Katherine Verdolini

Frequency and risk factors for voice problems in teachers of singing and control subjects

Using a questionnaire format, 125 teachers of singing and 49 control subjects indicated whether they had a current or past voice problem, and provided information about their demographic characteristics, voice use patterns, and medication use. The results revealed similar rates of current voice problems reported by the two subject groups. However, teachers of singing were considerably more likely to report ever having had a voice problem than controls (64 vs. 33%). Risk factors were similar for the two groups. Dehydrating medications and a report of a past voice problem both increased the likelihood of perceiving a current problem, by a factor of three and five, respectively. Females were twice as likely to report a past voice problem as males, and younger subjects were slightly more likely to report a past problem as compared with older subjects. The implications of the findings are discussed from a theoretical as well as pragmatic perspective.

A Patient-Specific in silico Model of Inflammation and Healing Tested in Acute Vocal Fold Injury

The development of personalized medicine is a primary objective of the medical community and increasingly also of funding and registration agencies. Modeling is generally perceived as a key enabling tool to target this goal. Agent-Based Models (ABMs) have previously been used to simulate inflammation at various scales up to the whole-organism level. We extended this approach to the case of a novel, patient-specific ABM that we generated for vocal fold inflammation, with the ultimate goal of identifying individually optimized treatments. ABM simulations reproduced trajectories of inflammatory mediators in laryngeal secretions of individuals subjected to experimental phonotrauma up to 4 hrs post-injury, and predicted the levels of inflammatory mediators 24 hrs post-injury. Subject-specific simulations also predicted different outcomes from behavioral treatment regimens to which subjects had not been exposed. We propose that this translational application of computational modeling could be used to design patient-specific therapies for the larynx, and will serve as a paradigm for future extension to other clinical domains.

Effects of Dehydration on Phonation in Excised Canine Larynges

The effects of exposure to dry air on phonation were measured in an ex vivo model of vocal fold vibration. Excised canine larynges were mounted on an apparatus and made to phonate at a constant subglottal pressure by means of unhumidified airflow. The phonation threshold pressure (FTP), glottal airflow, sound intensity of the acoustic output, and effects on vocal efficiency were also assessed. Students r-test was performed on the results. In 17 larynges, the average PTP increased from 10.0 cm H2O to 15.0 cm H2O after exposure to dry airflow (p < .001). In addition, the average flow increased from 585 mL/s to 801 mL/s at a constant suprathreshold subglottal pressure (p < .001), and from 323 mL/s to 610 mL/s at the PTP (p < .001). The average acoustic output levels, measured during stable phonation segments, markedly decreased with exposure to the dry airflow, from 91.5 dB to 88.5 dB (p < .001). The average vocal efficiency decreased from 3.63 × 10−4 to 7.00 × 10−5 (p < .001). No such changes were seen in control larynges phonated with 100% humidified air used for driving the airflow. The results support previously reported modeling and experimental findings that dehydration of the vocal fold generally degrades laryngeal performance.

Acute Vocal Fold Wound Healing in a Rabbit Model

Several authors have eloquently described the characteristics of vocal fold scar, a long-term consequence of vocal fold injury. However, events in the acute stage of mucosal injury, which lead up to fibrosis, have been largely overlooked. The current study describes acute events with regard to mucosal re-formation in a rabbit model. Vocal fold injury was induced surgically. A fibrinous clot was present 1 day after injury. Massive cellular infiltration was noted on day 3, and complete epithelial coverage was achieved by day 5. Also, neo-matrix deposition was noted as early as 5 days after injury, and more mature collagen was seen by day 7. The general timetable described in the current study can contribute to the experimental foundation for the development of regenerative models of healing in the vocal folds. Most notably, the proliferation phase of wound healing appears to occur approximately 3 days after injury, indicating a critical time for intervention. Manipulation and/or alteration of naturally occurring neo-matrix deposition and organization may yield improved biophysical function of the injured vocal fold.

Correspondence of electroglottographic closed quotient to vocal fold impact stress in excised canine larynges

The purpose of this study was to explore the possible use of the electroglottographic closed quotient (EGG CQ) as a noninvasive estimate of vocal fold impact stress (SI). Two excised canine larynges were used. Each larynx was mounted and vocal fold oscillation was induced using a humidified air source. Twenty-seven experimental trials were conducted for each larynx. Trials involved variations in vocal process gap, vocal fold elongation, and subglottic pressure. Simultaneous measures were made of vocal fold SI at the midpoint of the membranous vocal folds, and EGG CQ (dimensionless ratio). The results indicated that when threshold and saturation effects were excluded, the SI and the CQ were strongly related (linear correlation r = .83 and .96 for the two individual larynges, and .81 for the combined data). Within the region of linear relation, an increase of.15 in the CQ corresponded to about 1 kPa increase in SI for the combined data. Discussion focuses on possible clinical implications and the likely reasons for threshold and saturation phenomena.

Shifts in biochemical markers associated with wound healing in laryngeal secretions following phonotrauma: a preliminary study.

The current study sought to determine whether shifts in key components of the inflammatory process could be detected from laryngeal secretions sampled before and after vocal loading. a healthy 44-year-old woman served as the subject. The vocal folds were swabbed to collect baseline secretions. Ten and 20 minutes after nearly constant loud phonation for 1 hour, the vocal folds were swabbed again. The findings indicated strong shifts in several key inflammatory mediators: interleukin-1β, tumor necrosis factor a, and matrix metalloproteinase 8. The concentrations of those mediators continued to increase from the 10- to 20-minute postloading time-points. Transforming growth factor β and prostaglandin E2 did not demonstrate clear shifts. In summary, mediators reflecting the acute inflammatory process could be detected from laryngeal secretions in an awake human. The upward slope of the curves at the 20-minute time interval indicates the need for longer follow-up sampling to determine the full biological response of the vocal folds to acute phonotrauma.

Vocal Fold Impact Stress Analysis

Vocal fold impact stress (force/area) has been implicated as a factor possibly contributing to the formation of nodules and polyps. The force of impact of a moving body is related to its acceleration. Since the mass of the folds is relatively constant, one expects impact force to be directly proportional to acceleration. A measure that reflects the relative displacement of the vocal folds is photoglottography (PGG). The velocity and acceleration of the folds are easily obtained by calculating the first and second derivatives of the PGG displacement waveform. This study, therefore, compared the second derivative of the PGG signal with simultaneously measured impact stress in an excised canine larynx model. Glottal transillumination (PGG) was measured with a subglottic transducer. A miniature force transducer placed in the midline between the vocal folds measured impact stress at the midglottal position. For nine different larynges, there was a positive and linear relationship between the second derivative of PGG and impact stress. The statistically significant results support the hypothesis that the second derivative of PGG m ay provide a use fulnoninvasive way to estimate relative vocal fold impact stress.

Time-of-day effects on voice range profile performance in young, vocally untrained adult females

Time-of-day effects on voice range profile performance were investigated in 20 vocally healthy untrained women between the ages of 18 and 35 years. Each subject produced two complete voice range profiles: one in the morning and one in the evening, about 36 hours apart. The order of morning and evening trials was counterbalanced across subjects. Dependent variables were (1) average minimum and average maximum intensity, (2) Voice range profile area and (3) center of gravity (median semitone pitch and median intensity). In this study, the results failed to reveal any clear evidence of time-of-day effects on voice range profile performance, for any of the dependent variables. However, a reliable interaction of time-of-day and trial order was obtained for average minimum intensity. Investigation of other subject populations, in particular trained vocalists or those with laryngeal lesions, is required for any generalization of the results.

Effects of Voice Disorders on Quality of Life

Severity of obstructive sleep apnea (OSA) is currently described according to various parameters obtained from the all-night polysomnogram. Nevertheless, clinicians recognize that patients can present with a variety of medical and functional complaints despite having similar polysomnographic features. This study was performed to improve the classification of severity of OSA through the incorporation of patient-based factors. Patients enrolled in the American Academy of Otolaryngology-Head and Neck Surgery-sponsored Treatment Outcomes Pilot Study were classified by physicians into four severity classes: very mild, mild, moderate, and severe. For the 110 patients, 8% were categorized as very mild, 32% as mild, 36% as moderate, and 23% as severe. The physical examination variables related to the physicians overall rating of severity were body mass index and presence of redundant pharyngeal tissue; the polysomnographic variables were respiratory distress index and minimum 02 saturation during apnea. The score on the Epworth Sleepiness Scale was also related to overall rating of severity. The two physicat examination variables, two polysomnographic variables, and the Epworth Sleepiness Scale were combined through a form of multivariable analysis known as conjunctive consolidation to form the Clinical-Severity Index. The rate of moderate or severe physician-assessed severity in each Clinical-Severity stage was 27% (4 of 15) in stage I; 36% (12 of 33) in stage II; and 81% (50 of 62) in stage III. General and disease-specific health status scores were more strongly associated with Clinical-Severity stages than with polysomnographic variables alone. Logistic regression, a more standard multivariable technique than conjunctive consolidation, confirmed the prognostic importance of the five component variables and the Clinical-Severity Index. These results suggest that easy-to-obtain patient-based factors can be combined with polysomnographic factors to create a formal staging system that correlates with the physicians estimate of severity. Research is presently underway to assess the correlation of the Clinical-Severity Index with patient outcomes, such as mortality, health status, quality of life, and satisfaction with care. The incorporation of patient-based factors with traditional polysomnographic descriptions will lead to the improved classification of patients and more accurate assessments of treatment effects.

Markers of Wound Healing in Vocal Fold Secretions from Patients with Laryngeal Pathology

This study seeks to determine the ability of enzyme-linked immunosorbent assays of vocal fold secretions to detect and describe the inflammatory response in the vocal folds. Vocal fold and palatal secretions were collected during operation from patients with a range of vocal fold disorders and from control patients. The secretions were subjected to assays for interleukin-1β, prostaglandin E2, and transforming growth factor β. The results indicate a differential expression of mediators associated with the wound healing cascade in the vocal folds. The prostaglandin E2 levels clearly differentiated vocal fold secretions associated with laryngeal disease versus control sites. Furthermore, the interleukin-1β concentrations were significantly elevated in subjects with epithelial lesions of the vocal folds as opposed to lesions of the lamina propria. Although still in its infancy, such analysis may ultimately hold scientific and clinical utility in the study and management of patients with vocal fold disease.