Guidelines for the Use of Botulinum Toxin in Otolaryngology From the Korean Society of Laryngology, Phoniatrics and Logopedics Guideline Task Force

The Korean Society of Laryngology, Phoniatrics and Logopedics created a task force to establish clinical practice guidelines for the use of botulinum toxin (BT) in otolaryngology. We selected 10 disease categories: spasmodic dysphonia, essential vocal tremor, vocal fold granuloma, bilateral vocal fold paralysis, Frey's syndrome, sialocele, sialorrhea, cricopharyngeal dysfunction, chronic sialadenitis, and first bite syndrome. To retrieve all relevant papers, we searched the CORE databases with predefined search strategies, including Medline (PubMed), Embase, the Cochrane Library, and KoreaMed. The committee reported 13 final recommendations with detailed evidence profiles. The guidelines are primarily aimed at all clinicians applying BT to the head and neck area. In addition, the guidelines aim to promote an improved understanding of the safe and effective use of BT by policymakers and counselors, as well as in patients scheduled to receive BT injections.

Mechanism and clinical use of botulinum neurotoxin in head and facial region

PURPOSE

Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region.

STUDY SELECTION

MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles.

RESULTS

The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia.

CONCLUSIONS

BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

The incidence of Frey syndrome and treatment with botulinum toxin in the Central Denmark Region

Objectives

Frey syndrome (FS) is a common complication to large salivary glands surgery. This study primarily aims to describe the incidence of FS among parotid surgery patients in the Central Denmark Region. The secondary aim is to describe predisposing characteristics to syndrome development and the effect of treatment with botulinum toxin (Botox) injection.

Methods

This is a retrospective qualitative study spanning the years 2015-2020. Data on patients diagnosed with FS after parotid surgery with symptoms severe enough to require Botox was extracted from electronic patient records. Incidence of FS development was calculated using data from all parotid gland surgeries in the same period and region.

Results

The incidence of treatment-requiring FS was 2.6% (20/775), with an annual incidence ranging from 0.8% (1/125) in 2017 to 4.5% (5/112) in 2016. Difference in FS development for men and women was not statistically significant (p = .07), although it was significantly more common after total parotidectomy compared to superficial resection (p = .003), and after malignant compared to benign diagnosis (p = .01). Complications in the postoperative period arose for 30% of FS patients. Repeated treatment with Botox was necessary after 6-12 months and at a median interval of 11 months. Forty-five percent of patients received only one injection. The average dose per injection was 48.3 IU.

Conclusion

This study revealed a rather low incidence of FS in the Central Denmark Region compared to current international literature. Total parotidectomy and malignant diagnosis predisposed to syndrome development. Botox injection had a wide-ranging effective duration but typically lasted for around 1 year.

Level of evidence

Level IV.

Frey's Syndrome: A Review of Aetiology and Treatment

First described by Polish Neurologist Łucja Frey in 1923, Frey's syndrome (FS), or auriculotemporal syndrome, is a rare condition characterised by gustatory sweating, typically encountered as sequelae following invasive head and neck surgery. The pathophysiology of FS can be described by aberrant reinnervation of postganglionic parasympathetic neurons to the surrounding denervated sweat glands and cutaneous blood vessels. Multiple invasive procedures have been associated with FS ranging from salivary gland surgery to burn reconstruction and thoracoscopic sympathectomies. Rarely, FS can be secondary to trauma or non-surgical aetiologies, including diabetes and infection. Physical symptoms vary based on the severity and surface area affected by FS and range from mild symptoms to severe psychosocial morbidity for patients. Surgeons operating in the head and neck, including otolaryngologists, maxillofacial surgeons, and plastic surgeons, should be aware of this potential complication and be up to date with diagnosis and treatment strategies for FS. This review article summarises the literature relating to FS focusing on its aetiologies, symptomatology, prevention, and available treatments, aiming to provide an up-to-date review of this condition for surgeons operating in the head and neck region. Although various treatment options have been suggested, these are often limited to topical agents that require life-long administration for symptom control. Further research is recommended to identify the optimal treatment for this condition and the role of surgery as a treatment for severe or refractory cases.

Infrahyoid myofascial flap transfer for the prevention of concave deformity and gustatory sweating after parotidectomy

OBJECTIVE

Concave deformities and gustatory sweating are the most common complications that cause substantial patient dissatisfaction after parotidectomy. Various surgical methods to prevent these complications have been described. However, effective techniques have not been established, especially in patients with medium- to large-sized parotidectomy defects. We evaluated the utility of infrahyoid myofascial flap reconstruction of parotidectomy defects for the prevention of these complications.

METHODS

We conducted a retrospective case series study in patients with a benign or malignant parotid tumor measuring over 4 cm who underwent immediate pedicle infrahyoid myofascial flap reconstruction after total or subtotal parotidectomy or total resection of either the superficial or deep parotid gland at our hospital. Subjective analyses of facial symmetry, postoperative concave deformities of the anterior neck, gustatory sweating, voice disorders, odynophagia, neck scarring in the parotid and anterior neck areas, sensory disorders, pain, and neck stiffness were performed using patient interview data. Objective evaluations of facial symmetry were made by the first or second author. Both analyses were performed after a follow-up of more than six months. Additionally, patient demographic data, clinicopathological factors, parotidectomy and skin incision types, flap survival, and postoperative complications were evaluated.

RESULTS

We included eight patients (male, n=5; mean age, 69.3 years [range, 37-93 years]). Procedures included total or subtotal parotidectomy (n=4), superficial lobe parotidectomy (n=2), and deep lobe parotidectomy with partial superficial lobe parotidectomy (n=2). Infrahyoid myofascial flaps reached the cranial tip of the parotid defect without tension, and their volume sufficiently filled the parotidectomy defect in all patients. There were no local signs of insufficient blood flow within the transferred flaps. OBJECTIVE AND SUBJECTIVE: assessments were made after a mean duration of 1.2 years (range, 0.6-1.8). Postoperatively, no patient subjectively reported facial asymmetry. Objectively, facial symmetry was "good" in four patients and "fair" in four patients. No distinctly visible concave deformity in the parotid or anterior neck area occurred in any patient. Gustatory sweating occurred in one patient; this individual had the largest parotidectomy defect. Only one patient experienced donor site morbidity (mild anterior neck stiffness) related to infrahyoid myofascial flap elevation.

CONCLUSION

Although complete prevention of gustatory sweating was unsuccessful, infrahyoid myofascial flap reconstruction of medium- to large-sized parotidectomy defects led to postoperative facial symmetry with minimal donor site morbidity.

Alternative Clinical Indications of Botulinum Toxin

Botulinum toxin type A (BoNTA) is a powerful neurotoxin that inhibits acetylcholine release from presynaptic vesicles. The potency and safety profile of BoNTA grant the toxin vast therapeutic potential. It has been used off-label for a variety of dermatologic conditions. This review aims to analyze published literature regarding the benefits and risks of the off-label use of BoNTA beyond facial lines, including eccrine hidrocystomas, enlarged pores, keloids and hypertrophic scars, hidradenitis suppurativa, hyperhidrosis, masseter muscle hypertrophy, and salivary gland hypertrophy, among others. A MEDLINE search from January 2000 to December 2019 was conducted on the off-label uses of botulinum toxin in dermatology.

Not only gustatory sweating and flushing: Signs and symptoms associated to the Frey syndrome and the role of botulinum toxin A therapy

BACKGROUND

The classic symptoms of Frey syndrome are gustatory sweating and flushing. Aims of the study were to describe prevalenceand severity of typical and atypical presentations of the disorder and to assess the effects of botulinum neurotoxin A (BoNT-A) therapy in patients with Frey syndrome after parotidectomy.

METHODS

In this prospective, observational study on 18 patients, we assessed symptom severity before therapy, after 15 days, 1, 3 and 6 months' follow-up with the sweating-flushing-itch-paresthesia-pain (SFIPP) Frey scale specifically designed by the authors themselves for this study.

RESULTS

Before BoNT-A injection, all patients (100%) complained gustatory sweating, 80% paresthesia, 77% gustatory flushing, 60% pain and 60% gustatory itch. The SFIPP-Frey overall score and the symptom-specific ones decreased significantly at each post-therapy control.

CONCLUSIONS

The prevalence of "unusual" manifestations is not negligible. BoNT-A improves symptoms severity. The SFIPP-Frey scale may be useful to assess symptoms and to monitor post-therapy outcomes.

Use of botulinum toxin in Frey's syndrome

Frey's syndrome is the most common adverse event after parotidectomy, and usually, it appears after 6 months. In our case, symptoms appear 20 years from surgery, an uncommon condition. Intralesional botulinum toxin gives excellent results in therapy, regardless of the time elapsed between surgery and the first treatment.

The preventive effect of decellularized pericardial patch against Frey's syndrome following the superficial parotidectomy

PURPOSE

This study aimed to investigate the feasibility of adopting the ThormalGEN surgical patch (a porcine decellularized pericardial patch) in the superficial parotidectomy to prevent postoperative Frey's syndrome in patients with benign parotid tumor.

MATERIALS AND METHODS

A total of 59 patients with benign parotid tumor undergoing superficial parotidectomy between April 2016 and January 2017 were enrolled, and divided into the ThormalGEN group (n = 37) and the control group (n = 22) based on their willingness to have the ThormalGEN surgical patch used in the superficial parotidectomy. At 6 months postoperation, the incidences of postoperative complications and Frey's syndrome were assessed by subjective assessment (patient self-assessment) and objective assessment (starch-iodine test), respectively. The risk factor of Frey's syndrome was analyzed by the multivariate logistic regression model.

RESULTS

The starch-iodine test, for objective assessment, showed that the ThormalGEN group had a significantly lower incidence of Frey's syndrome than the control group (8.11% vs. 40.91%, p = 006). However, in the patient self-assessment, there was no significant difference in the incidence of Frey's syndrome between groups (8.11% [3/37] vs. 13.64% [3/22], p = 0.4968). The incidences of postoperative complications were not significantly different between group (all p > 0.05). Two patients (5.41%) in the ThormalGEN group had salivary fistula. Multivariate logistic regression analysis showed that the ThormalGEN group had a significantly lower risk of Frey's syndrome than the control group (odds ratio = 0.11, 95% confidence interval = 0.02-0.51, p < 0.01).

CONCLUSION

These results suggest that the ThormalGEN surgical patch can effectively reduce the incidence of Frey's syndrome following superficial parotidectomy in patients with benign parotid tumor, and that this patch has a good safety and biocompatibility profile.