Evidence Suggesting that the Buccal and Zygomatic Branches of the Facial Nerve May Contain Parasympathetic Secretomotor Fibers to the Parotid Gland by Means of Communications from the Auriculotemporal Nerve

Botulinum Toxin-Induced Parotitis: A Postoperative Complication Following Masseter Muscle Injection

Botulinum toxin (BTX) injection is a common treatment for bruxism, but there is no literature on potential salivary gland complications. This paper presents a case of acute parotitis in a 60-year-old female following BTX injections to the masseter muscle. This case highlights the possible salivary gland complications after injection of BTX into the masticatory muscles. An electronic search of PubMed and Embase databases was conducted to create a literature review in order to delve into the etiology behind the presented case and suggest potential preventive measures to avoid salivary gland complications. Thirty-one articles are reviewed and discussed. Currently, there is no consensus on the causes of the mentioned complication. However, various factors have been proposed, encompassing anatomical, physiological, biological, and physical aspects. Several methods have been recommended for the safe injection of BTX, which, along with better medical training and knowledge, are warranted to achieve predictable results.

Connections between postparotid terminal branches of the facial nerve: An immunohistochemistry study

It has been assumed that connections between the postparotid terminal branches of the facial nerve are purely motor. However, the nature of their fibers remains unexplored. The aim of this study is to determine whether these connections comprise motor fibers exclusively. In total 17 connections between terminal facial nerve branches were obtained from 13 different facial nerves. Choline acetyltransferase antibody (ChAT) was used to stain the fibers in the connections and determine whether or not all of them were motor. All connections contained ChAT positive and negative fibers. The average number of fibers overall was 287 (84-587) and the average proportion of positive fibers was 63% (37.7%-91.5%). In 29% of the nerves, >75% of the fibers were ChAT+ (strongly positive); in 52.94%, 50%-75% were ChAT+ (intermediately positive); and in 17.65%, <50% were ChAT+ (weakly positive). Fibers traveling inside the postparotid terminal cranial nerve VII branch connections are not exclusively motor.

Adverse Events of Intense Pulsed Light Combined With Meibomian Gland Expression Versus Meibomian Gland Expression in the Treatment of Meibomian Gland Dysfunction

BACKGROUND AND OBJECTIVE

To analyze the occurrence and causes of adverse events (AEs) in intense pulsed light (IPL) combined with meibomian gland expression (MGX) and MGX treatment alone for meibomian gland dysfunction (MGD).

STUDY DESIGN/MATERIALS AND METHODS

A retrospective study was conducted on MGD patients treated in Wuhan Aier Hankou Eye Hospital from February 2018 to October 2019 to compare the AEs between IPL-MGX and MGX groups. Relevant AEs that occurred during the treatment and within 1 month after the patients' last treatment were recorded and the causes of the AEs were analyzed.

RESULTS

A total of 2,282 patients received IPL-MGX and 1,407 received MGX treatment. No serious AEs occurred in both groups. There were 74 AEs in the IPL-MGX group, with an incidence of 3.24%, including 14 significant AEs (2 cases of epidemic keratoconjunctivitis, 1 recurrent herpes simplex keratitis (HSK), 9 new onsets of floaters, 1 recurrent glaucomatocyclitic crises, and 1 recurrent iridocyclitis). There were 27 AEs in the MGX group with a rate of 1.92%, including 4 significant AEs (2 cases of keratoconjunctivitis epidemic, 2 new cases of floaters). Compared with the IPL-MGX group, the incidence of AEs in the MGX group was lower (P = 0.017).

CONCLUSIONS

Both IPL-MGX and MGX treatment are safe therapies with low risk for AEs. IPL treatment is not recommended for young children (age 10 or less) as well as patients with anterior uveitis or glaucomatocyclitic crises. The previous history of HSK and eyes with high myopia are advised to exercise caution in IPL treatment. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

The underappreciated role of auriculotemporal nerve involvement in local failure following parotidectomy for cancer

BACKGROUND

Locoregional recurrence rates following parotidectomy for cancer remain as high as 20-30%. The auriculotemporal nerve (ATN) may allow parotid cancers to spread from the facial nerve (FN) toward the skull base, causing local recurrence.

METHODS

Retrospective review of 173 parotidectomies for malignancy. Preoperative and post-recurrence imaging were reviewed by a neuroradiologist for signs of tumor adjacent to the ATN.

RESULTS

Clinical and imaging signs of possible ATN involvement correlated with FN weakness and sacrifice. Eight patients had pathologically confirmed tumor from the ATN or V3. Forty-four percent of local recurrences had post-recurrence imaging showing tumor along the course of the ATN. Locoregional failure along the ATN was also associated with preoperative FN weakness, intraoperative FN sacrifice, and failure to complete recommended adjuvant therapy.

CONCLUSIONS

Parotid cancers may invade the FN and spread to the skull base via the ATN. If not appropriately managed, this may lead to local recurrence.

Auriculotemporal Nerve Involvement in Parotid Bed Malignancy

OBJECTIVE

To identify and evaluate patients with parotid bed malignancy demonstrating radiographic findings of auriculotemporal (AT) nerve involvement.

METHODS

A retrospective review of patients with parotid bed malignancy was performed to identify patients with imaging findings of AT nerve involvement and record associated clinical findings, symptoms, and pathology information. Independent, blinded review of radiographic images by a senior neuroradiologist was performed to identify imaging characteristics and categorize patients into highly likely or possible involvement groups.

RESULTS

Of 547 patients identified with parotid bed malignancy, 23 patients exhibited radiographic findings suggestive of AT nerve involvement. Thirteen patients met criteria for highly likely involvement, and 10 patients met criteria for possible involvement. Cutaneous malignancy with metastasis to the parotid bed accounted for 11 of 23 patients, and the most common histology was squamous cell carcinoma (9 patients). Primary parotid malignancy accounted for 12 of 23 patients, and the most common histology was salivary ductal carcinoma (3 patients). All 13 highly likely patients reported periauricular pain, and 11 of 13 demonstrated facial weakness. Features suggesting advanced disease included radiographic findings of intracranial involvement (10/23 patients), nonsurgical primary treatment (13/23 patients), and positive margins on pathology report (7/10 patients).

CONCLUSION

AT nerve involvement is an uncommon but important phenomenon that often occurs in the setting of advanced disease and is commonly associated with periauricular pain and coexisting facial weakness. Awareness of the associated clinical features and imaging patterns can allow for appropriate identification of this pattern of spread and help to optimize treatment planning.

Communication between the transverse cervical nerve (C2,3) and marginal mandibular branch of the facial nerve: a cadaveric and clinical study

Several branches of the facial nerve are known to anastomose with branches of the cervical plexus, other cranial nerves, and the trigeminal nerve. Communication between the sensory transverse cervical nerve (C2, 3) and marginal mandibular nerve is, however, less well known, and in a previous study of 86 neck dissections we reported a 2.3% incidence of anastomoses between them. In this prospective study, we meticulously searched for more examples using both formalin-fixed cadavers and neck dissections. A total of 102 necks were included (both sides of 36 cadavers (n=72 necks), and 30 patients who had neck dissection for the management of squamous cell carcinoma). We found communications between these nerves on one side of a cadaver and in one neck dissection. When combined with the numbers from our previous study, the overall incidence was 2.1% in 188 necks. The marginal mandibular nerve was inseparable from the anastomosis with the transverse cervical nerve, and the variant should not be forgotten if we are to reduce the chance of postoperative weakness of the lower lip, particularly when operative exposure is more limited (such as during removal of the submandibular gland).

An unusual finding of the auriculotemporal nerve: possible risk factor during preauricular skin incisions

The auriculotemporal nerve (ATN) is a branch of the mandibular nerve and has been implicated for some migraines and its role in Frey's syndrome is well known. An adult cadaver was found to have a duplicated ATN. The anterior trunk ascended as the superficial temporal artery and gave off the branches to the temporomandibular joint, parotid gland, external acoustic meatus and temporal region and communicated with a posterior trunk of the ATN. The posterior trunk ascended via the subcutaneous tissues 1 mm anterior to the auricle and gave off the branches to the anterior auricular region, temporal region and communicated with the anterior trunk. Such a duplicated ATN might be injured with preauricular skin incisions. Knowledge of such an anatomical variation might assist surgeons in iatrogenic injury of the ATN.

Parotid Branches of the Auriculotemporal Nerve: An Anatomical Study With Implications for Frey Syndrome

The auriculotemporal nerve is one of the many branches of the mandibular division of the trigeminal nerve. Of these, its superficial temporal branch has been most described. Although the parotid branches, secretomotor fibers to the parotid gland, are well known as the cause of Frey syndrome, there have been almost no descriptions of their anatomy. In this study, the authors dissected the parotid branches of the auriculotemporal nerve to elucidate their anatomy. A total of 10 sides from 7 adult and embalmed cadaver heads were used in this study. The specimens were derived from 3 males and 4 females, the age of cadavers at death ranged from 65 to 92 years old. Measurements included their diameter and the distance of their branching point from the main trunk of the auriculotemporal nerve from the middle of the tragus. Three of 10 sides had 2 parotid branches and 7 sides were found to have 1 parotid branch. The vertical distance between middle of the tragus to branching point of the parotid branch ranged from 1.79 to 16.17 mm. The horizontal distance between middle of the tragus to branching point of the parotid branch ranged from 3.03 to 12.62 mm. The diameter of the parotid branch ranged from 0.31 to 0.49 mm. An improved knowledge of the parotid branch of the auriculotemporal nerve might decrease injury to these structures with the potential for postoperative.