Petra Zwirner

Effects of botulinum toxin therapy in patients with adductor spasmodic dysphonia: Acoustic, aerodynamic, and videoendoscopic findings

Botulinum toxin has been previously reported to be successful in the treatment of spasmodic dysphonia. To objectively document results, 11 patients with adductor spasmodic dysphonia who received unilateral treatment of the thyroarytenoid muscle were studied. Acoustic analyses and airflow rates during sustained phonation and flexible videoendoscopy were performed prior to, 1 week and 1 month after injection. 1. Acoustic parameters demonstrated significant voice improvement, although abnormal characteristics remained. 2. Mean airflow rates were increased 1 week after injection with almost normal values 1 month later. 3. Videolaryngoscopy showed an effective reduction of intrinsic laryngeal muscle hyperfunction with less effect on extrinsic muscle activity. Interrelations between videolaryngoscopic rating scores, acoustic results and aerodynamic results are discussed.

Acoustic changes in spasmodic dysphonia after botulinum toxin injection

Summary Botulinum toxin A injections in the left thyroarytenoid muscle were performed in 19 patients with adductor spasmodic dysphonia. Acoustic recordings were taken prior to and 1 week after injection and in a 2-week interval for a normal control group of 11 subjects. Fundamental frequency, standard deviation of fundamental frequency, jitter, shimmer, signal-to-noise ratio, and the voice break factor were studied. Each of the variables were measured from each subjects longest sustained phonation sample of the vowel quality /a/. Findings of the present study indicated: (a) Spasmodic dysphonia patients had significantly higher mean values of standard deviation of fundamental frequency, jitter, shimmer, and voice break factor and significantly lower mean values of signal-to-noise ratio when compared with normal controls; (b) a significant reduction post botulinum toxin injection was found for standard deviation of fundamental frequency and the voice break factor only

Phonatory Function of Neurologically Impaired Patients.

Previous studies investigated the use of acoustic perturbation measures as a screening tool for neuropathologies with conflicting results. In the present study, five parameters of phonatory function (jitter, shimmer, signal-to-noise ratio, fundamental frequency, and standard deviation of fundamental frequency) were obtained from samples of sustained phonation in three neuropathological groups (Parkinson, Huntington, cerebellar ataxia) and a normal control group to assess the use of acoustic measures in differential diagnosis. In addition, perceptual judgements of the severity of dysphonia for each patient were obtained. The results indicated that perturbation measures of the neuropathological groups showed a higher degree of variability compared to normals. From the five parameters studied, only the standard deviation of fundamental frequency differentiated among neuropathological subgroups. The acoustic parameters studied did not clearly reflect the perceived dysphonia for all subgroups.

Use of flexible fiberoptic laryngoscopy to assess patients with spasmodic dysphonia

Summary Flexible videolaryngoscopy was used to study 38 patients with spasmodic dysphonia, rating excessive activation of intrinsic laryngeal muscles, extrinsic muscle hyperfunction, tremor, and dystonic movements. Seventeen patients were also studied after unilateral botulinum toxin injection. Dysfunction varied greatly; however, discrete patterns could not be identified. Functional status correlated significantly with the total score of all pathologic indicators, but not with any single parameter. Botulinum toxin was highly effective in reducing intrinsic laryngeal muscle activation, but did not always improve tremor. Extrinsic laryngeal muscle hyperfunction was not significantly affected by the toxin

Perceptual-acoustic relationships in spasmodic dysphonia**

Perceptual ratings were obtained from voice samples of 19 patients with adductor spasmodic dysphonia before and 1 week after unilateral treatment with Botulinum toxin. Five experienced listeners judged samples of sustained phonation using a seven-point equal-interval scale. The perceptual parameters assessed were overall severity, strain-strangled voice quality, and breathiness. Perceptual results were related to the standard deviation of fundamental frequency and the voice break factor, two acoustic parameters previously shown to be significantly improved following Botulinum toxin injection. Results indicate that in general the spasmodic dysphonia voice is perceived as less severe, less strain-strangled, and more breathy 1 week after treatment. Interrelations among perceptual parameters and relationships with acoustic analyses are discussed.

Functional assessment of patients with spasmodic dysphonia

Summary 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 Influence of Hearing Impairment on Preverbal Emotional Vocalizations of Infants

The aim of the study was to compare the vocalizations of normally hearing and profoundly hearing-impaired infants in the first year of life. After the first recording all hearing-impaired infants were provided with hearing aids. We focused on three issues: (1) Are there different types of preverbal vocalizations in the vocal repertoire of normally hearing and hearing-impaired infants? (2) Do the vocal types emerge at similar age? (3) Does hearing impairment influence the acoustic structure of the preverbal vocalization types common to normally hearing and hearing-impaired infants? The study shows that both normally hearing and hearing-impaired infants have the same vocal repertoire. Except for babbling, there were no differences in the time of emergence of preverbal utterances. Structural differences could only be found in ‘cries’. In general, it seems that normal auditory input is not essential for the production of single preverbal utterances.

Medical evaluation of patients with spasmodic dysphonia

Summary 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.

Treatment of Spasmodic Dysphonia with Botulinum Toxin: Clinical Experiences and Research Issues

Spasmodic Dysphonia is a disabling speech disorder characterized by excessive contractions of laryngeal muscles. Botulinum toxin has been demonstrated in several clinical trials to be very effective in improving speech in most patients and its clinical use is becoming more widespread. Although the benefits of botulinum toxin treatment are considerable, few patients achieve a totally normal voice and minor side effects are common. Clinical research is needed to determine the factors limiting improvement, to determine the role of adjunctive speech therapy, and to develop treatment protocols which will maximize benefits and diminish side effects.