Spontaneous pneumomediastinum is an uncommon problem which is rarely recurrent. The etiology is idiopathic in most patients. This case illustrates an unusual cause of this problem that may merit consideration in these patients.
A 28-year-old woman presented to the emergency room with acute “puffiness” of her neck and face which appeared after she fell and struck her neck against her car. She reported multiple prior episodes of pneumomediastinum and subcutaneous emphysema which were typically preceded by minor trauma, paroxysms of coughing or hiccups. Her past surgical history was non-contributory. She was a lifelong non-smoker but had a history of opiate abuse. On examination the patient had puffiness and palpable crepitus in the chest, neck and face. The remainder of her physical examination was unremarkable. A chest radiograph showed subcutaneous air and pneunomediastinum without a coexisting pneumothorax. No pulmonary parenchymal pathology was noted. Shortly after admission the patient developed bradycardia. Subsequent computed tomography (CT) imaging confirmed the soft tissue emphysema and pneumomediastinum. The CT images also demonstrated a distal tracheal diverticulum and air dissecting along both carotid arteries –the presumed cause of her bradycardia. An esophagogram showed no contrast leakage. After stabilization in the ICU, the patient was referred for thoracic surgery evaluation. A preoperative fiber-optic bronchoscopy (FOB) revealed multiple, dynamic diverticulae of varying sizes protruding from the distal tracheal and proximal mainstem bronchial walls. Several large, well-defined diverticulae were obliterated using cautery and fibrin glue with good short-term results.
Pneumomediastinum –defined as air in the mediastinum –usually occurs secondary to leakage of air into the mediastinal cavity due to a traumatic injury to the chest wall, airway or esophagus. Such trauma may be iatrogenic (thoracic surgery, chest tube placement, dental procedures, tracheostomy placement). While pneumomediastinum may also occur with pulmonary diseases (necrotizing pneumonia, obstructive lung disease, malignancy), pneumothorax is usually seen in such cases. Less often, pneumomediastinum may occur in the absence of a predisposing condition: in this case it is referred to as “spontaneous” pneumomediastinum. Spontaneous pneumomediastinum is considered a relatively benign condition and needs to be differentiated from secondary pneumomediastinum which is often associated with a grave prognosis. The diagnosis of spontaneous pneumomediastinum rests on ruling out causes of secondary pneumomediastinum like esophageal perforation, pleuropulmonary diseases or trauma. Evaluation includes a detailed history, physical examination, chest radiography and a contrast esophagogram (barium swallow). A significant number of patients with spontaneous pneumomediastinum have a history of asthma, cough or emesis. This suggests a role for increased intrathoracic pressure in the pathogenesis of spontaneous pneumomediastinum. Such patients most likely have an unknown anatomic defect that, in the presence of increased intrathoracic pressure, leads to the formation of pneumomediastinum. Tracheobronchial diverticular disease, as illustrated by this case, may be one such possible abnormality. CT scans of the chest and neck coupled with routine FOB may identify such cases of tracheal diverticulae. As illustrated by this case tracheal reconstruction or snare resection of diverticulae should be considered in patients with recurrent disease or in those who develop life-threatening complications.
Tracheal diverticulae may constitute an under-recognized cause of secondary pneumomediastinum and should be evaluated in patients with “spontaneous” pneumomediastinum.
Manu Kaushik, No Financial Disclosure Information; No Product/Research Disclosure Information