Parsonage-Turner syndrome (PTS) is a rare disorder usually characterized by a sudden onset of upper extremity pain followed by progressive neurologic deficits, including weakness, atrophy, and occasionally sensory abnormalities. The exact cause and pathophysiology of PTS are complex and not completely understood. Autoimmune, genetic, infectious, and mechanical processes have all been implicated. No specific treatments have been proven to reduce neurologic impairment or improve the prognosis of PTS. The majority of persons with PTS are treated with a multidisciplinary approach that includes both physical therapy and pharmacologic treatment, frequently with multiple agents. Additional research is needed.