Diaphragm Dysfunction Due to Remote Poliomyelitis in a Patient With Unexplained Dyspnea

Late onset of new neuromuscular symptoms occurring many years after the initial illness is the hallmark of postpolio syndrome (PPS) [1]. In PPS, the new onset of motor weakness usually involves muscles that were previously affected; however, new symptoms also may occur in muscles that were clinically asymptomatic. This new weakness is thought to be due in part to overuse and excessive metabolic stress on the remaining motor neurons, eventually leading to their deterioration [1]. Respiratory compromise as a late feature of PPS has been reported and typically is associated with the following risk factors: history of ventilator assistance during the onset of poliomyelitis, central causes of hypoventilation, cranial nerve involvement, and/or musculoskeletal deformities [1-3]. Although respiratory involvement is seen in only a small minority of patients with PPS, it poses a potentially life-threatening complication that presents a challenge to those who manage it. We describe a patient with a history of remote poliomyelitis with no initial respiratory involvement who was evaluated at our clinic; he had a 3-year history of exertional dyspnea and an elevated left hemidiaphragm revealed on a chest radiograph.