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.

Use of Botulinum Toxin in Spasmodic Dysphonia: A Review of Recent Studies

Spasmodic dysphonia (SD), also known as laryngeal dystonia, is a neurological voice disorder that causes involuntary spasms of the vocal cord muscles. This impacts speech to varying degrees and results in strained and strangled voice quality, as in adductor spasmodic dysphonia, or weak, quiet, and breathy, as in abductor spasmodic dysphonia. While there is currently no cure for SD, voice therapy and chemodenervation with botulinum toxin (btx) injections remain the mainstay of management. Surgery may be performed in some cases; however, btx injections are widely used to treat both adductor and abductor forms of SD. While btx injections may show vocal improvement in both types of SD, results can depend on several factors such as the general health of the patient, onset and severity of the condition, dosage, interval between injections, and expertise of the practitioner. While many studies have documented the efficacy of btx for improving vocal symptoms in individuals with SD, this review aims to discuss some of those studies from the last 10 years.

Factors influencing long-term treatment response to botulinum toxin injection for spasmodic dysphonia

OBJECTIVE

The purpose of this study was to evaluate the outcomes of long-term botulinum toxin type A (BoNTA) treatment for adductor spasmodic dysphonia (AdSD) and to determine the factors predictive of treatment response by investigating dose stability and average intervals.

DESIGN

Retrospective cohort study.

SETTING

Academic tertiary medical centre.

EXPOSURES

A total of 470 patients with adductor spasmodic dysphonia, who received electromyography-guided BoNTA injections over 12 years, were retrospectively enrolled in this study.

MAIN OUTCOMES AND MEASURES

The patients' demographic data, baseline voice dynamics and treatment profiles (dose, frequency and intervals) were evaluated. Factors correlating with the dose adjustment ratio (number of increasing dosing/total number of BoNTA toxin injections) and changes in intervals between injections were statistically analysed.

RESULTS

A total of 122 patients, who received ≥ 4 injections and whose average treatment interval was < 240 days, were finally evaluated. Of them, 115 (94.3%) were female and seven (5.7%) were male, and the mean age at initial treatment was 34.89 ± 13.07 and 41.14 ± 12.71 years, respectively. On average, patients received 18.00 ± 13.33 injections (1.67 ± 0.60 U/injection) to alternating unilateral vocal folds. The treatment period was 65.07 ± 43.28 months and the mean interval between injections was 4.16 ± 1.28 months. The mean dose adjustment ratio among patients who received ≥ 4 injections was 0.15 ± 0.13, and dose changes occurred 4.36 times/patient. The patients' age and gender significantly affected the treatment response, where younger or female patients showed greater dosing variability and shorter intervals between injections. However, the baseline voice dynamics (voice handicap index, fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, maximum phonation time and degree of voice breaks) did not predict the dose adjustment ratio or interval changes. In addition, patients with fluctuating doses showed lower age and higher VHI subscale scores, and patients with short-treatment interval (< 100 days) showed higher SDF0.

CONCLUSIONS

Almost all patients received stable low doses of BoNTA over time, irrespective of the baseline results. Patients' age, gender and VHI scores were correlated with poor treatment responses, such as frequent dose changes and shorter intervals between injections.

Treatment of Keloid Scars with Botulinum Toxin Type A versus Triamcinolone in an Athymic Nude Mouse Model

BACKGROUND

Keloid scarring is a serious condition that mostly affects patients of African or Asian descent. Often disfiguring, this condition can have devastating psychosocial consequences. To date, no treatment modality has been proven ideal. The authors' objectives were (1) to determine the efficacy of botulin toxin type A injection for the treatment of keloid scars compared to steroid injection and to control saline injection (this was achieved through a basic science animal model using athymic nude mice and implanted human keloid tissue); and (2) to analyze the histopathologic changes that occur in an organized keloid scar following botulinum toxin type A injection as compared to steroid and saline injections.

METHODS

Keloid scars from four patients were excised and implanted subcutaneously into 28 mice. Three small keloid tissue samples were implanted in each of the 28 mice. One week after implantation, each implant received one of three injections: botulinum toxin type A (treatment drug), saline (control), or steroid injection (first-line gold standard). The keloid tissue was extracted 3 weeks after implantation. Weight analysis, immunohistochemistry, and standard hematoxylin and eosin pathologic analysis were performed on each extracted tissue sample.

RESULTS

Paired t test analysis of pretreatment and posttreatment tissue weights revealed a statistically significant difference between the treatment and control groups (p < 0.05). Analysis by a blinded pathologist confirmed fewer collagen bundles in the treatment group. Immunohistochemistry with Ki-67, a marker of cell proliferation, revealed significantly less staining in the treatment groups.

CONCLUSION

Botulinum toxin type A could be an effective treatment for keloid scars.

Subcutaneous Neurotrophin 4 Infusion Using Osmotic Pumps or Direct Muscular Injection Enhances Aging Rat Laryngeal Muscles

Laryngeal dysfunction in the elderly is a major cause of disability, from voice disorders to dysphagia and loss of airway protective reflexes. Few, if any, therapies exist that target age-related laryngeal muscle dysfunction. Neurotrophins are involved in muscle innervation and differentiation of neuromuscular junctions (NMJs). It is thought that neurotrophins enhance neuromuscular transmission by increasing neurotransmitter release. The neuromuscular junctions (NMJs) become smaller and less abundant in aging rat laryngeal muscles, with evidence of functional denervation. We explored the effects of NTF4 for future clinical use as a therapeutic to improve function in aging human laryngeal muscles. Here, we provide the detailed protocol for systemic application and direct injection of NTF4 to investigate the ability of aging rat laryngeal muscle to remodel in response to NTF4 application. In this method, rats either received NTF4 either systemically via osmotic pump or by direct injection through the vocal folds. Laryngeal muscles were then dissected and used for histological examination of morphology and age-related denervation.

Spasmodic dysphonia: a seven-year audit of dose titration and demographics in the Indian population

Objectives:

This study aimed to evaluate the demographics of spasmodic dysphonia in the Indian population and to analyse the optimum dose titration of botulinum toxin type A in this group. A comparative analysis with international studies was also performed.

Method:

The study involved a retrospective analysis and audit of botulinum toxin type A dose titration in spasmodic dysphonia patients who visited our voice clinic between January 2005 and January 2012.

Results:

The average total therapeutic dose required for patients with adductor spasmodic dysphonia was 4.2 U per patient per vocal fold (total 8.4 U per patient), and for patients with abductor spasmodic dysphonia, it was 4.6 U per patient.

Conclusion:

Our audit revealed that 80 per cent of the spasmodic dysphonia patients were male, which contrasts dramatically with international studies, wherein around 80 per cent of spasmodic dysphonia patients were female. Our study also revealed a higher dose titration of botulinum toxin for the Indian spasmodic dysphonia population in both adductor and abductor spasmodic dysphonia cases.