A-P positioning of medialization thyroplasty in an excised larynx model.

Department of Surgery, Division of Otolaryngology Head and Neck Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA.
The Laryngoscope (Impact Factor: 2.03). 03/2009; 119(3):591-6. DOI: 10.1002/lary.20122
Source: PubMed

ABSTRACT Posterior positioning of medialization thyroplasty provides the best acoustic and aerodynamic outcomes.
Ex vivo excised canine larynx.
Unilateral thyroplasty windows were cut in the thyroid cartilages of 10 excised canine larynges. Each larynx was mounted on an artificial lung and the vocal fold opposite the thyroid window was adducted by medializing its arytenoid cartilage. Then, medialization thyroplasty was simulated with a probe placed anterior, central, and posterior in the thyroid window. The glottal area, airway reduction, medialization force, phonation threshold pressure and flow, aerodynamic power, intensity, efficiency, jitter, shimmer, and signal-to-noise ratio (SNR) were measured at each medialization position.
Posterior medialization probe placement minimized the glottal area, provided the best voice as determined by perturbation measures and SNR, reduced the work of phonation, and increased efficiency. Anterior and middle probe placement minimized the work of phonation but provided only modest gains in sound quality and decreased sound intensity. Medializing the vocal fold with posterior probe placement required twice as much force as central and anterior probe placement.
The results suggest that posterior medialization provides the greatest improvement in acoustic parameters and efficiency in patients who can tolerate the airway reduction. Middle and anterior medialization can decrease work of phonation, but in this experiment objective improvement in sound quality was limited. Subtle changes in displacement shim contour, especially in middle and anterior locations, have a substantial impact on voice outcome, affirming the value of intraoperative voice assessment.

  • [Show abstract] [Hide abstract]
    ABSTRACT: To describe the method of inserting a wedge-shaped adjustable balloon implant (wABI) via a minithyrotomy for medialization thyroplasty and evaluate its effect on a range of phonatory parameters using the excised larynx bench apparatus. Repeated measures with each larynx serving as its own control. A prototype wABI was deployed in six excised canine larynges of various sizes through a minithyrotomy and then filled with saline. Mucosal wave, aerodynamic, and acoustic parameters were measured for three conditions: normal, vocal fold paralysis, and paralysis with the wABI. Phonation threshold pressure (P < .001), flow (P < .001), and power (P = .002) were significantly lower for wABI compared to paralysis trials; values did not differ significantly from normal trials. Percent jitter (P = .002) and percent shimmer (P = .007) were also significantly decreased compared to the paralysis condition, and values were not significantly different compared to normal. The mucosal wave was preserved after insertion of the wABI. Effective vocal fold medialization with preservation of the mucosal wave was observed with the wABI in this preliminary excised larynx experiment. The wABI offers the potential for a minimally invasive insertion in addition to postoperative adjustability. Further studies in living animals and humans are warranted to evaluate clinical utility. LEVEL OF EVIDENCE: NA.
    The Laryngoscope 09/2013; · 2.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives/HypothesisMedialization thyroplasty (MT) is commonly used to treat glottic insufficiency. In this study, we investigated the phonatory effects of MT implant medialization depth and medial surface shape.Methods Recurrent laryngeal nerve (RLN) and vagal paralysis were simulated in an in vivo canine. A type 1 MT was performed using a silicone elastomer implant with variable medialization depths and medial surface shapes: rectangular, V-shaped, divergent, and convergent. The effects on phonation onset flow/pressure relationships and acoustics were measured.ResultsIncreasing depth of medialization led to improvements in fundamental frequency (F0) range and normalization of the slope of pressure/flow relationship toward baseline activation conditions. The effects of implant medial shape also depended on depth of medialization. Outcome measures were similar among the implants at smaller medialization depths. With large medialization depths and vagal paralysis conditions, the divergent implant maintained pressure/flow relationship closer to baseline. The vagal paralysis conditions also demonstrated decreased fundamental frequency range and worse flow/pressure relationship compared to RLN paralysis.Conclusions The depth and medial shape of a medialization laryngoplasty (ML) implant significantly affect both the F0 range and aerodynamic power required for phonation. These effects become more notable with increasing depth of medialization. The study also illustrates that ML is less effective in vagal paralysis compared to RLN paralysis.Level of EvidenceN/A. Laryngoscope, 2014
    The Laryngoscope 07/2014; · 2.03 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to figure out the application of pitch range (PR) evaluation subsequent to arytenoid adduction (AA) combined with type 1 thyroplasty (TP1) in unilateral vocal fold paralysis (UVFP). Retrospective review of clinical records. Subjects were 50 patients with UVFP for whom PR and maximum phonation time (MPT) could be evaluated before and 1 year after AA + TP1. Subjects were divided into two groups based on preoperative PR (pre-PR) (group 1: ≤1 semitone (ST); group 2: ≥2 ST). Correlations among pre-PR and post-PR, MPT, and age were assessed. We also evaluated PRs in subjects with PR deterioration and PRs by causative diseases. PR was significantly extended from a median of 17.0-22.0 ST in all subjects. Pre-PR was correlated with post-PR. Post-PR correlated with post-MPT in group 2 but not in group 1. There was no correlation between post-PR and age or causative diseases. The mean change in PR among subjects with PR deterioration (28.0%, 14/50) was -3.6 ST. Pre-PR and the improvement of post-PR were negatively correlated in group 2. PR evaluation can be useful for predicting post-PR. The effects of age and causative diseases were small compared with other factors, such as pre-PR width and surgical effects. The successful surgery may improve both PR and MPT. However, several cases showed obvious discrepancy of those postoperative improvements. It will be necessary to assess this discrepancy, particularly in subjects with postoperative voice insufficiency.
    Journal of voice : official journal of the Voice Foundation. 12/2013;

Full-text (2 Sources)

Available from
May 28, 2014