2032 HISTORY: A 15-year-old competitive swimmer presented to Mayo Clinic with a 24-hour history of sub-sternal chest pain with deep inspiration, associated with anterior neck pain. Onset was during the previous day's training session. The patient was swimming underwater three consecutive 25-meter pool lengths, emerging to take very short breaths, then resuming the described swimming exercise. He developed chest discomfort sub-sternally, and soon thereafter developed neck discomfort. He described this as fullness, as well as a sharp pain in the tracheal region. He had pain with flexion and rotation of the neck. With deep inspiration, he would have a dull sub-sternal ache. Within several hours, his voice changed to a higher pitch. Associated symptoms included mild anxiousness, but he denied shortness of breath. No prior episodes. PHYSICAL EXAM: Examination of the neck revealed pain anteriorly with rotation, flexion and extension. Palpation revealed crepitus in the thyroid region tracking along the trachea. Examination of the heart revealed regular rate and rhythm. No gallops, rubs or murmurs. Examination of the chest revealed no subcutaneous emphysema. Lungs were clear to auscultation bilaterally. However, at the posterior apices, there was a faint popping sound, which cleared. No wheezes were noted. DIFFERENTIAL DIAGNOSIS: Pneumomediastinum Pneumothorax Pneumopericardium Upper respiratory infection Reactive airway/allergic reaction Cervical injury Myocardial infarction/cardiac disease Gastroesophageal Reflux Disease Esophageal Spasm TEST AND RESULTS: Chest x-ray: spontaneous pneumomediastinum with subcutaneous emphysema of the soft tissues in the neck. No pneumothorax or acute changes in the lung fields. Heart size was normal. Neck x-rays: showed deep cervical soft tissue emphysema. Chest CT scan four days after initial chest x-ray: remarkable only for very subtle evidence of residual free air. FINAL/WORKING DIAGNOSIS: Spontaneous pneumomediastinum, with secondary anterior neck subcutaneous emphysema, from extreme breath-holding technique. TREATMENT AND OUTCOMES: Refrain from athletic activities until symptoms of chest discomfort resolve. Repeat chest x-rays must appear normal prior to resumption of swimming. Chest x-ray sequence on day one and day five revealed Saturday pneumomediastinum rapidly resolving. Parallel clinical course. Patient returned successfully to competitive swimming in ten days. Instructed to refrain from utilization of above breathing maneuver. No known recurrence to date.