Unilateral Phrenic Nerve Palsy Following Blunt Chest Trauma: A Case Report

Abstract

The phrenic nerve, the only nerve supply to the diaphragm, is both a sensory and motor nerve. Weakness in the primary respiratory muscle causes respiratory dysfunctions. The diaphragm functions as 2 separate units, a left and a right hemidiaphragm. The paresis of one hemidiaphragm can be completely asymptomatic as its counterpart and external intercostal muscles com-Phrenic nerve (PN) injury without a direct injury is unusual and difficult to diagnose. This case report is the first to describe the diagnosis of unilateral PN palsy following blunt chest trauma by fluoroscopic diaphragmatic movement testing (FDT) and electrodiagnostic testing. A 68-yearold man was admitted to the emergency department after a motorcycle accident. Chest radiography showed an elevated right hemidiaphragm. More than 7 months later, he experienced dyspnea on exertion and orthopnea, prompting him to visit the Department of Physical Medicine and Rehabilitation. FDT showed no movement in the right diaphragm during maximum inspiration and expiration, but the left diaphragm was intact. Electrodiagnostic testing showed absent compound motor action potential (CMAP) in the right diaphragm, but normal CMAP in the left diaphragm. We hypothesize that in patients with orthopnea symptoms after blunt chest trauma, electrodiagnostic testing paired with FDT may be useful for diagnosing diaphragm palsy.