Aneurysmal subarachnoid hemorrhage (SAH) is a life-threatening condition with increasing prevalence over the years (
1). Previous researches have been shown that intracranial aneurysms (IAs) are found in relatively 2% of adults without any risk of SAH (
1).
Active smoking, unruptured aneurysm with a large size, youthful ages, family history of cerebrovascular disease, and postmenopausal status in female patients are important risk factors for multiple aneurysms (
2,
3).
Pneumocephalus (asymptomatic intracranial air) after craniotomy is a common finding. In supratentorial craniotomy, the incidence of pneumocephalus has been reported as 100% (
4). However, transformation of pneumocephalus into tension pneumocephalus (symptomatic intracranial air) is an uncommon event. Tension pneumocephalus, after posterior fossa surgery, occurred in the sitting position, however, but we are not attuned with tension pneumocephalus reported after craniotomy in the supine position (
5). We report a case of developed tension pneumocephalus in the early postoperative period after a craniotomy in the supine position.