No abstract

None of the risk factors studied, including diabetes, influenced the appearance of phrenic neuropathy, thus indicating a role for nerve damage during surgery. Low morbidity and relatively rapid recovery were observed.

Two asthmatic patients developed unilateral diaphragmatic paralysis from phrenic nerve injury, in one case following cervical chiropractic manipulation and in the other after a motorcycle accident. Both presented with increased dyspnea and orthopnea. Diagnosis, severity, and level of the lesion were established by neurophysiological methods, which are preferred to chest radiography and diaphragmatic ultrasonography. In spite of only partial electrophysiological recovery of the nerve, both patients were asymptomatic 1 year later.

Objectives: To determine the sensitivity and specificity of B-mode ultrasound in the diagnosis of neuromuscular diaphragmatic dysfunction, including phrenic neuropathy.Methods: A prospective study of patients with dyspnea referred to the EMG laboratory over a 2-year time frame for evaluation of neuromuscular respiratory failure who were recruited consecutively and examined with ultrasound for possible diaphragm dysfunction. Sonographic outcome measures were absolute thickness of the diaphragm and degree of increased thickness with maximal inspiration. The comparison standard for diagnosis of diaphragm dysfunction was the final clinical diagnosis of clinicians blinded to the diaphragm ultrasound results, but taking into account other diagnostic workup, including chest radiographs, fluoroscopy, phrenic nerve conduction studies, diaphragm EMG, and/or pulmonary function tests.Results: Of 82 patients recruited over a 2-year period, 66 were enrolled in the study. Sixteen patients were excluded because of inconclusive or insufficient reference testing. One hemidiaphragm could not be adequately visualized; therefore, hemidiaphragm assessment was conducted in a total of 131 hemidiaphragms in 66 patients. Of the 82 abnormal hemidiaphragms, 76 had abnormal sonographic findings (atrophy or decreased contractility). Of the 49 normal hemidiaphragms, none had a false-positive ultrasound. Diaphragmatic ultrasound was 93% sensitive and 100% specific for the diagnosis of neuromuscular diaphragmatic dysfunction.Conclusion: B-mode ultrasound imaging of the diaphragm is a highly sensitive and specific tool for diagnosis of neuromuscular diaphragm dysfunction. Classification of evidence:This study provides Class II evidence that diaphragmatic ultrasound performed by well-trained individuals accurately identifies patients with neuromuscular diaphragmatic respiratory failure (sensitivity 93%; specificity 100%). Neurology ® 2014;83:1264-1270 GLOSSARY CMAP 5 compound muscle action potential; NCS 5 nerve conduction study; T MAX 5 thickness at maximal inspiration; T MAX /T MIN 5 diaphragm thickening ratio; T MIN 5 thickness at resting end-expiration.Diaphragm dysfunction can be difficult to diagnose, particularly when diaphragm paralysis is bilateral. The usual workup of patients presenting with unexplained dyspnea may include chest radiographs, fluoroscopy, phrenic nerve conduction studies (NCS), needle EMG of the diaphragm, pulmonary function testing, and transdiaphragmatic pressure measurements; all of these diagnostic tests can produce false-positive and false-negative findings, and some tests are invasive or uncomfortable for the patient.