Objective We report a case of misdiagnosed neuralgic amyotrophy (brachial plexus neuritis, Parsonage-Turner syndrome). Our primary objective is to review the scientific basis for errors in clinical reasoning.

Case Report We herein report a patient in whom signs and symptoms compatible with neuralgic amyotrophy presented after shoulder surgery. The patient's brachial plexopathy was attributed incorrectly as a complication of interscalene brachial plexus block. The true diagnosis was made only after the patient developed neuralgic amyotrophy in the contralateral upper extremity after a subsequent shoulder surgery on that side, this time without a brachial plexus block.

Conclusions Cognitive bias may lead to errors in clinical reasoning and consequent misdiagnosis. Temporal proximity may falsely implicate regional anesthesia as the causative agent.