Unexpected prominent tension pneumosella five years after endoscopic endonasal transsphenoidal surgery.

Tension pneumosella (TP) is a rare entity reported as the invagination of the sphenoid sinus mucosa into the skull base after endonasal transsphenoidal surgery. Few studies have reported on TP, and in these studies, invagination is confined to either the intrasellar or suprasellar area. We encountered a case of unexpected prominent TP toward the intracranial space 5 years after endoscopic endonasal transsphenoidal surgery (EETS) for a nonfunctioning pituitary adenoma. In addition, we present a hypothesis of the underlying mechanism by a pressure gradient change between the extracranial and intracranial space in TP formation. For repair, a pedicled nasal septal flap was fabricated from the remaining part of the septal mucosa, and a pedicled inferior turbinate flap was created. Moreover, the nasal septal cartilage was used as a rigid support for reconstruction, which was useful for preventing TP recurrence. This is the first report of an unexpected prominent TP after EETS. It is important for otorhinolaryngologists and neurosurgeons to be aware of the possibility of TP following EETS. Laryngoscope, 1798-1801, 2018.