Histological and immunohistochemical findings of the action of botulinum toxin in salivary gland: systematic review

The Volumetric Effect of Botulinum Toxin Type A Injection on the Parotid Gland: A Randomized Controlled Trial

BACKGROUND

Botulinum neurotoxin type A (BTX-A) to the masseter muscle is a useful tool for the aesthetic narrowing of the width of the lower face. The administration of BTX-A to visible parotid glands is also effective to reduce lower facial width. However, no studies have quantitatively analyzed the effect of BTX-A on the parotid glands.

METHODS

The purpose of this study was to confirm the impact of BTX-A injection on the parotid gland and to suggest the effective dosage of BTX-A in facial slimming. This study was conducted by selecting patients who desired facial slimming from among patients who required surgery for a facial bone fracture. Patients undergoing BTX-A injection were randomized to high-dose, low-dose, and placebo groups, and different doses of BTX-A for each group were injected into both parotid glands during facial bone surgery.

RESULTS

A total of 30 patients were enrolled in this study. Ten patients in the high-dose group, eight in the low-dose group, and nine in the control group completed the clinical trial. There were significant changes in both the high- and low-dose groups compared with the control group ( P < 0.001, P < 0.001), and in interaction of time and group ( P < 0.001). Volume recovery after 3 months was found in 7.6% in the high-dose group and in 4.8% in the low-dose group.

CONCLUSION

BTX-A injection into parotid glands can be an effective treatment option in managing salivary gland enlargement for lower face contouring.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

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.

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.

Botulinum toxin therapy: functional silencing of salivary disorders

Botulinum toxin (BTX) is a neurotoxic protein produced by Clostridium botulinum, an anaerobic bacterium. BTX therapy is a safe and effective treatment when used for functional silencing of the salivary glands in disorders such as sialoceles and salivary fistulae that may have a post-traumatic or post-operative origin. BTX injections can be considered in sialoceles and salivary fistulae after the failure of or together with conservative treatments (e.g. antibiotics, pressure dressings, or serial aspirations). BTX treatment has a promising role in chronic sialadenitis. BTX therapy is highly successful in the treatment of gustatory sweating (Frey's syndrome), and could be considered the gold standard treatment for this neurological disorder.