Diaphragmatic Abnormalities

The diaphragm abnormalities chapter discusses a variety of acquired and congenital conditions of the diaphragm, the principal muscle of respiration. Most diaphragmatic abnormalities encountered on imaging relate to abnormal contour or abnormal function. The latter is usually due to phrenic nerve palsy or neoplastic involvement. Abnormal contour often results from congenital thinning (eventration). Herniation and rupture following trauma are associated with a high risk of gastric ischemia and require prompt diagnosis and treatment. Thus, radiologists must be familiar with CT findings of traumatic diaphragmatic injury. Nontraumatic hernias (namely, Bochdalek, foramen of Morgagni and hiatal hernias) have typical imaging appearances as well. Rarely, a subpulmonic pleural effusion may mimic an elevated hemidiaphragm on radiography. A pleural effusion may also invert the diaphragm and impair respiration.