Approach to Acute Traumatic and Nontraumatic Diaphragmatic Abnormalities

Congenital Diaphragmatic Hernia Diaphragmatic hernias are divided into congenital and acquired. Congenital diaphragmatic hernias occur in approximately 2.5 per 10 000 births and arise from an embryologic defect in pleuroperitoneal canal closure or in septum transversum fusion to the anterolateral body wall ( 1, 5). As a result, abdominal contents herniate into the thoracic cavity, given the negative intrathoracic pressure. Hernia type can be differentiated by the anatomic location of the defect. Among larger hernias present at birth, 70%–75% are posterolateral Bochdalek hernias (85% left sided) ( Fig 4), 23%–28% are anterior Morgagni hernias ( Fig 5), and 2%–7% are central hernias ( 5). Collectively, just over 80% of congenital hernias are left sided ( 6). Around 63%–82% of larger hernias are detected with prenatal US, depending on the location, although smaller right-sided hernias are more frequently missed ( 6). Herniated abdominal organs restrict the growth and development of the cardiopulmonary system; therefore, affected neonates not diagnosed prenatally usually present in the first few hours to weeks of life with varying degrees of cardiopulmonary ( 5) and gastrointestinal ( 7) distress, constituting a pediatric emergency. Radiographs showing abdominal contents herniated into the thoracic cavity, with or without mediastinal shift, allow confirmation of the diagnosis. Other signs of herniation include little to no visible aerated lung on the affected side and abnormal nasogastric tube placement ( Fig S1) ( 7). Fetal MRI allows better characterization of hernia sac contents, pulmonary volume, and associated malformations ( 5, 6). Management includes careful cardiopulmonary stabilization and surgical repair ( 5, 6). In adults, smaller Bochdalek and Morgagni hernias are more commonly asymptomatic and incidentally found at imaging ( Figs 4, 5). If diagnosis is delayed until adulthood, these hernias can lead to vague chest or gastrointestinal discomfort ( 8, 9). Rarely, organ incarceration, strangulation, ischemia, or perforation can occur, generally in the context of intestinal obstruction ( 8). Endometriosis-related Diaphragmatic Disease Diaphragmatic Endometriosis.—Endometriosis is a common gynecologic condition where endometrial tissue is found ectopic to the uterus. Diaphragmatic endometriosis ( Fig 6) is an uncommon manifestation found in 0.7%–1.5% of reproductive-age females with pelvic endometriosis ( 12, 13), although it rarely occurs in the absence of pelvic endometriosis ( 14). The pathogenesis remains unclear, but theories to explain its occurrence include retrograde menstruation with peritoneal implantation of endometrial tissue and subsequent lymphovascular spread of cells. Alternative hypotheses have been proposed, such as the coelomic metaplasia model, given that endometrial tissue has a similar embryonic origin to that of thoracic mesothelial tissue ( 15). Patients with diaphragmatic endometriosis generally present with recurrent episodes of perimenstrual chest or shoulder pain that may radiate to the neck and arm or else epigastric pain, dyspnea, hemoperitoneum, and hemoptysis ( 12). Diaphragmatic endometriosis largely affects the right hemidiaphragm (86.9%); uncommonly, the disease is left sided (2.2%) or bilateral (10.9%) ( 13). The reason for the right-sided preference is unclear, but it supports the reflux theory: clockwise peritoneal flow of refluxed endometriotic tissue becomes obstructed by the falciform ligament ( 13). Contrast-enhanced CT may show hypo- or isoattenuating endometrial implants, diaphragmatic defects, and associated features like pneumoperitoneum. However, sensitivity is low; thus, CT is primarily used to rule out other diagnoses ( 16). In comparison, MRI has approximately 80% sensitivity for diaphragmatic endometriosis, which primarily appears as hyperintense lesions on fat-suppressed T1- and T2-weighted images ( Fig 6). Less commonly, nodules are isointense or of mixed signal intensity. However, small superficial nodules and diaphragm holes can be difficult to detect ( 17). Ultimately, explorative video-assisted laparoscopic or thoracoscopic surgery is used to characterize the extent of the disease. Definitive diagnosis is made with tissue confirmation ( 15). Treatment involves surgical resection of endometriotic nodules and diaphragm repair, with subsequent suppressive hormone therapy (hormonal contraceptives or gonadotropin-releasing hormone agonists) ( 12, 13). Catamenial Pneumothorax.—Few patients with diaphragmatic endometriosis present with catamenial pneumothorax, a recurrent spontaneous pneumothorax occurring in relation to menstruation (within 72 hours before or after the onset) ( 15, 18) ( Fig 7). This is likely due to diaphragmatic and pleural-based endometrial lesions that cause diaphragmatic or pleural compromise with hormonal changes, although it can occur in the absence of diaphragmatic and pelvic endometriosis ( 15, 18). Like diaphragmatic endometriosis, catamenial pneumothorax is largely right sided, with rare reports of left-sided or bilateral occurrence ( 15, 18, 19). Chest radiography allows identification of pneumothorax, although clinical correlation is needed to diagnose catamenial pneumothorax ( 19). Occasionally, diaphragmatic defects can be seen at imaging (CT and MRI) in patients with catamenial pneumothorax ( 18). Immediate management for pneumothorax ranges from oxygen and observation to emergency thoracentesis. Definitive management may require diaphragmatic resection, defect repair, pleurectomy, or pleurodesis ( 18). Endometriosis-related diaphragmatic rupture occurs when many small untreated diaphragmatic endometriotic nodules or holes become confluent. Rupture occurs more commonly in the tendinous portion and can lead to abdominal content herniation ( 20). Eventration and Paralysis Diaphragmatic dysfunction can be divided into eventration and weakness or paralysis. Diaphragmatic eventration is abnormal focal elevation or bulging of part of the hemidiaphragm ( Fig 8), often with associated thinning, primarily affecting the anteromedial aspect of the right hemidiaphragm. Diaphragmatic eventration is most often congenital and asymptomatic ( 1). In contrast, diaphragmatic paralysis is abnormal weakness and elevation of the entire hemidiaphragm (either one or both, depending on the cause). Diaphragmatic paralysis is often acquired and symptomatic ( Fig S2) ( 1, 21). When weakness is unilateral, patients can be asymptomatic, with diaphragmatic elevation found incidentally at imaging. However, when weakness is severe or bilateral, patients generally present with respiratory distress requiring significant accessory muscle use or respiratory failure ( 1, 21). Causes are congenital or acquired pathologic conditions that yield phrenic nerve damage or diaphragmatic muscle atrophy. The wide differential diagnosis that affects the neuromuscular axis includes trauma (eg, spinal cord injury), degenerative conditions (eg, cervical spondylosis), neurologic diseases (eg, amyotrophic lateral sclerosis), infection (eg, herpes zoster, neurosyphilis), autoimmune disorders (eg, Guillain-Barré syndrome, myasthenia gravis), thermal damage (eg, cold cardioplegia in cardiac surgery), aggressive tumors, myopathies (eg, muscular dystrophy), metabolic disease (eg, diabetes), and iatrogenic conditions (eg, thoracic surgery, radiation therapy) ( Fig S3) ( 1, 21, 22). Eventration and paralysis can generally be identified and differentiated at chest radiography and CT. Eventration is focal elevation or bulging of the hemidiaphragm without focal discontinuity of the diaphragm. There may be a sharp transition to the elevated segment, which can appear mushroom shaped ( 1). In contrast, weakness or paralysis results in elevation of the whole hemidiaphragm, again without focal discontinuity. For diaphragmatic weakness or paralysis, particular attention should be paid to the posterior costophrenic sulcus, which can be at a more narrow acute angle. Alternatively, it can appear elevated and somewhat flattened ( 21). In comparison, eventration is focal and more commonly affects the anterior aspect of the diaphragm, so these changes in the posterior costophrenic sulcus are often not seen. Chest CT is typically used to identify the underlying pathologic condition, differentiate eventration from paralysis, and ensure that no focal discontinuity of the diaphragm is present ( 21). Differential diagnoses include hernia, masses, elevated diaphragm secondary to increased intra-abdominal pressures (eg, ascites, organomegaly), or diaphragmatic elevation secondary to pulmonary volume loss (eg, atelectasis) ( 1, 22). For both diaphragmatic eventration and paralysis, depending on the severity, pulmonary function tests may reveal a restrictive pattern ( 1, 22). The diagnosis can be supported by the fluoroscopic sniff test ( Movie 1), where the affected portion of the diaphragm either fails to lower with normal excursion or elevates during inspiration with paradoxical motion ( Movie 2). US ( Movie 3) reveals decreased movement, or even paradoxical movement, and lack of associated thickness change of the affected portion during respiration ( Fig S2) ( Movie 4) ( 1). Management depends on the cause and severity of the disease. Most cases of unilateral weakness, in particular those that are viral or postviral, resolve spontaneously. Along with treating the underlying cause where possible, supportive measures with supplemental oxygen or ventilatory support and pulmonary rehabilitation can be used. In severe cases, surgical plication to reposition the diaphragm and phrenic nerve stimulation may be considered ( 1, 21). Thoracoabdominal Fistulas Thoracoabdominal fistulas are abnormal connections between the abdominal and chest cavities through the diaphragm. Fistulas may be acquired with infection, trauma, or neoplasm; be iatrogenic from surgery; or be congenital. Thoracoabdominal fistulas can be divided into hepatothoracic, pancreaticothoracic, and enterothoracic fistulas and others, such as nephrothoracic fistulas ( 29). Along with clinical suspicion and laboratory findings (eg, pleural fluid analysis), diagnosis of thoracoabdominal fistulas is made with cross-sectional imaging (primarily CT and MRI), aided by other modalities such as scintigraphy and endoscopic retrograde cholangiopancreatography (ERCP) ( 2, 29, 30). Hepatothoracic Fistula.—Hepatothoracic fistulas are abnormal communications between the liver or biliary tree and the thorax across the diaphragm. Types of hepatothoracic fistulas include hepatopleural ( Fig 12), hepatopulmonary, biliopleural, and biliobronchial ( Fig 13) ( 30). These diseases are most commonly right sided, involving the susceptible bare area of the liver ( 2). Causes include tumors, biliary obstruction, hepatic hydatid infection or abscess ( Fig 14), blunt or penetrating trauma, iatrogenic from procedures or radiation therapy, and congenital ( 31, 32). As such, hepatothoracic fistulas have variable manifestations reflecting the underlying pathologic condition, which may involve respiratory symptoms, fever, signs of biliary obstruction, abdominal pain, or chest pain. Bilioptysis is highly suspicious for bronchobiliary disease ( 31). Chest radiography may show right-sided pleural effusion, atelectasis, and consolidation ( 32). Direct visualization of fistulas with CT is challenging. However, indirect signs including pleural effusion, fluid collection, and diaphragmatic interruption can be seen ( 33– 35). Contrast-enhanced MR cholangiography showing leakage of hepatobiliary contrast material into the thoracic space confirms the diagnosis ( 33). Similarly, transdiaphragmatic migration of radiotracer from the liver into the thorax at hepatobiliary scintigraphy is diagnostic ( 34, 35). Management of the fistula depends on the underlying cause, in addition to closing of the diaphragmatic defect. Infectious abscesses require drainage and antimicrobial therapy. In the setting of trauma, surgical resection and repair are likely needed. Obstructions can be treated with biliary drainage, ERCP sphincterotomy, or stent placement. Treatment of a neoplasm will depend on the type, stage, and grade of the tumor ( 31, 32). Pancreaticothoracic Fistula.—Pancreaticothoracic fistulas are abnormal communications between the pancreas and thorax across the diaphragm. These include pancreaticopleural ( Fig 15), pancreaticomediastinal, pancreaticobronchial, and pancreaticopericardial fistulas ( 36, 37). These are rare complications of chronic pancreatitis and less commonly of acute pancreatitis, pseudocyst drainage, surgery (eg, pancreatic resection), and trauma ( 29). Variable manifestations include dyspnea, chest pain, abdominal pain, and fever ( 36, 38). If the pericardium is involved, patients are at risk for cardiac tamponade ( 36). CT can reveal pericardial effusions (predominantly left sided), mediastinal effusions, pericardial fluid collections, and pulmonary opacities in addition to evidence of acute or chronic pancreatitis ( 37– 39). MR cholangiopancreatography can confirm CT findings with higher sensitivity and specificity ( 38), while ERCP is used to directly visualize and manage the fistula ( 36, 38). Elevated amylase or lipase level in pleural or pericardial fluid confirms the diagnosis ( 36– 38). In addition to initial stabilization and supportive care, effusions and pseudocysts should be drained. Fistulas are often endoscopically managed with stent placement or sphincterotomy. Octreotide may be added for exocrine suppression. When endoscopic management is not possible or fails, operative management may be required ( 36, 39). Gastrothoracic Fistula.—Gastrothoracic fistulas are abnormal communications between the stomach and thorax across the diaphragm caused by trauma, herniation, or neoplasm or as a rare complication of gastric surgery ( 40, 41). These include gastropleural, gastropulmonary ( Fig 16), gastrobronchial, and gastropericardial ( Fig 17) fistulas ( 40, 42, 43). Patients present with dyspnea, cough, recurrent pneumonia, fever, hemoptysis, chest pain, or abdominal pain ( 42). Chest radiography often shows pleural effusion. When the pericardium is involved, pneumopericardium, hydropneumopericardium, and thickened pericardium can be seen ( 40). Leakage of oral contrast material into the thoracic space at fluoroscopy confirms the fistula, which may be directly visualized with upper endoscopy ( 40– 42). CT shows pleural effusions, complex fluid collections, diaphragmatic discontinuity, and air- or fluid-filled fistulous tracts ( 40– 43). Management includes supportive care, endoscopic treatment (with stent placement, closure, and argon ablation), or direct surgical repair ( 42, 44). Colothoracic Fistula.—Colothoracic fistulas are abnormal communications between the colon and thorax. These include colopleural ( Fig 18), colobronchial, and colopericardial fistulas ( 45– 47). More common causes include Crohn disease, postoperative adhesions, pulmonary infection, diaphragmatic hernia, trauma, and malignancy ( 45, 46). Productive cough with foul-smelling sputum is indicative of a colobronchial fistula, alongside constitutional symptoms, chest pain, and dyspnea ( 45). Bowel changes and gastrointestinal bleeding can be associated. Chest radiography may reveal pneumopericardium, cardiomegaly, pleural effusions, or consolidation ( 46, 47), depending on the cause. CT offers the additional benefits of allowing visualization of gas tracking into the thorax from the colon and leakage of enteric contrast material ( 46). The diagnosis can be confirmed by detecting leakage of enteric contrast material into the thoracic space ( 45). Alongside supportive care and nutritional support, these fistulas are generally managed surgically with fistula resection and diaphragm repair ( 45).