Spontaneous pneumo-mediastinum - A benign rarity

Background: Spontaneous pneumo-mediastinum (SPM) is defined as the spontaneous occurrence of free gas in the mediastinum. Although SPM is rare, this is a unique differential cause for pneumo-mediastinum. It bears a benign clinical course with good clinical outcome, unlike others potentially life threatening causes of pneumo-mediastinum, such as oesophageal perforation and necrotizing mediastinitis. Methods and Results: A retrospective study about SPM was conducted in the Department of Surgery, Tuen Mun Hospital, HKSAR. SPM cases were retrieved through hospital's electronic records from 7/2000 to 6/2020. Patients' demographic data, clinical presentation, management and outcomes were reviewed. One hundred five SPM patients were retrieved with mean age 21.3 (0-68). More than 85% (91 cases) of them were younger age group (younger than the age of 30). Eighty-seven cases (82.9%) were male while 18 cases (17.1%) were female. The top 3 presentation symptoms were: chest pain (69 cases, 65.7%), neck pain (43 cases, 41%) and sore throat (42 cases, 40%). Physical examination revealed surgical emphysema in 63 patients (60%). 61 (58.1%) patients enjoyed good past health and without any potential predisposing factors. Common precipitating factors included: vigorous cough (28 cases, 26.7%), vigorous exercise (16 cases, 15.2%), sneezing (15 cases, 14.3%) and vomiting/retching (14 cases, 13.3%). CXR showed pneumo-mediastinum in 98 cases (93.3%). Additional investigations, such as CT neck/thorax/abdomen with contrast (63 cases, 60%) and oesophago-gastro-duodenoscopy (OGD) (29 cases, 27.6%), were performed to rule out other differential diagnosis in suspicious cases. All the SPM patients were treated conservatively (e.g. bed rest, analgesics, antibiotics, oxygen supplement). None of them required operative treatment with recurrence rate 0%. Average length of hospital stay was 4.1 days (1-35 days). Two out of 105 cases (1.9%) resulted in hospital mortality due to other underlying medical illnesses. Conclusion: SPM is an uncommon disease, mainly affecting the younger age group. Although SPM carries a benign and good clinical outcome, it is essential to exclude other potential life threatening conditions with similar presentations.