Mediastinal emphysema syndrome: a proposed etiopathogenetic classification and current diagnostic and therapeutic approaches

This review summarizes domestic and international published data on the etiology, pathogenesis, diagnosis, and management of mediastinal emphysema syndrome. Pneumomediastinum—the presence of air or other gas in the mediastinal tissue—is both a pathological condition and a radiological finding, identified through physical and/or radiological examination of the chest organs. It is currently classified as either spontaneous (occurring without apparent external triggers) or secondary (associated with identifiable provoking factors). However, several authors have questioned the accuracy of these terms and called for a revised classification. This article traces the history of our understanding of this condition, from its earliest descriptions in the 17th century to experimental studies in the mid-20th century. We review a wide range of triggers and etiological factors (biological, mechanical, inflammatory, toxic, and thermal) reported in the global literature. Particular attention is given to the clinical presentation and diagnosis of both spontaneous and secondary pneumomediastinum using various physical, laboratory and instrumental—primarily imaging—examination methods. The opinions of various authors on the diagnostic algorithm and treatment strategy are presented, depending on the suspected cause of gas syndrome, with the use of both conservative therapy and a range of surgical techniques, from subcutaneous insertion of large-bore needles to sternotomy. Potential complications, mortality, and recurrence rates were also reviewed. Based on our literature review and clinical experience, we propose an original etiopathogenetic classification rooted in the concept of trauma—either pulmonary barotrauma or external injury—precipitated by various etiological factors. We illustrate the practical utility of this classification through our own clinical cases, demonstrating how it can guide a rational diagnostic and treatment algorithm in patients with pneumomediastinum. Importantly, our proposed framework abandons the terms “primary” and “secondary” pneumomediastinum, as well as labels such as “spontaneous,” “idiopathic,” “iatrogenic,” “non-iatrogenic,” and “non-traumatic.”