[A case of left phrenic nerve paralysis caused by compression of the left auricle due to congenital partial left pericardial defect].

We report a case of left phrenic nerve paralysis due to compression of left auricle caused by congenital partial left pericardial defect. A 56-year-old man was admitted with left phrenic nerve paralysis. His congenital partial left pericardial defect was incidentally diagnosed on video assisted thoracoscopic surgery (VATS). This case of left phrenic nerve paralysis was due to compression of the left auricle which protruded through the hole of a partial defect in the pericardium. When the patient was examined for dyspnea at our hospital, the chest X-ray revealed left diaphragmatic relaxation and chest computed tomography showed a high density mass in front of the left pulmonary artery. Electrophysiologic evaluation of the diaphragm by transcutaneous phrenic nerve stimulation indicated complete paralysis of the left phrenic nerve. VATS revealed that the phrenic nerve was compressed by the protruding left auricle due to a congenital partial left pericardial defect. Because of the complete paralysis of the left phrenic nerve, we chose to perform plication of the left diaphragm. The postoperative course was uneventful and the patient was discharged on the 23rd day after the operation. Congenital pericardial defect is an abnormality that is rarely found incidentally on thoracotomy or autopsy. However, we should perform a careful examination and consider the possibility of congenital pericardial defect in the differential diagnosis of phrenic nerve paralysis.