ABSTRACT
Phrenic nerve palsy causing hemidiaphragm paralysis is a very uncommon feature of thoracic aortic aneurysm. In one case, a 45-year-old man complained of chronic chest pain, dysphagia, and hoarseness of voice; posteroanterior view chest radiograph revealed lobular enlargement of the superior mediastinum and elevated right hemidiaphragm. Contrast-enhanced computed tomography (CT) of the thorax revealed a giant partially thrombosed aneurysm originating from the ascending aorta and extending into the aortic arch, causing a widening of the aorta-pulmonary window and a compression of the thoracic esophagus. Right hemidiaphragm elevation was explained by the gross mass effect of the aneurysm on the right hilum, causing right phrenic nerve palsy. The patient was to be operated on for surgical correction of the aneurysm, but died before surgery due to spontaneous rupture.