 69 patients with symptoms of brachial plexopathy of various etiologies to investigate the degree of agreement between magnetic resonance imaging (MRI) and electrodiagnostic testing (EDX). Of the 69 patients reviewed, 12 were excluded due to diagnoses of other diseases during the assessment, or due to lack of evidence to support the diagnosis on either test (EDX or MRI).

EDX was in all cases performed by a board certified physiatrist or neurologist specialized in peripheral nervous system disorders (the board certification and years of experience were not reported). MRI was reviewed by a musculoskeletal radiologist who was blinded to the patient clinical information.

Results were classified into location along the plexus (preganglionic root, post ganglionic root, trunk, division, cord, and distal branches). An experienced physiatrist made the determination regarding similarities between EDX and MRI based on comparison of anatomic location(s) identified on each test. Patients were then divided into three groups (complete match, partial match, or mismatch).

Results indicated an overall complete or partial match in 63.2% of cases. A mismatch, where either only one modality identified the diagnosis, or where the modalities did not overlap at all in terms of location of lesion, was noted in 36.8% of cases.

In the cases of a mismatch, 16 were due to brachial plexitis, and in 8 of these cases, only one modality revealed an abnormality (6 of the 8 were only apparent on EDX, 2 of the 8 were only apparent on MRI). All 4 of the trauma cases identified as mismatch were only apparent on EDX.

Conclusions drawn from this study were that, overall, MRI and EDX presented in agreement with each other in the evaluation of brachial plexopathy. However, only one test demonstrated the lesion in 12 cases. Time intervals between tests was offered as a potential factor that could cause discrepancy. Each test has its own advantages and disadvantages, and can provide unique information. Discrepencies existed in a fairly significant number of cases, either partially or completely. The testing methods were determined to be complementary in the work up of suspected brachial plexopathy.

Comments: EDX should continue to be a valuable and necessary component to the work up of patients with brachial plexus pathology, even in the event that an MRI has already been performed and localization has been identified. This is especially in cases where the MRI is negative and clinical suspicion is high, as well as milder cases and trauma.

Neuromuscular specialists caring for patients with brachial plexopathy of various etiologies should take from this article further support for their efforts in EDX in the context of work up and surgical or interventional planning. 4 trauma and 6 brachial plexitis cases showed no abnormalities on MRI and localization was only available via EDX (in contrast with only 2 in the brachial plexitis group with abnormalties only on MRI). Advocating for EDX in these patients early and in tandem with MRI may provide enhanced sensitivity and should continue to be employed in patients with symptoms concerning for brachial plexopathy.

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