We report our experience with four patients presenting with spontaneous pneumomediastinum (SPM) within a 3-month period. The patients (three male and one female, aged 15–17 years) were hospitalised with SPM. All patients were kept under observation, successfully treated and followed up for several years, with no recurrences reported. Two patients had histories of asthma, while the other two developed SPM during sporting activities. SPM carries the possibility of being latent. For symptoms such as chest pain without evidence of pneumothorax in young people, it is necessary to always consider SPM and make the diagnosis accordingly.
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Spontaneous pneumomediastinum (SPM) is defined as the migration of air into the mediastinum without apparent cause.1 However, many cases are not spontaneous and are caused by increased intra-alveolar pressure (coughing, vomiting or sporting activities). It is a rare disease and usually affects healthy young people. We experienced four SPM cases within a short period of 3 months. Therefore, we assume that this disease is latent in everyday life.
We experienced four cases (three males and one female) of SPM in Gunma Prefecture Saiseikai-Maebashi Hospital over a short period of 3 months. None had a history involving trauma or surgical or therapeutic problems, and all were previously healthy individuals. The patients were 17 years or younger (age range, 15–17). Two of the patients had a history of asthma, one presenting with a history of coughing just prior to the onset of symptoms. In the other two cases, SPM occurred during sporting activities (running and heading the ball while playing soccer).
SPM was diagnosed in all patients by neck x-ray and/or CT. The presence of Hamman's sign (crackling heard on chest auscultation) was considered for clinical examination. We examined body temperature and inflammatory reaction (white blood cell count) at the time of hospitalisation.
The patients were kept under observation, and all recovered in 4–5 days without any complications. Follow-up was maintained for 3 years in all the patients, and there were no relapses. A predisposing factor was bronchial asthma in two patients. The chief complaints were neck and chest pain in three patients, and dyspnoea and discomfort in the chest in one patient. x-Rays of the neck and chest showed mediastinal emphysema, with air extending to the tissues of the neck (figure 1). In all the patients, the air pocket extended between the trachea and cervical vertebrae. CT was performed on three patients, confirming the diagnosis of SPM. Hamman's sign was not recorded. On admission, no patient demonstrated decrease in the oxygen saturation level, and no inflammatory condition such as a fever was observed. There were no abnormal findings on electrocardiography. Although an oesophageal study with a water-soluble contrast material was conducted in one patient to rule out oesophageal perforation, there were no abnormal findings.
SPM is defined as the presence of free air in the mediastinum with no apparent cause, and the mechanism of occurrence has been detailed by Macklin.2 In short, alveolar pressure increases and air enters the pulmonary interstitial spaces, followed by spread along the pulmonary perivascular sheets and then to the mediastinum. Air enlarges into the retropharyngeal and subcutaneous spaces of the neck, along the layers of the deep cervical fascia, which is the case in 40–70% of patients.3–6 SPM resulting from trauma, physical exertion or vocal exercise should not be included among idiopathic cases. The most frequent triggers in children are asthma,3 ,4 infection, diabetic ketoacidosis,7 vomiting and ingestion of the drug ‘Ecstasy’.8 Some reports have described occurrences in relation to sporting activity, with scuba diving and soccer being the two most commonly encountered predisposing sporting activities.9 By pure definition, our patient who developed SPM just after heading the ball while playing soccer might not be considered an idiopathic case. One patient showed symptoms of SPM while running. Although the other two patients had histories of asthma, there was no asthmatic episode at the time of development of SPM symptoms. Since the structure of the mediastinum of a young person is not complete anatomically, such individuals may tend to show symptoms of SPM when engaged in a light sport such as running. In our study, all four patients suddenly showed symptoms of SPM during activities of everyday life.
In general, the incidence of SPM ranges from 1 in 320 to 1 in 42 000 patients,1 ,4 ,5 ,10 and it is a relatively rare disorder. Our experiences of SPM were distinctive in that they occurred within a very short period of 3 months. SPM developing into a more serious condition is, fortunately, also rare, and chest pain in young people is often the result of pneumothrax or cardiac disease. Therefore, SPM is not often diagnosed. The most common clinical findings are the presence of interstitial emphysema and Hamman's sign auscultated synchronously with cardiac systole.8 ,10 In all four patients, there was no evidence of Hamman's sign, and all recovered in 4–5 days. Therefore, SPM may be latent in everyday life.
In conclusion, when young people complain of neck and chest pain and/or dyspnoea, particularly with a history of bronchial asthma, clinicians should be conscious of SPM as well as pneumothrax or cardiac disease. x-Ray of the neck is an easy and effective procedure to diagnose SPM. In addition, if CT is performed, the progressive extent of SPM can be diagnosed. Patients should be observed for several days thereafter.
Spontaneous pneumomediastinum (SPM) carries the possibility of being latent.
For symptoms, such as chest pain without evidence of pneumothorax in young people, it is necessary to always consider SPM.
All patients are kept under observation, and are successfully treated.
Competing interests None.
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