An Anatomical Comparison of Transpalpebral, Endoscopic, and Coronal Approaches to Demonstrate Exposure and Extent of Brow Depressor Muscle Resection

Abstract

Approaches for exposure of the muscles of brow depression include transpalpebral, endoscopically assisted, and open coronal techniques. The purpose of this anatomical study was to compare the capacity for visualization and amount of brow depressor muscle resection with each technique. The corrugator supercilii, depressor supercilii, medial orbicularis oculi, and procerus muscles were studied by gross anatomical dissection carried out on 24 sides of 12 cadaver heads. First, all visible corrugator and depressor supercilii muscles were resected by means of an upper blepharoplasty incision. Subsequently, a subgaleal endoscopic approach was used to evaluate the extent of resection performed and remove the remaining muscle after transpalpebral corrugator resection. This was followed by coronal exposure to assess the anatomical location and extent of muscle resection accomplished by the two previously mentioned techniques. In all dissections, endoscopy demonstrated that up to one-third of the lateral aspect of the transverse heads of the corrugator supercilii remained following transpalpebral resection. Oblique corrugator head resections were complete, without significant residual muscle following transpalpebral corrugator resection. The procerus muscle was able to be blindly transected by means of the transpalpebral incision but exposed and ablated in all 12 specimens using endoscopy. Coronal exposure demonstrated that no significant amount of corrugator, depressor supercilii, or procerus muscle remained in any of the 12 heads following endoscopically assisted exposure and resection. The medial head of the orbital portion of the orbicularis oculi was visualized and accessible regardless of the technique used. In 24 anatomical dissections, transpalpebral corrugator resection failed to remove up to one-third of the transverse head of the corrugator muscle. Removal of the brow depressor muscles was accomplished with the endoscopic approach, as confirmed by coronal exposure.