Pneumomediastinum Revisited

Abstract

Pneumomediastinum may result from a variety of causes that may be either intrathoracic (eg, narrowed or plugged airway, straining against a closed glottis, blunt chest trauma, alveolar rupture) or extrathoracic (eg, sinus fracture, iatrogenic manipulation in dental extraction, perforation of a hollow viscus [corrected]. The radiographic signs of pneumomediastinum depend on the depiction of normal anatomic structures that are outlined by the air as it leaves the mediastinum. These signs include the thymic sail sign, "ring around the artery" sign, tubular artery sign, double bronchial wall sign, continuous diaphragm sign, and extrapleural sign. In distal esophageal rupture, air may migrate from the mediastinum into the pulmonary ligament. Pneumomediastinum may be difficult to differentiate from medial pneumothorax and pneumopericardium. Occasionally, normal anatomic structures (eg, major fissure, anterior junction line) may simulate air within the mediastinum. Iatrogenic entities that may simulate pneumomediastinum include helium in the balloon of an intraaortic assist device. In addition, pneumomediastinum may be simulated by the Mach band effect, which manifests as a region of lucency adjacent to structures with convex borders. The absence of an opaque line, which is typically seen in pneumomediastinum, can aid in differentiation. Computed tomographic (CT) digital radiography and conventional CT can also be helpful in establishing or confirming the diagnosis.

Neumomediastino espontáneo (síndrome de Hamman): Una enfermedad benigna mal diagnosticada

“…Los signos que se evidencian son la presencia de aire separando estructuras mediastínicas o rodeándolas, el enfisema subcutáneo y el aire subesternal (Tabla 4) 37 . La TC de tórax se ha demostrado superior a la Rx de tórax, tanto en el diagnóstico, localización y extensión, como en el diagnóstico diferencial 38 .…”

Pneumomediastinum and Cervical Soft Tissue Emphysema as an Important Vital Sign in Hanging: An Autopsy Based Prospective Study

“…There is subsequent dissection of air along the visceral spaces around trachea, bronchi, oesophagus and large vessels in the mediastinum and further up in the neck into superficial and/or deep soft tissues. This is the well accepted mechanism at present, also known as Macklin effect [10]. A pressure gradient is formed between the site of alveolar rupture and obstruction zone in the neck, leading to the formation and dissection of air bubbles in the mediastinal and neck soft tissues.…”

“…The proposed mechanism for this finding includes either direct or indirect trauma to the cervical airways because of ligature pressure and stretching, or rupture of terminal alveoli caused by elevated intra-thoracic pressure with subsequent dissection of air in the mediastinal and cervical soft tissues around visceral structures [8,9] . The latter mechanism is known as Macklin effect [10]. The aim of this study was to determine the frequency of pneumomediastinum and CSTE at autopsy in cases of deaths due to hanging.…”

Spontaneous Pneumomediastinum. Case report

“…Hay que tener en mente la 'banda de Mach' , que es un efecto óptico que consiste en la percepción de una banda en la zona de transición entre una banda luminosa o blanca y una oscura o negra por inhibición lateral de la retina; este efecto psicofisiológico de realce de los bordes puede simular un neumomediastino en determinado momento, para lo cual hay que buscar otros signos asociados. (1,15,16) Nuestro paciente se realiza una tomografía computarizada (TC), de tórax,en la que se constata el neumomediastino, la TC es la modalidad diagnóstica de elección, ya que es considerada el gold estándar, por su sensibilidad cercana al 100 %. (1,17,18) Cerca del 30% de los casos de neumomediastino no se visualizan en los estudios de radiología simple y solo pueden ser diagnosticados con una TC, por otra parte, la extensión del proceso generalmente es subestimada en los estudios de radiología convencional.…”