Botulinum toxin therapy: functional silencing of salivary disorders

Embracing the Versatility of Botulinum Neurotoxins in Conventional and New Therapeutic Applications

Botulinum neurotoxins (BoNTs) have been used for almost half a century in the treatment of excessive muscle contractility. BoNTs are routinely used to treat movement disorders such as cervical dystonia, spastic conditions, blepharospasm, and hyperhidrosis, as well as for cosmetic purposes. In addition to the conventional indications, the use of BoNTs to reduce pain has gained increased recognition, giving rise to an increasing number of indications in disorders associated with chronic pain. Furthermore, BoNT-derived formulations are benefiting a much wider range of patients suffering from overactive bladder, erectile dysfunction, arthropathy, neuropathic pain, and cancer. BoNTs are categorised into seven toxinotypes, two of which are in clinical use, and each toxinotype is divided into multiple subtypes. With the development of bioinformatic tools, new BoNT-like toxins have been identified in non-Clostridial organisms. In addition to the expanding indications of existing formulations, the rich variety of toxinotypes or subtypes in the wild-type BoNTs associated with new BoNT-like toxins expand the BoNT superfamily, forming the basis on which to develop new BoNT-based therapeutics as well as research tools. An overview of the diversity of the BoNT family along with their conventional therapeutic uses is presented in this review followed by the engineering and formulation opportunities opening avenues in therapy.

Idiopathic dilatation of the submandibular gland duct

Lithiasis and stenosis may cause salivary duct dilatation due to the increased pressure in the duct upstream of the obstruction. Idiopathic dilatations, also called megaducts, with no associated increase in pressure, have only been described in the parotid gland. The aim of this study was to describe the characteristics of submandibular duct dilatation unrelated to lithiasis, stenosis, or an imperforate duct, to report the existence of submandibular megaducts. This retrospective single-centre study included patients treated at La Conception University Hospital, Marseille, France, between 2007 and 2019. Patients with submandibular duct dilatation of ≥4 mm confirmed by magnetic resonance imaging sialography (sialo-MRI), who also underwent sialendoscopy to identify any associated stenosis, were included. Patients with lithiasis, stenosis, an imperforate ostium, or a history of trauma or surgery to the floor of the mouth were excluded. Five patients (three female, two male) aged 30-76 years with idiopathic duct dilatations in nine submandibular glands were included. The most commonly reported symptoms were submandibular swelling, pruritus, and discomfort, mostly outside mealtimes. Recurrence of symptoms after treatment was frequent. This study is novel in describing submandibular megaducts as opposed to dilatation caused by high pressure associated with stenosis, with confirmation by sialo-MRI and sialendoscopy.

Revision Rhytidectomy: Pearls and Pitfalls

While rhytidectomy can yield remarkable results, some patients may subsequently require revision rhytidectomy due to either unsatisfactory outcomes from primary surgery or the natural aging process many years later. Like most other secondary plastic surgical procedures, revision rhytidectomy is a complex undertaking and fraught with potential pitfalls. This can be attributable to natural or postsurgical alterations that can occur with the facial skin, superficial musculoaponeurotic system/platysma muscle, and/or facial nerve landmarks. Additionally, complications such as cobra neck deformity, pixie ear deformity, and synkinesis can add an extra level of complexity to revisional surgery. Furthermore, as more surgeons are performing deep-plane facelifts and more aggressive neck procedures, the risks are further amplified in revisional surgery. In this article, we review the challenges that a facelift surgeon may face when performing revision rhytidectomy and the technical considerations to overcome these obstacles.

Management of a salivary fistula following removal of mandibular distractors in a neonate

There are multiple management options for treatment of iatrogenic salivary fistulas including reduced oral intake, pressure dressings, total parotidectomy, tympanic neurectomy, surgical repair, radiation therapy, and pharmacotherapy. However, the optimal management of salivary fistulas is unclear due to uncertain efficacy and adverse outcomes. We present a case of a neonate that developed a submandibular fistula following removal of mandibular distractors and was ultimately successfully managed using intralesional botulinum toxin injection. The purpose of this communication is to summarize the management of this complication in the context of the current literature.

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.

Botulinum toxin for chronic parotid sialadenitis: A case series and systematic review

OBJECTIVE

To evaluate salivary gland chemodenervation with botulinum toxin in chronic parotid sialadenitis.

METHODS

Patients who underwent parotid gland chemodenervation for chronic sialadenitis due to duct stenosis refractory to siaendoscopy were reviewed (case series). Additionally, a systematic review of the literature on botulinum toxin injection for chronic parotid sialadenitis was performed. Inclusion criteria included studies containing original data on botulinum toxin injections in patients with chronic sialadenitis symptoms.

RESULTS

Sialadenitis symptoms from 10 patients with 13 affected parotid glands were examined. All had duct stenosis diagnosed on sialendoscopy, refractory sialadenitis symptoms, and received parotid onabotulinum toxin injection(s) (median dose 65U). Of patients with 3-month follow-up, 78% reported significant improvement in symptoms. Mean Chronic Obstructive Sialadenitis Symptoms (COSS) Score improved at 3 months post-injection (47-25.9, P = .039) with significant reduction in gland pain frequency and gland swelling severity. No patients had a facial nerve paralysis or increased xerostomia. With the systematic review, 518 abstracts were reviewed and 11 studies met inclusion criteria and included case series or case reports with a total of 40 patients treated with botulinum toxin for chronic parotitis. Thirty-four out of a total of 35 patients in the studies (97%) reported complete (9, 26%) or partial (25, 71%) improvement in sialadenitis symptoms with minimal complications.

CONCLUSION

Parotid gland chemodenervation with botulinum toxin is a minimally invasive treatment option for symptomatic chronic sialadenitis refractory to medical treatment or sialendoscopy. Botulinum toxin injections alleviate gland pain and swelling associated with salivary obstruction and provide an alternative to parotidectomy for recurrent sialadenitis.Level of evidence: 4.

Management of parotid fistula and Frey's syndrome with Botulinum neurotoxin type A

The common cause of parotid fistula is parotid gland surgery and is frequently due to injury to the gland rather than to the duct. The frequency of postparotidectomy fistula is 14%. Other causes include facial trauma, congenital anomalies of the parotid gland, malignancies originating from the parotid gland and infections. Although there are several options for the treatment of parotid fistula and Frey's syndrome, very few treatment options are deemed optimal. The use of Botulinum A neurotoxin as a conservative method of treatment for parotid fistula and Frey's syndrome is a recent and evolving concept.

Management of Acute Facial Nerve and Parotid Injuries

Acute soft tissue trauma to the head and neck is a common reason for emergency department presentation and should be appropriately evaluated by a facial plastic surgeon. The evaluation of a patient who has suffered facial trauma should always include a comprehensive facial nerve exam and carry a low threshold of suspicion for parotid duct injury when involving the cheek. Injuries to the facial nerve and parotid duct can result in significant long-term functional, cosmetic, and emotional morbidity, particularly when diagnosis is delayed. In the repair of facial nerve transection, neurorrhaphy technique is primarily based on the ability to obtain tension-free anastomosis and outcomes are in large part related to timing of repair. Parotid duct injuries are generally repaired based on the site of ductal injury. In this article, we present a guide to the relevant anatomy of the facial nerve branches and the parotid duct, the important factors guiding treatment decisions alongside their related risks and benefits, as well as the management of complications of facial nerve neurorrhaphy and parotid duct injuries and repair.

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.

Botulinum Toxin Injection for Chronic Parotitis: A Multi-Center and Prospective Trial

OBJECTIVE

When conservative therapy fails for chronic parotitis, sialendoscopic treatment or surgical excision can be considered. However, these are financially costly or invasive. Thus, this study aimed to evaluate the clinical efficacy and safety of botulinum toxin (BTX) injection and to further analyze its effect on parotid gland function and volume using salivary single-photon emission computed tomography (SPECT)-computed tomography (CT).

METHODS

This clinical trial has been registered in the Clinical Research Information Service, Republic of Korea. Fourteen patients with chronic parotitis received BTX injections into the parotid glands. Pain, postprandial pain, swelling, aesthetic discomfort, and salivary flow rate were assessed before injection, at 2 weeks, and at 1, 3, and 6 months. Salivary SPECT-CT was performed before injection and again 3 and 6 months after to assess the volume and uptake changes.

RESULTS

All subjective symptoms decreased significantly until 1 month and then increased. However, at 6 months, all subjective symptoms were determined to be better than before injection. The unstimulated and stimulated salivary flow rate did not show a significant difference over time. No significant difference was noted in parotid gland volume or uptake on salivary SPECT-CT over time.

CONCLUSION

BTX injection can be an alternative treatment option for chronic parotitis.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E1903-E1909, 2021.

Type a botulinum toxin in the management of spontaneous salivary otorrhea: a case report

BACKGROUND

Spontaneous salivary otorrhea is a rare presentation only previously documented twice in literature where parotid salivary secretions are found in the external auditory canal. Conventional treatment of spontaneous parotid salivary fistulas includes surgical management with interposed grafts, fistula tract ablation, and possible superficial parotidectomy. Associated risks include facial nerve injury, Frey syndrome and facial scarring. Here we report the first case of spontaneous salivary otorrhea conservatively managed with a type A botulinum toxin (BTA) injection.

CASE PRESENTATION

A 17-year-old female presented with a 5-month history of left sided otorrhea and transient left facial swelling associated with gustatory stimulation. The otorrhea fluid tested positive for salivary amylase and negative for beta 2 transferrin. Fifty units of BTA were injected into the left parotid gland under ultrasound guidance. Cessation of symptoms was achieved 3 weeks after intervention. The patient remains symptom-free at the 2 year follow up.

CONCLUSION

BTA injection was well tolerated under ultrasound guidance and has led to long-term resolution of the patient's symptoms. BTA injection appears to be a safe and effective way to conservatively manage this rare presentation of spontaneous salivary otorrhea.

Botulinum toxin A is an effective therapeutic tool for the management of parotid sialocele and fistula: A systematic review

OBJECTIVES

In the management of parotid sialocele and fistula, various conservative and surgical methods have been described. Some studies have described the use of Botulinum toxin A (Botox A) for the management of parotid sialocele and fistula. This is a less invasive and potentially equally effective option. We therefore conducted a systematic review on the current body of literature relating to this specific use of Botox A.

METHODS

A search strategy was conducted in July 2019 using the following electronic databases: Cochrane Database of Systematic Reviews, EMBASE, Google Scholar, PubMed, Scopus, and Web of Science. A search of all articles from inception until 31 August 2019 was performed.

RESULTS

Literature searches of electronic databases identified 67 articles eligible for review, of which 15 fulfilled all criteria. These studies were small and in total only 47 patients were included. The majority of sialoceles and fistulas presented as a complication of surgery (77%) with the remaining cases occurring as a result of trauma. The typical age at presentation was between 32 and 88 years of age (mean age of 52 years). All patients were initially treated with and failed other conservative measures. Botox A injection was considered as a final conservative treatment option. The toxin was administered percutaneously in all cases of parotid sialocele and fistula. Dosage of Botox ranged from 10 to 200 units with majority of patients (58%) requiring only one injection. The overall success rate for patients treated with Botox A injections ranged between 70 and 100% for parotid sialoceles and fistulas.

CONCLUSION

Botox A injections are successful in the treatment of parotid sialoceles and fistulas and should be considered before the use of invasive conventional options. Further studies with larger numbers are needed to ratify this recommendation. Success rate for patients, treated with Botox A injection was between 70 and 100% for parotid sialocele and fistula. Patients who failed initial treatment with Botox A were re-administered with Botox A and eventually resolved.

Botulinum Neurotoxins and Cancer-A Review of the Literature

Botulinum neurotoxins (BoNT) possess an analgesic effect through several mechanisms including an inhibition of acetylcholine release from the neuromuscular junction as well as an inhibition of specific pain transmitters and mediators. Animal studies have shown that a peripheral injection of BoNTs impairs the release of major pain transmitters such as substance P, calcitonin gene related peptide (CGRP) and glutamate from peripheral nerve endings as well as peripheral and central neurons (dorsal root ganglia and spinal cord). These effects lead to pain relief via the reduction of peripheral and central sensitization both of which reflect important mechanisms of pain chronicity. This review provides updated information about the effect of botulinum toxin injection on local pain caused by cancer, painful muscle spasms from a remote cancer, and pain at the site of cancer surgery and radiation. The data from the literature suggests that the local injection of BoNTs improves muscle spasms caused by cancerous mass lesions and alleviates the post-operative neuropathic pain at the site of surgery and radiation. It also helps repair the parotid damage (fistula, sialocele) caused by facial surgery and radiation and improves post-parotidectomy gustatory hyperhidrosis. The limited literature that suggests adding botulinum toxins to cell culture slows/halts the growth of certain cancer cells is also reviewed and discussed.

Intraductal Salivary Gland Infusion With Botulinum Toxin

Background

Administration of botulinum toxin through intraductal salivary infusion may decrease the risks of percutaneous needle injection and improve delivery to permeate the entire gland parenchyma.

Methods

The safety of intraductal salivary gland infusion was tested with prospective evaluation of two patients using interviews, clinical examination, and pressure measurement during infusion. Retrospective chart review of two subsequently treated patients assessed treatment of a parotid-cutaneous fistula and sialorrhea.

Results

No complications were identified in the safety study. Pressure changes during infusion supported the concept of botulinum neurotoxin delivery to permeate the gland. Patient-assessed success was subjectively reported as a reduction in the parotid-cutaneous output "by 95%" and the sialorrhea "by 90%" at 2-week follow-up.

Conclusions

The intraductal route of botulinum toxin delivery to salivary glands was without complication and was effective in two patients treated therapeutically. Pressure measurements during infusion may be helpful to direct treatment.

Level of Evidence

4.

Botulinum Toxin A for Sialorrhoea Associated with Neurological Disorders: Evaluation of the Relationship between Effect of Treatment and the Number of Glands Treated

Background: Sialorrhoea and drooling are disabling manifestations of different neurological disorders. The aim of this study was to evaluate the effects of botulinum neurotoxin type A (BoNT/A) injection on hypersalivation in 90 patients with neurological diseases of different aetiologies, and to define the minimum number of injected salivary glands to reduce sialorrhoea. Determining the minimum number of glands that need to be engaged in order to have a significant reduction in drooling may be very useful for establishing the minimum total dosage of BoNT/A that may be considered effective in the treatment of hypersalivation. Methods: Twenty-five mouse units (MU) of BoNT/A (onabotulinumtoxin A, Botox; Allergan, Irvine, CA, USA; 100 MU/2 mL, 0.9% saline; or incobotulinumtoxin A, Xeomin; Merz Pharma, Germany; 100 MU/2 mL, 0.9% saline) were percutaneously injected into the parotid (p) glands and/or submandibular (s) glands under ultrasound control. On this basis, patients were divided into three groups. In group A (30 patients), BoNT/A injections were performed into four glands; in group B (30 patients), into three glands, and in group C (30 patients), into two glands. Patients treated in three glands (group B) were divided into two subgroups based on the treated glands (2 p + 1 s = 15 patients; 2 s + 1 p = 15 patients). Similarly, patients being injected in two glands (group C) were subdivided into three groups (2 p = 10 patients; 1 p + 1 s = 10 patients; 2 s = 10 patients). In patients who were injected in three and two salivary glands, saline solution was injected into the remaining one and two glands, respectively. Assessments were performed at baseline and at 2 weeks after the injections. Results: BoNT/A significantly reduced sialorrhoea in 82 out of 90 patients. The effect was more evident in patients who had four glands injected than when three or two glands were injected. The injections into three glands were more effective than injections into two glands. Conclusions: Our results have shown that BoNT/A injections induced a significant reduction in sialorrhoea in most patients (91%). In addition, we demonstrated that sialorrhoea associated with different neurological diseases was better controlled when the number of treated glands was higher.