Tailored Midline Supra-orbital Craniotomy for Anterior Skull Base Tumors: Anatomic Description of a New Surgical Technique and Case Series

Introduction: Open transcranial approaches to the anterior skull base remain an integral component of current skull base practice. Evolution of these and other techniques have resulted in revisions of standard, tried-and-true methods in attempts to improve patient outcomes and cosmesis, while still providing the surgeon with the best combination of surgical exposure and ergonomics.

Methods: We described the anatomy and techniques of a modification to the extended bifrontal craniotomy for anterior skull base tumors. Methods for the osteotomy cuts outside of the orbital contents required were outlined. Several case examples and a post-operative 3D computed tomographic reconstruction of the craniotomy are provided.

Results: The technique has been employed with success in several cases where the anterior limit of the tumor is several centimeters back form the inner table of the frontal bone in the midline. Cases included 3 tuberculum sellae meningiomas. The mean distance from the tumor to inner table was 2.8 cm (range 1.3 – 3.8 cm). Mean tumor dimensions were 3.0 cm (transverse), 3.5 cm (anterior-posterior), and 2.2 cm (cranio-caudal). Average operative time was 557 minutes (range 467 – 619 minutes). No cases had new T2 MRI signal of the inferior frontal lobe to indicate retraction injury. There were no ocular, brain, or wound complications and cosmetic results have been satisfactory.

Conclusion: The tailored midline supra-orbital craniotomy for anterior skull base tumors provides adequate access to the anterior cranial fossa and has replaced our standard extended bifrontal approach. Keeping the osteotomy cut lines outside of the orbit reduce orbital swelling and mechanical disruption of conjugate eye movements in the early post-operative period, while allowing for minimal frontal lobe retraction and providing sufficient surgical exposure along the anterior skull base.

Fig. 1 Demonstration of the tailored supra-orbital osteotomy. The osteotomy cuts are placed medial to the supraorbital notches on both sides and stay outside the orbits (dotted line) bilaterally (A). The final exposure (B) provides similar access to the previously described approach (C). The osteotomy (D) is seen in comparison to the traditional approach (E) which includes the orbital roof.

Fig. 2 Three-dimensional representation of tailored supraorbital osteotomy. Postoperative CT with 3D reconstruction demonstrating the tailored supraorbital osteotomy that avoids disruption of the periorbital and provides good cosmetic results.

Fig. 3 Patient 1 pre- and postoperative imaging. Preoperative MRI shows a 3.3 × 1.9 × 3.8 cm tuberculum meningioma interdigitating the distal branches of the anterior cerebral artery with extension down both optic canals in the sagittal (A), coronal (B), and axial (C) planes. Postoperative MRI shows near total resection with trace residual tumor in the left optic canal in the sagittal (D), coronal (E), and axial (F) planes.