Fig. 1.

Steps of modified one-piece supraorbital approach in a skull model. Numbers indicate the location of the burr holes defined here. (A) Three burr holes are placed: the MacCarty keyhole (burr hole 1) that exposes the anterior cranial fossa (arrow) and orbit (arrowhead), burr hole 2 just above the medial supraorbital rim, and burr hole 3 on the superior temporal line. (B, C): Outside (B) and inside views (C). Through burr hole 2, a small hole (arrow) is created with a diamond drill bit on the roof of the orbit, ∼ 10 mm in depth from the surface. (D) The cut of the medial part of the supraorbital rim, made with a diamond-coated threadwire saw (diamond T-saw: arrows), introduced into burr hole 2 and the small hole in the roof. (E) Rongeuring of the roof through burr hole 1 is continued to as close to the small hole as possible. (F) The cut of the lateral orbital rim made with a diamond T-saw (arrows), introduced into the inferior half of burr hole 1. The small bridge in the roof (asterisk) that was left in the previous step is seen. (G) Frontal osteotomies between burr holes 1 and 3, and between holes 2 and 3. A craniotome is used for osteotomy. The bony bridge (asterisks) left at each corner of the osteotomy is cut with a diamond T-saw (arrows). (H) The flap is raised in a medial to lateral direction, and the remaining small bridge in the roof (asterisk) is cracked. (I) Inside view of the one-piece supraorbital flap. (J) Superior view after completing the craniotomy. The orbital roof has been sufficiently removed en bloc to expose a tumor in the orbital apex (asterisk). The dashed line indicates the rim of the opening of the roof. (K) At repositioning of the flap, sutures are placed through small drill holes (dots) in the cuts made with a diamond T-saw to support the flap.