Cortical Thickness Parameters for Endoscopic Browlift Fixation

Abstract

Techniques for endoscopic browlift include bony fixation over the lateral frontal region and soft tissue fixation over the temporal region. Although bony fixation over the lateral frontal region is advocated universally, limited information exists about bicortical thickness in this area. The authors provide bicortical thickness measurements between the frontal midline and the most inferior temporal region to assist surgeons in identifying appropriate fixation planes. Bicortical thickness was measured in the hemicraniums of 13 female cadavers, along the coronal planes that travel through the anterior border of the mandibular condyles and at the junction of the posterior mandibular condyles and the external auditory meatuses. Measurements began at the midline and coursed laterally at 1-cm intervals. Average cranial thickness along the frontal region ranged from 8.9 ± 2.4 mm to 6.4 ± 2.8 mm over the anterior coronal line and 8.8 ± 2.2 mm to 5.6 ± 1.8 mm over the posterior line. Average thickness along the temporal region ranged from 5.6 ± 2.8 mm to 2.8 mm ± 1.4 mm over the anterior coronal line and 5.1 ± 1.8 mm to 3.4 ± 1.4 mm over the posterior line. Minimum thickness was 3.7 mm and 1.3 mm over the frontal and temporal regions, respectively. There was no significant difference between left and right hemicranial thickness. To avoid violation of the inner cortex during surgery, endoscopic browlift procedures should include measurement of cortical thickness at various fixation points. Bony fixation over the temporal region should be avoided. Minimal bicortical thickness was observed in the lateral frontal region.