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

From Toxin to Treatment: A Narrative Review on the Use of Botulinum Toxin for Autonomic Dysfunction

Since its regulatory approval over a half-century ago, botulinum toxin has evolved from one of the most potent neurotoxins known to becoming routinely adopted in clinical practice. Botulinum toxin, a highly potent neurotoxin produced by Clostridium botulinum, can cause botulism illness, characterized by widespread muscle weakness due to inhibition of acetylcholine transmission at neuromuscular junctions. The observation of botulinum toxin's anticholinergic properties led to the investigation of its potential benefits for conditions with an underlying etiology of cholinergic transmission, including autonomic nervous system dysfunction. These conditions range from disorders of the integument to gastrointestinal and urinary systems. Several formulations of botulinum toxin have been developed and tested over time, significantly increasing the availability of this treatment for appropriate clinical use. Despite the accelerated and expanded use of botulinum toxin, there lacks an updated comprehensive review on its therapeutic use, particularly to treat autonomic dysfunction. This narrative review provides an overview of the effect of botulinum toxin in the treatment of autonomic dysfunction and summarizes the different formulations and dosages most widely studied, while highlighting reported outcomes and the occurrence of any adverse events.

Botulinum toxin in the treatment of sialorrhea in severe neurological patients with tracheotomy

OBJECTIVE

To observe the clinical effect of botulinum toxin type A (BTA) injection into the salivary glands of the severe neurological patients with tracheotomy METHODS: Seven patients with severe neurological disorders after tracheotomy and obvious drooling symptoms were enrolled. BTA was injected into bilateral parotid glands and submandibular glands under the guidance of ultrasound. Unstimulated salivary flow rate (uSFR) and Drooling Severity and Frequency Scale (DSFS) were used to evaluate drooling before injection, 1 week, and 4 weeks after injection. We compared the extubation time, time of changing from balloon cannula to metal cannula, hospitalization time and incidence of recurrent pulmonary infection between these patients and other patients accepted conventional curation.

RESULTS

(1) The drooling severity scale (DSFS-S), the drooling frequency scale (DSFS-F), the drooling frequency and severity scale total score (DSFS-T) were significantly lower at 4 weeks after BTA injection compared to prior-treatment (p < .001). (2) uSFR of 1 week and 4 weeks were both statistically decreased than the untreated condition (p < .001). (3) Compared with the conventional group, the time of changing from balloon cannula to metal cannula was shortened obviously (p < .05) and incidence of recurrent pulmonary infection was clearly decreased (p < .05) after BTA treatment CONCLUSION: Ultrasound-guided BTA injection into salivary glands can effectively reduce saliva secretion. We also found that the time of changing cannula was shortened obviously and the incidence of recurrent pneumonia infection was reduced. BTA injection of salivary glands to cure drooling could advance to the clinical therapy in severe neurological patients after tracheotomy.

[Therapy of Sialorrhea with Botulinum Toxin - An Update]

The most important salivary glands are the paired parotid and submandibular glands. Adults produce 1 to 1.5 liters of saliva which are then regularly swallowed. When the act of swallowing is disturbed, salivation occurs. More rarely, the cause can be found in increased saliva production, for example, when caused through medication. Sialorrhea impairs the quality of life substantially and is frequently often socially stigmatizing. Therapy includes conservative measures such as functional dysphagia therapy, oral or transdermal application of anticholinergics, as well as, in selected cases, radiation and surgical measures. Over the last 20 years, local injection of botulinum toxin has been successfully applied in the treatment of this condition. With approval of incobotulinumtoxinA toxin for children and adults, this procedure will become the therapy of choice for chronic sialorrhea. The results of the phase III registration trials have demonstrated high efficacy and good safety of the injection treatment in both children and adults.

Placebo-Controlled Clinical Trial of IncobotulinumtoxinA for Sialorrhea in Children: SIPEXI

BACKGROUND AND OBJECTIVES

To investigate the efficacy and safety of repeated injections of incobotulinumtoxinA (incoBoNT/A) for treatment of chronic sialorrhea (drooling) associated with neurologic disorders (e.g., cerebral palsy, traumatic brain injury) or intellectual disability in children and adolescents in a prospective phase III study (SIPEXI [Sialorrhea Pediatric Xeomin Investigation]).

METHODS

The study enrolled 2- to 17-year-old patients with sialorrhea due to neurologic disorders or intellectual disability. Patients received body weight-dependent doses of incoBoNT/A (20-75 U). A main period with 1 injection cycle (placebo-controlled, double-blind, 6- to 17-year-olds) was followed by an open-label extension with up to 3 further cycles. An additional cohort of 2- to 5-year-olds received active treatment throughout the study. Coprimary endpoints were the change in unstimulated salivary flow rate (uSFR) from baseline to week 4 and the carers' Global Impression of Change Scale (GICS) rating at week 4. Adverse events were recorded.

RESULTS

In the main period, 220 patients aged 6-17 years were randomized and treated (148 patients in incoBoNT/A group, 72 patients in placebo group). A total of 35 patients aged 2-5 years received incoBoNT/A (no placebo). A total of 214 patients aged 6-17 years and 33 patients aged 2-5 years continued treatment in the open-label extension period. For the 6- to 17-year-olds, a significant difference between incoBoNT/A and placebo was seen in mean uSFR decrease (difference -0.06 g/min; p = 0.0012) and the carers' GICS rating (difference 0.28 points; p = 0.032) at week 4, in favor of active treatment. The secondary endpoints consistently supported these results. A sustained benefit was observed during the extension. Incidences of adverse events were comparable between incoBoNT/A and placebo and did not increase notably with repeated injections. The most common adverse events were respiratory infections. Efficacy and safety were also favorable in the uncontrolled cohort of 2- to 5-year-olds.

DISCUSSION

Both co-primary efficacy endpoints were reached and superiority of incoBoNT/A over placebo was confirmed. IncoBoNT/A (up to 75 U, up to 4 cycles) is an effective and well-tolerated treatment for sialorrhea associated with neurologic disorders in children.

TRIAL REGISTRATION INFORMATION

Clinicaltrials.gov: NCT02270736 (clinicaltrials.gov/ct2/show/results/NCT02270736); EU Clinical Trials Register: 2013-004532-30 (clinicaltrialsregister.eu/ctr-search/search?query=2013-004532-30).

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that injection of incobotulinumtoxinA decreases drooling in children aged 6 to 17 years with neurologic disorders.

Efficacy and safety of botulinum toxin for treating sialorrhea: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Sialorrhea often happens in patients with neurologic disorders, and botulinum toxin (BoNT), which inhibits acetylcholine activation, may be an effective treatment for drooling. This systematic review and meta-analysis of randomized control trials aims to evaluate the efficacy and safety of BoNT in adults and children with sialorrhea due to neurological disorders.

METHODS

The PubMed, Embase, and Cochrane databases were searched for relevant studies published before August 2021. The pooled estimate of outcomes was calculated using a random effect model.

RESULTS

The review included 17 studies involving 981 patients. Compared with placebo, both BoNT type A (BoNT-A) and BoNT type B (BoNT-B) alleviated drooling frequency and severity (mean difference, 95% CI; BoNT-A: -1.20, -1.89 to -0.51; BoNT-B: -1.62, -2.07 to -1.17), reduced saliva weight (BoNT-A: -1.70, -2.30 to -1.10; BoNT-B: -1.12, -1.97 to -0.27), and improved global impression of change (BoNT-A: -1.30, -1.73 to -0.86; BoNT-B: -1.58, -1.95 to -1.21) in adults 4 weeks postinjection. BoNT-B remained effective at 12 weeks. In children, BoNT-A and BoNT-B alleviated sialorrhea symptoms (BoNT-A: -1.63, -2.42 to -0.85; BoNT-B: -5.20, -6.03 to -4.37) and BoNT-A reduced saliva weight (-0.77, -1.54 to 0.00) at 4 weeks postinjection. After 12 weeks, BoNT-B remained efficacious. Most adverse effects (AEs) were mild to moderate and self-limited.

CONCLUSIONS

There is moderate certainty of evidence (COE) that either BoNT-A or BoNT-B could relieve sialorrhea after 4 and 12 weeks of follow-up without significantly more severe AEs in adults. However, the COE is very low to low in children.

MicroRNA-mRNA expression profiles and functional network after injection of botulinum toxin type A into submandibular glands

Botulinum toxin type A (BTXA) is effective for the treatment of sialorrhea. MicroRNAs (miRNAs) have significant functions in salivary diseases, but the role of miRNAs during BTXA-inhibited salivary secretion is not yet clear. A total of 19 differentially expressed (DE) miRNAs and 1072 DE mRNAs were identified following BTXA injected into submandibular glands of rats (n = 4) through miRNA sequencing and microarray analysis. Bioinformatic analysis identified that several pathways may be associated with the inhibition of salivary secretion, such as the MAPK signalling pathway, tight junctions, and cytokine-cytokine receptor interaction. We predicted the target genes of DE miRNAs and established the miRNA-mRNA interaction network. The intersection of DE mRNAs and target genes of DE miRNAs was performed and seven mRNAs were obtained: Egr2, Paqr9, Zkscan1, Usp6n, Cyb561a3, Zfhx4, and Clic5. These findings explore the mechanism of BTXA in inhibiting salivary secretion and probably will provide new ideas for clinical application.

Dysphagia in neurological diseases: a literature review

Dysphagia is defined as an impairment of this complex and integrated sensorimotor system. It is estimated that 400,000 to 800,000 individuals worldwide develop neurogenic dysphagia per year. Neurogenic dysphagia is typically occurring in patients with neurological disease of different etiologies. A correct and early diagnosis and an appropriate management of dysphagia could be useful for improving patient’s quality of life and may help to prevent or delay death. In the present review, we discuss thoroughly the anatomy and physiology of swallowing and also the pathophysiological mechanisms involved in impaired swallowing, as well as the diagnosis, management, and potential treatments of neurogenic dysphagia. Assessment of neurogenic dysphagia includes medical history, physical exam, and instrumental examinations (fiberoptic endoscopic evaluation of swallowing, videofluoroscopic swallowing study, electromyography). Pharmacological treatment of these problems includes oral anticholinergic drugs. Surgical myotomy of the cricopharyngeal muscle showed an important improvement of oropharyngeal dysphagia associated to upper esophageal sphincter hyperactivity. Chemical myotomy of the upper esophageal sphincter by local injections of botulinum toxin type A into the cricopharyngeal muscle has been proposed as an alternative less invasive and less unsafe than surgical myotomy.

Cost-Effectiveness of IncobotulinumtoxinA in the Treatment of Sialorrhea in Patients with Various Neurological Conditions

INTRODUCTION

Sialorrhea is a common and debilitating symptom associated with neurological conditions, which can result in considerable physical and psychosocial complications. In Australia, management options are limited and further impeded by the lack of approved treatments. Whilst there is emerging evidence for the efficacy and tolerability of botulinum toxin (BoNT) for the treatment of sialorrhea in patients with neurological conditions, the cost-effectiveness of the treatment is yet to be established.

OBJECTIVES

To evaluate the cost-effectiveness of incobotulinumtoxinA for the treatment of chronic troublesome sialorrhea caused by various neurological conditions from the Australian healthcare perspective.

METHODS

A Markov state transition model was developed to perform a cost-utility analysis comparing incobotulinumtoxinA with standard of care (SoC). The model consisted of a hypothetical cohort of patients transiting between three severity-based health states, defined according to the Drooling Severity and Frequency Scale (DSFS), in 16-weekly cycles over 5 years. All clinical and utility inputs were sourced from a single placebo-controlled randomised clinical trial. Only direct healthcare costs were considered, and potential indirect costs such as carer's time and lost productivity were ignored. The primary outcome measure was the incremental cost per quality-adjusted life-year (QALY). Univariate and probabilistic sensitivity analyses were conducted.

RESULTS

The model demonstrated that proportionally more patients spent time in less severe sialorrhea health states in the incobotulinumtoxinA arm. For example, over the 5-year period, patients receiving incobotulinumtoxinA were estimated to spend 1.6 years with minimal or no sialorrhea, while no patients achieved this level of improvement under SoC. IncobotulinumtoxinA was shown to have an incremental cost per QALY gained of A$23,445 when compared with SoC.

CONCLUSIONS

The quality of life (QoL) of patients with sialorrhea caused by neurological conditions was considerably compromised. IncobotulinumtoxinA was shown to successfully alleviate sialorrhea and it was demonstrated to be a cost-effective intervention when compared with SoC alone.

Therapy of Sialorrhea with Botulinum Neurotoxin

Botulinum neurotoxin (BoNT) is considered the treatment of choice for various symptoms and diseases such as focal dystonia and focal spasticity. The effects of BoNT on the salivary glands have also been known for years, but their use was limited because of a lack of approval studies. Now the indication of sialorrhea is approved in some countries for incobotulinumtoxinA, such as the USA and Europe, and therapy could also become the treatment of choice. According to the pivotal study, a dose of 100 units of incobotulinumtoxinA, which is divided into the parotid and submandibular glands, is recommended. RimabotulinumtoxinB is approved in the USA only. To define the value of this therapy, we must consider anatomy, physiology, and available therapies. Therapy includes conservative measures such as functional dysphagia therapy, oral or transdermal application of anticholinergics, and, in selected cases, radiotherapy and surgical procedures. A combination of different approaches is optional. On the basis of the evidence and clinical experience, BoNT injections will be the first line of pharmacotherapy for chronic sialorrhea.

The burden of sialorrhoea in chronic neurological conditions: current treatment options and the role of incobotulinumtoxinA (Xeomin®)

Sialorrhoea is a frequent symptom of neurological diseases (e.g. Parkinson’s disease, motor neuron disease, cerebral palsy, and stroke) and is defined as excessive saliva accumulation leading to unintentional loss of saliva from the mouth. Sialorrhoea increases the overall burden on the patient and their caregivers, the impact of which can be both physical and psychosocial. Treatments for sialorrhoea range from lifestyle and behavioural guidance, to medications, surgery or radiation. Nonpharmacological interventions include advice on posture, swallowing control, cough management, dietary changes, eating and drinking techniques, and behavioural modification; however, these conservative measures may be ineffective for people with progressive neurological conditions. The pharmacological treatment of sialorrhoea is challenging because medications licensed for this purpose are limited, but treatments can include anticholinergic drugs and botulinum toxins. Surgical treatment of sialorrhoea is typically reserved as a last resort for patients. IncobotulinumtoxinA (Xeomin®) is the first botulinum toxin type A to receive US and UK marketing authorization for the symptomatic treatment of chronic sialorrhoea due to neurological disorders in adults. In this review, we discuss and compare the frequency and method of administration, location of treatment delivery, approximate annual costs and main side effects of botulinum toxin and different anticholinergic drugs. Management of patients with chronic neurological conditions requires input from multiple specialist teams and thus a multidisciplinary team (MDT) approach is considered fundamental to ensure that care is consistent and tailored to patients’ needs. To ensure that adult patients with neurological conditions receive the best care and sialorrhoea is well managed, we suggest a potential clinical care pathway for sialorrhoea with a MDT approach, which healthcare professionals could aspire to.

Long-term incobotulinumtoxinA treatment for chronic sialorrhea: Efficacy and safety over 64 weeks

BACKGROUND

Botulinum neurotoxin (BoNT) is an effective treatment for chronic sialorrhea; however, reliable and robust evidence supporting long-term efficacy and safety is lacking. This study investigated the efficacy and safety of repeated incobotulinumtoxinA injections for chronic sialorrhea over 64 weeks.

METHODS

Adults with sialorrhea were randomized (2:2:1) to incobotulinumtoxinA 75 U, incobotulinumtoxinA 100 U (n = 74 each), or placebo (n = 36) in the double-blind, placebo-controlled main period (NCT02091739). Eligible subjects entered the extension period and received dose-blinded incobotulinumtoxinA 75 or 100 U in three further 16±2-week injection cycles. Efficacy and safety assessments in subjects who received incobotulinumtoxinA throughout the study included unstimulated salivary flow rate (uSFR), subjects' Global Impression of Change Scale (GICS), Drooling Severity and Frequency Scale (DSFS), modified Radboud Oral Motor Inventory for Parkinson's Disease (mROMP) drooling, speech, and swallowing symptom scores, and incidence of adverse events (AEs).

RESULTS

In total, 173/184 subjects (94%) completed the main period and entered the extension period; 141 subjects received incobotulinumtoxinA 75 U (n = 69) or 100 U (n = 72) in both periods. Mean uSFR decreased consistently with repeated incobotulinumtoxinA 75 and 100 U treatment and by -0.16 and -0.17, respectively, at the end-of-study visit. Subjects' GICS, DSFS, and mROMP drooling scores also improved at all assessments. mROMP speech and swallowing scores remained stable. The most common treatment-related AEs during the extension period were dry mouth (4.4% and 11.1%) and dysphagia (1.5% and 4.2%).

CONCLUSIONS

Data support long-term efficacy and safety of repeated incobotulinumtoxinA treatment for sialorrhea, with no additional safety concerns reported over 64 weeks.

Botulinum Toxin Type A in Dental Medicine

Botulinum toxins (BoNTs) are a product of the bacteria Clostridium botulinum. By entering nerve endings, they cleave and inactivate SNARE proteins, which are essential for neurotransmitter release. Prevention of acetylcholine release at the neuromuscular junction causes long-lasting and potentially fatal flaccid paralysis-a major feature of botulism. However, an intramuscular injection of minute amounts of BoNTs, primarily type A (BoNT-A), has useful long-lasting muscle relaxation effects on spastic motor disorders. This characteristic of BoNT-A is widely used in neurology and cosmetics. Over the last few decades, it has been demonstrated that the functions of BoNT-A are not limited to muscle-relaxing or autonomic cholinergic effects but that it can act as an analgesic agent as well. More recently, it was revealed that this antinociceptive effect starts after entering the sensory nerve endings, where these agents are axonally transported to the central nervous system, suggesting that at least part of their analgesic effect might be of central origin. Because of its antinociceptive effect, BoNT-A is currently approved for treatment of chronic migraine; nonetheless, case reports and preclinical and clinical experiments indicating its benefit in numerous potential painful conditions have increased. In the field of dentistry, the US Food and Drug Administration approved BoNT-A for the treatment of sialorrhea only. Legal status of the use of BoNT-A in other countries is less known. However, there are controlled clinical trials suggesting its efficacy in other conditions, such as bruxism, temporomandibular disorders, and trigeminal neuropathic pain. Thereby, using criteria of the American Academy of Neurology, we critically reviewed the uses of BoNTs in oral medicine and found it effective for trigeminal neuralgia (category A) and probably effective in temporomandibular disorders and bruxism.

IncobotulinumtoxinA for hypersalivation in patients with amyotrophic lateral sclerosis: an open-label single-centre study

The objective of this study is to discover whether incobotulinumtoxinA (inco) can reduce relative hypersalivation in patients with amyotrophic lateral sclerosis (ALS). 14 patients with ALS (8 males and 6 females, age 55.4 ± 16.3 years) received ultrasound-guided injection of inco 100 MU in both parotid glands and inco 50 MU in both submandibular glands. Saliva production was gravimetrically measured with three cotton rolls placed in the mouth. Weight increase after 5 min was measured on an electronic scale. Subjective saliva production was registered with drooling frequency scale (DFS) and drooling severity scale (DSS). Saliva production was gravimetrically reduced at week 4 (p = 0.04), week 8 (p = 0.01) but not after week 12 after BT application. DFS was reduced at week 4 (p = 0.04), week 8 (p = 0.02), but not after week 12. DSS was reduced at week 4 (p = 0.03), week 8 (p = 0.04) and week 12 (p = 0.04). Patients in our study did not experience changes in their swallowing patterns or any other safety-relevant events. Inco is effective and well tolerated for saliva reduction in patients with ALS for 8-12 weeks.

Botulinum toxin for ductal stenosis and fistulas of the main salivary glands

This study was performed to present the authors' experience with botulinum toxin therapy for salivary stenosis and salivary fistula in terms of the procedure, dosage, effectiveness, and complications. A retrospective study of all patients treated in the maxillofacial surgery department for salivary stenosis or fistula from January 2014 to September 2018 was performed. Intraglandular injections of incobotulinumtoxinA (Xeomin) were utilized. The frequency of relapse and the pain recorded before injection and at 3 months after each injection or fistula resolution were assessed. Swallowing dysfunction or any diffusion of toxin into the facial muscles was recorded. This study included 22 patients (mean age 53 years). Botulinum therapy was indicated for parotid duct stenosis in 14 patients, submandibular duct stenosis in four patients, and parotid fistula in four patients. The frequency of relapse (P =  0.0001) and pain level (P =  0.0001) decreased after botulinum therapy. The average duration of the botulinum effect was 4.50±2.00 months after the first injection. No complication was observed. Botulinum therapy with 100 IU of Xeomin proved effective at resolving salivary fistula. Botulinum therapy is an effective treatment for symptoms of salivary duct stenosis in patients for whom minimally invasive procedures have failed. Botulinum therapy can also be used for the treatment of salivary fistulas.

SIAXI: Placebo-controlled, randomized, double-blind study of incobotulinumtoxinA for sialorrhea

Objective

This pivotal phase III study, SIAXI, investigated the efficacy and safety of incobotulinumtoxinA for the treatment of chronic sialorrhea due to Parkinson disease (PD), atypical parkinsonism, stroke, or traumatic brain injury (TBI).

Methods

Adult patients with PD (70.7%), atypical parkinsonism (8.7%), stroke (19.0%), or TBI (2.7%) were randomized (2:2:1) to double-blind treatment with placebo (n = 36), or total doses of incobotulinumtoxinA 75 U (n = 74) or 100 U (n = 74), in a single treatment cycle. The coprimary endpoints were change in unstimulated salivary flow rate from baseline to week 4, and patients' Global Impression of Change Scale score at week 4. Adverse events were recorded throughout.

Results

A total of 184 patients were randomized. Both incobotulinumtoxinA dose groups showed reductions in mean unstimulated salivary flow rate at week 4, with a significant difference vs placebo in the incobotulinumtoxinA 100 U group (p = 0.004). Patients' Global Impression of Change Scale scores also improved at week 4, with a significant difference vs placebo in the incobotulinumtoxinA 100 U group (p = 0.002). A lasting effect was observed at week 16 post injection. The most frequent treatment-related adverse events in the incobotulinumtoxinA 75 U and 100 U groups were dry mouth (5.4% and 2.7% of patients) and dysphagia (2.7% and 0.0% of patients).

Conclusions

IncobotulinumtoxinA 100 U is an effective and well-tolerated treatment of chronic sialorrhea in adults.

ClinicalTrials.gov identifier

NCT02091739.

Classification of evidence

This study provides Class I evidence that incobotulinumtoxinA reduces salivary flow rates in patients with chronic sialorrhea due to PD, atypical parkinsonism, stroke, or TBI.

Incobotulinumtoxin A for Sialorrhea in Neurological Disorders: A Real-Life Experience

Botulinum toxin type A is one of the most useful treatments of sialorrhea in neurological disorders. Evidence for the use of incobotulinumtoxin A (inco-A) in the treatment of sialorrhea is limited. Thirty-six patients with sialorrhea were treated with infiltrations of inco-A into both parotid glands. The severity of sialorrhea was evaluated by the Drooling Severity Scale (DSS), and the Drooling Frequency Scale (DFS). Patients’ perceptions of clinical benefit were recorded via the Patient Global Impression of Improvement (PGI-I) scale. Following treatment, there was a significant difference in both the DFS and the DSS (p < 0.001). Clinical benefits on the basis of the PGI-I were present in up to 90% of patients.