Tension pneumocephalus is a rare medical emergency. Spontaneous atraumatic tension pneumocephalus is reported in cases of neoplasm, Valsalva manoeuvres, and air cell hyperpneumatization. For the first time, we describe a case of atraumatic tension pneumocephalus induced by nasal cannula in a patient with ventriculoperitoneal shunt. Our case report discusses the possible mechanisms of the tension pneumocephalus in this case.