R.E. Stone

Silastic medialization and arytenoid adduction : the Vanderbilt experience : a review of 116 phonosurgical procedures

From April 1987 to April 1992, 116 phonosurgical procedures were performed to treat glottal incompetence. The initial numbers of these surgical procedures included the following: 29 primary Silastic medializations, 3 primary Silastic medializations with arytenoid adduction, 53 secondary Silastic medializations, 4 secondary Silastic medializations with arytenoid adduction, and 11 bilateral Silastic medializations. These procedures are useful in treating unilateral true vocal cord paralysis, scarring, bowing, or paresis, as well as bilateral true vocal cord bowing. Of the initial 100 patients, 16 later underwent a revision with either a larger implants being placed or an arytenoid adduction. Primary Silastic medialization is the placement of an implant under general anesthesia in the same surgical setting in which laryngeal innervation is sacrificed. Secondary Silastic medialization is the placement of an implant under local anesthesia for a preexistent vocal cord malfunction. In either case, overall voice results for unilateral paralysis are very good. Primary Silastic medialization significantly decreases the postoperative rehabilitation period in skull base patients because of the immediate postoperative glottal competence and decreased use of perioperative tracheotomy. Bilateral implants yielded good results in 6 patients with presbylaryngis, but 6 other patients with bowing from other causes experienced only moderate improvement in speech quality. There were no implant extrusions; however, 1 implant was removed secondary to a persistent laryngocutaneous fistula in a patient who had previously undergone laryngeal irradiation. This was the only complication in this series.

Aerodynamic and acoustical measures of speech, operatic, and Broadway vocal styles in a professional female singer.

Understanding how the voice is used in different styles of singing is commonly based on intuitive descriptions offered by performers who are proficient in only one style. Such descriptions are debatable, lack reproducibility, and lack scientifically derived explanations of the characteristics. We undertook acoustic and aerodynamic analyses of a female subject with professional experience in both operatic and Broadway styles of singing, who sang examples in these two styles. How representative the examples are of the respective styles was investigated by means of a listening test. Further, as a reference point, we compared the styles with her speech. Variation in styles associated with pitch and vocal loudness was investigated for various parameters: subglottal pressure, closed quotient, glottal leakage, H1-H2 difference (the level difference between the two lowest partials of the source spectrum), and glottal compliance (the ratio between the air volume displaced in a glottal pulse and the subglottal pressure). Formant frequencies, long-term-average spectrum, and vibrato characteristics were also studied. Characteristics of operatic style emerge as distinctly different from Broadway style, the latter being more similar to speaking.

Recurrent Laryngeal Nerve Avulsion for Treatment of Spastic Dysphonia

Treatment of spastic dysphonia by recurrent laryngeal nerve section has resulted in reproducibly good results in the early postoperative period in most patients. However, critical long-term follow-up has shown a high recurrence rate of adductor spasms by the third year after initial nerve section. A patient who developed recurring adductor spasms 1 year after nerve section was reexplored, with identification of neural regrowth into the distal segment of the recurrent laryngeal nerve. The technique of neural avulsion removing the distal nerve up to its insertion into the laryngeal muscles is described. Neural regrowth, which is just one of the possible mechanisms for recurrence of spastic dysphonia, should be prevented by this surgical modification. Twelve patients who have undergone neural avulsion primarily for spastic dysphonia are being followed up without recurrence of symptoms thus far. Although these results appear promising, this short follow-up that averages 1.5 years must be extended to firmly support these concepts.

Long-Term Follow-up of Recurrent Laryngeal Nerve Avulsion for the Treatment of Spastic Dysphonia

Long-term follow-up of 3 to 7 years is reported on 18 patients who had undergone recurrent laryngeal nerve avulsion (RLNA) for the treatment of adductor spastic dysphonia (SD). Data on neural regrowth after previous recurrent laryngeal nerve section (RLNS) are presented in 2 of these 18 patients. We introduced RLNA as a modification of standard RLNS to prevent neural regrowth to the hemiparalyzed larynx and subsequent recurrence of SD. We have treated a total of 22 patients with RLNA, and now report a 3- to 7-year follow-up on 18 of these 22 patients. Resolution of symptoms was determined by routine follow-up assessment, perceptual voice analysis, and patient self-assessment Sixteen of 18, or 89%, had no recurrence of spasms at 3 years after RLNA as determined at routine follow-up. Two of the 16 later developed spasms after medialization laryngoplasty for treatment of weak voice persistent after the avulsion. This yielded a total of 14 of 18, or 78%, who were unanimously judged by four speech pathologists to have no recurrence of SD at the longer follow-up period of 3 to 7 years. Two of these 4 patients were judged by all four analysts to have frequent, short spasms. The other 2 were judged by two of four analysts to have seldom, short spasms. Three of 18 patients presented with recurrent SD after previous RLNS. At the time of subsequent RLNA, each patient had evidence of neural regrowth at the distal nerve stump as demonstrated by intraoperative electromyography and histologic evaluation of the distal nerve stump. One remained free of SD following RLNA, 1 was free of spasms at 4 years after revision avulsion but developed spasms after medialization laryngoplasty, and the final patient developed spasms 3.75 years after revision RLNA. Medialization laryngoplasty with Silastic silicone rubber was performed in 6 of 18, with correction of postoperative breathiness in all 6, but with recurrence of spasm in 3. Spasms resolved in 1 of these with downsizing of the implant. We conclude that RLNA represents a useful treatment in the management of SD in patients not tolerant of botulinum toxin injections.

Intra- and intersubject variability in acoustic measures of normal voice

Summary Twenty-four normal adult women read part of the Rainbow Passage and sustained vowels three trials each. Utterances were assessed for selected parameters measured by Visi-Pitch (average and SD of fundamental frequency ( F 0 ), average and SD of dBA, perturbation, and percent voiced/unvoiced/pause). Assessment of each parameter included measures of central tendency, dispersion, and distribution characteristics (skewness and kurtosis) of the data and of the ranges of values that would include 95% of the scores (95% fiduciary limits). Generally, differences for the group between the three trials were not significant. Intersubject variability for only a few parameters was less than 20% of the parameters mean. For vowels, variability of jitter was 30–48% of the mean. Eight subjects provided performances 2 months later to obtain an estimate of intrasubject variability over time. There were desirable intrasubject correlations between performances for mean F 0 , jitter in reading and on vowels /i/ and /a/, and percent of voicing. Inter- and intrasubject variability seems restricted and the data appear to resemble a normally distributed function for mean F 0 on reading, jitter on /i/, and percent of voicing. Thus, these parameters may have statistical merit for use in vocal testing.

Biological Activity of Botulinum Toxin Type A in the Chronically Implanted Rat

It is well known that the larynx has three functions: phonation, lower airway protection, and respiration. Many studies have explored the mechanisms of phonatory function and lower airway protection of the larynx, whereas there have been few studies dealing with laryngeal respiratory function. Recently it was revealed that the sensory afferents from the larynx transmit to the medullary respiratory neurons and affect respiratory rhythmogenesis. Furthermore, some studies have reported an interaction between the medullary respiratory neurons and laryngeal motoneurons located in the nucleus ambiguus. From these findings it was suggested that the larynx participates in respiration actively and influences respiratory regulation. Therefore we studied the changes in the activity of the intrinsic laryngeal muscles during hypercapnia in the decerebrated cat. The electromyographic activity of the posterior cricoarytenoid and lateral cricoarytenoid muscles were recorded simultaneously with an electromyogram of the diaphragm, intratracheal pressure, and endotracheal partial concentration of 02 and CO 2. Hypercapnia was induced by inhalation of CO 2 gas, and the end-tidal CO 2 was maintained at 8% to 10%. The activity of the intrinsic laryngeal muscles during hypercapnia was analyzed in comparison with that during eucapnia. In hypercapnia, both the posterior cricoarytenoid and lateral cricoarytenoid muscles increased their electromyographic activities, and the intratracheal pressure during expiration was elevated to a higher level than that in eucapnia. These findings suggested a further widening of the glottis during inspiration to decrease inspiratory resistance and a further narrowing of the glottis during expiration to prevent alveolar collapse. Thus it may be concluded that the larynx actively participates in respiratory regulation under the control of the brain stem.

Pharmacological Agents that Improve Botulinum Toxin Efficacy in the Treatment of Spasmodic Dysphonia

Summary 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.