Patient history: A 40-year-old male with a history of anorexia, depression, and recent weight loss presents for a general medical evaluation prompted by his concerned father. A computed tomography (CT) scan of his chest shows a moderate amount of pneumomediastinum (PM) extending superiorly into the tissues of the neck. He also has a moderate-size pericardial effusion. The patient denies symptoms of chest pain, shortness of breath, nausea, vomiting, or recreational drug use. Specifically, the patient admits to a depressed mood, but denies any vomiting, retching, or auto-destructive behavior. He has no history or evidence of underlying pulmonary disease.
Figure 1: Paratracheal air
Other notable findings consistent with the patient’s eating disorder are a body mass index (BMI) of 15, leukopenia, hyponatremia, bradycardia, and low blood pressure. A subsequent gastrograffin esophagram shows no obvious leaks or abnormalities. The patient is admitted to the hospital, allowed nothing by mouth, and placed on intravenous piperacillin and tazobactam, and nutrition. A transthoracic echocardiogram to evaluate the pericardial effusion on the first hospital day shows early tamponade physiology. Repeat evaluation two days later shows mild right atrial collapse but no evidence of hemodynamic compromise. Inpatient psychiatry consultation is obtained regarding his depression and eating disorder. On the fifth hospital day, a repeat CT scan shows moderate improvement of the PM. The patient is discharged home with outpatient follow-up.
Discussion: PM is defined as free air or gas in the mediastinum and is an uncommon finding. The etiology is usually from the airway, esophagus, or external trauma/surgery. Spontaneous PM occurs in the absence of an apparent identifiable cause and can exist in isolation or in conjunction with pneumothorax and soft-tissue emphysema. Elevated intraalveolar pressures related to mechanical ventilation or activities involving Valsalva maneuvers, along with pre-existing lung disease, account for the majority of pulmonary-related PM.1 Esophageal tear or rupture is another, less common cause of PM. Several case reports of PM in patients with anorexia nervosa exist, and some experts have postulated that one possible mechanism is vomiting or some other auto-destructive behavior.2-4 Loss of pulmonary connective tissue related to prolonged starvation leading to spontaneous pneumothorax and PM has also been postulated using rat models.5
Figure 2: Pericardial effusion
The most common symptoms associated with PM are chest pain, voice change, and cough. In rare cases, PM can lead to decreased cardiac output. Common triggers of spontaneous PM, such as cough, physical exercise, and drug abuse, have been reported. A high percentage of patients with spontaneous PM have underlying pulmonary disease, including asthma and COPD.1 PM in conjunction with Boerhaave’s syndrome may have a mortality rate as high as 50% to 70%. In patients with anorexia nervosa, PM is often seen in conjunction with other advanced findings, including pancytopenia, electrolyte disturbances, bradycardia, and hypotension.
The age and gender of the patient are atypical for anorexia nervosa, although he does indeed have a restrictive eating disorder. The PM and pericardial effusion are additive unique findings that likely relate to his malnourished state and possible auto-destructive behavior.
Management: Spontaneous PM has been managed in a variety of ways, ranging from outpatient radiographic follow-up to close, inpatient monitoring. Identifying the etiology and monitoring for further progression or complications is important. For patients in whom esophageal tear or microperforation is suspected, early surgical consultation is recommended. An acceptable algorithm for patients with suspected esophageal perforation after endoscopy is to begin with a contrast CT scan of the neck and chest with oral contrast or to use a water-soluble contrast (gastrograffin) esophagram followed by a barium swallow if the water-soluble study is negative.6,7 When imaging reveals no leakage, the PM can be followed radiographically—typically after 48 hours and thereafter slowly advancing the diet. TH