Botulinum Toxin Therapy for Spasmodic Dysphonia in Japan: The History and an Update

Botulinum toxin injection for abductor spasmodic dysphonia under cervical ultrasonography guidance

Ultrasound (US) imaging effectively provides real-time anatomical information for clinical examinations. In otolaryngology, US imaging can visualize laryngeal muscles as well as cervical muscles. Here we present the case where US imaging was used while injecting botulinum toxin (BT) for the treatment of abductor spasmodic dysphonia, which provided definite results. We could visualize not only the injection pathway but also the infiltration of the BT solution into the posterior cricoarytenoid muscles. Therefore, our laryngeal US imaging is useful for both improving the success rate and avoiding injection complications of BT.

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.

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.