MR neurography findings of brachial plexopathy following total shoulder arthroplasty

To characterize nerve injury patterns following total shoulder arthroplasty (TSA).

This retrospective study reviewed brachial plexus MR neurography (MRN) in patients with brachial plexopathy within 180 days post TSA from 2016 to 2023. Patients with pre-existing neurologic symptoms or without available electrodiagnostic testing (EDX) data were excluded. MRN findings were extracted from the original report and independently reviewed by a second, musculoskeletal fellowship trained radiologist.

A total of 27 patients (15F/12 M, mean age 67) were included. MRN and EDX-confirmed nerve injury localization matched in 13 patients, with nerve hyperintensity and/or enlargement identified in 7 cases at the plexus proper and 6 cases at the branch nerve level (suprascapular, axillary, radial, median). Nerve impingement by screw (n = 3) or extruded cement (n = 1) and mass effects including soft tissue edema (n = 1), hematoma (n = 2), or joint effusion (n = 2) were identified. MRN detected muscle denervation in 8 of 19 patients with EMG abnormalities, with a median TSA-to-MRN interval of 62.5 days (range, 19-95) versus 3 days (range, 2-155) in those without denervation on MRN (p = 0.003). Inter-rater reliability demonstrated substantial to almost perfect agreement for MRN assessments, except for cord hyperintensity. All patients were clinically followed up: 3 had complete symptomatic resolution and 21/27 reported partial improvement at a mean follow-up time of 25.5 months.

MRN findings closely correlated with EDX-confirmed clinical diagnoses in cases with MRN abnormalities. Additionally, MRN identified secondary findings, such as local mass effect on nerve segments, that can guide management.