Borle's triangle: A reliable anatomical landmark for ease of identification of facial nerve trunk during parotidectomy

Defining the Safe Entry Point in Deep Plane Facelifting with Novel Landmark for the Buccal Branch of the Facial Nerve

Background

In deep facial surgery, accurate preoperative landmarking of branches of the facial nerve is helpful in avoiding inadvertent facial nerve injury. The objective of our study was to determine the accuracy at which the intersection point of two bisecting lines that join facial surface landmarks can be used to accurately locate the buccal branch(es) of the facial nerve, specifically at the deep plane entry point (ie, intercept landmark).

Methods

Thirty-three cadavers were dissected to determine the position of the buccal rami relative to the intercept.

Results

Buccal rami crossed the intercept in 12.12% of specimens (0 mm from intercept, n = 4). Buccal rami passed superiorly in 66.67% of specimens (3.71 ± 3.28 mm from intercept, n = 7) and inferiorly in 21.21% of specimens (2.44 ± 0.92 mm from intercept, n = 7). Noteworthy, buccal rami were located within 1 cm of the intercept landmark with 96.97% accuracy (32/33 cadavers).

Conclusions

These data suggest that this novel intercept (1) reliably locates the buccal branch of the facial nerve as it courses distal to the parotid gland, and (2) helps define a "safe zone" for entry into the deep plane where the likelihood of encountering the facial nerve is extremely low.

The retromandibular loop of the external carotid artery

BACKGROUND

The external carotid artery (ECA) is a major artery of the head and neck. Although numerous studies describe the variability of ECA branches, the course variation of the ECA was seemingly overlooked. It was aimed to study the morphological possibilities of the retromandibular segment of the ECA.

METHOD

A retrospective study was performed on 60 computed tomography angiograms of 26 male and 31 female adult patients. Three types of retromandibular ECA were defined: type 1 - the ECA has a straight course deep to the anatomical plane of the ramus of the mandible; type 2 - the ECA makes a retromandibular loop directed laterally, extending externally to the anatomical plane of the ramus of the mandible; and type 3 - the retromandibular loop directed laterally reaches just behind the posterior margin of the ramus of the mandible.

RESULTS

Type 1 was found in just 43.33%, type 2 in 18.33%, and type 3 in 38.33% of 120 sides cases. On the right, type 1 was significantly associated with the male gender, and type 3 with the female gender (Pearson Chi2=10.9, p=0.004). On the left, there were no statistically significant associations (Pearson Chi2=3.5, p=0.153). In 20 cases, the retromandibular course of the ECA was asymmetrical; in 21 cases, type 1 was recorded bilaterally; in 5 cases, type 2 was bilaterally symmetrical; and in 14 cases, type 3 was found bilaterally.

CONCLUSION

These previously undocumented types of ECA are relevant during parotid surgery and should be investigated preoperatively on a case-by-case basis.

Penetration of the facial nerve by the posterior auricular artery: case report, comprehensive review and clinical-surgical applications

Anatomical variations between the facial nerve and adjacent arteries are rare. However, knowledge of such anatomical variations is important to the surgeon who operates on or near the facial nerve. Herein, we report an unusual finding between the extracranial part of the facial nerve and a nearby artery. During routine dissection of the right facial nerve trunk, the posterior auricular artery was found to pierce the nerve effectively forming a nerve loop. The nerve was pierced by the artery soon after its exit from the stylomastoid foramen. This case is detailed and a review on this topic presented, specifically identifying previously reported studies describing this or similar variations, and the relationship between the posterior auricular artery and facial nerve trunk in general. Piercing of the facial nerve trunk by the posterior auricular artery appears to be rare. However, such a relationship should be known by the clinician who treats patients with pathologies of the facial nerve trunk. To our knowledge, this is the first report of this variation in an adult. Due to such rarity, this case is of archival value for those who might describe it or similar cases in the future.

Posterior auricular artery as a novel anatomic landmark for identification of the facial nerve: A clinical study

BACKGROUND

In our previous cadaveric study, we highlighted the posterior auricular artery (PAA) as a potential landmark for early identification of facial nerve (FN) when performing parotidectomy. However, further clinical study is critically needed before this landmark could be applied in clinical practice.

METHODS

For 31 patients enrolled, we tried to identify the FN by the guide of the PAA during parotidectomy. Additionally, the FN function was evaluated during follow-up.

RESULTS

PAA could be exposed in 28 out of 31 (90.3%) patients during parotidectomy. Moreover, the FN trunk could be identified by the guide of the PAA in all these 28 patients with identifiable PAA. Furthermore, no iatrogenic FN damage happened in this study and the transient FN dysfunction rate was 5.7%.

CONCLUSION

The PAA is an ideal landmark for early identification of the FN trunk when performing parotidectomy.

Salivary gland function, development, and regeneration

Salivary glands produce and secrete saliva, which is essential for maintaining oral health and overall health. Understanding both the unique structure and physiological function of salivary glands, as well as how they are affected by disease and injury, will direct the development of therapy to repair and regenerate them. Significant recent advances, particularly in the OMICS field, increase our understanding of how salivary glands develop at the cellular, molecular, and genetic levels: the signaling pathways involved, the dynamics of progenitor cell lineages in development, homeostasis, and regeneration, and the role of the extracellular matrix microenvironment. These provide a template for cell and gene therapies as well as bioengineering approaches to repair or regenerate salivary function.

The spiral ladder technique of facial nerve trunk identification during parotidectomy: A convenient roadmap for the beginners

The intricate relationship between the facial nerve and the parotid gland makes the surgeries involving the gland challenging. Though several landmarks have been described to locate the nerve trunk, variations do exist due to the physical and racial characteristics of an individual. The spiral ladder technique described here uses multiple landmarks that appear in a stepwise manner as a beginner proceeds through the surgery as a road map to the nerve trunk. This simple adoption of a cluster of existing landmarks increases the certainty factor. This method may help beginners and in turn, reduce the chances of iatrogenic facial nerve injuries.

Facial nerve: A review of the anatomical, surgical landmarks and its iatrogenic injuries

Facial nerve iatrogenic injuries are serious and can negatively affect the quality of life of the patients. Due to the properties of the nerve, the complications are devastating involving the aesthetic appearance and the function of the face. Moreover, the multiple branches of the nerve increase the risk of an iatrogenic injury making the detailed knowledge of the anatomical correlations around them critical. In this review, a meticulous analysis was performed including the surgical procedures posing the greater risk of an iatrogenic injury as well as the full description of all the reported anatomical landmarks involving the extracranial course of the facial nerve.

New classification of branching pattern of facial nerve during parotidectomy: A cross sectional study

Background

Parotidectomy is one of the most frequent modes to treate tumors of parotid gland. Previous studies documented a variation in the facial nerve branching which might risk facial nerve injury during Parotidectomy.

Aim of study

To make a new classification system that includes a new branching pattern of facial nerve trunk that has not been described before, also to mention a simple method of how to identify the facial nerve trunk, all that will help the new surgeon in performing parotidectomy with less complications and unpredictable outcome.

Methods

A prospective cross sectional study on 460 patients underwent partial or total parotidectomy for different pathologies were enrolled during the period January 2004 till September 2020. Three investigations were considered; the anatomy of the facial nerve trunk (FNT), exact site of facial nerve trunk in relation to fixed landmarks, finally we observed any communications between the branches. We made a new classification based mainly on the anatomical variations in the branching pattern of the FNT; namely, types (I, II and III). Each type subdivided according to the length of facial nerve trunk and also according to the communication between the branches.

Results

Type I reported in majority of cases; 78.26%. type II (15.2%) which is the newly discovered branching pattern, and type III (6.6%). Total FNT length was 1–10 mm in more than half (54.35%) of cases. In 64.35% of cases FNT was in the midpoint between the tragal pointer (TP) and tip of mastoid's process (TMP). In 50 (10.87%) of the cases there was anastomotic connection between the buccal and mandibular branches, and in 20(4.34%) the communication was always a loop between the upper and lower divisions of FNT.

Conclusion

There is a profound variation in the facial nerve branching pattern that has not been previously reported. Awareness about differences in the anatomy of the facial nerve assisted useful information to surgeon to preserve FN during parotidectomies.

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Previous studies documents variation in the facial nerve branching which might risk FN injury during parotidectomy.

•

A new classification system is made that includes a new branching pattern of FN trunk that has not been described before.

•

a simple method of how to identify the facial nerve trunk.

•

All that will help the new surgeon in performing parotidectomy with less complications and unpredictable outcome.

Feasibility of Using Posterior Auricular Artery as Landmark for Identification of Facial Nerve Trunk in Parotid Surgery: A Cadaver Study

INTRODUCTION

Despite good surgical knowledge of the anatomy of parotid gland and meticulous surgical technique, the incidence of facial palsy in parotid surgeries is up to 26.7% transient and 1.7% complete facial palsy(1). The risk of facial palsy increases further in malignant and revision cases.

METHOD

Superficial parotidectomy was done in 14 cadaveric hemi faces in 10 cadavers. Posterior auricular artery and its stylomastoid branch was dissected and facial nerve trunk was identified in all cases. The relationship of posterior auricular artery along with its stylomastoid branch with the facial nerve trunk was studied and recorded.

RESULT

Posterior auricular artery was found running inferior to the facial nerve trunk in 12 cadaveric dissection while the posterior auricular artery was found crossing below the main trunk of facial in 2 cadaver dissection. The average distance between PAA and facial nerve trunk was 7 mm (2-14 mm) Stylomastoid artery was found arising from Posterior auricular artery in 12 of 14 and it was found running medial to the facial nerve trunk in all the 8 cadavers.

CONCLUSION

Post auricular artery can be used as another landmark for identification of the main trunk of facial nerve in parotid surgeries.

Variations in Facial Nerve Branches and Anatomical Landmarks for Its Trunk Identification: A Pilot Cadaveric Study in the Lithuanian Population

Objective The purpose of this study was to evaluate facial nerve (FN) branching variations based on Davis and Kopuz classifications in the Lithuanian population and measure the shortest distance from the facial nerve trunk (FNT) to its anatomical landmarks. Methods Twenty-two hemifaces of 11 cadavers were dissected. The preauricular skin cut was made and extended behind the ear lobe and along the inferior border of the mandible. The skin with subcutaneous tissue and superficial fascia were separated and medially retracted, and the parotid gland was dissected anterogradely. The FNT and its furcation type and branching pattern were disclosed and noted based on Davis and Kopuz classifications. Further, the shortest distance from the FNT to the anatomical landmarks of the tragal pointer (TP), the angle of mandible (AM), and the tip of mastoid process (TMP) was measured. Results The prevalence of branching patterns did not differ significantly compared to Davis classification. Based on Kopuz, type IVA pattern was the most common in six cases (27%). Eighteen (82%) trunks split as bifurcations and two (9%) trifurcations, while two (9%) had separate double trunks. The shortest distance (mm) from the FNT to the TP is 9.30 ± 0.93, AM 36.45 ± 4.14, and TMP 12.52 ± 2.30. Conclusion The prevalence of FN variations in the Lithuanian population is similar to Davis classification. The AM and TMP are consistent superficial bony landmarks for trunk identification, while the distance from the TP highly varies among studies. Surgeons should be aware of double FNT during parotidectomy, which is described in Kopuz classification.