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The mediastinum--is it wide?

The 8 cm upper limit for normal mediastinal width, set in the 1970s does not apply in the modern trauma room. Changes in the position of the x ray cassette, and lengthening of the distance between the patient and the x ray source will significantly reduce magnification. A new range of upper limits is defined for the radiographical techniques possible in different trauma settings.

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 The emergency management of mediastinal masses

The mediastinum is the segment of the thorax that includes structures vital to life – the heart, major blood vessels, and the airway. The way we understand mediastinal anatomy has recently changed, dividing it into three compartments based on location: pre-vascular, visceral and paravertebral.

Articles of Interest

Can a chest X-ray (X-ray) visualize the mediastinum?

A chest X-ray can visualize the mediastinum, but with significant limitations, and is not the preferred method for detailed evaluation of mediastinal structures, as CT scans or MRI offer superior contrast resolution and better visualization of specific mediastinal components

Mediastinal Masses - differential diagnosis

This review will focus on how to narrow down the differential diagnosis of mediastinal lesions by localizing and characterizing them.

The Mediastinum Anatomy

The chest cavity: the cavity that extends upward about one fingerbreadth through the root of the neck above the clavicle, and downward to the diaphragm, It’s surrounded by the chest wall on each side, the thoracic vertebrae posteriorly and the sternum and manubrium anteriorly.

A Modern Definition of Mediastinal Compartments

Division of the mediastinum into compartments is used to help narrow the differential diagnosis of newly detected mediastinal masses, to assist in planning biopsy and surgical procedures, and to facilitate communication among clinicians of multiple disciplines. Several traditional mediastinal division schemes exist based upon arbitrary landmarks on the lateral chest radiograph.

A Widened Mediastinum

Acute descending necrotizing mediastinitis, a variant of acute mediastinitis, is a rare but life-threatening infection originating in the oropharynx and characterized by rapid tissue destruction in the mediastinum. Oropharyngeal infections (such as odontogenic infection, Ludwig's angina and retropharyngeal abscess) can occasionally descend to the mediastinum. The descent of the infection from the oropharynx to the mediastinum is enhanced by gravity and negative intrathoracic pressure.

Disorders of the Mediastinum

Computed tomography (CT) scanning is the most valuable imaging technique for evaluating mediastinal masses and is the only imaging technique that should be done in most instances. Barium studies of the gastrointestinal tract are indicated in many patients with posterior mediastinal lesions, becauseg hernias, diverticula, and achalasia are readily diagnosed in this manner.

Mediastinal Trauma

The mediastinum is contained within the thoracic cavity and has a high concentration of major vascular and visceral structures. Traumatic injury to any of these can be immediately life-threatening. The majority of patients with thoracic trauma are treated conservatively without surgical intervention, but a high index of suspicion should be maintained for patients with a potential mediastinal injury.

Mediastinitis

Mediastinitis is an infection of the mediastinum; a rapidly fatal surgical emergency if not recognized and treated early. Causes include esophageal perforation, oropharyngeal infections (e.g., Ludwig’s angina), prevertebral or carotid space infections, and iatrogenically (endoscopy, hypopharyngeal perforations during intubation, etc.).

Mediastinum Disease

Mediastinum disease refers to a range of benign and malignant conditions that occur within the mediastinum, the central compartment of the thoracic cavity. Effective management typically necessitates a multidisciplinary approach and relies on various diagnostic imaging techniques to guide treatment.

Mediastinum: The Mediastinum

The mediastinum is the central space of the thorax located between the two pleuropulmonary cavities to the right and left, the cervicothoracic inlet above, and the interdiaphragmatic thoracoabdominal outlet inferiorly. It contains the heart and great vessels, the thymus, the esophagus, the trachea and main bronchi, lymph nodes, and mediastinal pleural reflections, as well as the vagus and phrenic nerves.

Pneumomediastinum

The most common cause of pneumomediastinum is a small rupture in an alveolus, which causes air to leak out of the alveolus and into the pulmonary interstitium (the connective tissue within the lung). This rupture often functions as a one-way valve, allowing air to leak out of the alveolus without allowing air back into the alveolus. Each breath may cause a tiny amount of air to enter the lung interstitium. Over time, air accumulates within the pulmonary interstitium.

Significance of Mediastinum

The mediastinum refers to the central compartment of the thoracic cavity, located between the lungs and containing vital structures such as the heart and trachea. It serves as a separator of the right and left lungs and is described as a space in the chest that houses essential organs. Additionally, in medical imaging, conditions such as masses may infiltrate this area, highlighting its significance in thoracic anatomy and health.

Surgical access to the mediastinum—all roads lead to Rome: a literature review

The mediastinum is a complex, heterogeneous area, which leads vertically across the thoracic cavity between the bilateral mediastinal pleurae, connecting the head and neck region with the thoracic cavity. Different classifications have been published to differentiate between the so-called mediastinal compartments while the most used classification surely is the 4-compartments Gray`s classification, dividing it into the superior, anterior, middle and posterior mediastinum.

The mediastinum

The number of patients suffering from lung diseases is increasing worldwide. Lung cancer, for example, is now one of the most common cancers. Many of these diseases having mediastinal lymph node involvement. Accurate diagnosis or possible staging of the mediastinum is important not only to determine the prognosis but to decide the most suitable treatment plan. CT, MRI, PET and PET-CT are used for noninvasive imaging of the mediastinum.

The Mediastinum, Its Compartments, and the Mediastinal Lymph Nodes

The mediastinum is defined as the thoracic space that lies between the two pleural cavities. It extends from the thoracic inlet cephalad to the superior surface of the diaphragm caudad. It is bounded by the undersurface of the sternum ventrally and the anterior longitudinal spinal ligament dorsally. The paravertebral areas (the costovertebral sulci) situated bilaterally are not truly within the mediastinum, but lesions arising within these regions are classically defined in medical literature as mediastinal in origin.

Widened mediastinum at elderly: a challenge in the emergency room (ER)

The first consideration when a widened mediastinum is noted on x-ray is the quality of the chest film as poor technique can cause this presentation. An AP chest x-ray, typically obtained as a portable chest x-ray, is taken at a closer distance and therefore also reveals larger and less sharp structures. Patient positioning also plays an important role.2 If the patient is rotated or slouched, the mediastinum may appear falsely widened. After you have ensured the processing of an adequate film, the second consideration is to compare the chest x-ray to prior studies, if available. The most significant life-threatening concern associated with a wide mediastinum is an acute aortic rupture or aortic dissection.

Widened Mediastinum on Chest X-Ray as an Indicator of Mediastinal Injuries: A Relic of the Past?

This large retrospective comparison of CXR to CT thorax findings in our trauma patients found that mediastinal injury was a rare entity that did not commonly manifest as widened mediastinum on CXR. There were also some patients who appeared to have widened mediastinum on CXR but did not have any injuries seen on CT thorax. We therefore recommend that while CXR has an invaluable role in the detection of bony or pulmonary injuries, widened mediastinum does not appear to play a major role in the decision process of whether a CT thorax is necessary.

Resources

Fiveable

The mediastinum acts as a passageway for important structures, allowing them to travel between the thoracic inlet and diaphragm.

Neupsy Key

Imaging plays an important role in detecting and characterizing mediastinal masses in order to optimally direct patient management. Thus, a practical and systematic imaging approach is important. This chapter begins with a description of the embryological development and radiologic anatomy of the mediastinum. For standardization, the CT-based compartment scheme for the mediastinum that was introduced by the International Thymic Malignancy Interest Group (ITMIG) is utilized in this chapter.1,2 Various currently available imaging techniques for the evaluation of mediastinal lesions are presented, along with suggestions for a practical approach to imaging. The wide spectrum of nonvascular and vascular lesions is discussed, with descriptions of typical imaging manifestations and current management considerations pertaining to relevant disorders in the pediatric population.

Radiology Key

The intrathoracic compartment, which is situated between the sternum anteriorly and the vertebral column posteriorly and is bounded laterally by the parietal pleura, is considered the mediastinum. The thoracic inlet and the diaphragm form the superior and inferior boundaries, respectively. In humans, the mediastinum completely separates the left and right pleural spaces. The mediastinum contains several fundamental structural components including soft tissues, vessels, and nerves. A wide variety of congenital and developmental anomalies, inflammatory and infectious diseases, and benign and malignant neoplasms can affect these structural components in pediatric patients. An up-to-date knowledge of the practical diagnostic approach combined with a clear understanding of the characteristic imaging appearances of these conditions can lead to optimal patient management.

Radiopaedia

The mediastinum is a space in the thorax that contains a group of organs, vessels, nerves, lymphatics and their surrounding connective tissue. It lies in the midline of the chest between the pleura of each lung and extends anterior to posterior from the sternum to the vertebral column and superior to inferior from the superior thoracic aperture to the diaphragm.

StatPearls

The thoracic mediastinum is the compartment that runs the length of the thoracic cavity between the pleural sacs of the lungs. This compartment extends longitudinally from the thoracic inlet to the superior surface of the diaphragm. Although there are no physical barriers between compartments other than the pericardium, the mediastinum is typically discussed based on subdivisions.