Efficacy of laryngeal botulinum toxin injection: comparison of two techniques

Novel Image-Guided Simulator for Transcervical Intralaryngeal Injection Training

OBJECTIVE(S)

To assess the impact of a novel 3D-printed simulation model with Brainlab Image Guidance on enhancing otolaryngology residents' skills and confidence in performing transcervical intralaryngeal injection (TII) compared with conventional training methods.

METHODS

Utilizing a 3D-printed larynx model derived from computed tomography (CT) scans, this study involved 16 otolaryngology residents divided into two groups for TII training: one with Brainlab Image Guidance (LMIG) and the other without (LM). Pre- and post-training evaluations measured participants' confidence while the Brainlab system measured the accuracy of their needle placements.

RESULTS

After training, participants exhibited a significant increase in confidence with an average rise from 1.56 to 2.75 on a 5-point scale. The LMIG group outperformed the LM group in accuracy achieving statistically significant reductions in target distances after training (3.5 mm right, 3.6 mm left). The LMIG also demonstrated a significantly greater increase in procedural confidence over the LM group after training.

CONCLUSION

The TII laryngeal model with Brainlab Image Guidance significantly improves procedural confidence and accuracy among otolaryngology residents, signifying potential advantage over a more conventional training approach. The model's realistic tactile and live instrument positioning feedback augments the process of surgical skill refinement in a controlled, risk-free, simulation environment.

LEVEL OF EVIDENCE

NA Laryngoscope, 135:763-768, 2025.

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.

Spasmodic Dysphonia Patients' Perception of Pain with Botulinum Toxin Injections

OBJECTIVES

To evaluate spasmodic dysphonia patients' perception of pain associated with laryngeal botulinum toxin (BTX) injections and to determine factors associated with higher pain scores relative to other included patients.

METHODS

Prospective cohort study. Adult patients with adductor spasmodic dysphonia that presented to a tertiary laryngology practice for BTX injections were recruited from March to July 2022. Patients completed the visual analog scale (VAS) pre-procedure to quantify predicted pain. Ten minutes post-procedure they completed VAS and the short form McGill Pain Questionnaire (SF-MPQ). Factors that may affect pain were extracted from charts. Descriptive statistics, univariate, and multivariate analyses were conducted (alpha = 0.05).

RESULTS

One hundred and nineteen patients were included (63 ± 14 yo, 26% Male). SF-MPQ reported mild pain (4.12 ± 4.05 out of 45) with a pain intensity of none to mild (0.70 ± 0.89 out of 5). Bilateral injections yielded significantly higher SF-MPQ scores (5.19 ± 4.66) than unilateral injections (3.30 ± 3.30) (p = 0.012). There was a significant VAS reduction from pre 28.9 ± 24.6 mm (out of 10 mm) to post 24.5 ± 22.3 (p < 0.001). On multiple regression analyses, receiving a bilateral injection significantly (p < 0.05) contributed to a model that predicted higher pre-VAS (p = 0.013). Bilateral injections (p < 0.05) and higher VHI-10 (p < 0.05) contributed to a model that predicted higher total SF-MPQ (p = 0.001) and affective SF-MPQ (p = 0.001) scores. Not being a professional voice user (PVU) significantly (p < 0.05) contributed to a model that predicted higher post-VAS (p = 0.008) scores.

CONCLUSIONS

BTX injections were well tolerated with low pain scores. Factors associated with higher relative predicted or experienced pain included bilateral versus unilateral injection, PVU status, and higher VHI-10.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:240-246, 2024.

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.

The Patho-Neurophysiological Basis and Treatment of Focal Laryngeal Dystonia: A Narrative Review and Two Case Reports Applying TMS over the Laryngeal Motor Cortex

Focal laryngeal dystonia (LD) is a rare, idiopathic disease affecting the laryngeal musculature with an unknown cause and clinically presented as adductor LD or rarely as abductor LD. The most effective treatment options include the injection of botulinum toxin (BoNT) into the affected laryngeal muscle. The aim of this narrative review is to summarize the patho-neuro-physiological and genetic background of LD, as well as the standard recommended therapy (BoNT) and pharmacological treatment options, and to discuss possible treatment perspectives using neuro-modulation techniques such as repetitive transcranial magnetic stimulation (rTMS) and vibrotactile stimulation. The review will present two LD cases, patients with adductor and abductor LD, standard diagnostic procedure, treatments and achievement, and the results of cortical excitability mapping the primary motor cortex for the representation of the laryngeal muscles in the assessment of corticospinal and corticobulbar excitability.

Quantitative laryngeal electromyography parameters may correlate with improved outcomes following botulinum toxin injection for spasmodic dysphonia

BACKGROUND

Despite use of qualitative laryngeal electromyography (LEMG) guided botulinum toxin A (BoNT-A) injection for treatment of adductor spasmodic dysphonia (AdSD), unsatisfactory injections and complete "misses" remain problematic. We aimed to determine if the quantitative LEMG measure of number of small segments (NSS) correlates with voice outcomes following (BoNT-A injection for AdSD.

METHODS

Automated quantitative LEMG analysis was performed during electromyography (EMG) -guided BoNT-A injection into the thyroarytenoid-lateral cricoarytenoid muscle complex for treatment of AdSD. Pre-injection phonatory NSS values were correlated with clinical voice outcomes and patient reported injection results.

RESULTS

Quantitative LEMG measures were obtained for 45 AdSD patients (28 female, mean age 60.8 ± 12.8 years) during EMG-guided BoNT-A injection. Mean sampled NSS during phonation immediately prior to BoNT-A injection was 524 ± 323 (range: 2-904). Mean follow up was 36.5 ± 9.4 days; one patient was lost to follow-up. In comparison to their previous BoNT-A injection, the current injection was rated as worse, same, and better by 13 (29.5%), 25 (56.8%), and 6 (13.6%) patients, respectively. All 4 (9.1%) patients with NSS < 200 rated their BoNT-A injection result as worse than previous, and change in Voice Handicap Index-10 (VHI-10) scores were worse or without change.

CONCLUSIONS

Aiming for an NSS value greater than 200 during phonation prior to BoNT-A toxin injection for AdSD may reduce unfavorable voice outcomes.

Laryngeal Electromyography-Guided Hyaluronic Acid Vocal Fold Injections for Glottic Insufficiency

OBJECTIVES

To assess voice outcomes using the novel technique of in-office laryngeal electromyography-guided vocal fold injections (LEVFI) with hyaluronic acid to treat glottal insufficiency. Secondary objectives included determining the complication/completion rates and if any factors were associated with improved voice outcomes.

METHODS

Retrospective review of patients who received their first LEVFI from August 2017 to December 2018. Three- and six-month voice outcomes were assessed. Outcomes included voice handicap index-10 (VHI-10), maximum phonation time (MPT), perceptual analysis of voice (GRBAS), fundamental frequency, and stroboscopy.

RESULTS

Of the 121 eligible patients (55.4% male, age 63.7 years), 94 (77.7%) had complete 3-month data and 59 (48.8%) had complete 6-month data. VHI-10 was significantly improved from 25.7 ± 7.5 to 20.9 ± 10.9 at 3 months (P < .001) and to 19.1 ± 11.5 at 6 months (P < .001). MPT improved from 6.2 ± 5.4 seconds to 9.4 ± 7.1 seconds at 3 months (P < .001) and to 11.3 ± 8.2 seconds at 6 months (P < .001). GRBAS was improved in 74.8% of patients ([65.2, 82.8] 95% CI) at 3 months and 80.8% ([69.9, 89.1]) 95% CI) at 6 months. Stroboscopy showed a glottic gap improvement in 74.8% of patients ([65.8, 82.4] 95% CI) at 3 months and in 80.3% ([65.9, 88.5] 95% CI) at 6 months. Fundamental frequency was unchanged, as expected. Multivariate analysis reported that no factors were associated with better voice outcomes. Overall, 177/181 (97.8%) injections were completed. There were no complications.

CONCLUSION

In-office LEVFI is an effective, novel technique to treat glottic insufficiency with improved voice outcomes, high completion rate, and no significant complications.

Factors Associated with Failure of Botulinum Toxin Injection in Adductor Spasmodic Dysphonia

Objective:

Electromyography (EMG) Guided botulinum toxin (BTX) injection is considered first-line treatment for adductor spasmodic dysphonia (SD). Failure rate can range between 6% and 29%. Study objective was to determine which factors were associated with failure.

Methods:

This was a retrospective review conducted at a tertiary, academic center. Adductor SD patients presenting for BTX injections from August 2017 to October 2018 were eligible. Age, gender, Voice Handicap Index (VHI-10), Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V), number of injections, disease duration, unilateral/bilateral injection, right/left injection, dose quantity, body mass index (BMI), professional voice user, employment, psychiatric comorbidity, breathiness, and dysphagia were investigated. Outcomes included failure as defined by the patient and dosage change. Univariate and multivariate statistical analysis was conducted.

Results:

Sixty seven out of 564 injections (12%) were categorized as failure by 131 patients. In multivariate analysis, dosage change was associated with shorter duration of good effect ( P < .001), BTX dose ( P = .016), breathiness ( P < .001), bilateral injection ( P = .024), dysphagia ( P = .012) and professional voice user ( P = .021). Failure was associated with first injection with a new physician ( P < .001), professional voice user P < .001) and lack of breathiness ( P = .003). Failure rate was not associated with age, gender, VHI-10, CAPE-V, disease duration, left/right injection, dose quantity, BMI, psychiatric comorbidity, and dysphagia.

Conclusion:

Failure rate was 12% and associated with patients’ first injection with a physician, professional voice user, and lack of breathiness. Dosage change occurred in 29% of injections and was associated with injection side effects, bilateral injections, BTX dose, professional voice user, and shorter duration of good effect. Level of evidence: 3