Background: Intracranial air may become trapped inside the cranial vault after cranial surgery, causing tension pneumocephalus with a variety of possible neurological symptoms. The authors reported a unique case in which position-dependent tension pneumocephalus developed after standard pituitary adenoma resection, causing severe intermittent visual symptoms.
Observations: A tiny hole in the sellar floor after transsphenoidal surgery created a valve mechanism, allowing pressurized air accumulation inside the tumor capsule that periodically compressed the optic chiasm. This caused acute visual field defects only when the patient was in an upright position. Symptoms resolved when the patient lay down because pressurized air was allowed to escape from the cranial vault and compression of the optic chiasm was relieved. This phenomenon was verified with consecutive magnetic resonance imaging sequences demonstrating the relaxation of suprasellar space, after the intracranial air had escaped in a horizontal imaging position.
Lessons: Imperfect sealing of the sellar floor after transsphenoidal surgery is not uncommon. Even a tiny defect may in rare cases work in a valve-like manner, leading to intermittent air accumulation in the suprasellar space and causing corresponding visual symptoms. Pressure pneumocephalus inside an empty tumor capsule should be kept in mind as a possible rare complication after transsphenoidal surgery.
Keywords: pituitary adenoma; pneumocephalus; transsphenoidal surgery.