Botulinum toxin management of spasmodic dysphonia (laryngeal dystonia): a 12-year experience in more than 900 patients

"Lombard Effect" and Voice Changes in Adductor Laryngeal Dystonia: A Pilot Study

OBJECTIVES

The aim was to describe the acoustic, auditory-perceptive, and subjective voice changes under the Lombard effect (LE) in adductor laryngeal dystonia (AdLD) patients.

METHODS

Subjective perception of vocal effort (OMNI Vocal Effort Scale OMNI-VES), Maximum Phonation Time (MPT), and the perceptual severity of dysphonia (GRBAS scale) were assessed in condition of stillness and under LE in 10 AdLD patients and in 10 patients with typical voice. Speakers were asked to produce the sustained vowel /a/ and to read a phonetically balanced text aloud. Using the PRAAT software, the following acoustic parameters were analyzed: Mean Pitch (Hz), Minimum and Maximum Intensity (dB), the Fraction of Locally Unvoiced Frames, the Number of Voice Breaks, the Degree of Voice Breaks (%), the Cepstral Peak Prominence-Smoothed (CPPS) (dB).

RESULTS

Under LE, the AdLD group showed a decrease of both G and S parameters of GRBAS and subjective effort, mean MPT increased significantly; in the controls there were no significant changes. In both groups under LE, pitch and intensity of the sustained vowel /a/ significantly increased consistently with LE. In the AdLD group the mean gain of OMNI-VES score and the mean gain of each parameter of the speech analysis were significantly greater than the controls' ones.

CONCLUSION

Auditory feedback deprivation obtained under LE improves subjective, perceptual-auditory, and acoustics parameters of AdLD patients. These findings encourage further research to provide new knowledge into the role of the auditory system in the pathogenesis of AdLD and to develop new therapeutic strategies.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:3754-3760, 2024.

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.

Incidence and risk factors for secondary extralaryngeal dystonia in patients with laryngeal dystonia

BACKGROUND AND OBJECTIVES

Laryngeal dystonia (LD) is a focal dystonia affecting adductor and/or abductor muscles of the larynx. It can be isolated or may spread to extra laryngeal muscles. The aim of this study was to report the characteristics of LD over time in a large single-center study with a long follow-up.

METHODS

Retrospective review of patients with LD referred to our institution between 1991 and 2021. Demographic data, time to diagnosis, type of LD, follow-up and spread of dystonia [SD] were recorded. Risk factors for spread of dystonia during follow-up were analyzed.

RESULTS

Over the 30-year period, 516 patients (77.3 % female, median age 50 years, range 5-87 years) were analyzed. Three hundred and fifteen patients (61 %) had adduction laryngeal dystonia, 136 patients (26.4 %) had abduction laryngeal dystonia, 46 patients (8.9 %) had adductor respiratory laryngeal dystonia, 12 patients (2.3 %) had mixed laryngeal dystonia, and seven patients (1.4 %) had singer's laryngeal dystonia. A previous history of dystonia was found in 47 patients (9.1 %). A laryngeal tremor was found in 68 patients (13.2 %). Since the onset of symptoms, LD was diagnosed after a median of 3 years (IQR: 1.0, 7.0). SD occurred in 55 patients (10.7 %) after a median time of 4 year (IQR: 1.5, 13.0). Patients with mixed laryngeal dystonia had higher probability of SD (p = 0.018).

DISCUSSION

This study reports a large European study of LD, with a long follow-up. SD occurred in 10.5 % of patients. Patients with mixed laryngeal dystonia had a higher probability of SD. A close follow-up may be recommended for patients with mixed laryngeal dystonia.

Comparison of Botulinum Toxin Injections and Type 2 Thyroplasty for Adductor Spasmodic Dysphonia

OBJECTIVES

Injection of botulinum toxin type A (BTX) into intrinsic laryngeal muscles is the current gold standard therapy for adductor spasmodic dysphonia (AdSD). However, a surgical procedure could potentially offer more stable and long-lasting voice quality to AdSD patients. Here, we report the long-term results of type 2 thyroplasty (TP2) with TITANBRIDGE® (Nobelpharma, Tokyo, Japan) compared with those of BTX injections.

METHODS

In total, 73 AdSD patients visited our hospital between August 2018 and February 2022. Patients were provided the option of BTX injections or TP2. They were assessed via the Voice Handicap Index (VHI)-10 before treatments and at scheduled clinical follow-ups at 2, 4, 8, and 12 weeks for BTX and at 4, 12, 26, and 52 weeks for TP2.

RESULTS

Overall, 52 patients selected the BTX injection and had a pre-injection mean VHI-10 score of 27.3 ± 8.8. Following injections, the scores significantly improved to 21.0 ± 11.1, 18.6 ± 11.5, and 19.4 ± 11.7 at 2, 4, and 8 weeks, respectively. There were no significant differences between the pre-injection scores and the 12-week scores (21.5 ± 10.7). Alternately, 32 patients opted to be treated with TP2 and had a pre-treatment mean VHI-10 score of 27.7. All patients reported an improvement in their symptoms. Additionally, the mean VHI-10 score significantly improved to 9.9 ± 7.4 at 52 weeks following treatment. There was a significant difference between the two treatment groups at 12 weeks. Some patients received both treatments.

CONCLUSION

These preliminary results provide important insights into the value of TP2 as a potential permanent treatment for AdSD patients.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:3443-3448, 2023.

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.

How can we make better decisions about dystonic voice management?

PURPOSE OF REVIEW

The optimal diagnosis and management of dystonic voice disorders are rooted in the nuanced understanding of their phenomenology. Distinguishing between subtypes of vocal dystonia is challenging, not only because the audible and physical presentations of these dystonia's can seem similar, but also because there is a lack of scientific consensus regarding the diagnostic criteria for these conditions. To help improve the clinician's acumen we focus on outlining the classification of the top three neurological voice disorders, notably: spasmodic dysphonia, (2) spasmodic dysphonia with tremor, and essential tremor of the voice. We also provide an algorithmic approach based on current evidence-based literature to guide practitioners through the clinical diagnosis and management of each possible etiology.

RECENT FINDINGS

Much remains unknown about the subtypes of vocal dystonia, and this gap in our knowledge likely limits our ability to advance clinical management. Still, continued experience evaluating and treating these patients yields refined clinical evaluations and decision making.

SUMMARY

Improvements in our clinical decision-making can be made by acknowledging that our limited understanding of vocal dystonia may hinder what therapeutic interventions we can offer, yet our ability to accurately diagnose the dystonia is central to providing optimal patient management.

Titanium bridge modification for type 2 thyroplasty to improve device mechanical & safety performance

OBJECTIVE

Titanium bridges are used to separate the thyroid ala during type 2 thyroplasty for adductor spasmodic dysphonia. Revision surgeries have adventitiously indicated that bridge wing failure occurs in the area of the medial hole in some cases. This study investigated the rate and cause of device malfunctions and developed an improved device.

METHODS

We conducted a questionnaire survey to determine the number of surgeries performed in Japan up to the end of 2014, and to obtain information about revision cases. In addition, damage analyses were performed on the fracture surfaces of recovered titanium bridges through use of scanning electron microscopy (SEM).

RESULTS

Between 2002 and 2014, titanium bridges were used in 385 patients. Revision surgery was performed in 19 cases. Revision surgeries revealed that in 11 cases breakage occurred in the wings of the device in the region of the medial hole. However, such fractures were not associated with any signs of recurrence or any adverse events. SEM analyses of fracture surfaces confirmed that fatigue fractures were caused by repeated bending stress in the area of the medial hole. Based on these results, the shape of the hole was changed from round to oval and the wing thickness was increased to prevent breakage.

CONCLUSIONS

The wings of titanium bridges may break without any associated signs, symptoms or tissue damage. Based on the malfunctions detected and analyses of the devices recovered following malfunction, changes to the specification were made for commercial development of the titanium bridge.

Sulcus vocalis in spasmodic dysphonia-A retrospective study

BACKGROUND

Spasmodic dysphonia (SD) is a neurological condition of the larynx characterised by task specific, involuntary spasms of the intrinsic laryngeal muscles causing frequent voice breaks during speech. The current treatment modality involves Botulinum Toxin injections into the affected group of muscles. This has yielded satisfactory results in Adductor SD (ADSD) and mixed SD but not in Abductor SD (ABSD). Sulcus vocalis is a morphological condition of the vocal folds with invagination of the superficial epithelium into the lamina propria or deeper layers. It is characterised by breathiness in voice and hypophonia. In our voice clinic, patients diagnosed with SD were occasionally found to have a sulcus on flexible stroboscopy. Studies have revealed an asymmetric stimulation of both the adductor and abductor group of muscles in ABSD and a predominant possibly symmetric stimulation of the adductor group of muscles in ADSD. Our objective was to study any significant association between vocal fold sulcus and two groups within SD; group one being ADSD and group two being both ABSD and Mixed SD. A literature review did not reveal any studies suggesting an association between SD and vocal fold sulcus to date.

METHODS

A retrospective review of the stroboscopic video recordings as well as file records of all patients diagnosed with SD between January 2016 and September 2019 was conducted at our voice clinic. The first author was the laryngologist who had diagnosed SD and its type on the basis of hearing the voice and making the patient perform various vocal tasks with and without flexible videostroboscopy. The SD patients were divided into two groups with the first group consisting of ADSD patients and the second group consisting of ABSD as well as Mixed SD patients. The presence or absence of vocal fold sulcus was noted in all the SD patients. Odds ratio was used to establish statistical significance of the presence of vocal fold sulcus in the two SD groups.

RESULTS

Among the 106 patients of SD, 62 patients were males and 44 were females. A total of 84 patients were diagnosed as ADSD, 10 as ABSD and 12 as Mixed SD patients. Vocal fold sulcus was noted in 5 out of 84 patients of ADSD, 4 out of 10 patients of ABSD, and in 3 out of 12 patients of mixed SD. Odds Ratio of 7.37 (C.I. = 2.063-26.35) was obtained for the second group of patients i.e. ABSD and Mixed SD.

CONCLUSION

Our study revealed a significant association between patients of SD having an abductor component (ABSD and mixed SD) and vocal fold sulcus. The two hypothesis proposed for this are the possibility of asymmetrical adductor and abductor muscle stimulation in SD being responsible for the development of a vocal fold sulcus or the primary presence of a vocal fold sulcus contributing to altered sensory feedback resulting in SD. Further study to evaluate this, as well as a study of the vocal response to medialisation procedures for patients of ABSD with sulcus is recommended.

Classification of vocal tremor using updated consensus-based tremor classification criteria

OBJECTIVES

This study characterized the clinical phenotypes of individuals with vocal tremor (VT) using tremor classification criteria published by the International Parkinson and Movement Disorder Society (IPMDS) including laryngeal features from the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS).

METHODS

VT phenotypic descriptors were extracted from participant medical records from 2017 to 2019. Clinical phenotype descriptors included the: (a) chief complaint and discipline for the first appointment, (b) demographics, (c) tremor body distribution, condition, frequency, and progression, (d) exacerbating/alleviating factors, (e) treatment approaches, and (g) neurologic comorbidities. Descriptive statistics were conducted.

RESULTS

Of 179 meeting inclusion criteria, 2/3 were female; tremor onset affected voice (43%) or extremity (32%) and 2/3 were documented with tremor duration of 3 years or more. Those with primary VT first saw otolaryngology or speech language pathology (59%), whereas those with primary extremity/head tremor first saw neurology (36%). Documentation commonly omitted tremor clinical features such as (a) observed conditions of tremor (64%), (b) laryngeal features (64%), and (c) tremor frequency (92%). Thus, VT classification was based on comorbidity in 49% of patients (ie, essential tremor (48%), dystonia (72%), and Parkinson's disease (100%)) and 32% had inadequate documentation to classify.

CONCLUSION

The majority of individuals with VT were unable to be classified based on documented clinical features highlighting the need for consistent multidisciplinary assessment of tremor affecting speech structures. The primary site of tremor determined the first discipline seen. Most commonly classified VT categories included essential tremor (47%), dystonia (28%), Parkinsonism (7%), and isolated VT (19%).

LEVEL OF EVIDENCE

4.

Botulinum Toxin in Movement Disorders: An Update

Since its initial approval in 1989 by the US Food and Drug Administration for the treatment of blepharospasm and other facial spasms, botulinum toxin (BoNT) has evolved into a therapeutic modality for a variety of neurological and non-neurological disorders. With respect to neurologic movement disorders, BoNT has been reported to be effective for the treatment of dystonia, bruxism, tremors, tics, myoclonus, restless legs syndrome, tardive dyskinesia, and a variety of symptoms associated with Parkinson's disease. More recently, research with BoNT has expanded beyond its use as a powerful muscle relaxant and a peripherally active drug to its potential central nervous system applications in the treatment of neurodegenerative disorders. Although BoNT is the most potent biologic toxin, when it is administered by knowledgeable and experienced clinicians, it is one of the safest therapeutic agents in clinical use. The primary aim of this article is to provide an update on recent advances in BoNT research with a focus on novel applications in the treatment of movement disorders. This comprehensive review of the literature provides a critical review of evidence-based clinical trials and highlights recent innovative pilot studies.

Auditory Feedback Control of Vocal Pitch in Spasmodic Dysphonia

OBJECTIVES/HYPOTHESIS

Hearing plays an important role in the maintenance of vocal control in normal individuals. In patients with spasmodic dysphonia (SD), however, the ability to maintain sustained control of phonation is impaired. The origins of SD are unknown, and it is unclear whether auditory feedback-dependent vocal control is compromised in these patients.

STUDY DESIGN

Prospective case-control study.

METHODS

We tested 15 SD patients and 11 age-matched controls. Voice recordings were performed while subjects repeated the vowel /e/ and auditory feedback of their vocal sounds was altered in real-time to introduce a pitch-shift (±2 semitones), presented back to subjects using headphones. Recordings were analyzed to determine voice changes following the pitch-shifted feedback. Results were further compared with patient demographics and subjective measures of dysphonia, including the Voice Handicap Index (VHI).

RESULTS

Despite considerable pitch variability and vocal breaks, SD patients exhibited significantly higher average vocal pitch compensation than control subjects. SD patients also exhibited greater variability than controls. However, there were no significant correlations between vocal compensation and patient demographics, although there was a significant inverse correlation with VHI.

CONCLUSIONS

In this pilot study, patients with SD exhibited increased sensitivity to altered auditory feedback during sustained phonation. These results are consistent with recent theories of SD as a disorder of sensory-motor feedback processing, and suggest possible avenues for future investigation.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:2070-2075, 2021.

Neural Representations of the Voice Tremor Spectrum

OBJECTIVES

Voice tremor is a common movement disorder that manifests as involuntary oscillations of laryngeal muscles, leading to rhythmic alterations in voice pitch and loudness. Differential diagnosis of essential tremor of voice (ETv) is often challenging and includes dystonic tremor of voice (DTv), which is characterized by irregular, isometric contractions of laryngeal muscles during dystonic activity. Although clinical characteristics of voice tremor are well described, the pathophysiology underlying its heterogeneous phenomenology remains limited.

METHODS

We used a multimodal approach of functional magnetic resonance imaging for assessment of brain activity during symptomatic speech production, high-resolution magnetic resonance imaging for the examination of cortical thickness and gray matter volume, and diffusion-weighted imaging for evaluation of white matter integrity to identify disorder-specific neural alterations and their relationships with the symptomatology of ETv and DTv.

RESULTS

We found a broad overlap between cortical alterations in ETv and DTv, involving sensorimotor regions responsible for the integration of multisensory information during speech production, such as primary sensorimotor, inferior/superior parietal, and inferior temporal cortices. In addition, ETv and DTv showed unique patterns of abnormalities in regions controlling speech motor preparation, which were localized in the cerebellum in ETv and the premotor cortex, insula, and superior temporal gyrus in DTv. Neural alterations in superior parietal and inferior temporal cortices were correlated with ETv severity, whereas changes in the left premotor cortex were associated with DTv severity.

CONCLUSIONS

Our findings point to the pathophysiological spectrum underlying ETv and DTv and favor a more heterogeneous rather than dichotomous diagnostic classification of these voice tremor disorders. © 2020 International Parkinson and Movement Disorder Society.

Auditory-Perceptual Evaluation of Deep Brain Stimulation on Voice and Speech in Patients With Dystonia

OBJECTIVE

To determine the effects of globus pallidus interna (GPi) deep brain stimulation (DBS) on speech and voice quality of patients with primary, medically refractory dystonia.

METHODS

Voices of 14 patients aged ≥18 years (males = 7 and females = 7) with primary dystonia (DYT1 gene mutation dystonia = 4, cervical dystonia = 6, and generalized dystonia = 4) with bilateral GPi DBS were assessed. Five blinded raters (two fellowship-trained laryngologists and three speech/language pathologists) evaluated audio recordings of each patient pre- and post-DBS. Perceptual voice quality was rated using the Grade, Roughness, Breathiness, Asthenia, and Strain scale and changes in speech intelligibility were assessed with the Clinical Global Impression scale of Severity instrument. Inter-rater and intrarater reliability rates for perceptual voice ratings were assessed using the kappa coefficient.

RESULTS

Voice quality parameters showed mean improvements in Grade (P < 0.0001), Roughness (P = 0.0043), and Strain (P < 0.0001) 12 months post-DBS. Asthenia increased from baseline to 6 months (P = 0.0022) and declined significantly from 6 to 12 months (P = 0.0170). Breathiness did not change significantly over time. Speech intelligibility also improved from 6 to 12 months (P = 0.0202) and from pre-DBS to 12 months post-DBS (P = 0.0022). Grade and Strain ratings had nearly perfect and substantial inter-rater agreement (0.84 and 0.71, respectively).

CONCLUSIONS

Voice and speech intelligibility improved after bilateral GPi DBS for dystonia. GPi DBS may emerge as a potential treatment option for patients with medically refractory laryngeal dystonia.

Medical and Surgical Treatments for Dystonia

The dystonias are a large and heterogenous group of disorders characterized by excessive muscle contractions leading to abnormal postures and/or repetitive movements. Their clinical manifestations vary widely, and there are many potential causes. Despite the heterogeneity, helpful treatments are available for the vast majority of patients. Symptom-based therapies include oral medications, botulinum toxins, and surgical interventions. For some subtypes of dystonia, specific mechanism-based treatments are available. Advances in understanding the biological basis for many types of dystonia have led to numerous recent clinical trials, so additional treatments are likely to become available in the very near future.

Outcomes of Onabotulinum Toxin A Treatment for Adductor Spasmodic Dysphonia and Laryngeal Tremor

Importance

The relative outcomes of onabotulinum toxin A injections for treatment of adductor spasmodic dysphonia (ADSD), ADSD with lateral laryngeal tremor (ADSD+LT), and lateral LT without ADSD are unclear.

Objective

To compare the outcomes of onabotulinum toxin A treatment on ADSD, ADSD+LT, and lateral LT without ADSD.

Design, Setting, and Participants

A retrospective cohort study was conducted from January 1, 1990, to September 30, 2016, at a tertiary referral voice center. Participants included 817 patients treated with onabotulinum toxin A injections for diagnosis of ADSD, ADSD+LT, and lateral LT without ADSD.

Exposure

Injection of onabotulinum toxin A into the thyroarytenoid/lateral cricoarytenoid muscle complex.

Main Outcomes and Measures

Data from patient diaries were used to evaluate patient-perceived effectiveness of onabotulinum toxin A injection. Primary outcomes were (1) patient-reported good voice days (voice breaks or tremor minimized to patient satisfaction) and (2) percentage of injections in which maximal voice quality was reached (significant or complete reduction in vocal tremor or spasms during a treatment cycle). Multivariate analysis of variance tests compared differences in outcomes between groups. Subanalysis was performed to compare outcomes in patients with isolated LT with those who had mixed tremor (lateral with concomitant anterior-posterior and/or vertical components).

Results

Of 817 patients treated with onabotulinum toxin A injections for laryngeal movement disorders, 548 patients (12 771 injection sessions) met inclusion criteria (ADSD: n = 328, ADSD+LT: n = 77, lateral LT without ADSD: n = 143). Of these, 408 (80.8%) were women; mean (SD) age was 57.2 (13.7) years. Among patients with tremor, those with isolated LT had better outcomes than those with mixed tremor. In adjusted analysis, good voice days in patients with ADSD, ADSD+LT, and lateral LT without ADSD were 81.1, 75.4, and 71.3 days, respectively (partial η2, 0.05; 95% CI, 0.01-0.09). The percentage of maximally beneficial injections was 88.1% for ADSD, 83.4% for ADSD+LT, and 70.4% for LT without ADSD (partial η2, 0.12; 95% CI, 0.06-0.17).

Conclusions and Relevance

Onabotulinum toxin A injections into the thyroarytenoid/lateral cricoarytenoid muscle complex are an effective treatment for ADSD, ADSD+LT, and LT without ADSD; however, the greatest effectiveness was observed among patients with ADSD. Defining tremor directionality may help to prognosticate the effectiveness of onabotulinum toxin A injection among patients presenting with tremor components.

Movement Disorders and Voice

The primary movement disorders affecting the voice are laryngeal dystonia (including spasmodic dysphonia), essential voice tremor, and Parkinson disease. Diagnosis of these conditions is clinical and based on a detailed history, voice evaluation, and physical and laryngoscopic examination. Laryngeal dystonia and essential voice tremor are hyperfunctional disorders and are treated most commonly with botulinum toxin injections. Parkinson disease is a hypofunctional disorder that may affect the voice and most commonly is treated with Lee Silverman Voice Treatment.

A separation of innate and learned vocal behaviors defines the symptomatology of spasmodic dysphonia

OBJECTIVE

Spasmodic dysphonia (SD) is a neurological disorder characterized by involuntary spasms in the laryngeal muscles. It is thought to selectively affect speaking; other vocal behaviors remain intact. However, the patients' own perspective on their symptoms is largely missing, leading to partial understanding of the full spectrum of voice alterations in SD.

METHODS

A cohort of 178 SD patients rated their symptoms on the visual analog scale based on the level of effort required for speaking, singing, shouting, whispering, crying, laughing, and yawning. Statistical differences between the effort for speaking and the effort for other vocal behaviors were assessed using nonparametric Wilcoxon rank-sum tests within the overall SD cohort as well as within different subgroups of SD.

RESULTS

Speech production was found to be the most impaired behavior, ranking as the most effortful type of voice production in all SD patients. In addition, singing required nearly similar effort as speaking, ranking as the second most altered vocal behavior. Shouting showed a range of variability in its alterations, being especially difficult to produce for patients with adductor form, co-occurring voice tremor, late onset of disorder, and familial history of dystonia. Other vocal behaviors, such as crying, laughing, whispering, and yawning, were within the normal ranges across all SD patients.

CONCLUSION

Our findings widen the symptomatology of SD, which has predominantly been focused on selective speech impairments. We suggest that a separation of SD symptoms is rooted in selective aberrations of the neural circuitry controlling learned but not innate vocal behaviors.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:1627-1633, 2019.

OnabotulinumtoxinA for adductor spasmodic dysphonia (ADSD): Functional results and the role of dosage

OBJECTIVE

To report the results of functional outcome, dose trend and relationship between onabotulinumtoxinA (onabotA) dosage and the severity of disease or time between therapy sessions in patients affected by adductor spasmodic dysphonia (ADSD).

PATIENTS AND METHODS

Thirty-two patients underwent 193 EMG-guided intracordal injections of a starting dose of 2 MU of onabotA. At enrollment, each subject was administered the VHI. The response was evaluated using a subjective rating scale (0-100% of normal phonation).

RESULTS

The quality of voice improved significantly after 1 month and stabilized by 3 months. The percentage of normal voice improved 33.34 ± 11.5% (min 26 - max 68). The functional gain was significantly worse in patients presenting with ADSD associated with dystonias in other body regions (31% vs 45% - p < 0.05). The mean dose employed was 3.64 MU (min 1 - max 6) with a trend of increasing dosages up to the 5th treatment after which the doses stabilized over time. The pre-treatment VHI showed a weakly positive correlation with the cumulative dose at the 5th and 10th injections. Benefit duration and the mean between treatment interval were 103 and 136 days respectively. The correlation between dose and inter-injection time is weakly negative (r = -0.22, p < 0.05), however, this is influenced predominantly by the first-to-second injection. After this initial treatment effect, the correlation becomes weakly positive (r = 0.12).

CONCLUSIONS

Our data confirm the efficacy of onabotA to improve the quality of voice in cases of ADSD. The trial period for optimal dosage lasted up to a mean of five injections. The dosage of onabotA impacted the length of response and was influenced by the severity of ADSD. Finally the efficacy of onabotA did not change significantly after repeated administrations.

Defining differences in patient characteristics between spasmodic dysphonia and laryngeal tremor

OBJECTIVE

To compare presenting characteristics of patients with adductor spasmodic dysphonia (ADSD), ADSD with laryngeal tremor (ADSD + LT), and laryngeal tremor without ADSD (LT).

DESIGN

Cross-sectional analysis.

METHODS

Patients treated for laryngeal movement disorders (1990-2016) were included. Analysis of variance and chi square tests measured differences in patient characteristics across the three disease groups. Using ADSD as the referent, multivariable logistic regression models were used to determine whether potential risk factors including patient demographics, family history, presence of potential inciting events prior to disease onset, and coprevalent movement disorders were associated with ADSD + LT or LT.

RESULTS

In all, 652 patients with ADSD (n = 377), ADSD + LT (n = 98), and LT (n = 177) were included. ADSD patients were significantly younger than those with ADSD + LT and LT (52.5 ± 13.4, 63.9 ± 11.3, and 69.3 ± 10.5 years, respectively; P < 0.001). Coprevalent movement disorders were more common in ADSD + LT (38.7%) and LT (57.1%) groups than in the ADSD group (11.5%; P < 0.001). Compared to ADSD, patients with ADSD + LT and LT were more likely to develop an additional movement disorder during follow-up. In multivariable analyses, increasing age, female gender, and having a movement disorder at presentation were associated with significantly greater odds of having ADSD + LT or LT when compared to ADSD.

CONCLUSION

ADSD + LT patients demonstrate intermediate gender composition and age distributions between those with ADSD and LT. These findings suggest that ADSD + LT may be a distinct phenotype in the spectrum of laryngeal movement disorders.

LEVEL OF EVIDENCE

4 Laryngoscope, 129:170-176, 2019.

Office-based endoscopic botulinum toxin injection in laryngeal movement disorders

INTRODUCTION

Botulinum toxin injection is widely used for the treatment of laryngeal movement disorders. Electromyography-guided percutaneous injection is the technique most commonly used to perform intralaryngeal botulinum toxin injection.

OBJECTIVE

We describe an endoscopic approach for intralaryngeal botulinum toxin injection under local anaesthesia without using electromyography.

TECHNIQUE

A flexible video-endoscope with an operating channel is used. After local anaesthesia of the larynx by instillation of lidocaine, a flexible needle is inserted into the operating channel in order to inject the desired dose of botulinum toxin into the vocal and/or vestibular folds.

CONCLUSION

Endoscopic botulinum toxin injection under local anaesthesia is a reliable technique for the treatment of laryngeal movement disorders. It can be performed by any laryngologist without the need for electromyography. It is easy to perform for the operator and comfortable for the patient.

Review of differential diagnosis and management of spasmodic dysphonia

PURPOSE OF REVIEW

The recent literature on spasmodic dysphonia is reviewed with regard to pathogenesis, differential diagnosis, treatment options, audits, and current methods of management.

RECENT FINDINGS

Advances in technology have enabled clinicians to better understand the connection between brain and laryngeal function and dysfunction. Refinements in imaging and genetic investigation techniques have led to advances in the understanding of the underlying mechanism of this neurolaryngeal disorder. Development of diagnostic assessment tools and measures of quality of life hold the potential to improve treatment and care.

SUMMARY

Fifty articles published between 2014 and 2015 were selected for this review. The sources were drawn from several clinical specialties: 54% come under the scope of laryngology, 32% from neurology, and 14% from other areas. It remains poorly understood, misdiagnosed, and underdiagnosed. Its identification, diagnosis, treatment selection, and coordination of care require an expert specialist multidisciplinary team. More training is required to help people who have this chronic and psychosocially disabling voice disorder, which impinges on all aspects of their lives. Spasmodic dysphonia is now classified as a 'rare' disease in the United States. This designation will assist in international standards of diagnosis, assessment, treatment, and management.

Multidose Botulinum Toxin A for Intralaryngeal Injection: A Cost Analysis

OBJECTIVES

Botulinum toxin A (BtxA) injection is the mainstay treatment for laryngeal dystonias. BtxA product labeling states that reconstituted toxin should be used within 4 hours on a single patient despite several studies that have demonstrated multidose BtxA to be safe and effective. Many insurance carriers mandate the use of an outside pharmacy which necessitates a single-use approach. This study compares the cost savings of multidose BtxA for laryngeal dystonia compared to single-use.

STUDY DESIGN

This is a retrospective review and projected cost savings analysis.

METHODS

Records and billing information were reviewed for patients receiving BtxA for intralaryngeal injection at a single laryngology division in 2015. Inclusion criteria included CPT 64617 or J0585; exclusion criteria included CPT 64616. The price of BtxA 100 unit vial for calculation was $670.

RESULTS

A total of 142 patients were seen for intralaryngeal BtxA injection resulting in 337 visits over 1 year. The average BtxA dose per visit was 2.86 units with an average of 3.06 procedure visits per year. The calculated cost of BtxA treatment using a single vial approach was found to be $2,050 per patient per year. If billed instead for $7/unit with 5 units wastage charge per visit, the yearly per patient charge is $168. Single vial-use of BtxA injection thus represents a 1,118% price increase versus multidose use. When estimated for yearly prevalence of spasmodic dysphonia, multidose BtxA use would save almost $100 million annually.

CONCLUSIONS

Multidose botulinum toxin A application utilizing per unit billing is significantly less expensive than per single-use vial billing and would save the health-care system significant amount of money without any sacrifice in safety or effectiveness.

History of Botulinum Toxin Treatment in Movement Disorders

BACKGROUND

The frontiers of clinical medicine constantly expand as a result of the innovative efforts of visionary researchers and keen observations of seasoned clinicians. In medicine, rarely has a therapeutic agent been found efficacious in the management of so many symptoms and in such a relatively short time as botulinum toxin. One of the most notable contributions of botulinum toxin therapy in clinical medicine is in the field of movement disorders.

METHODS

The English literature was searched using the Yale search engine including but not limited to PubMed and Ovid. The search includes articles from January 1 1980 to March 1 2016.

RESULTS

A total of 2055 articles were identified. Of these, 132 met the criteria for this review.

DISCUSSION

This historical review highlights early and seminal contributions that have introduced the application of botulinum toxins in the field of movement disorders and provides evidence-based contributions that have established botulinum toxin as an effective treatment for abnormal movements.

Surgical approach to the thyroarytenoid branch of the inferior laryngeal nerve through the thyroid cartilage

PURPOSE

To describe the anatomical course of the intralaryngeal portion of the inferior laryngeal nerve (ILN) and to standardize the surgical access to its thyroarytenoid branch (TAb) through the thyroid cartilage.

METHODS

Under surgical microscopy, 33 adult human excised larynges were dissected, to expose the intralaryngeal portion of ILN. The point of entry of TAb, ILN's terminal branch, in the thyroarytenoid (TA) muscle was determined and correlated with thyroid cartilage dimensions.

RESULTS

After entering the larynx, the ILN consistently traveled between the thyroid cartilage and the lateral cricoarytenoid muscle in an anterior and slightly cranial course. The distance from the point of entry of the TAb in the TA muscle to the midline (TAb-H) and to the inferior border (TAb-V) of the thyroid cartilage differed according to gender. In females, mean distances of TAb-H and TAb-V were 20.5mm and 5.2mm and in males, 22.3mm and 5.9mm, respectively.

CONCLUSION

The intralaryngeal course of the inferior laryngeal nerve presents low variability and measures from landmarks in the thyroid cartilage help to estimate the point of entry of thyroarytenoid branch in thyroarytenoid muscle.