Botulinum Toxin Type B for Treatment of Spasmodic Dysphonia: A Case Report

Although treatment with botulinum toxin type A (BTXA) has become the standard of care for most patients with laryngeal dystonia, its use is limited by the development of resistance to the toxin in some patients. Botulinum toxin type B (BTXB) has been found to be safe and effective in the treatment of cervical dystonia, but it has not been used previously to treat spasmodic dysphonia. Our experience with BTXB in a patient who developed resistance to BTXA suggests that BTXB may be safe and effective for the treatment of laryngeal dystonia, as well.     

Botulinum Toxin Therapy for Abductor Spasmodic Dysphonia

Botulinum toxin has been widely accepted as an effective therapy for controlling the symptoms of adductor spasmodic dysphonia (ADSD). Reported experience with botulinum treatment for abductor spasmodic dysphonia (ABSD) has been less impressive. Factors that may impair outcomes for ABSD include differences in the pathophysiology of ADSD and ABSD and limitation of maximal dose from airway restriction with posterior cricoarytenoid muscle (PCA) weakness. We report our experience with botulinum injection of the PCA with an asymmetric dose escalation protocol, based on clinical observations that in ABSD, abductor spasms are often stronger on one side, usually the left. The nondominant side was injected with 1.25 units. Dominant side dose began at 5 units, with step-wise increments of 5 units per week until one of three endpoints was reached: Elimination of breathy voice breaks, complete abductor paralysis of the dominant side, or airway compromise. Fourteen of 17 patients achieved good or fair voice, with dominant-side doses ranging from 10 to 25 units. Exercise intolerance limited PCA dose in two patients. One patient had persisting breathiness that improved with medialization thyroplasty. Asymmetric botulinum toxin injection into PCA muscles can suppress abductor spasm in patients with ABSD, but breathiness may persist, because of inadequate glottal closure.     

Acoustic Measures of Symptoms in Abductor Spasmodic Dysphonia

Speech of patients with abductor spasmodic dysphonia (ABSD) was analyzed using acoustic analyses to determine: (1) which acoustic measures differed from controls and were independent factors representing patients' voice control difficulties, and (2) whether acoustic measures related to blinded perceptual counts of the symptom frequency in the same patients. Patients' voice onset time for voiceless consonants in speech were significantly longer than the controls (p = 0.015). A principle components analysis identified three factors that accounted for 95% of the variance: the first factor included sentence and word duration, frequency shifts, and aperiodic instances; the second was phonatory breaks; and the third was voice onset time. Significant relationships with perceptual counts of symptoms were found for the measures of acoustic disruptions in sentences and sentence duration. Finally, a multiple regression demonstrated that the acoustic measures related well with the perceptual counts (r² = 0.84) with word duration most highly related and none of the other measures contributing once the effect of word duration was partialed out. The results indicate that some of the voice motor control deficits, namely aperiodicity, phonatory breaks, and frequency shifts, which occur in patients with ABSD, are similar to those previously found in adductor spasmodic dysphonia. Results also indicate that acoustic measures of intermittent disruptions in speech, voice onset time, and speech duration are closely related to the perception of symptom frequency in the disorder.     

Vocal Fold Paralysis Following Radiotherapy for Nasopharyngeal Carcinoma: Laryngeal Electromyography Findings

Laryngeal electromyography was used to study the pattern of neurological injury in three patients with unilateral vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma. The thyroarytenoid and cricothyroid muscles were assessed to give an indication of recurrent and superior laryngeal nerve function. Two patients demonstrated both recurrent and superior laryngeal neuropathy suggesting injury at the skull base. The other patient had only recurrent laryngeal neuropathy indicating more distal involvement. Subclinical neuropathic changes were seen in two cases on the side contralateral to the vocal fold paralysis. These patients may be at increased risk of developing bilateral vocal fold paralysis and potentially life-threatening airway obstruction. Long-term follow-up is recommended for such patients, especially if medialization thyroplasty is being considered. This is the first report describing the use of electromyography to determine the pattern of nerve injury in patients with vocal fold paralysis following head and neck radiotherapy.     

Longitudinal Effects of Botulinum Toxin Injections on Voice-Related Quality of Life (V-RQOL) for Patients with Adductory Spasmodic Dysphonia

Adductory spasmodic dysphonia is a focal dystonia of laryngeal muscles. Patients with this disorder typically have severe vocal difficulties, with significant functional, social, and emotional consequences. There is no widely accepted cure for this condition, however, botulinum toxin injections of the thyroarytenoid muscles are considered by most voice clinicians to be the state of the art treatment. Based on extensive experience treating patients for adductory spasmodic dysphonia, we feel that traditional means of voice assessment do not adequately measure either the disease severity or the treatment outcomes. That is, listening to or acoustically analyzing limited phonatory samples does not capture the functional, social, and emotional consequences of this disorder. These consequences will be reflected in a patient's voice-related quality of life (V-RQOL). Using a validated voice outcomes instrument, the V-RQOL Measure, the purpose of this study was to quantify longitudinal changes in the V-RQOL of patients with adductory spasmodic dysphonia who are undergoing botulinum toxin injections. Twenty-seven consecutive new patients presenting with dysphonia to our institution during an 18-month period were diagnosed with adductory spasmodic dysphonia, and treated patients were evaluated prospectively using the V-RQOL Measure. Results indicated that (1) V-RQOL was initially very low for these patients, (2) botulinum toxin injections improved it significantly for each injection cycle studied, and (3) the magnitude of the treatment effect appears to change across injections.     

Vocal Fold Mucosal Tears: Maintaining a High Clinical Index of Suspicion

Vocal fold mucosal tears have been discussed in the literature rarely, although they are not uncommon clinically. Disruptions in the epithelium usually follow trauma that may result from voice abuse and/or misuse, coughing, and other causes. A high index of suspicion is necessary to avoid missing vocal fold mucosal tears, and strobovideolaryngoscopy is indispensable in making the diagnosis. A brief period of complete voice rest is the standard of care and appears to be helpful in avoiding adverse sequelae and advancing the healing process, but there are no scientific studies to confirm its efficacy. Mucosal tears may heal completely or may be followed by the development of vocal fold masses, scar, and permanent dysphonia.     

Unilateral Versus Bilateral Injections of Botulinum Toxin in Patients with Adductor Spasmodic Dysphonia

Both unilateral and bilateral thyroarytenoid muscle injections of Botox provide effective management of voice symptoms in patients with adductor spasmodic dysphonia; however, the preferred injection technique has not been established. In this study, 16 patients were treated with unilateral injections (72 injections total) and 33 patients were managed with bilateral injections (133 injections total). Individual assignments to injection type were based on treatment previously received and dose was adjusted according to the patient's previous treatment response. An optimal treatment included a benefit lasting 3 months or more with side effects lasting 2 weeks or less. Compared to patients receiving bilateral injections, those receiving unilateral injections more frequently noted a benefit of 3 months or more (p = 0.03), side effects of 2 weeks or less duration (p = 0.03), as well as both a 3-month benefit and a 2-week or less side effect (p = 0.0004). Injection type had no effect on optimal Botox dosing with repeat injections. Successive unilateral injections at the same dose were more likely (p = 0.012) than successive bilateral injections to produce the same or longer duration of benefit. We conclude that a unilateral injection routine has a more optimal and consistent treatment effect/side effect profile.     

Mild Vocal Fold Paresis: Understanding Clinical Presentation and Electromyographic Findings

The implications of mild vocal fold hypomobility are incompletely understood. This study describes the clinical, electromyographic, and probable etiologic findings in patients who presented with complaints of dysphonia and whose physical examination revealed vocal fold paresis as a factor possibly contributing to their voice complaints. A retrospective chart review of all patients who presented to a tertiary laryngology referral center over a 13-month period, who had a clinical diagnosis of mild vocal fold hypomobility and who underwent laryngeal electromyography, were included in the study. A total of 22 patients completed the medical evaluation of their voice complaint. Of these patients, 19 (86.4%) were found to have evidence of neuropathy on laryngeal electromyography. The clinical picture indicated the following probable origins for the vocal fold paresis: goiter/thyroiditis (7/22 or 31.8%), idiopathic (4/22 or 18.2%), viral neuritis (4/22 or 18.2%), trauma (3/22 or 13.6%), and Lyme's disease (1/22 or 4.5%). This article describes the clinical entity of mild vocal fold hypomobility and associated flexible laryngoscopic, rigid strobovideolaryngoscopic, and laryngeal electromyographic findings.     

Vocal Fold Wound Healing: A Review for Clinicians

SUMMARY: The basic science of wound healing is largely omitted from the curriculum of many voice clinicians. This fact is relatively disheartening as most therapeutic manipulation in the realm of laryngology and voice disorders deals with injured tissue. Therefore, the selection of therapeutic tasks for persons with vocal injury should ideally be informed by basic science in wound healing. Recently, several investigators have initiated lines of research to determine the course of vocal fold wound healing and the potential role of therapeutic agents, including behavioral agents. The current review seeks to provide a foundation of basic wound healing science and present the most current data regarding the wound healing process in the vocal folds.