A Computational Tool
for Simulation of Phonosurgical Procedures (R03 DC006801)
Principle Investigator:
Eric J. Hunter, Ph.D.
Progress as of January 2006
The designing and constructing stage of the model has commenced
using the detailed three-dimensional laryngeal muscle data and a
laryngeal cartilage database. To help with the design and flexibility
of the model, the individual specimen results of laryngeal cartilage
measures (44 laryngeal measures: 18 for the thyroid cartilage, 18
for the cricoid cartilage, and 8 for the arytenoid cartilage) for
multiple specimens of human (male/female), canine, ovine was compiled
in a single database. While previous studies have focused on average
data, individual specimen data (and, thus, more detailed anatomy)
are necessary to verify current biomechanical models which have
been increasing in complexity and moving from generic to specific
representations of functions (normal and/or abnormal) in a specific
larynx. Individual subject data for four groups (sorted by cartilage)
were gathered and recommendations for their use in the scientific
community were made. [A paper entitled, “Individual Subject
Laryngeal Dimensions of Multiple Mammalian Species for Biomechanical
Models” by E.J. Hunter, and I.R. Titze was published in Annals
of Otology, Rhinology and Laryngology. In addition, the electronic
data has been made available for other researchers and modelers
via E. J. Hunter and I.R. Titze. NCVS Memo No 09. Individual Subject
Laryngeal Dimensions of Multiple Mammalian Species for Biomechanical
Models: A Supplement. NCVS Online Technical Memo 09 Febuary 2005,
www.ncvs.org/ncvs/library/tech.
Denver, CO.].
The range of vocal fold medialization/lateralization has been compiled
from the literature to help experimental cross-validation of the
proposed model and future models. It was found in a review of the
literature that although there was general inter-study agreement
was found in the range of vocal process motion, there was substantial
variation. Best-practice guidelines and research avenues in future
studies of vocal posturing were also outlined. [A paper entitled,
“Review of range of arytenoid cartilage motion” by E.J.
Hunter and I.R. Titze was published in ARLO].
References:
E. J. Hunter and I. R. Titze. NCVS Memo No 09. Individual Subject
Laryngeal Dimensions of Multiple Mammalian Species for Biomechanical
Models: A Supplement. NCVS Online Technical Memo 09 Febuary 2005.
http://www.ncvs.org/ncvs/library/tech
E. J. Hunter and I. R. Titze. Review of range of arytenoid cartilage
motion. Acoustic Research Letters Online 6 (3):112-117, 2005. [PMID:
16570110] http://scitation.aip.org/dbt/dbt.jsp?KEY=ARLOFJ&Volume=6&Issue=3
E. J. Hunter and I. R. Titze. Individual subject laryngeal dimensions
of multiple mammalian species for biomechanical models. Ann.Otol.Rhinol.Laryngol.
114 (10):809-818, 2005. [PMID: 16285273]. http://www.annals.com/2005/Oct2005_abstracts.htm#809
Aims
The long-term goal of this project is to predict outcomes of laryngeal
phonosurgery with physiologically based voice simulation. The proposed
research will move towards this goal by developing a model of vocal
fold posturing. Vocal fold posturing, a fundamental aspect of phonation
control, is defined as adduction, abduction or elongation of the
vocal folds. Because posturing is based on laryngeal joint mechanics
and soft tissue deformation, fundamental theories of continuum mechanics
are used to formulate this model. The application of continuum mechanics
to laryngeal posturing requires an accurate geometric and mechanical
description of various tissues in the larynx, such as the vocal
ligament and intrinsic laryngeal muscles. Furthermore, because many
of these tissues are fibrous and thus have distinct lines of action,
a portrayal of passive and contractile stress contributions and
fiber direction is needed. The specific aims of the current project
are:
- To mathematically represent the orientation of differentiated
laryngeal muscle bundles, allowing for distributed muscle forces
over various cartilages.
- To create, with the distribution of intrinsic muscle bundles,
a three-dimensional finite element model of vocal fold mechanics
that can predict both the speed and the range of vocal fold medialization
and lateralization.
- To simulate a Type I Thyroplasty phonosurgery and predict the
resultant glottal configuration as well as the resultant stress
distribution in the repaired vocal fold.
It is expected that the posturing model will have a significant
impact on surgically based voice therapies, as well as on vocal
fold modeling in general.
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