Deep temporal nerve transfer: A systematic review of anatomy, anatomical landmarks and clinical applications.

Background: Facial paralysis has a debilitating impact on facial function, especially the eyebrow. Static procedures have long been the standard treatment strategy, but in more recent years, dynamic procedures are being developed. To reconstruct the upper branches of the facial nerve (temporal and zygomatic branches), the deep temporal nerve (DTN) and its branches, with its close proximity to the eyebrow, can be used as a possible donor nerve for reinnervation. This systematic review provides an overview of the DTN anatomy and possible surgical treatment strategies. Materials and methods: A PubMed systematic literature search was performed in October 2021. Studies on cadavers and clinical studies providing anatomical or surgical information on the dissection of the DTN as well as surgical treatment strategies using the DTN were included. Results: The literature search produced 311 results, including 36 duplicates. After screening on title and abstract, 11 studies were found possibly relevant and underwent a full-text critical appraisal, resulting in 4 exclusions. In total seven studies were included. The data gathered were used to adequately describe the DTN anatomy, surgical approaches and landmarks used during surgery. Conclusion: The DTN and its branches prove to be a viable donor for the reconstruction of facial nerve branches, since the location and anatomical consistency can be relied upon through a multitude of studies, especially of the middle branch. Our study describes anatomy and nerve characteristics for its use in facial reanimation.