Optimizing Botox regimens in patients with adductor spasmodic dysphonia and essential tremor of voice: A 31-year experience

An Overview of Laryngologic Manifestations of Neurologic Diseases

PURPOSE OF REVIEW

Patients with various neurological disorders often present with or manifest during their disease process laryngologic pathology that can lead to significant morbidity. Recognizing and treating this aspect of their disease may be crucial in optimizing patient outcome.

RECENT FINDINGS

We discuss updated information and management regarding various neurological disorders that affect the larynx and how these sequelae are diagnosed and treated. An understanding of the laryngologic manifestations of neurological disorders will facilitate management of these patient populations. Preventing and minimizing complications arising from these sequelae will improve quality of life and optimize patient outcomes.

Patient-Reported Outcomes after False Vocal Folds Injections for Adductor Spasmodic Dysphonia

OBJECTIVES

The primary objective of this study is to investigate if false vocal folds (FVF) or simultaneous FVF with thyroarytenoid (FVF+TA) Botox® injections achieve comparable treatment effects to standard TA injections. This study also aims to determine how patient-reported outcomes contribute to the transition to, and continuation of, FVF or FVF+TA injections.

METHODS

Retrospective chart review was performed for all patients receiving Botox® for adductor spasmodic dysphonia at a laryngology practice between 2005 and 2018. Twenty out of 103 patients met the study's inclusion criteria. All subjects began standard treatment with TA injections. Based on response to injection, patients either continued to receive TA injections (group TA; n = 7), switched to FVF injections (group FVF; n = 7), or switched to FVF+TA injections (group FVF+TA; n = 6). A comparison of group means before and after initiation of FVF±TA injections was performed between groups FVF and FVF+TA to group TA for the injection dosage, the duration of injection cycles, the patient-reported duration of best voice, and the presence and duration of breathiness and choking. Within-group observations were also compared before and after FVF±TA injections.

RESULTS

There were no significant findings for the variables between group FVF and group TA before FVF injections. The duration of injection cycles was significantly shorter for group FVF than group TA after FVF injections (95% CI: -66.05, -0.34; P = 0.05). However, duration of best voice quality, breathiness, and choking were similar (P > 0.05) for group FVF to group TA after FVF injections. Group FVF+TA had a significantly shorter duration of injection cycles (95% CI: -66.97, -3.22; P = 0.03), best voice (95% CI: -0.76, -0.03; P = 0.04), and choking (95% CI: -2.68, 0.02; P = 0.05) than group TA before FVF+TA injections. Group FVF+TA displayed a similar duration (P > 0.05) of injection cycles, best voice quality, breathiness, and choking to group TA after FVF+TA injections. Within-group, increased duration of injection cycles and best voice were observed after FVF±TA injections for both group FVF and FVF+TA. Acute adverse events were variable within groups after FVF±TA injections.

CONCLUSION

This study compared outcomes of FVF or FVF+TA injections to successive TA injections among patients. FVF injections displayed similar duration of best voice quality, breathiness, and choking to TA injections. FVF+TA injections achieved similar duration of injection cycles, best voice quality, breathiness, and choking to TA injections. This study demonstrates that patients guided by a reduced duration of adverse events, while tolerating a shorter injection cycle, may benefit from initiation and continuation of FVF injections. Patients guided by increased duration of injection cycle and best voice, while tolerating the duration of adverse events, may benefit from initiation and continuation of FVF+TA injections.

Comparison of the efficacy and adverse effects of unilateral or bilateral botulinum toxin injections for adductor spasmodic dysphonia: a systematic review and meta-analysis

PURPOSE

This study aims to aggregate and analyze existing clinical evidence to compare the efficacy and adverse effects of unilateral or bilateral botulinum toxin injections for the treatment of adductor spasmodic dysphonia (ADSD).

METHODS

Reports from non-randomized controlled trials and cohort studies pertaining to the efficacy and adverse effects of unilateral and bilateral botulinum toxin injections for ADSD were identified and retrieved from four electronic databases from inception to July 2023. The meta-analysis employed fixed or random effects models to assess pooled relative risks (RR), mean differences (MDs), and standard mean differences (SMDs) with their corresponding 95% confidence intervals (CIs).

RESULTS

We included two non-randomized controlled trials and seven cohort studies comprising 854 total patients. Meta-analysis of the included studies showed that bilateral botulinum toxin injections associated with a longer duration of vocal improvement (MD =  - 2.89, 95% CI - 3.13 to - 2.65, I2 = 0%, P < 0.00001). However, bilateral botulinum toxin injections associated with an increase in adverse effects, including a longer duration of breathy voice quality (SMD =  - 0.51, 95% CI - 0.79 to - 0.22, I2 = 35%, P = 0.0005) and a higher occurrence of swallowing difficulties (RR = 0.46, 95% CI 0.35 to 0.11, I2 = 0%, P < 0.00001).

CONCLUSION

Bilateral botulinum toxin injections for ADSD showed a longer duration of vocal improvement, a longer breathy voice duration and a higher dysphagia occurrence and duration than unilateral 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.