Isolated Unilateral Brachial Neuritis of the Phrenic Nerve (Parsonage-Turner Syndrome) in a Marathon Runner With Exertional Dyspnea

Parsonage-Turner syndrome, or acute brachial neuritis/plexitis, is a rare condition that should be included in the differential diagnosis of any athlete who presents with antecedent flulike symptoms, with progression to significant neuropathic pain, followed by profound weakness in the affected upper extremity. In rare cases, the main presenting symptom of this condition may be dyspnea on exertion secondary to an isolated unilateral brachial neuritis of the phrenic nerve.