The modified orbitozygomatic approach (OZA) is a pterional craniotomy extended with the osteotomy of the orbital roof, the lateral wall of the orbit, and the frontal process of the zygomatic bone. This extension allows wide exposure of the anterior and middle cranial fossae, parasellar and interpeduncular spaces as well as targets located in the orbit. The osteotomy of the orbital walls increases angles of attack and working area in the listed regions1.

At the beginning of the twentieth century, L. L. McArthur2 (1912) and C.H. Frazier3 (1913) independently from one another described the supraorbital approach to hypophysis which included the resection of the roof and lateral wall of the orbit. Initially, the technique of the approach that was similar to the modern modified OZA and provided access to the orbit, anterior and middle cranial fossae, parachiasmatic and parasellar regions was described by J.A. Jane4 in 1982 (Fig. 1). This technique was used by A. Hakuba5 in 1986 to develop the first OZA which was modified by J.M. Zabramski6 in 1998. It is notable that in 1987 O. Al-Mefty7 proposed a one-piece supraorbital-pterional craniotomy that exposes anterior and middle cranial fossae and does not include the zygomatic arch. In modern neurosurgery, this approach is called the modified OZA. In a plethora of publications and books, this approach and its variations may be called modified supraorbital orbitozygomatic8, supraorbital9, orbital-pterional10, and mini-orbitozygomatic11.

Classic modified OZA requires two burr holes – one in the temporal or frontal region and the other in the MacCarty keyhole[4], [12] (Fig. 2). This way a single bone flap including parts of frontal and temporal bones, lateral aspects of the larger sphenoid wing, frontal process of the zygomatic bone, orbital roof, and lateral wall of the orbit can be formed. In 2016 Spiriev et al.13 proposed their modification of the one-piece OZA which included the zygomatic arch and only one burr hole that is not in the MacCarty keyhole but in the projection of the most anterior and thickest aspect of the sphenoid ridge. They called this new point the sphenoid ridge keyhole (Fig. 3). The anatomical study of 20 skull specimens with the method of transillumination conducted by the authors discovered the location of this point (Table 1) (Fig. 4).

Notably, to this day there has been no research describing the modified OZA with the sphenoid ridge keyhole.