The Anatomic Landmark Approach to Extratemporal Facial Nerve Repair in Facial Trauma

Abstract

In this study, we aimed to examine the topical anatomic landmarks of the facial nerve (facial nerve areas) and their application in cases of extratemporal facial nerve injury in maxillofacial trauma. Materials and methodsWe analyzed 25 maxillofacial trauma patients with facial paralysis who underwent facial nerve reanimation surgery at the Ho Chi Minh City National Hospital of Odonto-Stomatology. The characteristics of each trauma case, including the mechanism of injury, the length of the facial injury, and the location/position of injury, were recorded. The association of the injured nerves with the trauma characteristics and the external landmarks of the facial danger zones was analyzed. ResultsThe buccal branches had the highest rate of paralysis (22/25 cases), followed by zygomatic branches (15/25), frontal branches (11/25), marginal branches (6/25), and the main trunk (1/25). There were four areas related to the external facial nerve landmarks (facial nerve areas) that helped us find the affected nerves: wounds in Area 1 resulted in frontal branch paralysis in five out of eight cases (62.5%); wounds in Area 2 resulted in zygomatic branch paralysis in 8/13 cases (61.5%) and buccal branch paralysis in 12/12 cases (100%); wounds in Area 3 resulted in marginal branch paralysis in 5/10 cases (50%); and wounds in Area 4 alone resulted in main trunk paralysis in one out of four cases or at least two main branches in three out of four cases. ConclusionExtratemporal facial paralysis after facial trauma can be complex and highly variable, leading to difficulty in finding and repairing facial nerves. Thorough clinical examination and evaluation of trauma characteristics can aid in the identification of facial paralysis and repair. Mapping facial wounds using the four anatomic surface landmarks (Areas 1-4 as outlined in this research) helped us anticipate which branches might be traumatized and estimate the position of the distal and proximal endings to repair the nerves in all cases.

Anatomical knowledge of zygomatico-buccal plexus in a cadaveric study

“…In addition, the BB was distributed anteriorly to the PG and medially traveled superficial to the buccal fat pad for facial expression muscle innervation. This factor will probably cause the highest rate of BB paralysis after trauma at the mid-face region [14]. Moreover, Tsai et al [32] recommended that thread lift procedure should performed in the deep plane of the face because the tread traveled under www.acbjournal.org https://doi.org/10.5115/acb.23.040 the buccal fat pad to avoid the BB injury.…”

“…Recently, the facial paralysis resulting from the BB injury was found in maxillofacial trauma at Original Article https://doi.org/10.5115/acb. 23 approximately 88% [14]. Consequently, the absolute information about the BB and its relationship to the soft tissue is indispensable for surgical and non-surgical interventions [9].…”

Rehabilitation Surgery for Peripheral Facial Nerve Injury after Facial Trauma

“…Operative indications for surgery include: 1) Traumatic wounds within zones 1 to 4 of the face; 7 2) Patients having FNGS 2.0 in at least one zone, greater than or equal to 4; 3) Patients with severe axonal damage on Electroneurography. Incision of the skin is made through an existing wound.…”

“…Based on the structure and anatomy of the branches of the peripheral facial nerve on the surface of the face, including the forehead, temporal area, cheeks, jaw, and other facial structures such as the prominence of the cheekbone, the angle of the mandibular bone, the parotid gland, and the parotid duct, it is possible to predict and connect the two ends of the damaged facial nerve branches together. 7 Once the terminal ends of the injured branches have been found, the damaged zone of the nerves should be evaluated to decide if any segments need to be removed. If the nerve ends are cut sharply and appear healthy, there may be no need to refresh them.…”

“…Based on the surface anatomical landmarks of the facial nerve in relation to certain fixed facial structures which has been described in our previous study, two damaged nerve endings are identified and matched successfully in all cases. 7 Once the two damaged nerve endings were found, a relatively wide damaged zone of the nerve needed to be removed, making end-to-end anastomosis more difficult than in cases of fresh nerve injury. Therefore, we emphasize that the timing of surgery plays an important role in deciding the surgical methods for cases of facial nerve injury due to trauma, in agreement with the findings of Brown et al and Volk et al 16,17 Volk documented that cases of nerve damage later than 2 months are difficult to perform anastomosis or nerve grafting as the distal end of the damaged nerves may not be visible.…”