Glabellar approach: simplified midline anterior skull base approach.

As a simplified microsurgical technique for lesions at the midline anterior skull base, a glabellar approach through a small incision (5 cm) between the eyebrows crossing the nasion was developed in four cadaver dissections. To determine the ideal positioning of the patient, the angle of the surgical trajectory was measured in the sagittal plane. In an effort to make an operation simple and accurate through this limited exposure, measurements were made in distance from the midline nasion to various intradural structures. Average distance from the midline point of the nasion (MPNa) to the midline of the tuberculum sella was 6.37 +/- 0.29 cm, 6.98 +/- 0.26 cm to the midline of the optic chiasm, and 8.00 +/- 0.11 to the lamina terminalis. In addition, measurements to other various anatomical landmarks were made. The angle of the line drawn from the MPNa to the midline of the tuberculum sella was 5.2 +/- 1 degrees against a line drawn between the lateral canthus and the tragus (LC-T) in the sagittal plane. Based upon this study, the positioning of the patient's head would be better if the LC-T line is positioned at 25 degree extension when the operating microscope is set at 20 degree inclination. Within 6 to 8 cm in depth from the MPNa, important landmarks are exposed without brain retraction. If surgical instruments are marked with ruler calibration, the depth of the surgical instruments will suggest the anatomical location. This glabellar approach has been used in three patients successfully. A brain retractor was not necessary and not used during the operations. This technique provides key exposures to the midline anterior skull base.