Fig. 4

Endoscopic endonasal view of the anterior skull base. a Dural defect area before pericranial flap placement. The dura defect on the cribriform plate area was pre-made prior to the periosteal flap harvest. CP, cribriform plate; P, pituitary region; C, clivus. b Using this nasoseptal flap, an attempt was made to cover the dural defect in the cribriform plate. The end of the nasoseptal flap could not reach the cribriform plate area. c Using our lateral pericranial flap method, the flap could fully cover the anterior frontal base, sellar, and clivus regions