Traumatic diaphragmatic hernia can result from either penetrating or blunt injury. Diaphragmatic rupture is associated with severe injury and a high mortality secondary to the associated injuries. Diaphragmatic rupture occurs in 0.8% to 8% of patients after blunt trauma. It usually affects the left side. Diagnosis of the diaphragmatic rupture is often missed but the lesion is more readily recognized if the injury is recent and the tear is large and left-sided. Diagnostic radiographic signs of diaphragmatic rupture include visualization of herniated stomach or bowel in the chest and cephalad extension of an intragastric tube above the level of the diaphragm. Suggestive findings include irregularity of the diaphragmatic contour, elevated hemidiaphragm in the absence of the atelectasis, and a contralateral shift of the mediastnum in the absence of the pleural effusion or pneumothorax. Characteristic CT findings of diaphragmatic tear include sharp discontinuity of the diaphragm, intrathoracic visceral herniation, lack of visualization of a hemidiaphragm (absent diaphragm sign), and constriction of bowel or stomach at the site of herniation (collar or waist sign). Although retrospective analysis indicates that most diaphragmatic tears are detectable by CT, several studies have found CT to be of limited value in diagnosis. In problematic cases, coronal and sagittal MR imaging or spiral CT with multiplaner reconstruction can be definitive. These imaging planes can be useful in depicting the secondary sign of focal bulge or mushrooming in the diaphragmatic contour, particularly on the right where diagnosis can be difficult. MRI has the advantage of being capable of identifying the entire diaphragm as a distinct and separate structure, whereas, CT is limited in this regard.
Fig 1: TRAUMATIC DIAPHRAGMATIC HERNIA
A 66-year-old man with previous history of car accident 13 years ago complained of increasing shortness of breath. A. Chest radiograph: apparent elevation of the right hemidiaphragm. B. Coronal T1-weighted MRI: discontinuity of the right diaphragm (black arrows) and bowel herniation. C. Barium enema and UGI: herniation of the colon and a portion of stomach through the tear.
Fig 2: RUPTURED DIAPHRAGM WITH CONGENITAL HIATAL HERNIA
A 59-year-old woman complained of exertional dyspnea since 3 years. She was involved in automobile accident 17 years previously. A. Radiograph: Numerous air-containing viscera within the lower portion of the left hemithorax. Note the old tuberculous lesion of the right lung and pleura. B. CT scan through the lower chest: herniation of a portion of the stomach in to the lower mediastinum and abnormally high position of the colon. C. Sagittal T1-weighted MRI: free edge of the torn left diaphragm (arrows) with herniated colon through the orifice of 5 cm in diameter. D. Coronal T1-weighted MRI: herniated stomach through the esophageal hiatus covered by hernial sac (small arrows). Sugery confirmed the diaphragmatic tear located just lateral to the esophageal hiatus.
Fig 3: TRAUMATIC DIAPHRAGMATIC HERNIA
A 35-year-old man with previous history of aortic surgery for isthmic pseudoaneurysm after a car accident 2 years ago complained of severe chest pain and dyspnea for 3 days. Chest radiograph at emergency room shows an opacification of the left hemithorax. A. Contrast-enhanced multi-detecter row CT scan: lack of visualization of the left hemidiaphragm and dependant viscera sign. B. Sagittal and C. Coronal reformatted image: severe constriction of the stomach at the site of herniation (collar sign). D. Coronal volume-rendered CT image shows well the herniated constricted stomach (long arrow), dilated esophagus, and pleural effusion and collapsed left lung. Note also the normal position of the nasogastric tube (small arrows) in the non herniated portion of the stomach. At surgey, gastric strangulation was found.