Spasmodic dysphonia: onset, course, socioemotional effects, and treatment response

Demographic and clinical characteristics of our patients diagnosed with laryngeal dystonia

PURPOSE

Laryngeal dystonia (LD) is a focal dystonia affecting laryngeal musculature with no known etiology or cure. The present study evaluated the sociodemographic and clinical features of patients diagnosed with LD.

MATERIALS AND METHODS

All patients diagnosed with LD at our University Hospital's Ear, Nose, and Throat Department between January 2017 and July 2023 were retrospectively analyzed. The study included 43 patients.

RESULTS

Out of the 43 patients, 19 (44%) were male. At the time of diagnosis, the mean age of the patients was 35.1 years (ranging from 17 to 65 years). The mean elapsed time between the first symptom onset and the first diagnosis was 49.2 months (min. 4 months, max. 240 months). Of the participants, 94% had adductor-type LD. None of the patients had a family history of LD. Of the patients, 9 (20%) experienced a life-altering event or trauma just before the onset of symptoms. All patients who consumed alcohol reported symptom relief with alcohol intake. A total of 67.6% of patients stated that their symptoms were triggered by stress. All of our patients received at least one Botulinum toxin injection, with an average of 2.75 dosages per patient.

CONCLUSION

The gender distribution was approximately equitable between males and females. There was a tendency for men to receive a diagnosis earlier than women following the manifestation of symptoms. A significant number of patients associate the emergence of their symptoms with a stressful event or traumatic experience. This study represents the initial investigation into the sociodemographic characteristics of patients within the Turkish population.

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.

Laryngeal Dystonia, Dystonic Tremor and Vocal Tremor: Three Different Entities

OBJECTIVE

The main objective of this study was to compare the demographic and clinical characteristics of patients with laryngeal dystonia (LD), dystonic tremor (DT), and vocal tremor (VT).

STUDY DESIGN

This was a retrospective longitudinal study.

METHODS

Data analysis from every patient diagnosed with LD, DT, or VT from January 1, 2010, to September 30, 2022, at a tertiary hospital center. Differential diagnosis between these entities was clinical (clinical history, voice assessment, and endoscopy) and confirmed by laryngeal electromyography.

RESULTS

A total of 87 patients were included in this study: 50 patients with LD, 23 with DT, and 14 with VT. Age at diagnosis was significantly lower in patients with LD, with a mean age of 56.2 years when compared to DT (67.6 years; P = 0.002) and VT (70.5 years; P = 0.009). Furthermore, VT had a higher female prevalence (92.9%) when compared with LD (52%; P = 0.011). LD was mainly adductor, with only two patients diagnosed with abductor LD, and DT was adductor in every case. Tremor direction in patients with VT was horizontal in 50% and mixed (horizontal + vertical) in 50%, while in DT was mixed in 65.2% and horizontal in 34.8%. LD was more commonly an isolated laryngeal movement disorder (78%) when compared to DT (47.8%; P = 0.015) or VT (28.5%; P < 0.001), which were more often secondary to generalized neurological disorders. There were no differences between groups on Voice Handicap Index-10, self-reported grade of dysphonia on a visual analogic scale (0-10), maximum phonation time, and G, R, B, A, and I in the GRBAS-I scale at diagnosis (P > 0.05). S was significantly higher in LD when compared to VT (P < 0.001) and nonsignificantly higher than in DT (P = 0.075).

CONCLUSIONS

LD, DT, and VT seem to be different entities with different demographics and clinical characteristics.

Spasmodic dysphonia: introductory phonetic analyses

Adductor spasmodic dysphonia (ADSD) is a neurological dystonia characterised by involuntary adductor spasms of the larynx during speech. Spasm frequency is often reported to increase during syllables that begin with voiced speech sounds, especially glottal stops. Because of its underlying physical and acoustic complexities, the voicing contrast in American English (AE) appears unlikely to interact consistently with a singular physical phenomenon like laryngeal spasm. This retrospective study investigated additional phonetic contrasts and their relationship to spasm frequency. Standardised, 144-word recordings of 36 participants with adductor spasmodic dysphonia were analysed. Productions were coded for rater-perceived syllable stress, voiced/voiceless onset, vowel/consonant onset, and word-onset place and manner of production. Phonetic contexts were compared using independent sample t-tests and Kruskal-Wallis statistics. Contexts in which spasm varied significantly included stressed/unstressed syllables, content/function words, and multisyllabic/monosyllabic words. Study results reaffirm the clinical usefulness of standardised ADSD/ABSD sentences during differential diagnosis but conflict with previous studies that report a connection between ADSD spasm and phoneme voicing.

Abnormal Laryngopharyngeal Sensation in Adductor Laryngeal Dystonia Compared to Healthy Controls

BACKGROUND/OBJECTIVES

Laryngeal sensory abnormality has been implicated as a component of adductor laryngeal dystonia (AdLD). The study objective was to assess laryngopharyngeal sensation in AdLD utilizing a calibrated, tactile aesthesiometer to deliver differential stimuli to lateral pyriform sinus (LPS), aryepiglottic fold (AEF), and false vocal fold (FVF).

METHODS

Patients with known Botox-responsive AdLD underwent sensory testing using a previously-validated methodology involving calibrated tactile stimuli (6-0, 5-0, 4.5-0, 4-0 nylon monofilaments). Laryngeal adductor reflex (LAR) and participant-rated perceptual strength of stimulI were evaluated. Responses were compared to normative controls (n = 33). Two-samples, Mann-Whitney and Fisher exact tests compared mean strength ratings and LAR between AdLD and control groups. Mixed-effects logistic regression and linear models assessed association of filament size, stimulus site, age, sex, and LD status on LAR and perceptual strength rating respectively.

RESULTS

Thirteen AdLD patients (nine women, mean age 60+/-15 years) completed testing. Average LAR response rates were higher amongst all filament sizes in AdLD versus controls at LPS (56.3% vs. 35.7%) and AEF (96.1% vs. 70.2%) with comparable rates at FVF (90.2% vs. 91.7%). AdLD had 3.3 times the odds of observed LAR compared to controls (p = 0.005), but differences in subjective detection of stimuli, perceptual strength ratings, and cough/gag rates were insignificant on multivariate modeling (p > 0.05).

CONCLUSIONS

This is the first study to objectively assess laryngopharyngeal sensation in AdLD. Findings demonstrated increased laryngopharyngeal sensation in AdLD compared to controls. The identification of increased laryngeal hypersensitivity in these patients may improve understanding of AdLD pathophysiology and identify future targets for intervention.

LEVEL OF EVIDENCE

2 Laryngoscope, 133:2271-2278, 2023.

Videostroboscopy Versus High-Speed Videoendoscopy: Factors Influencing Ratings of Laryngeal Oscillation

PURPOSE

The purpose of this study was to determine whether patient voice-related diagnosis, severity of dysphonia, and rater's experience influence the relationship between laryngeal oscillation ratings made from videostroboscopic and high-speed videoendoscopic (HSV) exams.

METHOD

Stroboscopy and HSV exams from 15 patients with adductor spasmodic dysphonia (ADSD) and 15 with benign vocal fold lesions were rated for laryngeal oscillation and closure by 10 licensed speech-language pathologists (SLPs). Raters were divided into low- (< 5 years) and high-experience (> 5 years) groups. Ratings of vocal fold amplitude, mucosal wave, periodicity, phase symmetry, nonvibrating portion of the vocal fold, and glottal closure were examined using an online form adapted from the Voice Vibratory Assessment of Laryngeal Imaging (VALI).

RESULTS

Stroboscopy and HSV ratings were more strongly positively correlated for patients with benign vocal fold lesions (r between .43 and .75) than for those with ADSD (r between .40 and .68). Differences between stroboscopy and HSV exams were significantly greater for ratings of amplitude, mucosal wave, and periodicity in patients with ADSD than for patients with benign vocal fold lesions. Raters with < 5 years of experience showed significantly greater differences between stroboscopy and HSV ratings of amplitude and nonvibrating portion of the vocal fold for patients with ADSD only. Significantly greater differences between ratings of periodicity and phase symmetry were observed in patients with more severe dysphonia.

CONCLUSIONS

Differences in laryngeal ratings made between HSV and stroboscopy exams may be influenced by patient diagnosis, severity of dysphonia, and rater experience. Future study is warranted to determine how the differences observed influence clinical diagnosis and outcomes.

Comparison of Outcome Measures (Subjective, Objective, and Patient-Based) in Laryngeal Dystonia Treatment With Botulinum Toxin A Injection

BACKGROUND

Outcome assessment in laryngeal dystonia is hindered by lack of consensus on a core set of outcome measures to quantify treatment effect and disease severity on quality of life. Potential outcome measure domains include objective voice, clinician reported, and patient reported outcome measures (PROMs) for determining treatment success and longitudinal disease tracking. We aim to determine correlations between a selections of outcome measure tools following Botulinum toxin injection.

METHODS

A selection of instruments were administered to assess adductor laryngeal dystonia patient outcomes before and after Botulinum toxin injection. Voice samples recorded using a cellular telephone application were used for objective acoustic measures (CPPS, acoustic voice quality index) and speech language pathologist perceptual analysis (CAPE-V). Additionally, patients completed a PROMs battery consisting of the Voice Handicap Index-10, Communicative Participation Item Bank-10, OMNI-Vocal Effort Scale, 3 visual analog scale (VAS) questions. Changes in these outcome measures pre-post treatment were compared between each other and with a global rating of change questionnaire (GRCQ) using Spearman's rank correlation coefficients.

RESULTS

Twenty six patients (20 female, mean age 57.7 years) participated. Using an anchor based GRCQ, patients reported Botox efficacy was the only outcome measure found to have significant correlation (r = 0.54, P = 0.022); all other outcome measures did not meet statistically significant correlation. Amongst the selected outcome tools, several moderate-strong correlations were identified, largely for outcome measures within the same domain. Most notable were correlations between the patient reported OMNI-VES and VAS questions (r > 0.68, P < 0.05), clinician CAPE-V strain and overall severity (r = 0.900, P < 0.001), and acoustic voice quality index with sustained vowel CPPs (r = -0.797, P = 0.002).

CONCLUSION

Correlation between outcome measures instruments used for patients with adductor laryngeal dystonia requires further attention. Weak correlations with an anchor based GRCQ were found for this study's selected outcome instruments. A select number of correlations were found between outcome instruments within each of the individual outcome measure domains (patient perception, clinical perception, objective acoustics), but there was largely a lack of correlation found for instruments between these three separate domains.

Symptom Expression Across Voiced Speech Sounds in Adductor Laryngeal Dystonia

OBJECTIVES

Differential diagnosis for adductor laryngeal dystonia (AdLD) is often carried out by comparing symptom expression during sentences with either all voiced or voiced and voiceless consonants. However, empirical research examining the effects of phonetic context on symptoms is sparse. The purpose of this study was to examine whether symptom probabilities varied across voiced speech segments in an all-voiced sentence, and whether this variability was systematic with respect to phonetic features.

METHODS

Eighteen speakers with AdLD read aloud a sentence comprised entirely of voiced speech sounds. Speech segment boundaries and AdLD symptoms (phonatory breaks, frequency shifts, and creak) were labeled separately, and speech segments were coded as symptomatic or asymptomatic based on their temporal overlap. Generalized linear mixed effects models with a binomial outcome variable were used to compare the probability of symptom expression across: 1) all speech segments in the sentence, and 2) four speech sound classes (vowels, approximants, nasals, and obstruents).

RESULTS

Significant symptom variability was found across voiced speech segments in the sentence. Furthermore, the estimated probability of a symptom occurring on vowels and approximants was significantly greater than that of nasals and obstruents.

CONCLUSION

These results indicate that AdLD symptoms are not uniformly distributed across voiced speech segments with systematic variation across speech sound classes.To explain these findings, future work should investigate how the complex interactions between the vocal tract articulators and glottal configurations may influence symptom expression in this population.

Validity of intraoperative voice monitoring undergoing type 2 thyroplasty with titanium bridges for adductor spasmodic dysphonia

Objectives

The success of type 2 thyroplasty (TP2) for adductor spasmodic dysphonia (AdSD) depends on the selection of optimally sized titanium bridges, which requires accurate assessment of intraoperative vocal changes. While this procedure has traditionally been performed according to the laryngologist's experience, the most appropriate method for voice monitoring and selection of titanium bridge size remains to be determined. This study aimed to investigate evaluation parameters useful for voice monitoring, as these may allow less experienced surgeons to perform TP2 properly.

Methods

In this prospective study, voice monitoring was performed in 18 patients with AdSD patients undergoing TP2. Evaluations were performed preoperatively, intraoperatively, 13 weeks postoperatively, and 52 weeks postoperatively using GRBAS (grade, roughness, breathiness, asthenia, and strain), as well as perceptual judgment and acoustic analyses.

Results

Preoperative and intraoperative assessments of the G, R, B, and S parameters, perceptual judgment, and harmonic‐to‐noise ratio (HNR) were in moderate or better agreement. Intraoperative and 13‐ or 52‐week postoperative measurements of the R, B, and G parameters and strangulation, tremor, and HNR were also in high agreement. When two different sizes of titanium bridges were compared (unselected vs. selected), ratings for G, R, S, strangulation, tremor, jitter, shimmer, HNR, standard deviation of F0, and degree of voice breaks were better for the selected width than the unselected width.

Conclusion

The candidate items for intraoperative voice monitoring during TP2 for AdSD are G, R, strangulation, tremor, and HNR. The use of these items may help to ensure successful TP2 and contribute to the advancement of laryngeal framework surgery.

Level of evidence

Level 4.

Globus Pallidus Interna and Ventral Intermediate Nucleus of the Thalamus Deep Brain Stimulation for Adductor Laryngeal Dystonia: a Case Report of Blinded Analyses of Objective Voice Outcomes in 2 Patients

BACKGROUND

Adductor laryngeal dystonia (ADLD) is a substantially debilitating focal progressive neurological voice disorder. Current standard of care is symptomatic treatment with repeated injections of botulinum toxin into specific intrinsic laryngeal muscles with extremely variable and temporary benefits. We report the use of bilateral deep brain stimulation (DBS) of globus pallidus (GPi) for long-term improvement of ADLD voice symptoms.

OBJECTIVE

To investigate the effects of bilateral DBS of the GPi and ventral intermediate nucleus (VIM) of the thalamus on vocal function in 2 patients with ADLD associated with voice and hand tremor.

METHODS

Blinded objective and quantitative analyses of voice were conducted before and after treatment in 2 female patients (70 and 69 years). Paired t-tests were conducted to compare voice measurements pre-GPi and post-GPi and VIM-DBS. A 2-way analysis of variance was conducted to determine the interaction between target (GPi/VIM) and time (pre/post) for each voice measure.

RESULTS

Although the follow-up period differed between patients, the GPi-DBS implanted patient had notable improvement in vowel voicing (%), extent of tremor intensity (%), and overall speech intelligibility (%), compared with preoperative status. GPi-DBS also resulted in significant improvement in cepstral peak prominence (dB). VIM-DBS resulted in a significantly greater change in the tremor rate (Hz).

CONCLUSION

Changes in phonatory function provide preliminary support for the use of bilateral GPi-DBS for treatment of ADLD and bilateral VIM-DBS for vocal tremor predominant ADLD. Future studies with larger sample sizes and standardized follow-up periods are needed to better assess the role of DBS for ADLD.

Rabbit model with vocal fold hyperadduction

OBJECTIVE

Adductor spasmodic dysphonia (AdSD) is caused by hyperadduction of the vocal folds during phonation, resulting in a strained voice. Animal models are not yet used to elucidate this intractable disease because AdSD has a difficult pathology without a definitive origin. For the first step, we established an animal model with vocal fold hyperadduction and evaluated its validity by assessing laryngeal function.

METHODS

In this experimental animal study, three adult Japanese 20-week-old rabbits were used. The models were created using a combination of cricothyroid approximation, forced airflow, and electrical stimulation of the recurrent laryngeal nerves (RLNs). Cricothyroid approximation was added to produce a glottal slit. Thereafter, both RLNs were electrically stimulated to induce vocal fold hyperadduction. Finally, the left RLN was transected to relieve hyperadduction. The sound, endoscopic images, and subglottal pressure were recorded, and acoustic analysis was performed.

RESULTS

Subglottal pressure increased significantly, and the strained sound was produced after the electrical stimulation of the RLNs. After transecting the left RLN, the subglottal pressure decreased significantly, and the strained sound decreased. Acoustic analysis revealed an elevation of the standard deviation of F0 (SDF0) and degree of voice breaks (DVB) through stimulation of the RLNs, and degradation of SDF0 and DVB through RLN transection. Formant bands in the sound spectrogram were interrupted by the stimulation and appeared again after the RLN section.

CONCLUSION

This study developed a rabbit model with vocal fold hyperadduction . The subglottal pressure and acoustic analysis of this model resembled the characteristics of patients with AdSD. This model could be helpful to elucidate the pathology of the larynx caused by hyperadduction, and evaluate and compare the treatments for strained phonation.

Botulinum Toxin Therapy: A Series of Clinical Studies on Patients with Spasmodic Dysphonia in Japan

Spasmodic dysphonia (SD) is a rare voice disorder caused by involuntary and intermittent spasms of the laryngeal muscles. Both diagnosis and treatment have been controversial. Therefore, a series of clinical studies has recently been conducted in Japan. A nationwide epidemiological survey revealed that adductor SD predominated (90–95% of all cases; 3.5–7.0/100,000), principally among young women in their 20s and 30s. To facilitate early diagnosis, we created diagnostic criteria for SD and a severity grading system. The diagnostic criteria include the principal and accompanying symptoms, clinical findings during phonation, the treatment response, and the differential diagnoses. The severity grade is determined using a combination of subjective and objective assessments. Botulinum toxin (BT) injection is the treatment of choice; however, there have been few high-quality clinical studies and BT has been used off-label. We conducted a placebo-controlled, randomized, double-blinded clinical trial of BT therapy; this was effective and safe. BT treatment is now funded by the Japanese medical insurance scheme. Studies thus far have facilitated early diagnosis and appropriate therapy; they have fostered patient awareness of SD.

Perceptions regarding communicative participation in individuals receiving botulinum toxin injections for laryngeal dystonia

BACKGROUND

Laryngeal dystonia (LD), or spasmodic dysphonia (SD), is a neurological disorder characterized by focal dystonia or involuntary spasms of the laryngeal muscles and associated voice symptoms. It is typically treated with injection of botulinum toxin (BoNT) that weakens the affected muscles.

AIMS

The primary purpose of this qualitative study was to explore participants' experience of living with LD and BoNT treatment. The secondary purpose was to examine those experiences as a function of participants' scores on the Communicative Participation Item Bank (CPIB). Results will enhance our understanding of restrictions in communicative participation, assist in planning intervention targeting these restrictions and aid in clinical interpretation of CPIB scores.

METHODS & PROCEDURES

Semi-structured interviews using a phenomenological tradition and focusing on BoNT treatment and communicative participation were conducted with 26 people with LD who are on established BoNT treatment regimens. Interviews were recorded, transcribed, coded and analysed inductively. Participants were categorized by CPIB scores into groups ranging from none to extensive participation restrictions. Both self- and expert ratings of voice were obtained.

OUTCOMES & RESULTS

Participants with different levels of CPIB scores had different experiences related to communicative participation in the context of BoNT treatment. These differences were organized into the following topics: BoNT and voice; attitudes toward participation; coping strategies; and advice. For all participants except those in the least restricted and most restricted groups, expert ratings of voice did not relate to CPIB scores.

CONCLUSIONS & IMPLICATIONS

Although most participants report improved voice with BoNT treatment, many participants experienced lingering restrictions in communicative participation, some to a severe extent. Participants reported coping with these restrictions in many ways; some of these strategies were more successful than others. Those with restricted participation recommended more support for daily life and the emotional toll of LD, as well as support for family members. This support might be offered by speech-language pathologists.

WHAT THIS PAPER ADDS

What is already known on the subject Participants with different levels of CPIB scores had different experiences related to communicative participation in the context of BoNT treatment. What this study adds to the existing knowledge Although most participants report improved voice with BoNT treatment, many participants experienced lingering restrictions in communicative participation, some to a severe extent. What are the potential or actual clinical implications of this work? SLP services that take a participation-focused approach to intervention and use multi-factorial approaches to help clients maximize their life participation in the context of LD are well within the SLP scope of practice. SLPs can help clients find and use their optimal voices within the constraints of the dystonia and BoNT effects.

The prevalence and clinical features of spasmodic dysphonia: A review of epidemiological surveys conducted in Japan

OBJECTIVES

Spasmodic dysphonia (SD) is a rare disease and its epidemiological status is unclear. This review aimed to explore the current prevalence and clinical features of SD in Japan.

METHODS

We reviewed Japanese surveys of SD and compared them to surveys reported from other countries. We focused on SD prevalence, clinical features (SD type, sex and age), and treatment modalities.

RESULTS

The SD prevalence in Japan was 3.5-7.0/100,000, similar to that in Rochester (NY, USA) and Iceland. Adductor SD predominated (90-95%) and females were four-fold more likely to be affected than males. Mean age at onset was approximately 30 years in Japan. Several years elapsed from onset to diagnosis. The most frequent treatment was botulinum toxin injection, and surgical intervention, particularly type 2 thyroplasty is becoming more popular.

CONCLUSIONS

Our review demonstrated some differences of clinical features of SD in Japan compared with other countries, such as a greater female predominance and younger age of onset. Many physicians and patients may be unfamiliar with the clinical features of SD leading to delayed of diagnosis. Therefore, we proposed diagnostic criteria to facilitate early diagnosis and an appropriate choice of treatment modalities.

Demographics and coexisting tremor, cervical dystonia and vocal fold disorders in a group of patients with spasmodic dysphonia

The primary aim of this study is to describe the demographic and clinical characteristics of a group of patients with spasmodic dysphonia (SD). As a secondary aim, we examined associations of age at SD diagnosis and sex with co-existing cervical dystonia and nonvocal tremor; as well as association of vocal tremor with sex and nonvocal tremor. Seventy-four consecutive patients who were treated for SD at the Mayo Clinic in Jacksonville, Florida between October 1, 2015 and March 31, 2018 were included in this retrospective study. Information was collected regarding sex, age at SD diagnosis, BMI, SD diagnosis type, recent history of major stress/depression, recent history of upper respiratory tract infection (URTI), co-existing neurological diseases, and co-existing vocal disorders. The majority of patients were female (75.7%) and median age at SD diagnosis was 61 years (range: 17 – 80 years). The median BMI was 25.7 (range: 16.9 – 63.7). The most common diagnostic combinations were adductor dysphonia only (52.7%), adductor dysphonia and MTD (18.9%), and adductor dysphonia and tremor (17.6%). Co-existing tremor was present in 36.6% of patients and cervical dystonia was present in 15.5%. Co-existing vocal disorders were observed as follows: paresis/paralysis (3.1%), cyst (3.1%), mass (4.7%), polyp (1.6%), and anterior glottis web (1.6%). Sex was not notably associated with either cervical dystonia or nonvocal tremor (all P ≥ 0.30). Older age at SD diagnosis was significantly associated with cervical dystonia (P = 0.049), but not nonvocal tremor (P = .22). Other than co-existing tremor, most patients had no co-existing neurological diseases or vocal disorders. Additionally, patients who were older at SD diagnosis were significantly more likely to have co-existing cervical dystonia.

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.

Quality of Life After Botulinum Toxin Injection in Patients With Adductor Spasmodic Dysphonia; a Systematic Review and Meta-analysis

INTRODUCTION

Adductor spasmodic dysphonia is an extremely disabling voice disorder that negatively impacts a patient's quality of life (QOL). We performed a systematic review to determine if Botulinum Toxin (BT) injections improved voice related QOL in patients with this disorder.

METHODS

PubMed, EMBASE, Web of Science, Cochrane Library, ProQuest, and Scopus from 2000, to and including November 1st, 2018, were searched. We identified randomized controlled trials, controlled trials, and observational studies of the effects of BT injections on the QOL in patients with adductor spasmodic dysphonia. The two authors, separately and individually chose the studies based on inclusion criteria, assessed study quality, and relevant extracted data.

RESULTS

Nine studies used the Voice Handicap Index (VHI). The results showed significant changes pre- to post-BT injection (SMD = -0.357; 95% CI: -0.579, -0.136; z = 3.16; P = 0.002; I-squared = 0.000%). Five studies used the Voice-Related QOL; their results also showed a significant improvement pre- to postinjection (SMD = -2.99; 95% CI: -3.27, -1.32; z = 4.61; P < 0.001; I-squared = 87%). Three other studies used other, shortened versions of the VHI, VHI-10. They also showed significant results (SMD = -0.145; 95% CI: -0.349, 0.06; z = 1.38; P = 0.17; I-squared = 0.000).

CONCLUSION

BT injections positively affect patients' QOL. However, patients' QOL scores may never be normalized, in line with perceptual voice quality and acoustic parameters.

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.

Validation of the OMNI vocal effort scale in the treatment of adductor spasmodic dysphonia

OBJECTIVES

To establish the validity of the OMNI Vocal Effort Scale (OMNI-VES) for resistance exercise, a single-question pictorial scale, in voice-related perceived exertion. Additionally, the study aimed to assess the role of the OMNI-VES as an outcome measurement in the treatment of adductor spasmodic dysphonia (ADSD).

METHODS

A prospective validation study was conducted on 226 participants. The case group was comprised of 178 patients receiving botulinum toxin (BTX) injections for ADSD and 48 controls without a voice disorder. Prior to a planned injection, the participants were asked to complete the OMNI-VES and the Voice-Related Quality-of-Life (V-RQOL) questionnaires, and the clinician completed the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). A subgroup of 17 patients were administered a repeat assessment 1 month after injection.

RESULTS

There was a weak correlation between the OMNI-VES and the V-RQOL score (Tau-b = -0.252, P < 0.001), and no significant correlation with the CAPE-V. Participants with ADSD had significantly higher OMNI-VES scores compared with normal controls, 5.07 ± 2.18 and 1.47 ± 2.28, respectively (P value < 0.0001). The average OMNI-VES score significantly improved 1 month following a BTX injection, from 6 ± 2.4 to 3.4 ± 2.8 (P value = 0.0003). Eighty-eight percent of the patients demonstrated a decrease in the OMNI-VES score following injection, whereas only 47% demonstrated an improvement in the V-RQOL score.

CONCLUSION

The OMNI-VES is a validated tool for rating perceived voice-related exertion in people with ADSD and can be used for evaluating response to BTX injection treatment.

LEVEL OF EVIDENCE

2b Laryngoscope, 129:448-453, 2019.

Epidemiology of Swallowing Disorders in Rheumatoid Arthritis: Prevalence, Risk Factors, and Quality of Life Burden

Objective:

This investigation examined the prevalence, symptoms, risk factors, and quality-of-life burden of swallowing disorders in rheumatoid arthritis (RA), a chronic, progressive autoimmune inflammatory disease.

Methods:

One hundred individuals with RA (84 women, 16 men; mean age = 61.1 years, SD = 13.1) were interviewed regarding the presence, nature, and impact of swallowing symptoms and disorders. Associations between swallowing disorders, medical factors, RA disease severity, and quality of life were examined.

Results:

Forty-one percent of participants reported a current swallowing disorder that began gradually and was longstanding (most experiencing symptoms on a daily basis for at least 4 years). Symptoms compatible with solid food dysphagia contributed disproportionately to reporting a current swallowing disorder. Risk factors for dysphagia included a self-reported voice disorder, thyroid problems, esophageal reflux, and being physically inactive. Swallowing disorders increased with self-reported RA disease severity and contributed to a significantly greater burden on overall quality of life.

Conclusion:

Chronic, longstanding swallowing disorders are common in individuals with RA and appear to increase with disease severity. Those individuals with dysphagia reported greater reductions in quality of life as compared to those without, highlighting the need for improved awareness, exploration, and management of swallowing disorders in this population.

Adductor focal laryngeal Dystonia: correlation between clinicians' ratings and subjects' perception of Dysphonia

Background

Although considerable research has focused on the etiology and symptomology of adductor focal laryngeal dystonia (AD-FLD), little is known about the correlation between clinicians’ ratings and patients’ perception of this voice disturbance. This study has five objectives: first, to determine if there is a relationship between subjects’ symptom-severity and its impact on their quality of life; to compare clinicians’ ratings with subjects’ perception of the individual characteristics and severity of AD-FLD; to document the subjects’ perception of changes in dysphonia since diagnosis; to record the frequency of voice arrest during connected speech; and, finally, to calculate inter-clinician reliability based on results from the Unified Spasmodic Dysphonia Rating Scale (USDRS) (Stewart et al, J Voice 1195-10, 1997).

Methods

Sixty subjects with AD-FLD who were receiving ongoing injections of BoNT participated in this study. Subjects’ mean age was 60.78 years and their mean duration of symptoms was 16.1 years. Subjects completed the Disease Symptom Questionnaire (DSQ) (specifically designed for this study) and the Voice Handicap Index-10 (VHI-10) (Jacobson et al, Am J Speech Lang Pathol 6:66–70, 1997) to measure the symptoms of their dysphonia and the impact of the disease on their quality of life.

Two speech-language pathologists and two laryngologists used the Voice Arrest Measure (VAM) (specifically designed for this study) and the USDRS to independently rate voice recordings of 56/60 subjects.

Results

The mean VHI-10 score was 21.3 which is clinically significant. The results of the DSQ and the USDRS were highly correlated. The most severe symptoms identified by both subjects and clinicians were roughness, strain-strangled voice quality, and increased expiratory effort. Voice arrest, aphonia, and tremor were uncommon. Subjects rated their current voice quality at the time of reinjection (i.e., at the time of the study) as significantly better than at the time of their initial AD-FLD diagnosis (p < 0.0001). Inter-clinician reliability on the USDRS was significant at the 0.001 level.

Conclusions

The findings from the VHI-10 suggest that AD-FLD has a profound impact on quality of life. The results of the DSQ and the USDRS suggest that there is a strong correlation between subjects’ perception and clinicians’ assessment of the individual symptoms and the severity of the dysphonia. The findings from the VAM suggest that voice arrests are infrequent in subjects with AD-FLD who are receiving ongoing BoNT injections. The strong inter-clinician reliability on the USDRS suggests that it is an appropriate measure for identifying symptoms and severity of AD-FLD.

Electronic supplementary material

The online version of this article (10.1186/s40734-017-0066-y) contains supplementary material, which is available to authorized users.

Reliability of High-speed Videoendoscopic Ratings of Essential Voice Tremor and Adductor Spasmodic Dysphonia

OBJECTIVES

The main objectives of this study were to (1) examine intrarater and inter-rater reliabilities in perceptual ratings of vocal fold vibratory patterns and supraglottic characteristics for essential vocal tremor and adductor spasmodic dysphonia (AdSD) using high-speed videoendoscopy (HSV), and (2) to investigate the specificity of the parameters in differentiating these two voice disorders.

METHODS

HSV recordings of 34 cases diagnosed with essential vocal tremor, AdSD, or AdSD with vocal tremor were evaluated blindly by two voice speech pathologists. The two raters examined all HSV video segments twice across nine supraglottic and vocal fold vibratory characteristics for inter-rater and intrarater reliabilities. A separate consensus rating was then developed, with the results analyzed to explore differentiation.

RESULTS

Raters demonstrated moderate intrarater reliability with mean Spearman's rho correlation coefficients of 0.68 (rater 1) and 0.73 (rater 2). Moderate inter-rater reliability for the two raters was seen across all parameters with a mean Cohen's kappa coefficient of 0.51. Raters showed higher intrarater and inter-rater reliabilities for supraglottic parameters. Only the presence of tremor differentiated between the two voice disorders in cases with a consistent diagnosis.

CONCLUSIONS

The high level of concomitance between vocal tremor and AdSD may affect subjective perceptual analysis of supraglottic and vocal fold vibratory patterns. Results indicate similar global involvement of supraglottic laryngeal structures for both vocal tremor and AdSD.

Speech-Language Pathology Evaluation and Management of Hyperkinetic Disorders Affecting Speech and Swallowing Function

Background

Hyperkinetic dysarthria is characterized by abnormal involuntary movements affecting respiratory, phonatory, and articulatory structures impacting speech and deglutition. Speech–language pathologists (SLPs) play an important role in the evaluation and management of dysarthria and dysphagia. This review describes the standard clinical evaluation and treatment approaches by SLPs for addressing impaired speech and deglutition in specific hyperkinetic dysarthria populations.

Methods

A literature review was conducted using the data sources of PubMed, Cochrane Library, and Google Scholar. Search terms included 1) hyperkinetic dysarthria, essential voice tremor, voice tremor, vocal tremor, spasmodic dysphonia, spastic dysphonia, oromandibular dystonia, Meige syndrome, orofacial, cervical dystonia, dystonia, dyskinesia, chorea, Huntington’s Disease, myoclonus; and evaluation/treatment terms: 2) Speech–Language Pathology, Speech Pathology, Evaluation, Assessment, Dysphagia, Swallowing, Treatment, Management, and diagnosis.

Results

The standard SLP clinical speech and swallowing evaluation of chorea/Huntington’s disease, myoclonus, focal and segmental dystonia, and essential vocal tremor typically includes 1) case history; 2) examination of the tone, symmetry, and sensorimotor function of the speech structures during non-speech, speech and swallowing relevant activities (i.e., cranial nerve assessment); 3) evaluation of speech characteristics; and 4) patient self-report of the impact of their disorder on activities of daily living. SLP management of individuals with hyperkinetic dysarthria includes behavioral and compensatory strategies for addressing compromised speech and intelligibility. Swallowing disorders are managed based on individual symptoms and the underlying pathophysiology determined during evaluation.

Discussion

SLPs play an important role in contributing to the differential diagnosis and management of impaired speech and deglutition associated with hyperkinetic disorders.

Employer Reactions to Adductor Spasmodic Dysphonia: Exploring the Influence of Symptom Severity and Disclosure of Diagnosis During a Simulated Telephone Interview

PURPOSE

The purpose of this study was to determine the influence of symptom severity and disclosure of adductor spasmodic dysphonia (ADSD) on the perceptions of human resource personnel members (HRPs) during a simulated phone interview.

METHOD

One female speaker with ADSD was recorded reading an interview script at two time points: (a) pre-BOTOX injection (severe), and (b) post-BOTOX injection (mild). Thirty-two HRPs evaluated the recording in one of the two conditions via a qualitative structured interview. HRPs gave their recommendations regarding when and how to disclose ADSD.

RESULTS

In the mild condition, no HRP perceived that the applicant had a voice disorder. Disclosure was not recommended as often, as an impairment was not initially noticed. However, 15/16 HRPs commented on the applicant's voice in the severe condition, with most suspecting she was a smoker or had lung/throat cancer. Disclosure in the severe condition was recommended more often, as it clarified symptoms that were noted at the outset.

CONCLUSIONS

Symptom severity in ADSD influences employer perceptions during the phone interview process. Incorrect assumptions may be made about applicants with severe symptoms, and apparentness of symptoms influences whether or not disclosure is recommended. Results have implications for counseling individuals with ADSD who are navigating the job interview process.

Dystonia-Causing Mutations as a Contribution to the Etiology of Spasmodic Dysphonia

OBJECTIVE

Spasmodic dysphonia is a focal dystonia of the larynx with heterogeneous manifestations and association with familial risk factors. There are scarce data to allow precise understanding of etiology and pathophysiology. Screening for dystonia-causing genetic mutations has the potential to allow accurate diagnosis, inform about genotype-phenotype correlations, and allow a better understanding of mechanisms of disease.

STUDY DESIGN

Cross-sectional study.

SETTING

Tertiary academic medical center.

SUBJECTS AND METHODS

We enrolled patients presenting with spasmodic dysphonia to the voice clinic of our academic medical center. Data included demographics, clinical features, family history, and treatments administered. The following genes with disease-causing mutations previously associated with spasmodic dysphonia were screened: TOR1A (DYT1), TUBB4 (DYT4), and THAP1 (DYT6).

RESULTS

Eighty-six patients were recruited, comprising 77% females and 23% males. A definite family history of neurologic disorder was present in 15% (13 of 86). Average age (± standard deviation) of symptom onset was 42.1 ± 15.7 years. Most (99%; 85 of 86) were treated with botulinum toxin, and 12% (11 of 86) received oral medications. Genetic screening was negative in all patients for the GAG deletion in TOR1A (DYT1) and in the 5 exons currently associated with disease-causing mutations in TUBB4 (DYT4). Two patients tested positive for novel/rare variants in THAP1 (DYT6).

CONCLUSION

Genetic screening targeted at currently known disease-causing mutations in TOR1A, THAP1, and TUBB4 appears to have low diagnostic yield in sporadic spasmodic dysphonia. In our cohort, only 2 patients tested positive for novel/rare variants in THAP1. Clinicians should make use of genetic testing judiciously and in cost-effective ways.

The Mayo Clinic Arizona Spasmodic Dysphonia Experience

Objective:

Analyze demographic data collected over a 25-year experience of 718 patients with spasmodic dysphonia (SD) who have been treated with botulinum toxin-A (BoNT-A) and compare our data with previously published studies.

Methods:

Seven hundred eighteen patients with SD were treated with 6621 BoNT-A injections at Mayo Clinic Arizona between 1989 and 2014. All patients were treated by the same physician team. Background demographic data for each patient were recorded.

Results:

Of 718 patients, 557 patients were female (77.6%). Six hundred sixty of 718 (91.8%) patients had adductor SD (AdSD), and 58 of 718 (8.1%) patients had abductor SD (AbSD). Average age of onset was 51 years. Of 718 patients, 378 (52.6%) had vocal tremor (VT); VT was present in 54.4% of AdSD patients and 32.1% of AbSD patients. Thirty-seven of 718 (5.2%) patients had other dystonias, including cervical dystonia (2.3%), blepharospasm (1.4%), limb dystonia (1.1%), and oromandibular dystonia (0.3%). A positive family history of SD was present in only 6 of 718 patients (0.8%) and of other dystonias in 11 of 718 patients (1.5%).

Conclusions:

Spasmodic dysphonia is a chronic and potentially disabling focal laryngeal dystonia. The Mayo Clinic Arizona SD experience compares to prior reports and reveals a female preponderance, onset in middle age, infrequent hereditary pattern, high co-occurrence of VT, and low co-occurrence of other dystonias.

Descriptive Epidemiology of Voice Disorders in Rheumatoid Arthritis: Prevalence, Risk Factors, and Quality of Life Burden

OBJECTIVES

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease which may adversely affect phonatory function. This study aimed to establish the prevalence, risks, and quality of life effects of voice disorders in RA.

STUDY DESIGN

This is a cross-sectional, descriptive epidemiology study.

METHODS

One hundred individuals with RA underwent a telephone interview to determine the frequency, severity, risks associated with, and quality of life burden of voice disorders. The results were analyzed using summary statistics, frequencies, chi-square tests, regression analysis, and risk ratios (P < 0.05).

RESULTS

Thirty-five percent of participants with RA reported a current voice disorder which was chronic and long-standing in most cases. The prevalence of a current voice disorder did not significantly differ across age, sex, medication use, voice use patterns, medical history, or RA severity. These chronic voice disorders produced significant adverse effects on both voice-related quality of life and short form 36 health-related quality of life scales. Specific voice symptoms such as "voice-related discomfort" and "chronic throat dryness" contributed disproportionately to the quality of life burden. Of those participants with a voice disorder, only 37% had ever sought professional help to improve their voice.

CONCLUSIONS

These results indicate that voice disorders are common in RA and produce significant adverse effects on quality of life. Further research is necessary to better understand the origin of these disorders and their potential response to treatment.

Treatment of spasmodic dysphonia with a neuromodulating electrical implant

OBJECTIVES/HYPOTHESIS

To investigate the feasibility of an implantable electrical stimulation device to treat spasmodic dysphonia (SD) by neuromodulation of the muscle spindle gamma loop.

STUDY DESIGN

Prospective case series.

METHOD

Five subjects underwent daily stimulation of the left thyroarytenoid muscle (TA) below the level of α-motor neuron activation (AMNA) for 5 consecutive days. Professional and patient voice evaluations were performed. Transcartilagenous placement of an implantable stimulation device lead was investigated in anesthetized porcine and cadaveric human models.

RESULTS

Three of 5 subjects improved in all categories of evaluation. One subject improved in three of four categories. These four subjects described significant carryover of effect after treatment. The fifth subject evidenced improvement until contracting an upper respiratory infection on day 3. Transcartilagenous electrode placement into the porcine TA with muscle stimulation was successful. The electrode lead was passed from the cadaveric larynx to the mastoid tip in the subplatysma layer with an absence of tension.

CONCLUSION

The symptoms of SD improve after electrical stimulation of the TA at levels below AMNA. This is likely through neuromodulation of the muscle spindle gamma loop. Implantation of an electrode into the TA with a postauricular implanted stimulator is feasible with modifications of an already existing device. With further investigation, such a device has the potential to deliver an alternative treatment for SD.

LEVEL OF EVIDENCE

4.

Abnormal striatal dopaminergic neurotransmission during rest and task production in spasmodic dysphonia

Spasmodic dysphonia is a primary focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. The pathophysiology of spasmodic dysphonia is thought to involve structural and functional abnormalities in the basal ganglia-thalamo-cortical circuitry; however, neurochemical correlates underpinning these abnormalities as well as their relations to spasmodic dysphonia symptoms remain unknown. We used positron emission tomography with the radioligand [(11)C]raclopride (RAC) to study striatal dopaminergic neurotransmission at the resting state and during production of symptomatic sentences and asymptomatic finger tapping in spasmodic dysphonia patients. We found that patients, compared to healthy controls, had bilaterally decreased RAC binding potential (BP) to striatal dopamine D2/D3 receptors on average by 29.2%, which was associated with decreased RAC displacement (RAC ΔBP) in the left striatum during symptomatic speaking (group average difference 10.2%), but increased RAC ΔBP in the bilateral striatum during asymptomatic tapping (group average difference 10.1%). Patients with more severe voice symptoms and subclinically longer reaction time to initiate the tapping sequence had greater RAC ΔBP measures, while longer duration of spasmodic dysphonia was associated with a decrease in task-induced RAC ΔBP. Decreased dopaminergic transmission during symptomatic speech production may represent a disorder-specific pathophysiological trait involved in symptom generation, whereas increased dopaminergic function during unaffected task performance may be explained by a compensatory adaptation of the nigrostriatal dopaminergic system possibly due to decreased striatal D2/D3 receptor availability. These changes can be linked to the clinical and subclinical features of spasmodic dysphonia and may represent the neurochemical basis of basal ganglia alterations in this disorder.

Respiratory disorders associated with dystonia

BACKGROUND

Respiratory difficulties are sometimes reported by patients with cranial-cervical and other forms of dystonia, but the nature or mechanisms of the breathing problems have not been well characterized.

CASE REPORT

We review 13 dystonic patients with various respiratory complaints and describe their symptoms and response to treatment, including botulinum toxin (BoNT) injections.

DISCUSSION

Gasping, stridor, interrupted flow of speech, paradoxical breathing, dyspnea on exertion, and other respiratory symptoms reported by patients suggest involvement of the upper airways, chest, and diaphragm. BoNT injections may be, at least partially, beneficial in some patients.

CONCLUSION

This series of patients draws attention to respiratory distress as a potentially serious, even life-threatening, complication of dystonia.

Epidemiologic Advances in Spasmodic Dysphonia

Recently research offers new insights into the pathogenesis, pathophysiology, and socioemotional implications of spasmodic dysphonia (SD). Among these advances are epidemiologic studies clarifying (1) SD onset and course, (2) SD risk factors, and (3) the relationships among SD course, treatment, and psychosocial impact. In this paper, I will provide a summary of recent epidemiologic and socioemotional research advances involving the onset, course, risk factors, and psychosocial impact of SD.

Botulinum toxin as treatment for focal dystonia: a systematic review of the pharmaco-therapeutic and pharmaco-economic value

Focal dystonia is a common, invalidating neurologic condition characterized by involuntary, sustained muscle contractions causing twisting movements and abnormal postures in one body part. Currently, botulinum toxin is the treatment of first choice. We performed a systematic review towards the pharmaco-therapeutic and pharmaco-economic value of botulinum toxin as treatment for focal dystonia, which yielded the following results. Botulinum toxin is the most effective treatment for reducing dystonic symptoms measured with dystonia-specific and general questionnaires, and pain in patients with focal dystonia. Seventy-one percent of patients with cervical dystonia had a reduction in neck pain compared to 12 % in placebo groups. Adverse events occur in 58 % of patients during treatment with botulinum toxin compared to 46 % treated with placebo. Especially dry mouth, neck weakness, dysphagia, and voice changes are common. Adverse events are usually mild and self-limiting. Health-related quality of life, measured with the SF-36 is 20-50 points lower in patients with focal dystonia compared to controls and the effect of botulinum toxin on health-related quality of life is unclear. Botulinum toxin treatment is expensive because the drug itself is expensive. Yearly costs for treating a patient with focal dystonia with botulinum toxin range from EUR 347 to EUR 3,633 and the gain in QALYs with BTX treatment is small. Focal dystonia impairs the productivity and the ability to work. At start of botulinum toxin treatment only 47-50 % was working. Botulinum toxin partly improves this. Overall, we conclude that botulinum toxin is an expensive drug with good effects. From a societal perspective, the costs may well weigh up to the regained quality of life. However, the available literature concerning costs, health-related quality of life and labor participation is very limited. An extensive cost-effectiveness study should be performed incorporating all these aspects.