Under endoscopic vision, the dissection proceeded to the glabella, where the periosteum was incised with a sharp dissector to expose the bone insertions of the procerus, corrugator and depressor supercilii muscles. A thin dissector and an endoscopic grasper with a diathermy cable (unipolar high-frequency cord, model 26002 M, Karl Storz) were used in the myotomy and partial myectomy of these muscles. This periosteotomy started at the glabella region, and continued transversally toward the lateral end of the eyebrow in both sides, passing by the supratrochlear nerve, and reaching the supraorbital nerve, where it was interrupted to be continued in a latero-medial direction in the next surgical step.