A 61-year-old woman presented with progressive dyspnea of 5 months' duration. She first noticed dyspnea while engaged in her usual daily activities, and it gradually progressed in severity. A primary care physician prescribed bronchodilators without relief. She was subsequently referred for a pulmonary evaluation. Her history was notable for stroke, peptic ulcer disease, hypertension, obstructive sleep apnea, depression, and osteoporosis; she had been in a motor vehicle crash 5 months ago. She denied orthopnea, paroxysmal nocturnal dyspnea, chest pain, cough, fevers, chills, night sweats, and weight loss. Physical examination: On physical examination, she was a healthy woman who showed no evidence of increased work of breathing at rest. Her temperature was 36.8°C (98.2°F), blood pressure was 128/90 mm Hg, and pulse was 85 beats per minute and regular. Respiration rate was 18 breaths per minute, and oxygen saturation was 96% on room air at rest. Lung examination revealed dullness at the right base with decreased fremitus and breath sounds. Neurologically, the patient had a right hemiparesis consistent with her recent history of stroke. Findings from the remainder of the physical examination were normal. Laboratory findings: Her white blood cell count was 7500/µL, with normal differential. Hemoglobin level was 14.4 g/dL. Arterial blood gases on room air were: pH, 7.41; PCO2, 37 mm Hg; and PO2, 67 mm Hg. Spirometry revealed a forced vital capacity (FVC) of 1.37 L (49% of predicted), forced expiratory volume in 1 second (FEV1) of 1.14 L (55% of predicted), FEV1:FVC ratio of 84%, total lung capacity (TLC) of 48%, functional residual capacity of 45%, residual volume (RV) of 47%, RV:TLC ratio of 37%, and carbon monoxide-diffusing capacity of 54%. On a 6-minute walk test, the patient walked 1400 meters and stopped because of dyspnea. Her baseline oxygen saturation was 95%, with a nadir of 93%. The patient's posteroanterior and lateral chest radiographs are shown below (Figure 1). MAKING THE DIAGNOSIS The patient's chest radiographs showed an elevated right hemidiaphragm and associated right lower lobe atelectasis. A CT scan of the chest was ordered to confirm the diagnosis; it showed the presence of the right lobe of the liver and transverse colon in the right hemithorax. DISCUSSION The diaphragm develops between the third and eighth weeks of fetal life from the fusion of septum transversum, the pleuroperitoneal membranes, the dorsal mesentery of the esophagus, and the lateral wall mesoderm. Because the diaphragm is formed by the fusion of several structures, it is prone to weakening at the point of fusion. This is the region through which the abdominal contents frequently herniate after a traumatic tear (Figure 2). The large, posterolateral foramen is known as the foramen of Bochdalek; it results from either the failure of the pleuroperitoneal folds to develop or the improper or absent migration of the diaphragmatic musculature. The other foramen of note is the anteriorly situated foramen of Morgagni. Diaphragmatic injuries occur in 0.8% to 1.6% of persons who sustain blunt chest and abdominal trauma.1 These injuries most commonly occur during motor vehicle crashes, but they also have been reported to occur with diving and falls and spontaneously with violent bouts of coughing. Blunt trauma causes about 75% of diaphragmatic injuries.2 The size of the tear has been reported as 2 to 15 cm. Larger tears are more commonly associated with blunt trauma, and smaller tears are associated with penetrating injuries. The most common site of rupture is the posterolateral area of the diaphragm's central tendon. Clinical case series suggest that left-sided tears are more common. Autopsy studies, however, indicate that both sides are equally involved. Diaphragmatic tears may occur with or without herniation. Diaphragmatic injuries usually remain unrecognized at the time of insult, because they are associated with more severe organ injuries and vascular disruption that demand immediate attention. If missed initially, diaphragmatic injury is associated with morbidity up to 50%.3 A diaphragmatic tear may remain silent for years, perhaps because of temporary closures through muscle contractions or omental interposition, and may become symptomatic when associated with herniation of abdominal organs. Spontaneous closure of a tear does not occur. Diaphragmatic hernias Diaphragmatic hernias are classified as congenital or acquired. Congenital hernias include foramen of Bochdalek, foramen of Morgagni, and hiatal hernia. Acquired hernias are caused by both blunt and penetrating trauma. Hiatal hernias are the most common acquired diaphragmatic hernias in adults. The congenital Bochdalek hernia is the most common congenital hernia (90%). It typically presents as acute respiratory distress after birth and is associated with herniation of small bowel, large bowel, or solid organs. The herniated organs cause pulmonary hypoplasia and pulmonary hypertension. It is more common on the left side, since the right side of the diaphragm is supported by the liver. The foramen of Morgagni hernia occurs in about 5% to 10% of cases. This hernia occurs in the anterior midline through the sternocostal hiatus of the diaphragm, with more than 90% occurring on the right. It is thought that the left anterolateral diaphragm is protected by the heart. The foramen of Morgagni hernia is typically silent throughout childhood. It may become symptomatic during adulthood when it commonly presents as an intestinal obstruction. A congenital hiatal hernia is rare in neonates. In most cases, it is detected incidentally in an adult. The patient may present with epigastric pain, dyspepsia, or gastroesophageal reflux disease. Clinical features of acquired diaphragmatic herniation are nonspecific, depend on the time of presentation and, in some cases, are overshadowed by the associated trauma. Acutely, there may be respiratory distress secondary to marked atelectasis, diaphragmatic dysfunction, or mediastinal shift. If the herniation is not detected at the time of injury, the presentation can be delayed for several years. In a study of 10 patients, the time at which the hernias became clinically significant ranged from 20 days to 28 years.4 These cases commonly present with signs of bowel obstruction. Diagnosis Chest radiography is the initial imaging modality to evaluate for diaphragmatic injuries. However, it has a poor sensitivity: 46% for left-sided ruptures and 17% for right-sided ruptures.5 A chest radiograph may show an elevated hemidiaphragm, mediastinal shift, an air-fluid level in the hemithorax, hydropneumothorax, associated rib fractures, or herniated organs. Ultrasonography may detect herniation, but it will miss small tears. Chest CT has a sensitivity of 70% to 80% for diagnosing diaphragmatic tears. However, in the presence of the dependent viscera sign (upper one third of liver abutted against posterior right ribs and stomach with bowel against posterior left ribs), the overall rate increases to 90%.6 MRI has sensitivity well over 90% for detecting diaphragmatic injuries and is the best noninvasive study.7,8 However, it is used infrequently in trauma patients who are hemodynamically unstable. MRI is very useful for diagnosing injuries in patients who have a delayed presentation.9 Thoracoscopy and/or laparoscopy are used in cases that require emergent exploration to both diagnose and manage diaphragmatic injuries. Barium studies can confirm the presence of herniated organs in the hemithorax but are limited to the evaluation of hollow viscera. Fluoroscopy can demonstrate decreased or abnormal motion of the diaphragm, but this is only suggestive and not diagnostic of injury. The lack of sensitivity of these modalities does not allow construction of an algorithm for diagnostic imaging. Hence, physicians need to maintain a high degree of suspicion and should not be dissuaded from further evaluation based on any single imaging result. Management Surgical repair is used to manage diaphragmatic injury. With traumatic injury, the surgical approach depends on the timing of the diagnosis. In the acute phase of trauma, an abdominal approach is preferable because most patients with traumatic rupture have other associated intra-abdominal injuries. In the latent phase of trauma, a transthoracic approach may be necessary because patients often have adhesions to intrathoracic organs. Most small diaphragmatic defects are repaired by primary closure-suture apposition of the unfused leaflets of the diaphragm;however, some may require the use of prosthetic material. Both autologous (muscle, fascia, omentum) and allogenic (Dacron, prolene, collagen, Teflon, silastic) materials have been used. Polytetrafluoroethylene is the most commonly used material in pediatric and adult surgery.1 The mortality from diaphragmat- ic injuries varies between 0% and 30% depending on associated organ injury.2,10 Diaphragmatic injuries are rarely associated with phrenic nerve paresis. About 50% of patients with associated phrenic nerve paresis have a complete recovery over months to years. The outcome in this case As a result of the motor vehicle crash, our patient had a right pneumothorax requiring chest tube placement. The chest radiograph at that time (not shown here) failed to reveal diaphragmatic injury, highlighting the point that radiography is a suboptimal screening tool. Subsequently, dyspnea developed, and the patient presented to our clinic 4 months after the motor vehicle crash. She received a delayed diagnosis with CT confirmation. She underwent a surgical repair of the diaphragm with resolution of her dyspnea. The diagnosis: Traumatic rupture of the diaphragm with herniation of the liver and the colon into the right hemithorax. MAKING THE DIAGNOSIS The patient's chest radiographs showed an elevated right hemidiaphragm and associated right lower lobe atelectasis. A CT scan of the chest was ordered to confirm the diagnosis; it showed the presence of the right lobe of the liver and transverse colon in the right hemithorax (Figure 2). DISCUSSION The diaphragm develops between the third and eighth weeks of fetal life from the fusion of septum transversum, the pleuroperitoneal membranes, the dorsal mesentery of the esophagus, and the lateral wall mesoderm. Because the diaphragm is formed by the fusion of several structures, it is prone to weakening at the point of fusion. This is the region through which the abdominal contents frequently herniate after a traumatic tear (Figure 3). The large, posterolateral foramen is known as the foramen of Bochdalek; it results from either the failure of the pleuroperitoneal folds to develop or the improper or absent migration of the diaphragmatic musculature. The other foramen of note is the anteriorly situated foramen of Morgagni. Diaphragmatic injuries occur in 0.8% to 1.6% of persons who sustain blunt chest and abdominal trauma.1 These injuries most commonly occur during motor vehicle crashes, but they also have been reported to occur with diving and falls and spontaneously with violent bouts of coughing. Blunt trauma causes 75% of diaphragmatic injuries.2 The size of the tear has been reported as 2 to 15 cm. Larger tears are more commonly associated with blunt trauma, and smaller tears are associated with penetrating injuries. The most common site of rupture is the posterolateral area of the diaphragm's central tendon. Clinical case series suggest that left-sided tears are more common. Autopsy studies, however, indicate that both sides are equally involved. Diaphragmatic tears may occur with or without herniation. Diaphragmatic injuries usually remain unrecognized at the time of insult, because they are associated with more severe organ injuries and vascular disruption that demand immediate attention. If missed initially, diaphragmatic injury is associated with morbidity up to 50%.3 A diaphragmatic tear may remain silent for years, perhaps because of temporary closures through muscle contractions or omental interposition, and may become symptomatic when associated with herniation of abdominal organs. Spontaneous closure of a tear does not occur. Diaphragmatic hernias Diaphragmatic hernias are classified as congenital or acquired. Congenital hernias include foramen of Bochdalek, foramen of Morgagni, and hiatal hernia. Acquired hernias are caused by both blunt and penetrating trauma. Hiatal hernias are the most common acquired diaphragmatic hernias in adults. The congenital Bochdalek hernia is the most common congenital hernia (90%), typically presents as acute respiratory distress after birth, and is associated with herniation of small bowel, large bowel, or solid organs. The herniated organs cause pulmonary hypoplasia and pulmonary hypertension. It is more common on the left side, since the right side of the diaphragm is supported by the liver. The foramen of Morgagni hernia occurs in 5% to 10% of cases. This hernia occurs in the anterior midline through the sternocostal hiatus of the diaphragm, with more than 90% occurring on the right. It is thought that the left anterolateral diaphragm is protected by the heart. The foramen of Morgagni hernia is typically silent throughout childhood. It may become symptomatic during adulthood when it commonly presents as an intestinal obstruction. A congenital hiatal hernia is rare in neonates. In most cases, it is detected incidentally in an adult. The patient may present with epigastric pain, dyspepsia, or gastroesophageal reflux disease. Clinical features of acquired diaphragmatic herniation are nonspecific, depend on the time of presentation and, in some cases, are overshadowed by the associated trauma. Acutely, there may be respiratory distress secondary to marked atelectasis, diaphragmatic dysfunction, or mediastinal shift. If the herniation is not detected at the time of injury, the presentation can be delayed for several years. In a study of 10 patients, the time at which the hernias became clinically significant ranged from 20 days to 28 years.4 These cases commonly present with signs of bowel obstruction. Diagnosis Chest radiography is the initial imaging modality to evaluate for diaphragmatic injuries. However, it has a poor sensitivity--46% for left-sided ruptures and 17% for right-sided ruptures.5 A chest radiograph may show an elevated hemidiaphragm, mediastinal shift, an air-fluid level in the hemithorax, hydropneumothorax, associated rib fractures, or herniated organs. Ultrasonography may detect herniation, but it will miss small tears. Chest CT has a sensitivity of 70% to 80% for diagnosing diaphragmatic tears. However, in the presence of the dependent viscera sign (upper one third of liver abutted against posterior right ribs and stomach with bowel against posterior left ribs), the overall rate increases to 90%.6 MRI has sensitivity well over 90% for detecting diaphragmatic injuries and is the best noninvasive study.7,8 However, it is not used often in trauma patients who are hemodynamically unstable. MRI is very useful for diagnosing injuries in patients with a delayed presentation.9 Thoracoscopy and/or laparoscopy are used in cases that require emergent exploration to both diagnose and manage diaphragmatic injuries. Barium studies can confirm the presence of herniated organs in the hemithorax but are limited to the evaluation of hollow viscera. Fluoroscopy can demonstrate decreased or abnormal motion of the diaphragm, but this is only suggestive and not diagnostic of injury. The lack of sensitivity of these modalities does not allow construction of an algorithm for diagnostic imaging. Hence, physicians need to maintain a high degree of suspicion and should not be dissuaded from further evaluation based on any single imaging result. Management Surgical repair is used to manage diaphragmatic injury. With traumatic injury, the surgical approach depends on the timing of the diagnosis. In the acute phase of trauma, an abdominal approach is preferable because most patients with traumatic rupture have other associated intra-abdominal injuries. In the latent phase of trauma, a transthoracic approach may be necessary because patients often have adhesions to intrathoracic organs. Most small diaphragmatic defects are repaired by primary closure-suture apposition of the unfused leaflets of the diaphragm;however some may require the use of prosthetic material. Both autologous (muscle, fascia, omentum) and allogenic (Dacron, prolene, collagen, Teflon, silastic) materials have been used. Polytetrafluoroethylene is the most commonly used material in pediatric and adult surgery.1 Mortality from diaphragmatic injuries varies between 0% and 30% depending on associated organ injury.2,10 Diaphragmatic injuries are rarely associated with phrenic nerve paresis. About 50% of patients with associated phrenic nerve paresis have a complete recovery over months to years. The outcome in this case As a result of the motor vehicle crash, our patient had a right pneumothorax requiring chest tube placement. The chest radiograph at that time (not shown here) failed to reveal diaphragmatic injury, highlighting the point that radiography is a suboptimal screening tool. Subsequently, dyspnea developed, and the patient presented to our clinic 4 months after the motor vehicle accident crash. She received a delayed diagnosis with CT confirmation. She underwent a surgical repair of the diaphragm with resolution of her dyspnea. References: REFERENCES 1. Schumpelick V, Steinau G, Schluper I, Prescher A. Surgical embryology and anatomy of the diaphragm with surgical applications. Surg Clin North Am . 2000;80:213-239, xi. 2. Shah R, Sabanathan S, Mearns AJ, Choudhury AK. Traumatic rupture of diaphragm. Ann Thorac Surg . 1995;60:1444-1449. 3. Drews JA, Mercer EC, Benfield JR. Acute diaphragmatic injuries. Ann Thorac Surg . 1973; 16:67-78. 4. Reber PU, Schmied B, Seiler CA, et al. Missed diaphragmatic injuries and their long-term sequelae. J Trauma . 1998;44:183-188. 5. Kirshenbaum MD. Diaphragmatic rupture due to blunt trauma: sensitivity of plain chest radiographs. AJR . 1991;157:411. 6. Bergin D, Ennis R, Keogh C, et al. The "dependent viscera" sign in CT diagnosis of blunt traumatic diaphragmatic rupture. AJR . 2001; 177:1137-1140. 7. Barbiera F, Nicastro N, Finazzo M, et al. The role of MRI in traumatic rupture of the diaphragm. Our experience in three cases and review of the literature. Radiol Med (Torino) . 2003;105:188-194. 8. Mirvis SE, Keramati B, Buckman R, Rodriguez A. MR imaging of traumatic diaphragmatic rupture. J Comput Assist Tomogr . 1988;12:147-149. 9. Daum-Kowalski R, Shanley DJ, Murphy T. MRI diagnosis of delayed presentation of traumatic diaphragmatic hernia. Gastrointest Radiol . 1991; 16:298-300. 10. Pagliarello G, Carter J. Traumatic injury of diaphragm: timely diagnosis and treatment. J Trauma . 1992;33:194-197. 11. Iochum S, Ludig T, Walter F, et al. Imaging of diaphragmatic injury: a diagnostic challenge? Radiographics. 2002;22:S103-S116.
