Optimal botulinum toxin therapy of dystonia in Germany: what would it cost?

Botulinum toxin (BT) therapy is the therapy of choice for most forms of dystonia. We want to describe its costs, if all dystonia patients in Germany would have access to optimal BT therapy. For this, we combined the latest data on epidemiology of dystonia and dosing of BT therapy for dystonia. Missing data were generated for this study. Based on official German pharmacy sales prices, optimal treatment for all dystonia patients in Germany with a population of 84.1 million would generate annual drug costs of €155.5 million (cervical dystonia 89.3, tardive dystonia 22.1, generalised dystonia 17.9, blepharospasm 9.3, segmental dystonia 5.9, writer's cramp 5.3, arm dystonia 3.2, oromandibular dystonia 2.3, musician's dystonia 0.3, spasmodic dysphonia 0.1) This is €1.85 annually per capita or 0.3% of the total 2021 drug budget and 42% of the 2021 Parkinson drug budget of German public insurance companies. Actual costs for the health care system are considerably lower, as there are various discounts to consider. Further reductions would be possible. BT therapy's individual costs are high. Its costs for the health care system, however, are marginal. Comparing projected and actual costs, would allow estimating availability and quality of BT therapy of dystonia in Germany.

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.

Patient Experience Contributing to Outcomes of Laryngeal Botulinum Toxin Injection

OBJECTIVES

Laryngeal Botulinum Toxin injection (LBTX) in the adductor musculature is the current therapy for Adductor Spasmodic Dysphonia. This study explores nonbiological factors that can affect the patient experience during this procedure and their association with better or worse self-reported effectiveness.

METHODS

A 14 item survey was used to evaluate the patient experience in patients who had undergone LBTX in Mayo Clinic Jacksonville, Florida, during 2019. Information from the survey, previous medical history, and demographic data were collected, and a descriptive analysis was performed.

RESULTS

Of the 36 patients who participated, the mean age was 65 years and a female predominance was found (66%). The average age at onset of symptoms was 57 years, and voice tremor was associated with 36.1% of patients. Preprocedure education was recognized as a factor affecting outcomes in 87% of patients; 11 patients reported that body position used during the injection could affect the results. Pain or stress experienced at the time of procedure was referred in one-third of patients as an influencing factor too.

CONCLUSION

This study has shown that nonpharmacological factors such as education before the procedure, body position, pain, and stress sensation before LBTX may have a role in the botulinum toxin effect on Adductor Spasmodic Dysphonia patients. This study is the first to describe these variables qualitatively, and further studies may help to improve the patient experience and outcome of LBTX around the world.

Influence of Lineage-Negative Stem Cell Therapy on Articulatory Functions in ALS Patients

Introduction

Amyotrophic lateral sclerosis (ALS) is a fatal, neurodegenerative disease, leading to loss of muscle strength and motor control. Impaired speech and swallowing lower the quality of life and consequently may induce acute respiratory failure. Bone marrow-derived stem and progenitor cells (SPCs) may be a valuable source of trophic factors. In this study, we assessed whether adjuvant cellular therapy could affect the levels of selected neurotrophins and proinflammatory factors in the cerebrospinal fluid (CSF) and subsequently prevent the deterioration of articulation.

Materials and Methods

The study group consisted of 32 patients with sporadic ALS who underwent autologous lineage-negative (Lin⁻) stem cell intrathecal administration to the spinal canal. Lin⁻ cells were aspirated from the bone marrow and isolated using immunomagnetic beads and a lineage cell depletion kit. Patients were examined for articulatory functions by means of the Voice Handicap Index (VHI) questionnaire and Frenchay Dysarthria Assessment (FDA). In parallel, we carried out the analysis of selected trophic and proinflammatory factors in CSF utilizing multiplex fluorescent bead-based immunoassays.

Results

Of the 32 patients who received the Lin⁻ progenitor cell therapy, 6 (group I) showed improvement in articulatory functions, 23 remained stable (group II), and 3 deteriorated (group III) on the 28^th day. The improvement was particularly noticeable in a better cough reflex, laryngeal time, and dribble reflex. A statistically significant lower level of brain-derived neurotrophic factor (BDNF) was observed on day 0 in group I compared to group II. The CSF concentrations of C-reactive protein (CRP) in group I significantly decreased 7 days after Lin⁻ SPC transplantation. On the contrary, a significant increase in the tumor necrosis factor receptor (TNF-R) level was confirmed among patients from group I with improvement of dribble and coughing reflex, tongue movements, and respiration on the 7^th day, as well as on day 28 including dribble reflex solely.

Conclusions

An application of Lin⁻ stem cells could potentate the beneficial humoral effect. The prevention of deterioration of articulatory functions in ALS patients after applying adjuvant Lin⁻ stem cell therapy seems to be promising. Although the procedure is safe and feasible, it requires further in-depth studies.

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.

Long-term Dose Stability of OnabotulinumtoxinA Injection for Adductor Spasmodic Dysphonia: A 19-Year Single Institution Experience

Objectives

Adductor spasmodic dysphonia (AdSD) is a focal dystonia predominantly involving the laryngeal adductor muscles. AdSD is reported to be a largely non-progressive neurological disorder, though fluctuations in symptom severity do occur. Repeated laryngeal onabotulinumtoxinA (BTX-A) injections are the primary management for AdSD. A number of studies have demonstrated long-term dose stability as evidence of this long-term disease stability.

Methods

A retrospective review was performed on all patients undergoing BTX-A injections for AdSD from April 1994 to September 2013 by a single laryngologist at a tertiary referral laryngology center. Patient demographics, injection doses, use of diazepam and/or lidocaine, and self-reported vocal function were recorded. Multiple linear regression analyses were performed.

Results

83 patients underwent a total of 1,168 injections over 19 years. The mean starting dose was 2.35 MU (0.79 SD). The mean long-term dose was 2.36 MU (0.79 SD). After adjusting for confounders, the change in the relative dose of BTX-A, with every year elapsed since initial dose was 0.13% (95% confidence interval -0.31 to 0.57%), p = 0.568.

Conclusion

BTX-A dose is stable over time in our large cohort of patients treated with bilateral thyroarytenoid injections for AdSD.

Vocal Exercise versus Voice Rest following Botulinum Toxin Injections: A Randomized Crossover Trial

Objectives

The intensity of muscle activity immediately following intramuscular botulinum toxin injection may affect the clinical efficacy of the injection. We tested this effect in patients who underwent botulinum toxin injections for adductor spasmodic dysphonia.

Methods

Patients were studied over 3 to 5 injection cycles. Cycle 1 was the baseline control; cycle 2 was randomized between a 1-hour reading aloud task (“exercise”) and a 24-hour period of complete voice rest. For cycle 3, the patient completed the task not performed in cycle 2. Patients who were willing to continue for cycles 4 and 5 repeated the experiment at one half the injection dosage. Efficacy was determined with a battery of voice recordings and clinical outcomes instruments administered via telephone at 2- to 4-week intervals. The primary outcome measure was the result of the Voice-Related Quality of Life (VRQOL) instrument.

Results

Nine patients (8 women, 1 man) with a mean age of 60.8 years (range, 42 to 76 years) completed at least 3 injection cycles. The VRQOL results were significantly higher for cycles that followed the exercise task. The patients reported subjectively that these were some of the best injection cycles they had ever experienced. Some achieved equivalent results with the half-dose injection plus exercise. The VRQOL results after voice rest cycles were not significantly different from the patients' baseline cycles.

Conclusions

These results support the conclusion that a period of intense vocalization immediately following laryngeal botulinum toxin injections improves the efficacy of the injection. Possible mechanisms are proposed.

Liquid-type Botulinum Toxin Type A in Adductor Spasmodic Dysphonia: A Prospective Pilot Study

OBJECTIVES

Botulinum toxin (BTX) has been widely used to treat adductor spasmodic dysphonia (ADSD). Most commercially available forms of BTX require reconstitution before use, which may increase the risk of contamination and requires careful titration. Recently, a liquid-type BTX type A (BTX-A) has been developed, which should simplify the procedure and enhance its efficacy. Herein, we present a prospective pilot study to investigate the efficacy and safety of liquid-type BTX-A in the treatment of ADSD.

METHODS

Twenty-six consecutive liquid-type BTX-A injections were performed in 12 patients with ADSD. We included as a control group 34 consecutive patients with ADSD who had previously undergone 52 vocal fold injection procedures with freeze-dried-type BTX-A.

RESULTS

All patients in both groups had improvement of symptoms related to ADSD and period of normal voice. Most patients experienced breathiness, and the onset time, the peak response time, and the duration of breathiness were similar in both groups. The duration of effect (days) was 96.96 ± 18.91 and 77.38 ± 18.97 in the freeze-dried-type and the liquid-type groups, and the duration of benefit (days) was 80.02 ± 18.24 and 62.69 ± 19.73 in the freeze-dried-type and the liquid-type groups. To compare the efficacy between the freeze-dried-type and the liquid-type BTX-A, the sessions of the unilateral vocal fold injection were included and were categorized as group A (1 ~ 2 units BTX-A) and group B (2 ~ 3 units BTX-A), according to the dose per vocal fold. There was no significant difference of effect time between freeze-dried-type and liquid-type BTX-A groups. No adverse events related to BTX or vocal fold injection were reported.

CONCLUSIONS

Liquid-type BTX-A is safe and effective for the treatment of spasmodic dysphonia. With the advantages of simple preparation, storage, and reuse and animal protein-free constituents, liquid-type BTX-A may be a good option in the treatment of spasmodic dysphonia.

Electromyography-Guided Botulinum Toxin Injection Into the Cricothyroid Muscles in Bilateral Vocal Fold Abductor Paralysis

Objectives

Bilateral vocal fold abductor paralysis (BVFAP) both deteriorates quality of life and may cause life-threatening respiratory problems. The aim of this study was to reduce respiratory symptoms in BVFAP patients using cricothyroid (CT) botulinum toxin (BTX) injection.

Methods

Before and 2 weeks and 4 months after bilateral BTX injection into the CT muscles under electromyography; alterations in respiratory, acoustic, aerodynamic and quality of life parameters were evaluated in BVFAP patients with respiratory distress. For the respiratory evaluation modified Borg scale and spirometry, for the voice and aerodynamic evaluations Voice Handicap Index-30 (VHI-30), GRBAS, acoustic analysis (sound pressure level, F0, jitter%, shimmer%, noise-to-harmonic ratio) and maximum phonation time and for the quality of life assessment Short Form-36 (SF-36) form were used.

Results

All patients were female with a mean age of 47±8.1 years. There was a mean time of 11.8±5.5 (minimum 2, maximum 23) months between BVFAP development and BTX injection. In all cases, other than one case with unknown aetiology, the cause of vocal fold paralysis was prior thyroid surgery. In total 18.6±3.1 units of BTX were applied to the CTs. In the preinjection period, and the 2nd week and 4th month after injection, the Borg dyspnea scale was 7.3/5.3/5.0, FIV1 (forced inspiratory volume in one second) was 1.7/1.7/1.8 L, peak expiratory flow (PEF) was 1.4/1.7/2.1 L/sec, maximum phonation time was 7.0/6.4/6.2 seconds and VHI-30 was 63.2/52.2/61.7 respectively. There was no significant alteration in acoustic analysis parameters. Many of the patients reported transient dysphagia within the first week. There were insignificant increases in SF-36 sub-scale values.

Conclusion

After BTX injection, improvements in the mean Borg score, PEF and FIV1 values and SF-36 sub-scale scores showed the restricted success of this approach. This modality may be kept in mind as a transient treatment option for patients refused persistent tracheotomy or ablative airway surgeries.

Lateral Cricoarytenoid Release: Development of a Novel Surgical Treatment Option for Adductor Spasmodic Dysphonia in a Canine Laryngeal Model

OBJECTIVE

To investigate the efficacy of a novel adductor muscle-releasing technique designed to decrease the force of vocal fold adduction, as a potential surgical therapy for patients with adductor spasmodic dysphonia (ADSD).

STUDY DESIGN

Experimental animal study.

METHODS

A canine laryngeal model was used to assess the acute and sustained efficacy of a lateral cricoarytenoid (LCA) muscle release. A total of 34 canine hemilaryngeal preparations were divided among 7 experimental groups. The LCA muscle was separated from its cricoid cartilage origin via an open, anterior, submucosal approach. The laryngeal adductory pressures (LAP) were assessed pre- and post-muscle release via direct recurrent laryngeal nerve stimulation. Measurements were repeated at 1.5, 3, or 6 months postoperatively. Another study evaluated release of the thyroarytenoid (TA) muscle from its thyroid cartilage origin.

RESULTS

Releasing the LCA muscle demonstrated a significant decrease in LAP acutely and was maintained at all 3 time points with the aid of a barrier (P < .05). Without the barrier, the LCA muscle reattached to the cricoid. Acute release of the TA muscle did not significantly decrease the LAP.

CONCLUSIONS

The proposed LCA release procedure may provide patients with a permanent treatment option for ADSD. However, longer-term studies and human trials are needed.

Considerations for Initial Dosing of Botulinum Toxin in Treatment of Adductor Spasmodic Dysphonia

Objectives

To assess the effect on voice improvement and duration of breathiness based on initial dose of onabotulinum toxin A (BTX-A) in the management of adductor spasmodic dysphonia (SD) and to compare voice outcomes for initial bilaterally injected doses of 1.25 units (group A) vs 2.5 units (group B) of BTX-A.

Study Design

Case series with chart review of patients with adductor SD treated at a tertiary care facility from 1990 to 2011.

Setting

Academic subspecialty laryngology practice.

Methods

Demographic data (age and sex), voice rating, duration of voice improvement, and breathiness were evaluated and compared between groups A and B using the Student t test and χ2 analysis.

Results

Of 478 patients identified, 305 (223 in group A, 82 in group B) patients met inclusion criteria. The average age was 56.2 years in group A and 57.4 years in group B ( P = .5). The female to male ratio was 2.91 for group A vs 3.56 for group B ( P = .61). Good voice outcomes (grade 3 or 4) were reported by 91% of group A patients vs 94% of group B ( P = .75). The average duration of voice improvement was 99.7 days for group A and 108.3 days for group B ( P = .54). The average duration of breathiness was 10.88 days for group A vs 15.42 days for group B ( P = .02).

Conclusion

Patients injected with 1.25 units bilaterally had a statistically significant shorter duration of breathiness without a statistically significant difference in clinical effectiveness or voice outcome. It is therefore recommended that a relatively low initial BTX-A dose be used with subsequent titration to achieve improved voice outcomes.

Botulinum toxin treatment in upper limb spasticity: treatment consistency

This study assessed treatment consistency of botulinum toxin administration in spastic upper limbs under pragmatic conditions, as derived through stability of dosages and between injections intervals. Over a period of 8 years, 153 children (81 with bilateral spastic cerebral palsy, 72 with unilateral) were treated according to accepted, experience-based guidelines with Botox and Dysport. Treatment response was based on assessment of spasticity and attainment of pre-determined goals at 3, 6 and 12 months post each treatment. Mean age at treatment onset was 6y 4mo (SD: 4y 10mo), median F/U, 2.5 years (4 months-6 8/12 years). Number of injection sessions was 1-10; few had more than 6 sessions. In 106 (69.28%) children, more than one anatomic regions of the limb were injected. Most (56.2%), had at least two injection sessions; median time interval between the sessions was 9 months (IQR: 4-35 months, similar for unilateral and bilateral cerebral palsy, p = 0.874). Children >4 years old at the first treatment had longer intervals between sessions (25.8%) compared to younger ones (p = 0.010). The mixed effects models demonstrated that botulinum toxin dosage was stable over subsequent visits (p = 0.144) and that intermediate intervals for subsequent visits were similar to the first one (p = 0.279).

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Vocal Exercise versus Voice Rest following Botulinum Toxin Injections: A Randomized Crossover Trial

Objectives:

The intensity of muscle activity immediately following intramuscular botulinum toxin injection may affect the clinical efficacy of the injection. We tested this effect in patients who underwent botulinum toxin injections for adductor spasmodic dysphonia.

Methods:

Patients were studied over 3 to 5 injection cycles. Cycle 1 was the baseline control; cycle 2 was randomized between a 1-hour reading aloud task (“exercise”) and a 24-hour period of complete voice rest. For cycle 3, the patient completed the task not performed in cycle 2. Patients who were willing to continue for cycles 4 and 5 repeated the experiment at one half the injection dosage. Efficacy was determined with a battery of voice recordings and clinical outcomes instruments administered via telephone at 2- to 4-week intervals. The primary outcome measure was the result of the Voice-Related Quality of Life (VRQOL) instrument.

Results:

Nine patients (8 women, 1 man) with a mean age of 60.8 years (range, 42 to 76 years) completed at least 3 injection cycles. The VRQOL results were significantly higher for cycles that followed the exercise task. The patients reported subjectively that these were some of the best injection cycles they had ever experienced. Some achieved equivalent results with the half-dose injection plus exercise. The VRQOL results after voice rest cycles were not significantly different from the patients' baseline cycles.

Conclusions:

These results support the conclusion that a period of intense vocalization immediately following laryngeal botulinum toxin injections improves the efficacy of the injection. Possible mechanisms are proposed.

Dysarthria in amyotrophic lateral sclerosis: A review

Dysarthria is a motor disorder of speech characterized by abnormalities of the articulation and intelligibility of speech. Phonation and the rate of facial movements may also be affected. Understanding the nature and course of dysarthria in amyotrophic lateral sclerosis (ALS) is important because loss of communication prevents patients from participating in many activities, may lead to social isolation, and reduces the quality of life. The goal of management of dysarthria in ALS patients is to optimize communication effectiveness for as long as possible. The information about dysarthria in ALS is dispersed in physiological, pathological, speech therapy, otorhinolaringological and neurological publications. This review summarizes the current state of knowledge on the clinical features, differential diagnosis, pathophysiology, investigations and management of dysarthria in ALS patients. There is a need to compare the different methods used to assess dysarthria and for controlled clinical trials to assess therapeutic strategies.

A single-centre retrospective review of unilateral and bilateral Dysport injections in adductor spasmodic dysphonia

We reviewed the results and side-effect profile of the Dysport preparation of botulinum toxin A (BTA) in the management of the adductor spasmodic dysphonia. We performed 272 injection episodes in 68 patients, 42 (62%) female, 26 (38%) male. A total of 116 of these injections were unilateral, and 156 were bilateral; 94% of the injections were considered to have been successful with a voice score of 2 or higher. The mean duration of effect (injection intervals) was 128.8 days in the unilateral cohort and 118.7 days in the bilateral (P > 0.05). We injected a relatively lower dose of BTA for unilateral injection episodes in our institution compared to those reported by others to produce comparable results and side-effect profiles.

Treatment for spasmodic dysphonia: limitations of current approaches

PURPOSE OF REVIEW

Although botulinum toxin injection is the gold standard for treatment of spasmodic dysphonia, surgical approaches aimed at providing long-term symptom control have been advancing over recent years.

RECENT FINDINGS

When surgical approaches provide greater long-term benefits to symptom control, they also increase the initial period of side effects of breathiness and swallowing difficulties. Recent analyses of quality-of-life questionnaires in patients undergoing regular injections of botulinum toxin demonstrate that a large proportion of patients have limited relief for relatively short periods due to early breathiness and loss-of-benefit before reinjection.

SUMMARY

Most medical and surgical approaches to the treatment of spasmodic dysphonia have been aimed at denervation of the laryngeal muscles to block symptom expression in the voice, and have both adverse effects as well as treatment benefits. Research is needed to identify the central neuropathophysiology responsible for the laryngeal muscle spasms in order target treatment towards the central neurological abnormality responsible for producing symptoms.

Dosage changes in patients with long-term botulinum toxin use for laryngeal dystonia

OBJECTIVE: To investigate the dosage consistency of botulinum toxin injections in patients with long-term treatment for laryngeal dystonia.

STUDY DESIGN: Chart review.

SUBJECTS AND METHODS: Patients with laryngeal dystonia who had received at least 20 injections to the thyroarytenoid muscle were selected. Change of botulinum toxin dose, patient-reported effective weeks, and intervals between injections were investigated; data from the first five injections were excluded to eliminate initial dose titration.

RESULTS: Fifty-five patients with an average follow-up of 12.5 years were identified. Mean dose of botulinum toxin was 2.37 ± 1.6 U at the sixth injection; there was a decrease in mean dose over time, which became statistically significant at the 13th injection with a mean dose of 2.02 ± 1.16 U. Mean duration of good effect and treatment intervals showed no significant change over time.

CONCLUSION: Botulinum toxin dose needed for a constant response in treatment of laryngeal dystonia decreases over time, without any accompanying change in effective weeks and intervals.