Most common cause of unilateral diaphragmatic paralysis is

(A) Surgical trauma # UNILATERAL DIAPHRAGMATIC PARALYSIS may be idiopathicl or secondary to multiple causes, among which the most common is a tumour with phrenic nerve involvement or surgical trauma,> Causes of unilateral paralysis are diseases of the cervical spinal cord affecting the anterior horn cells of the fourth segment, such as poliomyelitis, tumour, progressive muscular atrophy, myelitis, haemorrhage, and injuries and caries of the cervical vertebrae.> Peripheral lesions of the phrenic nerve or its roots include neck wounds, polyneuritis (usually diphtheritic), destruction by neoplastic masses (usually near the hilum of the lung), and avulsion from birth injury as an extension of Erb's palsy.> Unilateral diaphragmatic paralysis is often discovered incidentally in patients undergoing chest radiography for some other reason Patients usually are asymptomatic at rest but experience dyspnea upon exertion and have a decrease in exercise performance.> If the patient has an underlying lung disease, dyspnea may occur at rest.> Some patients may develop orthopnea, which is less intense than bilateral diaphragmatic paralysis.