Differentiating Diaphragmatic Paralysis and Eventration

Rationale and Objectives: Although elevation of the diaphragm can be appreciated on conventional PA and lateral chest radiography, the modality is commonly viewed as inadequate to differentiate diaphragmatic paralysis from eventration. Our objective was to qualitatively and quantitatively measure the utility of chest radiography in determining the presence or absence of diaphragmatic paralysis in patients with an elevated diaphragm. Materials and Methods: A retrospective analysis of chest radiographs in 32 patients, whom underwent fluoroscopic sniff test for elevated diaphragm, was performed. Diaphragm function was graded by a senior radiology resident, as either "paralyzed" or "non-paralyzed," based on appearance/shape of elevated hemidiaphragm on PA and lateral radiograph. The diaphragm position and shape for all patients were determined using measurements relating to skeletal structures and radius of curvature, respectively. These results were correlated with the results of the fluoroscopic sniff tests. Results: Of 32 patients with elevated diaphragm on chest radiograph, 17 had diaphragmatic paralysis confirmed with fluoroscopic sniff test. Our results indicate that the radius of curvature or shape of the diaphragm on lateral chest radiograph is the most important factor for detection of the presence or absence of diaphragmatic paralysis. HH/APD > 0.28 suggests against paralysis. Conclusion: Conventional chest radiography appears to be a useful modality for assessment of the functional status of an elevated diaphragm. Based on our results, evaluation of the shape of an elevated diaphragm may preclude the need for fluoroscopic sniff test to determine diaphragmatic paralysis.