Brachial neuritis masquerading as acute coronary syndrome

Brachial neuritis is a frequently misdiagnosed condition which can present to many medical or surgical specialties.

To report a case of brachial neuritis with bilateral phrenic nerve involvement and diaphragmatic weakness.

A 63-year-old man presented with acute-onset proximal upper extremity pain and weakness. He also developed severe orthopnoea. Examination revealed proximal upper limb wasting and dramatic paradoxical breathing. Cardiac investigations were unremarkable. Electromyographic studies were consistent with a C5 radiculopathy. Phrenic nerve studies were abnormal bilaterally and Sniff test was positive. A diagnosis of brachial neuritis with predominant C5 and bilateral phrenic nerve involvement was made. His symptoms resolved spontaneously over 3 months.

Brachial neuritis can mimic an acute coronary syndrome and is a rare cause of bilateral phrenic neuropathy. Phrenic nerve palsy should be considered in patients presenting with shortness of breath without any underlying respiratory or cardiovascular illness.