Acute brachial neuritis (Parsonage-Turner syndrome): MR imaging appearance--report of three cases.

Magnetic resonance (MR) imaging findings in three patients with acute onset of neuritic shoulder pain and weakness included high signal intensity in supra- and infraspinatus muscles (n = 2), partial involvement of infraspinatus muscle (n = 1) and of deltoid muscle (n = 1), and atrophy of supra- and infraspinatus muscles (n = 2). Clinical diagnosis of acute brachial neuritis (Parsonage-Turner syndrome) correlated with MR imaging results in all cases.