MR Neurography of Bilateral Parsonage-Turner Syndrome

A 40-year-old man developed sudden-onset severe bilateral shoulder pain preceded by 2 days of rhinorrhea and low-grade fever. Cervical spine and shoulder MRI examinations were unrevealing, and the pain was unresponsive to opioids. Five days later, right scapular winging and left-shoulder abduction weakness ensued. The pain subsided with oral steroids. Electromyography 3.5 months later demonstrated left supraspinatus and infraspinatus and right serratus anterior muscle denervation. Subsequent MR neurography showed intrinsic constrictions of the right lower subscapular nerve (Figure) and right long thoracic and left suprascapular nerves (not shown) supplying denervated muscles, the classic finding of Parsonage-Turner syndrome (1). The diagnosis of Parsonage-Turner syndrome was reached according to findings from clinical presentation, neurologic examination, and electrodiagnostic study and was corroborated with MR neurography. Other possibilities were excluded with cervical spine and shoulder MRI. The patient’s weakness is being treated with physical therapy, and he will undergo follow-up electromyography to determine improvement.

(a) Coronal T2-weighted Dixon MRI scan shows right teres major muscle (dashed arrow) and right serratus anterior muscle (solid arrow) denervation. (b) Curved multiplanar reformatted MRI scan from long–echo time short inversion time inversion-recovery sequence after intravenous administration of gadolinium-based contrast material shows multiple severe constrictions (brackets) of right lower subscapular nerve innervating the teres major muscle (stars).

Parsonage-Turner syndrome, or neuralgic amyotrophy, is a distinct syndrome characterized by severe, acute, spontaneous pain in the upper arm region followed by paresis in the distribution of one or more upper extremity peripheral nerves (2). Its cause is unknown, but it is thought to reflect an immune-mediated response to a stressor (eg, viral illness, physical exertion, or surgery). Parsonage-Turner syndrome is considered rare with a widely stated prevalence of one to three per 100 000 individuals, but its incidence has been measured to be as high as one per 1000 individuals (3). Treatment options are typically conservative, namely early corticosteroid administration, pain management, and physical therapy. In select cases, surgical intervention may be considered (4).