Post-procedural Brachial Neuritis: Clinical, Electrodiagnostic and Neuroimaging features.

Background and purpose: Brachial neuritis is a monophasic condition affecting the brachial plexus and its branches, manifesting as acute shoulder and upper arm pain, followed by weakness and paresthesias. It can be triggered by antecedent events, including procedures such as surgery. Misdiagnosis and delay in diagnosis is common. Imaging is important to confirm the diagnosis of post-procedural brachial neuritis and exclude other etiologies.

Materials and methods: Clinical, electrodiagnostic, and neuroimaging features of patients with post-procedural brachial neuritis from a single quaternary care institution were identified and analyzed.

Results: Six (2 female) patients were identified with median age 62 (range 49-70) years. Antecedent procedures included 4 cervical spine surgeries, 1 rotator cuff repair, and 1 central venous catheter placement. Time to symptom onset ranged from 1-day to 2-weeks. The initial symptom for 5/6 patients was severe upper extremity pain followed by weakness. All patients had electrodiagnostic tests and MR neurography consistent with brachial neuritis. MR neurogram showed plexus and/or terminal branch abnormalities with associated muscular denervation edema. The C5 or C6 root, and/or upper trunk were always involved. The most common branches affected were the suprascapular, long thoracic, and axillary nerves. Hourglass constrictions of these nerves were seen in 3/6 patients. The average time to diagnosis was 3.4 (range 1.5-5) months.

Conclusions: Post-procedural brachial neuritis is an underrecognized cause of acute upper extremity pain and weakness. MR neurography can exclude iatrogenic causes and document the presence of hourglass constrictions in affected nerves. Diagnostic neuroradiologists should be aware of this clinical entity and associated neuroimaging findings.

Abbreviations: HGC = hourglass constriction; EDX = electrodiagnostic; IRB = Institutional Review Board; ACDF = anterior cervical discectomy and fusion; NRS = Numerical Rating Scale; MUAP = motor unit action potential.