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

Fenestration of the facial nerve by the stylomastoid artery

BACKGROUND

Anatomic landmarks such as the tympanomastoid suture line, posterior belly of the digastric muscle, tragal pointer, and styloid process can assist the parotid surgeon in identifying and preserving the facial nerve. Vascular structures such as the posterior auricular artery and its branch, the stylomastoid artery, lay in close proximity to the facial nerve and have been proposed as landmarks for the identification of the facial nerve. In this case report, we describe an anatomic variation in which the stylomastoid artery has fenestrated the main trunk of the facial nerve, dividing it in two.

METHODS

Two patients underwent parotidectomy (one for a pleomorphic adenoma, the second for a parotid cyst) through a standard anterograde approach with identification of the usual facial nerve landmarks.

RESULTS

The appearance of the main trunk of the facial nerve was unusual in both patients due to its being fenestrated by the stylomastoid artery. The stylomastoid artery was divided, and the remainder of the facial nerve dissection was performed uneventfully with subsequent resection of the parotid mass in both patients.

CONCLUSIONS

In rare instances, the stylomastoid artery can penetrate through the common trunk of the facial nerve. This is an important anatomic variant for the parotid surgeon to be aware of, as it can increase the difficulty of facial nerve dissection.

Facial Nerve in Parotid Surgery- do Landmarks Differ With Varying Statures?

Aim: To measure the distance of facial nerve from tragal pointer, tympanic plate and digastric muscle, also length of the facial nerve trunk and to establish any variation according to different patient stature. Methodology: Intraoperative measurements were taken using Castroviejo Callipers (20 mm). Height and weight of each was taken and tabulated. Results: The average height was 162 ± 9 cm while the average weight was 58 ± 9 kg. The average length of the extratemporal part of the facial nerve trunk, distance of the facial nerve from the tragal pointer, distance from the outer edge of tympanic plate, distance from the posterior end of the superior border of posterior belly of digastric muscle was 1 ± 0.2 cm, 1 ± 0.1 cm, 0.3 ± 0.2 cm and 0.2 ± 0.1 cm, respectively. Summary: No major difference was found in the landmarks despite varying stature.

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.

Pattern of facial nerve palsy during parotidectomy: a single-center experience

OBJECTIVE

This study was performed to report and analyze the prevalence of permanent facial nerve paralysis following parotidectomy for various benign and malignant lesions in a single center.

METHODS

This single-center retrospective study included all patients who underwent parotidectomy (total and superficial) for benign and malignant tumors and chronic inflammatory diseases during a 6-year period. Patients who had previously undergone an operation of the parotid gland and those with preoperative facial weakness were excluded.

RESULTS

The study included 127 patients ranging in age from 14 to 83 years (median, 45.89 years). Most patients were female (n = 83, 65.4%). The most prevalent procedure was superficial parotidectomy (n = 117, 92.1%), followed by total parotidectomy (n = 6, 4.7%). The average operative duration was 138 minutes (range, 80-400 minutes). Histopathology revealed that 109 (85.8%) patients had benign tumors, 14 (11.0%) had malignant tumors, and 4 (3.1%) had chronic sialadenitis. Only two patients sustained an injury to the cervical branch of the facial nerve.

CONCLUSION

In this single-center experience of parotid surgery, the rates of transient and permanent facial paralysis were acceptably low at 9.0% and 1.6%, respectively, for all pathologies.

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.

Cervicofacial surgery and implantable hearing device extrusion: management of challenging cases

OBJECTIVE

To describe our management of implantable hearing device extrusion in cases of previous cervicofacial surgery.

METHODS

A review was conducted of a retrospectively acquired database of surgical procedures for implantable hearing devices performed at our department between January 2011 and December 2019. Cases of device extrusion and previous cervicofacial surgery are included. Medical and surgical management is discussed.

RESULTS

Four cases of implant extrusion following cervicofacial surgery were identified: one involving a Bonebridge system and three involving cochlear implants. In all cases, antibiotic treatment was administered and surgical debridement performed. The same Bonebridge system was implanted in the middle fossa. The three cochlear implants were removed, and new devices were implanted in a more posterior region.

CONCLUSION

Previous cervicofacial surgery is a risk factor for hearing implant extrusion. The middle fossa approach is the best option for the Bonebridge system. Regarding the cochlear implant, it is always suitable to place it in a more posterior area. An inferiorly based fascio-muscular flap may be a good option to reduce the risk of extrusion.

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.

A new landmark for the identification of the facial nerve during parotid surgery: A cadaver study

OBJECTIVE

Precise knowledge of facial nerve anatomy is crucial for parotid surgery. Although several surgical landmarks to identify the facial nerve have been described in literature, their position is variable, inconsistent, and difficult to follow in some cases. The purpose of this study was to prove that the facial nerve trunk (FNT) is located midway between the mastoid tip (MT) and osteocartilaginous junction of the external auditory canal (EAC).

METHODS

A prospective study of 7 frozen cadaver specimens, of which 13 facial sides were dissected. The distances between the osteocartilaginous junction and the MT, between the FNT and the MT, and between the FNT and the osteocartilaginous junction were recorded, respectively.

RESULTS

The distance between the osteocartilaginous junction and the MT ranged from 17 to 21 mm, with a mean of 19.5 mm (SD = ±1.19). The mean distances between the osteocartilaginous junction and the FNT and between the MT and the FNT were 9.2 mm (±1.58) and 10.3 mm (±1.79), respectively.

CONCLUSION

The FNT was consistently located close to the midpoint between mastoid tip inferiorly and bony-cartilaginous junction of the EAC superiorly.

LEVEL OF EVIDENCE

NA.

An Improved and Simplified Approach to Identify the Facial Nerve During Parotid Surgery

Precise identification and preservation of the facial nerve is mandatory to avoid dysfunction of the facial nerve during parotidectomy. In this article, the authors are introducing a new landmark to identify the facial nerve for parotidectomy that is more protective for the facial nerve. The authors use a simple approach to predict the position of facial nerve main trunk intraoperatively without geometric calculations and a lot of landmarks. An imaginary almost 2 cm line is drawn between mastoid tip inferiorly and bony-cartilaginous junction of the external auditory canal superiorly. The main trunk of the facial nerve can be visualized at the midpoint of this line. The authors have been using this landmark successfully for the last 10 years, without any functional deficit of the parotid nerve. Identifying the facial nerve at the trunk level by this landmark renders following the branches forward in the glandular parenchyma less complicated.

Fetal anatomy of the facial nerve trunk and its relationship with posterior auricular artery

PURPOSE

The aims of the study are to define anatomy of the facial nerve (FN) and its main trunks as well as their relationship with the posterior auricular artery in fetal period to evaluate the data for regional surgery in newborns and young infants.

METHODS

Formalin-fixed 34 fetuses from anatomy laboratory collection with a mean gestational age of 26.4 ± 4.6 (20-36) weeks were dissected. Parameters regarding the presence of major or minor trunks, width, length, branching pattern of FN were evaluated according to side, gender and trimester. The positional relationship of posterior auricular artery with the FN trunk was inspected.

RESULTS

On all sides only the major trunk of the FN was detected. For length and width parameters, there was no statistically significant difference for side and gender except for trimester. Linear functions were found as 0.329 + 0.025 × weeks for width and 5.264 + 0.185 × weeks for length. There are statistically significant linear relationships between width and length of the FN trunk and week parameters as r = 0.507, p < 0.001 and r = 0.484, p < 0.001, respectively. Posterior auricular artery crossed FN trunk laterally in 42 of 53 sides, medially in 9 sides while it was puncturing it proximally in 2 sides. In all cases, it was in close contact to the FN trunk. FN trunk showed bifurcation in 82% and trifurcation in 18%.

CONCLUSION

Dimensions of FN trunk, growth ratio and linear functions can be beneficial in understanding the fetal growth of FN trunk and its usage for grafts. Data about the relationship of the posterior auricular artery with FN trunk may be crucial in avoiding iatrogenic injuries during surgery in early ages.