Male, 57 years old, with right bicep and shoulder weakness, history of right tonsil cancer status post treatment. Ill-defined edema is seen within the paraspinal soft tissues of the right neck encompassing the roots, trunks and divisions of the brachial plexus. No masslike lesion or fluid collection is seen. Also noted is extensive right-sided muscular atrophy including the sternocleidomastoid muscle, scalene muscles, and muscles of the shoulder girdle, all of which demonstrate some degree of edema as well.
Although no focal lesions are identified, there is evidence of edema within the right neck which does encompass the proximal portion of the brachial plexus. Extensive muscular atrophy is seen at least as far distally as the shoulder girdle. These findings favor brachial plexitis perhaps related to prior radiotherapy with associated denervation muscular edema and atrophy.