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Biomedical subjects

T W Guyette

Publications and source records attributed to T W Guyette.

14 recordsLinked to original sources
PubMed2001

Changes in speech following unilateral mandibular distraction osteogenesis in patients with hemifacial microsomia.

OBJECTIVE: The purpose of this study was to describe changes in articulation, resonance, and velopharyngeal function following mandibular distraction osteogenesis. DESIGN: This is a descriptive, post hoc study comparing the performance of patients on measures of articulation, resonance, and velopharyngeal function before and after mandibular distraction. SETTING: The data were collected at a tertiary health care center located in Chicago. PATIENTS: The clinical data from preoperative and postoperative evaluations of seven mandibular distraction patients were used. OUTCOME MEASURES: The outcome measures were number of articulation errors, severity of hypernasality and audible nasal emission, and velopharyngeal orifice size as estimated using the pressure-flow technique. RESULTS: Immediately after distraction, 28% (2/7) experienced a temporary deterioration in articulation and 42% (3/7) experienced a deterioration in nasal resonance. But by the long-term follow-up evaluation, all had returned to their preoperative levels. Pressure-flow test results generally support the perceptual findings. CONCLUSIONS: Patients being considered for mandibular distraction surgery should receive preoperative and postoperative speech evaluations and be counseled about risks for changes in their speech following surgery.

Adolescent↗
PubMed2001

Changes in speech following maxillary distraction osteogenesis.

OBJECTIVE: The purpose of this study was to describe changes in articulation and velopharyngeal function following maxillary distraction osteogenesis. DESIGN: This is a descriptive, post hoc clinical report comparing the performance of patients before and after maxillary distraction. The independent variable was maxillary distraction while the dependent variables were resonance, articulation errors, and velopharyngeal function. SETTING: The data were collected at a tertiary health care center in Chicago. PATIENTS: The data from pre- and postoperative evaluations of 18 maxillary distraction patients were used. OUTCOME MEASURES: The outcome measures were severity of hypernasality and hyponasality, velopharyngeal orifice size as estimated using the pressure-flow technique, and number and type of articulation errors. RESULTS: At the long-term follow-up, 16.7% exhibited a significant increase in hypernasality. Seventy-five percent of patients with preoperative hyponasality experienced improved nasal resonance. Articulation improved in 67% of patients by the 1-year follow-up. CONCLUSIONS: In a predominately cleft palate population, the risk for velopharyngeal insufficiency following maxillary distraction is similar to the risk observed in Le Fort I maxillary advancement. Patients being considered for maxillary distraction surgery should receive pre- and postoperative speech evaluations and be counseled about risks for changes in their speech.

Adolescent↗
PubMed2000

Laryngeal airway resistance in cleft palate children with complete and incomplete velopharyngeal closure.

OBJECTIVE: This study investigated the effect of velopharyngeal insufficiency on aerodynamic measures of laryngeal function in children with cleft palate. DESIGN: Data were analyzed using analysis of covariance. The independent variable was velopharyngeal closure, and the dependent variables were laryngeal resistance, laryngeal airflow, and transglottal pressure. Age and gender were covariates. SETTING: The data were collected at The Craniofacial Center, University of Illinois, a tertiary health care center located in Chicago. PATIENTS: Thirty-six children with cleft palate were recruited from among the patients at The Craniofacial Center. Ten children with velopharyngeal areas >5 mm2 during oral speech were placed in the incomplete closure group, while 26 children with areas <1 mm2 were placed in the complete closure group. OUTCOME MEASURES: The three dependent variables (transglottal pressure, transglottal airflow, and laryngeal resistance) were measured. RESULTS: Laryngeal resistance and transglottal pressure were significantly higher, and transglottal airflow was significantly lower in the group with complete closure. CONCLUSIONS: In summary, cleft palate patients with complete velopharyngeal closure exhibited higher laryngeal resistances than those with incomplete closure.

Airway Resistance↗
PubMed1999

Velopharyngeal changes after maxillary advancement in cleft patients with distraction osteogenesis using a rigid external distraction device: a 1-year cephalometric follow-up.

The effect of maxillary advancement on speech may have benefits on articulation improvement but compromises velopharyngeal (VP) closure by increasing the nasopharyngeal distance. The purpose of this study was to evaluate the static VP anatomic changes on lateral cephalograms in patients who underwent maxillary advancement through distraction osteogenesis (DO) with a rigid external distraction device and to correlate these changes with clinical speech data. Twenty-two patients (5 female and 17 male) underwent maxillary advancement through DO utilizing a rigid external distraction device (age, 5.2 to 25.7 years) with various diagnoses, including 13 unilateral cleft lip and palate (CLP) patients, 5 bilateral CLP patients, 1 isolated cleft palate patient, 2 facial cleft patients, and 1 patient with craniosynostosis. Lateral cephalograms of preoperative, immediate postdistraction, and 1-year postdistraction were obtained for analysis. Speech evaluation was performed preoperatively, immediate postdistraction, and then at 6-month intervals, and included assessment of air pressure flow, hypernasality, and articulation. With an average amount of 8.9 mm maxillary forward advancement, 14% of patients (3 of 21) presented deterioration in hypernasality. However, 57% of patients (12 of 21) demonstrated improvement in articulation. The cephalometric analysis demonstrated an increase in nasopharyngeal depth by 8.5 mm (1:1 ratio with bony movement) and velar angle by 14.1 deg. The length of the soft palate remained unchanged. The need ratio (intersection of palatal plane and posterior pharyngeal wall-posterior nasal spine/posterior nasal spine--tip of uvula) worsens after distraction. The deterioration of hypernasality was related to the amount of forward distraction, especially in patients without a preexisting pharyngeal flap (PF). Speech evaluation is an important aspect concerning treatment planning for maxillary distraction. The increase in nasopharyngeal depth may compromise VP closure. The increase in velar angle was considered to be part of the compensation in the VP mechanism. An adverse effect of a preexisting PF on maxillary distraction was not observed; however, it prevented postoperative hypernasality.

Adolescent↗
PubMed1997

Effect of septal perforations on measures of nasal resistance.

OBJECTIVE: The purpose of this investigation was to determine the effect of septal perforations on posterior and anterior rhinomanometric measures of nasal resistance in an analog model. DESIGN: The data were analyzed using a repeated-measures ANOVA. Nasal resistance was the dependent variable, while type of rhinomanometry, septal perforation size, and position of resistance (proximal vs. distal) were nominal scale independent variables. PARTICIPANTS: The analog model used in this study was similar to that described by Warren and Devereux (1966), except that the nasal cavities of the model were modified to create septal perforations. OUTCOME MEASURES: The main dependent measure was nasal resistance. RESULTS: An Important finding of this investigation was that septal perforations resulted in large differences (> 3 cm H2O/L/sec) between posterior and anterior nasal resistance values in the bilateral proximal resistor condition. CONCLUSIONS: Anterior rhinomanometry may underestimate true nasal resistance when a septal perforation is present, because the septal perforation prevents accurate measurement of nasopharyngeal pressure. Posterior rhinomanometric measures should accurately reflect nasal resistance despite septal perforations, because the perforation does not invalidate the estimate of nasopharyngeal pressure.

Adult↗
PubMed1996

Pressure-flow differences in performance during production of the CV syllables /pi/ and /pa/.

Inconsistencies in velopharyngeal function were observed to have been reported in pressure-flow reports. This article introduces our findings from a sample of pressure-flow records and discusses possible implications for management. A retrospective review of the pressure-flow records for 51 patients was completed. All patients had been evaluated at the Craniofacial Center, University of Illinois at Chicago. Records were selected based on the following criteria: patients were referred for evaluation of velopharyngeal function and had no secondary surgeries on the velopharyngeal mechanism, no fistulae, no neurologic disorders, and no compensatory articulations. At the time of testing, patients ranged in age from 4 to 38 years with most being under 18 years of age. Velopharyngeal orifice areas were obtained using the pressure-flow technique during repeated CV syllables, including /pi/ and /pa/. Our results show that 8 of 51 patients exhibited a specific type of inconsistent velopharyngeal function (i.e., they exhibited velopharyngeal closing during /pa/ repetitions, but had openings during /pi/ repetitions). The reverse finding was not observed among any of the 51 patients. We concluded that the velopharyngeal incompetence observed during utterances involving /i/ may have been due to the downward pull on the palate of the palatoglossus muscle, which could not be counteracted by the already maximized levator activity in borderline patients.

Adolescent↗
PubMed1996

Mandibular distraction osteogenesis: effects on articulation and velopharyngeal function.

Mandibular distraction osteogenesis has gained popularity for the treatment of mandibular hypoplasia and asymmetry. With this technique, significant skeletal and soft tissue changes in the lower face can be produced in a relatively short time period without the need for extensive surgery. Despite general acceptance, the long-term sequelae of the procedure have not been well documented. In this report, we describe two patients who experienced changes in their articulation and velopharyngeal function after unilateral mandibular distraction. The first patient underwent 35 mm and the second patient 45 mm of mandibular lengthening. In both cases, articulation skills declined, and there was velopharyngeal inadequacy immediately after distraction. However, in both cases, the velopharyngeal inadequacy was transient; one patient recovered near-normal velopharyngeal function within 1 month after distraction and the second patient recovered function within 8 months. The relations among mandibular distraction, articulation, and velopharyngeal function are discussed.

Adaptation, Physiological↗
PubMed1994

Aerodynamic estimates of induced anterior orifice openings in human subjects.

This study first examined the accuracy of pressure-flow area estimates of experimental openings in anterior palatal obturators of three adult subjects. Second, we evaluated pressure-flow measures of the same experimental openings using a model. Results indicated that percent error in orifice estimates was slightly higher for induced openings in human subjects (13%) versus those in the model (11%). Results for our human subjects were similar to those reported by previous investigators.

Aged↗
PubMed1993

Component approach for partitioning nasal airway resistance: pharyngeal flap case studies.

Individuals with craniofacial anomalies often have nasal cavity and/or velopharyngeal constriction. The purpose of this clinical report was to illustrate a technique for partitioning nasal airway resistance into its nasal cavity and velopharyngeal components. This information would be helpful in determining intervention to reduce high nasal airway resistance as well as in providing information about the outcome of corrective procedures to establish velopharyngeal competence for speech. Data from two pharyngeal flap patients seen before and after surgery were utilized in this illustration. These case studies illustrate the usefulness of component resistance measures in quantifying nasal airway patency before and after corrective surgery for velopharyngeal function.

Adult↗
PubMed1992

Pressure-flow measurements for selected oral and nasal sound segments produced by normal adults.

Pressure-flow data are often used to provide information about the adequacy of velopharyngeal valving for speech. However, there is limited information available concerning simultaneous pressure-flow measurements for oral and nasal sound segments produced by normal speakers. This study provides normative pressure, flow, and velopharyngeal orifice area measurements for selected oral and nasal sound segments produced by 10 male and 10 female adult speakers. An aerodynamic categorization scheme of velopharyngeal function, including one typical category and three atypical categories (open, closed, and mixed) is proposed.

Adult↗
PubMed1991

Pressure-flow measurements for selected oral and nasal sound segments produced by normal adults.

Pressure-flow data are often used to provide information about the adequacy of velopharyngeal valving for speech. However, there is limited information available concerning simultaneous pressure-flow measurements for oral and nasal sound segments produced by normal speakers. This study provides normative pressure, flow, and velopharyngeal orifice area measurements for selected oral and nasal sound segments produced by 10 male and 10 female adult speakers. An aerodynamic categorization scheme of velopharyngeal function, including one typical category and three atypical categories (open, closed, and mixed) is proposed.

Adult↗
PubMed1989

Partitioning model nasal airway resistance into its nasal cavity and velopharyngeal components.

Nasal respiration may be assessed as part of the diagnosis and management of persons with orofacial growth disturbances. It is often evaluated by calculating nasal airway resistance. Traditional methods for measuring nasal airway resistance do not provide information about nasal cavity versus velopharyngeal resistance components. A method that partitions nasal airway resistance into its nasal cavity and velopharyngeal components would provide a localized measurement of airway obstruction useful in evaluating the effects of surgical reconstruction of the velopharynx, enlarged adenoids, adenoidectomy, and nasal cavity obstructions along the nasal airway. A modeling project is presented delineating a method for partitioning nasal airway resistance into its nasal cavity and velopharyngeal components.

Airway Obstruction↗
PubMed1988

Accuracy of pressure-flow estimates of velopharyngeal orifice size in an analog model and human subjects.

This study examined the accuracy of pressure-flow estimates of velopharyngeal (V-P) orifice size as applied to an analog model and two human subjects. Accuracy was assessed under differing conditions of degree of nasal resistance and type of instrumental interface. Known V-P orifice openings were introduced in the model through use of cover plates and in the humans through use of modified nasopharyngeal obturators. Nasal resistances were altered with perforated nasal plugs. Instrumental interfaces differed principally in the method used to detect nasal cavity pressure. Measures were applied to the hydrokinetic equation to estimate V-P area values. Data from the analog model and the human subjects were comparable in many respects. In low nasal resistance, area estimates were reasonably accurate regardless of the interface utilized. In high nasal resistance error typically increased, although not equally across interface types. Potential sources of error are identified and discussed.

Adult↗
PubMed1988

Estimation of nasal cross-sectional areas, using oral versus nasal pressure measurements.

This study examines calculations of model nasal cross-sectional area, using nasal versus oral pressure measurements. The results indicate that greater accuracy of nasal cross-sectional area estimation is achieved by using nasal rather than oral pressures. Nasal pressures measured in the anterior model nose more closely reflect nasopharyngeal pressures under a wide range of nasal constriction sizes and airflow rates.

Airway Obstruction↗