BACKGROUND: Pneumocephalus occurs as a result of traumatic or iatrogenic violation of the dura. Tension pneumocephalus, whereby air continues to accumulate with no mechanism for escape, can cause significant morbidity and mortality. METHODS: This case report reviews the underlying pathophysiology, clinical presentation, diagnosis, and management of tension pneumocephalus. RESULTS: We present the case of a 68-year-old man who presented to the Emergency Department with headache thought to be the result of a newfound intracranial mass. After admission, he became obtunded and was found to have tension pneumocephalus requiring emergent evacuation. A cervical esophagus carcinoma caused an esophageal-subarachnoid fistula that resulted in tension pneumocephalus after a retching episode. CONCLUSION: This case illustrates the importance of considering alternative sources of pneumocephalus in the absence of more typical differential diagnosis.