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

BACKGROUND: Despite use of qualitative laryngeal electromyography (LEMG) guided botulinum toxin A (BoNT-A) injection for treatment of adductor spasmodic dysphonia (AdSD), unsatisfactory injections and complete "misses" remain problematic. We aimed to determine if the quantitative LEMG measure of number of small segments (NSS) correlates with voice outcomes following (BoNT-A injection for AdSD. METHODS: Automated quantitative LEMG analysis was performed during electromyography (EMG) -guided BoNT-A injection into the thyroarytenoid-lateral cricoarytenoid muscle complex for treatment of AdSD. Pre-injection phonatory NSS values were correlated with clinical voice outcomes and patient reported injection results. RESULTS: Quantitative LEMG measures were obtained for 45 AdSD patients (28 female, mean age 60.8 ± 12.8 years) during EMG-guided BoNT-A injection. Mean sampled NSS during phonation immediately prior to BoNT-A injection was 524 ± 323 (range: 2-904). Mean follow up was 36.5 ± 9.4 days; one patient was lost to follow-up. In comparison to their previous BoNT-A injection, the current injection was rated as worse, same, and better by 13 (29.5%), 25 (56.8%), and 6 (13.6%) patients, respectively. All 4 (9.1%) patients with NSS < 200 rated their BoNT-A injection result as worse than previous, and change in Voice Handicap Index-10 (VHI-10) scores were worse or without change. CONCLUSIONS: Aiming for an NSS value greater than 200 during phonation prior to BoNT-A toxin injection for AdSD may reduce unfavorable voice outcomes.

Retrospective review of dosing trends in botulinum toxin injections for the treatment of adductor spasmodic dysphonia in a long-term cohort.

BACKGROUND: Botulinum toxin A (BT) is the gold standard treatment for adductor spasmodic dysphonia (AdSD) with established use for greater than thirty years. The spasmodic dysphonia (SD) literature would benefit from additional long-term cohort data, especially in the Canadian population. The goals of this study were to evaluate whether BT dosage required to achieve acceptable voice shifts over time and to elucidate differences in the subgroups of patients receiving unilateral vocal fold (UVF) injections. METHODS: Patient records were retrospectively reviewed at the regional tertiary Voice Clinic for AdSD patients from 1996 to 2017 to identify AdSD patients treated with serial BT injections. Descriptive statistics, paired t-tests for time between treatments and ANOVA tests were used to evaluate trends in subgroup age. RESULTS: One-hundred and twenty-six patients (61% female, mean age = 53 ± 15.5 years) met inclusion criteria and received laryngeal EMG-guided BT injections for up to twenty-two years and as many as 79 treatments. The mean total BT dosage for our population was 1.54 ± 0.35 Units per side. The majority of subjects had decreasing doses over time with a small subgroup having slowly increasing doses. Comparing treatment dosages between unilateral and bilateral injection groups, injection dosage per vocal fold was 1.65 ± 0.62 with time between injections was significantly shorter for the unilateral injection group (mean = 105 days, SD ± 19.8 days, p = 0.005) compared to the bilateral injection subgroup (137 ± 35.7 days, p < 0.005). The mean age of the unilateral injection population as younger at 42.4 ± 11.8 years (p = 0.004). CONCLUSION: The majority of patients in this study had decreasing BT injection dosages over time, with a smaller proportion having slowly increasing doses, thought to be likely relating to disease severity. The unilateral vocal fold injections were well tolerated despite needing more frequent injections, and found to be more prevalent in the younger age group.

Unilateral versus bilateral botulinum toxin injections in adductor spasmodic dysphonia in a large cohort.

OBJECTIVES/HYPOTHESIS: The primary treatment of adductor spasmodic dysphonia is repeated injections of botulinum toxin type A (Botox) into the thyroarytenoid muscles. Dosing can be performed into either one or both thyroarytenoid muscles. The objective of this study was to evaluate the treatment effect and side effect profile across a large number of injections. This study was performed previously in 2002 on 45 patients. STUDY DESIGN: Individual cohort study. METHODS: This is retrospective study of all patients with adductor spasmodic dysphonia with and without tremor treated by the senior laryngologist at George Washington University. In the current study, 272 patients (214 females and 58 males) were included in the current analysis. Duration of effects and side effects (vocal weakness and liquid dysphagia) were recorded into a database for each patient after each injection. These data were analyzed using χ2 analysis. RESULTS: A total of 4,023 injections (2,708 bilateral and 1,315 unilateral) were evaluated in this study. Optimal effect duration (≥3 months) was more commonly seen in the bilaterally injected patients (55%) compared to the unilaterally injected patients (47%) (P = .0001). Optimal side effect duration (≤2 weeks) was better for the unilaterally injected patients (77%) compared to the bilaterally injected patients (73%) (P = .023). Having both optimal effect and side effect in the same injection was more commonly seen in the bilaterally injected patients (36%) compared to the unilaterally injected patients (33%) (P = .0228). CONCLUSIONS: This study shows that bilateral injections of Botox are more effective in producing optimal effect/side effect profiles. LEVEL OF EVIDENCE: 2b Laryngoscope, 130:2659-2662, 2020.

Botulinum toxin-B injection into the lacrimal gland and posterior cricoarytenoid muscle for the treatment of epiphora and abductor spasmodic dysphonia secondary to Parkinson's disease.

In ophthalmology, there have been few reports of botulinum toxin type-A (BTX-A) injection into the lacrimal gland to treat epiphora. In ENT, adductor and abductor (ABSD) spasmodic dysphonia are often treated with BTX-A injections into the respective overacting vocal cord muscles. We describe a 53-year old male with Parkinson's disease who did not respond to BTX-A injections to either the lacrimal gland, for epiphora secondary to Parkinsonian-related blink lagophthalmos, or posterior cricoarytenoid (PCA) muscles for ABSD. Subsequent BTX type-B (BTX-B) injections into the lacrimal gland remarkably improved his epiphora. BTX-B injections into the PCA muscle also greatly improved his dysphonia. We describe the first reported case of (1) BTX-B injection into the lacrimal gland for epiphora, (2) use of Botox in treating epiphora due to blink lagophthalmos/reduced blink frequency secondary to Parkinson's disease, (3) BTX-B use in treating ABSD, and (4) association between ABSD and Parkinson's disease.

Comparison of botulinum toxin and propranolol for essential and dystonic vocal tremors.

OBJECTIVES: Vocal tremors, which cause social difficulties for patients, may be classified as resting or action tremors. Of the vocal action tremors, essential and dystonic tremors are the most common. Botulinum toxin and oral medications have been used to treat vocal tremors, but no comparative clinical trials have been performed. The aim of this study was to compare the effects of botulinum toxin injection and the oral administration of propranolol in the treatment of essential and dystonic vocal tremors. METHODS: This clinical trial recruited 15 patients, divided into essential and dystonic vocal tremor groups. Patients in both groups received successive treatment with botulinum toxin and propranolol. The treatments were administered at different times; the order of treatment was randomly selected. Patients were assessed with flexible nasofibrolaryngoscopy and with perceptual and acoustic voice evaluations. A statistical significance level of 0.05 (5%) was used. RESULTS: Botulinum toxin produced statistically significant improvements in perceptual measures of vocal instability in patients with dystonic vocal tremors compared with baseline values and treatment with propranolol. The acoustic measure of variability in the fundamental frequency was significantly lower in patients with dystonic vocal tremors after treatment with botulinum toxin. CONCLUSION: Essential and dystonic vocal tremors responded differently to treatment. Dystonic vocal tremors responded significantly to treatment with botulinum toxin but not oral propranolol. Essential vocal tremors did not respond significantly to either treatment, perhaps due to the small number of patients, which is a limitation of this research.

The effect of low-dose rocuronium on rapid tracheal intubation using a video laryngoscope: A randomized double blind controlled study.

BACKGROUND: The aim of this study was to investigate the clinical effectiveness of rocuronium in low doses on conditions during rapid tracheal intubation using video laryngoscope. METHODS: Ninety-eight patients undergoing otolaryngologic surgery were randomly divided into 2 groups: group L using 0.3 mg/kg of rocuronium intravenously (n = 49) and group C using 0.6 mg/kg of rocuronium (n = 49). Sixty seconds after rocuronium administration, tracheal intubation was performed using a video laryngoscope. The overall intubation condition was evaluated along with specific conditions, including laryngoscopy condition, vocal cord position, and intubation response. Intubation profiles, including Cormack-Lehane grade, 1st attempt success rate, and intubation time, were also evaluated. RESULTS: Overall intubation conditions showed a significant difference between group L and group C (P = .003). Although the incidence of vigorous response after tracheal intubation was higher in group L than in group C (P = .022), laryngoscopy condition and vocal cord position were similar between the 2 groups (P = .145 and .070, respectively). Intubation profiles showed no differences between the 2 groups. The frequency and amount of additional rocuronium administration during surgery were also similar. CONCLUSIONS: Low-dose rocuronium provided significantly worse overall intubation conditions compared to the conventional dose of rocuronium for rapid tracheal intubation. However, when using a video laryngoscope, it may provide clinically acceptable laryngeal muscle relaxation.

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.

Regenerative Effects of Basic Fibroblast Growth Factor on Restoration of Thyroarytenoid Muscle Atrophy Caused by Recurrent Laryngeal Nerve Transection.

OBJECTIVES: Vocal fold atrophy following unilateral vocal fold paralysis is caused by atrophy of the thyroarytenoid (TA) muscle and remains a challenge. Medialization procedures are popular treatment options; however, hoarseness often remains due to the reduction in mass or tension of the TA muscle. Therefore, in addition to medialization procedures, TA muscle reinnervation is desirable. In vivo studies have shown the potential for basic fibroblast growth factor (bFGF) to affect muscular and nerve regeneration. The present study aimed to examine the regenerative effects of bFGF on restoration of TA muscle atrophy caused by recurrent laryngeal nerve transection. STUDY DESIGN: Prospective animal experiments with controls. METHODS: TA muscle atrophy was induced by unilateral transection of the recurrent laryngeal nerve. One month after transection, different doses (200 ng, 100 ng, 10 ng) of bFGF in 50 µL were repeatedly injected into the TA muscle four times with an interval of 1 week between injections. Saline only was injected in the sham group. Larynges were harvested for histologic and immunohistochemical examination 4 weeks after the final injection. RESULTS: The cross-sectional TA muscle area was significantly larger in the bFGF-treated groups compared with the sham-treated groups. Immunohistochemistry indicated that bFGF significantly increases the number of neuromuscular junctions and satellite cells in the TA muscle. CONCLUSIONS: These results suggest that local application of bFGF to the TA muscle may improve TA muscle atrophy caused by recurrent laryngeal nerve paralysis. Furthermore, bFGF may have regenerative effects on both nerves and muscles.

Toxicity trial of canine posterior cricoarytenoid intramuscular vincristine injections.

OBJECTIVES/HYPOTHESIS: In animal studies, intramuscular vincristine injections have been shown to block reinnervation of the denervated target muscle. This application could be used selectively to influence recovery patterns following injury of recurrent laryngeal nerves (RLNs). However, vincristine is currently Food and Drug Administration approved only for intravenous use. A formal toxicity trial of intramuscular injections was performed. STUDY DESIGN: Animal study. METHODS: Sixteen female canines underwent direct laryngoscopy with injection of moderate- (0.4 mg, n = 8) or high-dose (0.6 mg, n = 8) vincristine into the posterior cricoarytenoid (PCA) muscles. Plasma samples were collected at various time points postinjection and vincristine levels determined. At 24 hours (n = 7) or 14 days (n = 9) postinjection, animals were anesthetized and videolaryngoscopy documented vocal fold mobility and mucosal appearance. Adductor function was measured during stimulation of the RLN. Larynges were processed for histology. RESULTS: Fifteen minutes after injection, plasma vincristine levels averaged 10.2% ± 6.7% of the intravenous maximum, suggesting about 90% of the vincristine remained within the PCA muscle. Plasma levels were usually below detectable limits within 24 hours. At the end points, all animals had grossly normal-appearing mucosa and full range of motion. Laryngeal adductor strength was normal in all cases. Histology showed moderate to severe acute inflammation in the submucosa only in the high-dose group at 24 hours. There was no necrosis of muscle or mucosa. CONCLUSIONS: Intramuscular vincristine injections into the canine PCA muscles resulted in no significant local toxicity, even at the maximum dose. It would be reasonable to evaluate this treatment strategy in a phase I human trial. LEVEL OF EVIDENCE: NA Laryngoscope, 128:E247-E250, 2018.

Botulinum Toxin Injections Into the Lateral Cricoarytenoid Muscles for Vocal Process Granuloma.

OBJECTIVE: Contact granulomas are benign, exophytic inflammatory lesions of the larynx that typically arise on or near the vocal process of the arytenoid cartilage. The most common management options include voice therapy and antireflux pharmacotherapy, intralesional steroid injections, botulinum toxin injections, and surgical excision. In-office Botox injection into the lateral cricoarytenoid (LCA) muscle can be effective even for recurrent granulomas. STUDY DESIGN: This is a retrospective chart review and literature review. METHOD: We reviewed more than 400 charts and included two patients, who underwent in-office injection with botulinum toxin A into LCA muscles bilaterally, after previously failing both conservative and surgical management. RESULTS: Both cases showed significant improvement of the laryngeal granulomas after 6 months and a single botulinum toxin injection. Both cases were initially grade III granuloma that improved to grade I. CONCLUSIONS: In-office injection of botulinum toxin A targeting the LCA muscle appears to be a safe and effective treatment modality in refractory laryngeal granuloma.

Comparison of botulinum toxin and propranolol for essential and dystonic vocal tremors

OBJECTIVES: Vocal tremors, which cause social difficulties for patients, may be classified as resting or action tremors. Of the vocal action tremors, essential and dystonic tremors are the most common. Botulinum toxin and oral medications have been used to treat vocal tremors, but no comparative clinical trials have been performed. The aim of this study was to compare the effects of botulinum toxin injection and the oral administration of propranolol in the treatment of essential and dystonic vocal tremors. METHODS: This clinical trial recruited 15 patients, divided into essential and dystonic vocal tremor groups. Patients in both groups received successive treatment with botulinum toxin and propranolol. The treatments were administered at different times; the order of treatment was randomly selected. Patients were assessed with flexible nasofibrolaryngoscopy and with perceptual and acoustic voice evaluations. A statistical significance level of 0.05 (5%) was used. RESULTS: Botulinum toxin produced statistically significant improvements in perceptual measures of vocal instability in patients with dystonic vocal tremors compared with baseline values and treatment with propranolol. The acoustic measure of variability in the fundamental frequency was significantly lower in patients with dystonic vocal tremors after treatment with botulinum toxin. CONCLUSION: Essential and dystonic vocal tremors responded differently to treatment. Dystonic vocal tremors responded significantly to treatment with botulinum toxin but not oral propranolol. Essential vocal tremors did not respond significantly to either treatment, perhaps due to the small number of patients, which is a limitation of this research.

Partial neuromuscular block impairs arytenoid abduction during hypercarbic challenge in anesthetized dogs.

OBJECTIVE: To evaluate the effect of two levels of partial neuromuscular block (NMB) on arytenoid abduction, tidal volume (VT) and peak inspiratory flow (PIF) in response to a hypercarbic challenge in anesthetized dogs. STUDY DESIGN: Prospective laboratory study. ANIMALS: Eleven healthy male Beagle dogs aged 3-5 years. METHODS: Dogs were anesthetized with propofol and dexmedetomidine infusions. The rima glottidis was observed via an endoscope placed through a laryngeal mask airway. Atracurium infusion was titrated to obtain two levels of partial NMB. The normalized glottal gap area (NGGA; glottal gap area normalized to height squared of rima glottidis) at peak inspiration during a hypercarbic challenge (10% CO2 inspired for 1 minute) was measured at baseline, during mild [train-of-four (TOF) ratio 0.4-0.6] and shallow (TOF ratio 0.7-0.9) NMB, and 30 minutes after spontaneous recovery from NMB. The VT and PIF were measured at the same time points and compared using anova for repeated measures and Tukey's post hoc tests. RESULTS: The NGGA and VT were significantly lower than baseline during both levels of partial NMB with no difference between mild and shallow NMB (p < 0.05). They returned to baseline values after spontaneous recovery from NMB. PIF was not altered significantly during partial NMB. CONCLUSIONS AND CLINICAL RELEVANCE: The NGGA and VT at peak inspiration in response to a hypercarbic challenge were reduced during partial NMB block, with decreased abduction of the arytenoid cartilages. This dysfunction was present even at shallow levels of NMB.

Subcutaneous Neurotrophin 4 Infusion Using Osmotic Pumps or Direct Muscular Injection Enhances Aging Rat Laryngeal Muscles.

Laryngeal dysfunction in the elderly is a major cause of disability, from voice disorders to dysphagia and loss of airway protective reflexes. Few, if any, therapies exist that target age-related laryngeal muscle dysfunction. Neurotrophins are involved in muscle innervation and differentiation of neuromuscular junctions (NMJs). It is thought that neurotrophins enhance neuromuscular transmission by increasing neurotransmitter release. The neuromuscular junctions (NMJs) become smaller and less abundant in aging rat laryngeal muscles, with evidence of functional denervation. We explored the effects of NTF4 for future clinical use as a therapeutic to improve function in aging human laryngeal muscles. Here, we provide the detailed protocol for systemic application and direct injection of NTF4 to investigate the ability of aging rat laryngeal muscle to remodel in response to NTF4 application. In this method, rats either received NTF4 either systemically via osmotic pump or by direct injection through the vocal folds. Laryngeal muscles were then dissected and used for histological examination of morphology and age-related denervation.

[Analysis of phonosurgical methods of treatment in spasmodic dysphonia]. / Analiza wybranych metod fonochirurgicznych w terapii dysfonii spastycznej.

Spasmodic dysphonia (SD) is rather a rare voice disorder. It is most often seen in woman aged 40-50. The disease is caused by deep emotional and neurological disorders of extrapyramidal system. Two main clinical forms of SD are distinguished: about 90% of cases - adductor spasmodic dysphonia and abductor spasmodic dysphonia roughly 10%. Conservative therapy does not always yield sufficient effects. Botulinum toxin - type A injections into the thyroarytenoid muscle are also used in therapy. Though results are temporary and reversible. Among phonosurgical methods thyroplasty type II according to Isshiki and tyroarytenoid muscle myectomy (TAM) should be also mentioned among phonosurgical methods. The aim of the work is to evaluate results of conservative and phonosurgical treatment of SD. Spasmodic dysphonia markedly restricts communication process of patients and public relations both social and occupational.

Contributions of rapid neuromuscular transmission to the fine control of acoustic parameters of birdsong.

Neural control of complex vocal behaviors, such as birdsong and speech, requires integration of biomechanical nonlinearities through muscular output. Although control of airflow and tension of vibrating tissues are known functions of vocal muscles, it remains unclear how specific muscle characteristics contribute to specific acoustic parameters. To address this gap, we removed heparan sulfate chains using heparitinases to perturb neuromuscular transmission subtly in the syrinx of adult male zebra finches (Taeniopygia guttata). Infusion of heparitinases into ventral syringeal muscles altered their excitation threshold and reduced neuromuscular transmission changing their ability to modulate airflow. The changes in muscle activation dynamics caused a reduction in frequency modulation rates and elimination of many high-frequency syllables but did not alter the fundamental frequency of syllables. Sound amplitude was reduced and sound onset pressure was increased, suggesting a role of muscles in the induction of self-sustained oscillations under low-airflow conditions, thus enhancing vocal efficiency. These changes were reversed to preinfusion levels by 7 days after infusion. These results illustrate complex interactions between the control of airflow and tension and further define the importance of syringeal muscle in the control of a variety of acoustic song characteristics. In summary, the findings reported here show that altering neuromuscular transmission can lead to reversible changes to the acoustic structure of song. Understanding the full extent of muscle involvement in song production is critical in decoding the motor program for the production of complex vocal behavior, including our search for parallels between birdsong and human speech motor control. NEW & NOTEWORTHY: It is largely unknown how fine motor control of acoustic parameters is achieved in vocal organs. Subtle manipulation of syringeal muscle function was used to test how active motor control influences acoustic parameters. Slowed activation kinetics of muscles reduced frequency modulation and, unexpectedly, caused a distinct decrease in sound amplitude and increase in phonation onset pressure. These results show that active control enhances the efficiency of energy conversion in the syrinx.

Vocal Parameters and Self-Perception in Individuals With Adductor Spasmodic Dysphonia.

OBJECTIVE: The study aimed to compare and correlate perceptual-auditory analysis of vocal parameters and self-perception in individuals with adductor spasmodic dysphonia before and after the application of botulinum toxin. STUDY DESIGN: This is a prospective cohort study. METHODS: Sixteen individuals with a diagnosis of adductor spasmodic dysphonia were submitted to the application of botulinum toxin in the thyroarytenoid muscle, to the recording of a voice signal, and to the Voice Handicap Index (VHI) questionnaire before the application and at two time points after application. Two judges performed a perceptual-auditory analysis of eight vocal parameters with the aid of the Praat software for the visualization of narrow band spectrography, pitch, and intensity contour. RESULTS: Comparison of the vocal parameters before toxin application and on the first return revealed a reduction of oscillation intensity (P = 0.002), voice breaks (P = 0.002), and vocal tremor (P = 0.002). The same parameters increased on the second return. The degree of severity, strained-strangled voice, roughness, breathiness, and asthenia was unchanged. The total score and the emotional domain score of the VHI were reduced on the first return. There was a moderate correlation between the degree of voice severity and the total VHI score before application and on the second return, and a weak correlation on the first return. CONCLUSIONS: Perceptual-auditory analysis and self-perception proved to be efficient in the recognition of vocal changes and of the vocal impact on individuals with adductor spasmodic dysphonia under treatment with botulinum toxin, permitting the quantitation of changes along time.

Effect of Levodopa + Carbidopa on the Laryngeal Electromyographic Pattern in Parkinson Disease.

BACKGROUND: Vocal impairment is one of the main debilitating symptoms of Parkinson disease (PD). The effect of levodopa on vocal function remains unclear. OBJECTIVE: This study aimed to determine the effect of levodopa on electromyographic patterns of the laryngeal muscle in patients with PD. STUDY DESIGN: This is a prospective interventional trial. METHODS: Nineteen patients with PD-diagnosed by laryngeal electromyography-were enrolled. Cricothyroid and thyroarytenoid (TA) muscle activities were measured at rest and during muscle contraction (phonation), when participants were on and off medication (12 hours after the last levodopa dose). RESULTS: Prevalence of resting hypertonia in the cricothyroid muscle was similar in the off and on states (7 of 19, P = 1.00). Eight patients off medication and four patients on medication had hypertonic TA muscle at rest (P = 0.289). No electromyographic alterations were observed during phonation for either medication states. CONCLUSION: Despite a tendency for increased rest tracings in the TA muscle when participants were on medication, no association was found between laryngeal electromyography findings and levodopa + carbidopa administration.

Botulinum Toxin-A Dosing Trends for Adductor Spasmodic Dysphonia at a Single Institution Over 10 Years.

OBJECTIVES: This study aimed to identify the changes in dosing of botulinum toxin-A for adductor spasmodic dysphonia (ADSD) over a prolonged period. STUDY DESIGN: This is a retrospective chart review. METHODS: One hundred thirteen subjects treated for ADSD from 2003 to 2013 were identified from a clinical database. Subject age, gender, and total injection dose amount were all recorded for all subjects who had at least 10 injections. RESULTS: Fifty-four subjects met criteria for inclusion. There were no age or gender differences in the starting dose for subjects. Dosing decreased significantly compared with the second dose (5.05 ± 1.623 Units), by the sixth dose (4.26 ± 1.698 Units), and continued through the 10th dose (4.08 ± 2.019 Units) (P < 0.005 for all). CONCLUSIONS: Botulinum toxin-A dosing for ADSD decreases consistently over subsequent injections after the initial two dose titrations.