Behavioral therapy for spasmodic dysphonia

This paper presents a general schema for classifying treatment approaches for both functional and organic voice disorders. It's use is illustrated by a review of treatments for Spasmodic Dysphonia. Most behavioral approaches have been found to be unsuccessful except for mild cases. Inhalation speech as a compensatory technique has been reported as somewhat successful for those mild/moderate cases for whom medical/surgical treatment has not been available. The fact that organic treatment levels have been more successful in the treatment of Spasmodic Dysphonia may lend support to an organic etiology     

Long-term results of recurrent laryngeal nerve resection for adductor spasmodic dysphonia

From a total of 43 adductor spasmodic patients over a 10-year period, 11 underwent resection of a portion of the recurrent laryngeal nerve on one side. The initial results were excellent but a varying degree of recurrence took place in 8 patients. In 4, a reoperation was done. At the final follow-up, 2–8 years after the primary operation, 4 patients were no longer suffering from spasmodic dysphonia, another 5 were better off than before surgery, and 1 remained unchanged. Only 1 was worse off. Electromyographic findings indicated that the recurrence of symptoms was due to regeneration of the nerve fibers.     

Medical evaluation of patients with spasmodic dysphonia

Evidence to date indicates that spasmodic dysphonia (SD) is a focal dystonia of the larynx, probably due to an abnormality of neurotransmitters in basal ganglia. A careful neurological examination is required to rule out other neurologic processes with similar vocal symptoms, such as Parkinsonism or pseudobulbar palsy. Signs of diseases known to cause secondary dystonia should also be sought. Patients with SD also often have other dystonias or essential tremor. Any other neurologic signs suggest that the dystonia is secondary. Without such associated neurologic findings, extensive testing including magnetic resonance imaging (MRI) is not likely to result in clinically useful information.     

Differential diagnosis of spasmodic dysphonia: A kinematic perspective

Although originally considered an hysterical functional disorder, spasmodic dysphonia (SD) appears to be a heterogeneic symptom complex that is associated with several neurological diseases. Perceptual, acoustic, and electromyographic studies have not clearly differentiated the underlying pathologies that result in spasmodic phonatory dysfunction. Kinematic analysis of documented laryngeal examinations during phonation and respiration indicates that particular different movement disorders affect laryngeal function and are associated with spasmodic phonatory characteristics. The particular features of dystonia, tremors, myoclonus, and progressive supranuclear pathology should be recognized, since they may present with disease focal to the laryngeal muscles. Other movement disorders may also be associated with spasmodic phonatory abnormalities, but are less likely to be focal. Treatment of SD signs and symptoms is more likely to be successful and assessments of treatment more likely to be meaningful if the underlying pathophysiology of spasmodic phonatory behavior is identified.     

Analysis of spasmodic dysphonia by aerodynamic and laryngostroboscopic measurements

Sequential assessment of laryngeal function using laryngostroboscopy and phonatory air flow assessment was carried out in 18 patients with spasmodic dysphonia (SD). Comparison was made between findings in patients before treatment (n = 18), after unilateral recurrent nerve block by lidocaine (n = 6), after bilateral injections of botulinum toxin (Botox) (n = 13), and prior to Botox reinjection (n = 3). Unilateral nerve block resulted in higher mean phonatory airflows than after bilateral Botox injections. Both unilateral nerve block and Botox injections increased fluctuant or alternating flow source (AC); however, unilateral nerve block resulted in more unmodulated airflow leakage. Phonation time on a single breath was longer than with Botox injection. Bilateral Botox injections resulted in better glottal closure, fewer instances of vocal fold level differences, and, better vocal fold vibrations with phase symmetry, as determined by laryngostroboscopy. Partial bilateral denervation using Botox resulted in laryngeal function, which appeared to be intermediate between that of tightly squeezed pretreatment status and a breathy voice with incomplete adduction after unilateral nerve block. Of all treatments assessed, bilateral partial denervation by Botox appeared to be the most physiologic in restoring normal vocal fold vibratory function and airflow.     

Functional assessment of patients with spasmodic dysphonia

Assessment of function in patients with spasmodic dysphonia is necessary to confirm diagnosis, plan therapy, predict response, and assess effectiveness of treatment. This task is difficult because symptom severity fluctuates, the test environment is artificial, and the objective parameters used to measure vocal function may not adequately reflect the handicap experienced by the patient. Available methods for assessing these patients are reviewed and the utility of each considered, particularly in managing patients with botulinum toxin therapy. Assessment should include a battery of tests, including subjective perceptual ratings and direct physical measurements.     

The effect of patient factors on response outcomes toBotox treatment of spasmodic dysphonia

Injection of botulinum toxin (Botox) into the laryngeal muscleshas become the treatment of choice for controlling the symptoms of spasmodic dysphonia (SD). Currently, no specific battery of objective tests to assess the outcome is universally accepted. The purpose of this study was to investigate demographic, clinical, and treatment factors with voice outcome following Botox injection. Sixty-eight patients with adductor SD who underwent at least one Botox injection during a 5-year period were studied. Voice outcome measures were made from patient self-reporting scales and included overall vocal quality, length of response, and duration of breathiness. Vocal quality was significantly correlated with the underlying severity of vocal symptoms prior to treatment, incidence of breathiness and unilateral versus bilateral injection. The length of response was greater in males and following bilateral injections. An increased period of breathiness significantly correlated with bilateral injections.     

Adductor spasmodic dysphonia and muscular tension dysphonia: Acoustic analysis of sustained phonation and reading

Acoustic phonatory events were identified in 10 women diagnosed with adductor spasmodic dysphonia (ADSD) and compared to 5 women and 5 men diagnosed with muscle tension dysphonia (MTD). The three acoustic parameters examined during sustained vowel production and reading included phonatory breaks, aperiodicity, and frequency shifts. Intra- and intermeasurer correlations showed high reliability for the measures. Findings indicated that those with ADSD produced a greater number of aberrant acoustic events than those with MTD. The results suggested that: (1) only those with ADSD show evidence of phonatory breaks during vocalization, albeit a sustained vowel or voicing during reading; (2) those with ADSD demonstrate greater variation in the type of aberrant acoustic events produced as a function of speech task. The latter point suggests that control of the larynx varies as a function of task demand, a finding not evident in the functionally based disorder of MTD. MTD is a disorder that often presents itself in a similar clinical manner to ADSD because of its perceptual commonalties and resembling laryngoscopic characteristics. The acoustic analysis presented in this study could be used as a method to assist in distinguishing between the two disorder types.     

Psychogenic spasmodic dysphonia: A case study with expert opinions

Spasmodic (spastic) dysphonia (SD) is considered by some to be a neurologic syndrome and by others a symptom complex of multiple etiologies, neurologic and psychogenic. A case of a 26-year-old female psychiatric nurse with psychogenic SD (PSD) is presented. The dysphonia was alleviated within one session of voice therapy. Psychogenic etiology was established by the author, based on three diagnostic criteria—symptom incongruity, symptom reversibility, and symptom psychogenicity. Seven nationally recognized voice experts listened to audio-recorded samples of the patient's pre- and posttherapy voice during conversational speech. The experts agreed that the dysphonia was psychogenic and characterized it as staccato-like speech, effortful phonation, and interrupted flow of speech; six characterized it with intermittent voice arrests (voice stoppages); five with hoarse-harsh voice; and four with waxing and waning, strained-strangled phonation. These are often described as salient features of SD. Nevertheless, the experts disagreed among themselves as to whether the dysphonia was characteristic of SD and should be labeled as such. The author argues that as long as the voice characteristics and pathophysiologic findings that constitute SD are not well delineated, and as long as the diagnosis of SD is based on symptoms alone, patients with psychogenic or poorly understood voice disorders are likely to be misdiagnosed with organic (neurologic) SD and thus subjected to undue medical treatment. The author also argues that the debate over the etiology of SD can be resolved if SD is considered a neurologic syndrome, PSD a nonorganic phonatory disorder that mimics the syndrome, and if the voice symptoms and pathophysiologic characteristics of SD are well defined and agreed on.     

Botulinum toxin treatment of spasmodic dysphonia: Techniques, indications, efficacy

A group of 58 patients with spasmodic dysphonia (SD) was treated perorally or transcutaneously with botulinum toxin (BT), and followed for at least 6 months. Most were treated by peroral injection using indirect laryngoscopy to facilitate precise placement. An effort was made to disperse the toxin over the entire thyroarytenoid muscle in order to affect the greatest number of motor end-plates using the smallest possible effective dose. Severely symptomatic patients with primarily adductor SD had the best results. A potentiation effect is suggested by analysis of a subpopulation of patients, mostly injected unilaterally, for whom the outcome was more favorable for those who had had prior injections. One-month postinjection studies reflect significant improvement in measured readings of a standard passage, and this is consistent with the subjective and perceptual improvements noted. There were no severe complications. Peroral injection seems inadvisable for patients with mixed or abductor SD as well as for those with an uncontrollable gag reflex.     

Use of acupuncture for the treatment of adductor spasmodic dysphonia: a preliminary investigation

Ten subjects with adductor spasmodic dysphonia participated in a study examining the effects of an acupuncture treatment protocol on their voice disorder. Treatment consisted of eight sessions, and it was designed and performed by two physicians certified in acupuncture. Voice characteristics were evaluated pretreatment and posttreatment using the CSL Motor Speech Profile (MSP), Unified Spasmodic Dysphonia Rating Scale, and Voice Handicap Index (VHI). Subjects also answered a posttreatment questionnaire regarding their experience. Significant pretreatment and posttreatment differences occurred for some MSP measures. Significant differences were found on all three subtests of the VHI, and the average total scores pretreatment and posttreatment differed by 17 points (considered significant according to VHI standardization). Seven of 10 subjects reported improvements in voice production, although expert raters did not detect perceptual changes in voice quality. Possible reasons for the discrepancies between objective measures and self ratings, and implications for further research, are discussed.     

Anatomy and cell biology of the laryngeal motor neurons: Implications for the treatment of spasmodic dysphonia

Changes in neuroanatomical pathways in the central nervous system presumably play key roles in the pathogenetic mechanism underlying spasmodic dysphonia. However, practical considerations of accessibility to clinical intervention have focused efforts on treatments based on manipulations of laryngeal motor neurons, the most peripheral extent of these pathways. This review discusses aspects of the anatomy and cell biology of the laryngeal motor neurons, which provide a basis for the understanding of current techniques for the treatment of this disorder. In addition, consideration is given to the significance of unusual morphological characteristics of the laryngeal motor neurons and to cellular processes, which may ultimately offer potential for more selective clinical strategies.     

The impact of long-term botulinum toxin injections on symptom severity in patients with spasmodic dysphonia

Injection of botulinum toxin (BT) into the muscles of the larynx is an effective treatment for the symptoms of spasmodic dysphonia (SD). To date, however, there have been no studies that have used blinded raters to assess the efficacy of BT injections on overall symptom severity in a cohort of SD patients followed over a prolonged period. In this study, 102 subjects with SD were treated with serial BT injections for up to 2 years. Voice recordings were obtained at several time points during treatment and were played to a panel of expert and novice listeners who rated them based on overall symptom severity in a single-blind fashion. Subjects demonstrated significant improvement over baseline at all time points. In addition, patients showed a sustained responsiveness to therapy over time. These results provide support for the efficacy of serial BT injections for SD and suggest that successful treatment may depend, in part, on patients' early recognition of returning symptoms.     

Pharmacological agents that improve botulinum toxin efficacy in the treatment of spasmodic dysphonia

Botulinum toxin (botox) injection into the thyroarytenoid (TA) muscle is currently the most favored treatment for spasmodic dysphonia. However, results are often inconsistent. The purpose of this study was to identify a fast-acting neuromuscular blocking agent that could mimic botox effects to screen patients for therapy while still in the clinic. If the agent was noninteractive, it could also be injected coincidentally with botox and the resulting changes in voice used to predict the delayed effects due to botox. Evoked electromyography responses were recorded from the TA muscle in animal experiments to determine the time course for neuromuscular depression by botox and three fast-acting blocking agents: lidocaine, tubocurarine, and succinylcholine. Tubocurarine and succinylcholine proved to be suitable screening or predictor agents of botox efficacy, since they were reversible and mimicked botox action. In contrast, lidocaine produced irreversible effects.     

Combined-modality treatment of adductor spasmodic dysphonia with botulinum toxin and voice therapy

A combined-modality treatment program consisting of botulinum toxin injection (Botox) and voice therapy was used to treat 17 subjects diagnosed with adductor spasmodic dysphonia (ADD SD). Ten subjects with ADD SD served as the control and were given Botox only. Voice therapy after Botox injection was directed toward reducing the hyperfunctional vocal behaviors, primarily glottal overpressure at voice onset and anterior-posterior squeezing. The results indicated that subjects who underwent combined-modality treatment maintained significantly higher mean airflow rates for significantly longer periods. Moreover, there was a carryover effect in these patients when they received Botox only. Adductor spasmodic dysphonia is treated most effectively when intrinsic laryngeal muscle spasms are reduced or eliminated by Botox injection and extrinsic hyperfunctional vocal behaviors are treated with voice therapy     

Technique of percutaneous EMG-guided botulinum toxin injection of the larynx for spasmodic dystonia

Percutaneous electromyography (EMG)-guided technique of botulinum toxin (BT) injection of the larynx evolved from similar techniques for extraocular muscle injection in strabismus, as well as from experience with diagnostic laryngeal EMG. This technique permits rapid accurate injection of BT into the laryngeal muscles. Although usually injected into the thyroarytenoid muscle, BT can also be directed to the posterior cricoarytenoid and cricothyroid muscles. Complications are minimal and of short duration.     

Variations in adductor spasmodic dysphonia:Acoustic evidence

Acoustic analysis was used to gain information about the normal, aswell as the abnormal acoustic events associated with adductor spasmodic dysphonia (ADSD). This analysis was completed to determine whether specific acoustic events could be used to differentiate the voice of individuals with ADSD from those with normal voice. A group comparison between 14 women diagnosed with ADSD and 14 women (age-matched) with no evidence of vocal pathology or vocal dysfunction was completed. Phonatory breaks, aperiodicity, and frequency shifts, acoustic parameters previously identified in ADSD, were found throughout sustained vowel productions. The duration of the phonatory breaks and aperiodic segments was calculated and the amount of frequency shift was determined. The location of each acoustic event was marked relative to the onset of the vowel production. The subjects with ADSD presented with normal phonation and various amounts of each of the three acoustic parameters. Aperiodic segments primarily characterized the phonation of ADSD, followed by frequency shifts and phonatory breaks. The location of each of these acoustic events was within the midportion of the vowel production. The advantages of segmenting the acoustic waveform into these measures and separating the spasmodic events from normal phonation when examining laryngeal motor control of spasmodic dysphonics is discussed     

Statistical analyses of electromyographic activity in spasmodic dysphonic and normal control subjects

Heterogeneity in the quality and task sensitivity of vocal symptoms in the spasmodic dysphonia (SD) population contributes to controversy as to whether this is a single disorder or two disorders with different etiologies (neurogenic versus psychogenic). Perceptual and acoustic assessments of vocal symptoms are inadequate to resolve this controversy. However, myoelectric events are intimately proximal to the source of vocal disruption and may be informative. The present report employs statistical modeling of quantitative amplitude measures of electromyographic activity recorded from thyroarytenoid to examine neuromotor bases of vocal symptoms in SD. Consideration of perceptual ratings of the quality and task sensitivity of vocal symptoms in the context of statistical models provides support for the conclusion that the range of vocal symptoms identified as SD represents a single, neurogenic disorder.     

Spasmodic dysphonia symptoms as initial presentation of amyotrophic lateral sclerosis

A patient initially diagnosed with adductor-type spasmodic dysphonia was referred for botulinum toxin (Botox) injections, but found on subsequent evaluation to have amyotrophic lateral sclerosis, and therefore Botox was not administered. This unique case underscores the need to delay botulinum toxin treatments in any patient with recent onset symptoms, and to obtain thorough motor speech and voice, otolaryngologic, and neurologic evaluation in all patients prior to consideration for injection.