Brachial plexitis or neuritis? MRI features of lesion distribution in Parsonage-Turner syndrome

This study seeks to characterize lesion distribution in Parsonage-Turner Syndrome (PTS) using high-resolution MRI.MRIs of 27 patients with clinically confirmed PTS were reviewed. Two radiologists independently evaluated the brachial plexus proper, side and terminal plexus branches, and more distal, upper extremity nerves.All patients had at least 1 clinically involved nerve. MRI revealed that the plexus appeared normal in 24 of 27 patients; in 3 other patients, signal hyperintensity was seen immediately proximal to the take-off of abnormal side or terminal branch nerves. Focal intrinsic constrictions were detected in 32 of 38 nerves. MRI interobserver agreement was high (Cohen's κ = 0.839).MRI findings, corroborated by electrodiagnostic testing, localized abnormalities to plexus branches and peripheral nerves, suggesting that PTS is characterized by 1 or more mononeuropathies rather than changes involving a portion of or the complete plexus proper. These results may improve diagnosis, prognostication, and management. Muscle Nerve 58: 359-366, 2018.