Reply: Anatomical Considerations to Prevent Facial Nerve Injury.
Reply: Anatomical Considerations to Prevent Facial Nerve Injury Sir: We congratulate Dr. Visconti and Dr. Salgarello for their letter, as it nicely complements our article entitled "Anatomical Considerations to Prevent Facial Nerve Injury."1 Their comments and figures help further clarify our attempt to improve understanding of facial nerve anatomy and the planes of dissection that are safe and help avoid injury. The complexity of facial nerve branches and their variable course can be appreciated in the elegant dissection performed by Dr. Visconti and Dr. Salgarello. Their anatomical figures further highlight the importance of understanding safe planes of dissection, the relative constant, as opposed to the complex and variable two dimensional course of facial nerve branches. For instance, with regard to the frontal branch, there are two planes of dissection that are safe, as one can appreciate in their figure. One can safely proceed either from a deep plane down onto the superficial leaf of the deep temporal fascia or from a superficial plane just above the temporoparietal fascia. This leaves the nerve safely located in what is referred to as the mesotemporalis in their figure. At the level of the zygomatic arch, the superficial leaf of the deep temporal fascia attaches to the arch, and surgeons should move to a subperiosteal plane when working from superior to inferior to make sure they are deep to the nerve, which is just superficial to the periosteum at that level. Otherwise, when moving from inferior to superior, one can stay within a plane just deep to the superficial musculoaponeurotic system that can be dissected off the parotid fascia, and the nerve will be safely maintained deep to that dissection. Having a good understanding of the third dimension of depth of the facial nerve, especially as one moves across different positions along the face, is of paramount importance to avoid injury. Another interesting finding from the letter by Dr. Visconti and Dr. Salgarello is the comment on cervical branch anatomy and that there is often an Even though the bidimensional anatomy (its projection on skin) of the frontal branch is quite established, its three dimensional (relationship with anatomical spaces) anatomy has been misunderstood because of the incorrect description given by anatomy books and by some papers. According to those sources, the frontal branch is situated just below the superficial musculoaponeurotic system (SMAS)/temporoparietal fascia layer at the level of the zygomatic arch. Interestingly, Barton4 and Connell and Marten5 popularized the high SMAS technique, in which they demonstrated clinically that it is technically safe to transect the SMAS at the level of zygomatic arch since the frontal branch is not at risk because it is situated in a deeper plane than the SMAS layer. Subsequent anatomical studies confirmed their statements. With this Letter, we would like to provide our cadaveric images of high SMAS face lift with dissection of the facial nerve branches, with particular focus on the frontal branch and cervicofacial branches (Fig. 1) Figure 1 may provide a nice adjunct to the comprehensive and excellent article by Dr. Roostaeian and colleagues. It may help in further understanding the three dimensional course of the frontal branch across the zygomatic arch, especially when applied to the high SMAS procedure, as well as the complexity of the cervicofacial branch anatomy, with its potential clinical implication in case of injury. DOI: 10.1097/PRS.0000000000002166
Plastic and reconstructive surgery