How the Lifting Amount in an Endoscopic Brow Lift is Influenced by Supraorbital Nerve Tension and Gliding-Layer Mobility of the Brow: A Cadaveric Study

Background: Sensory nerve tension and gliding-layer mobility in the brow may be significant factors affecting postoperative brow level in an endoscopic brow lift, yet they have rarely been studied. Methods: To investigate the effects of sensory nerve tension and gliding-layer mobility, the following measurements were performed alongside the endoscopic brow lift in 50 fresh cadaveric hemifaces: amount of brow elevation, critical lifting amount (as sensory nerves became tense), laxity of sensory nerve courses, and mobility of brow-gliding layers. The sensory nerve situations in the subperiosteal and subgaleal dissections were also observed. Results: Supraorbital nerve tension limited the cephalic advancement of the forehead flap. The mean elevation of the brow was 5.8 ± 1 mm (range, 3.5 to 8.6 mm). The mean critical lifting amount was 5.3 ± 1.1 mm (range, 4.0 to 7.3 mm). The mean amount of laxity in the supraorbital nerve (the permissible amount of lift) was 4.1 ± 0.9 mm (range, 2.5 to 5.5 mm). The galeal fat pad was responsible for 60% of brow mobility. The sensory nerve was more protected by a subgaleal dissection in the brow and inferior forehead and by a subperiosteal dissection in the middle and upper forehead. Conclusions: Cephalic movement of the forehead flap is limited by supraorbital nerve tension. The permitted lifting amount varies from 2.5 to 5.5 mm. Gliding-layer mobility in the brow offsets the postoperative amount of cephalic advancement of the forehead flap. Consideration of supraorbital nerve tension and gliding-layer mobility is recommended to obtain an optimal brow level in endoscopic brow lifts.