An insect has provided the inspiration for a surgical planning tool that could help restore speech for those with vocal fold paralysis.
After a swarm of cicadas left thousands of insect carcasses across the Vanderbilt University campus in 2011, researchers brought some of the insects back to the lab to develop a model of their wing movements. It was then that they found similarities in the way the cicada wings moved and the movement of human vocal folds.
Inspired by the similarity, a multidisciplinary team from the Vanderbilt Institute for Surgery and Engineering (VISE) and the Vanderbilt University Medical Center (VUMC), began working to design a software tool to help surgeons develop more precise surgery plans for the most common surgical intervention for unilateral vocal fold paralysis, type 1 laryngoplasty. The National Institutes of Health awarded them a five-year, $2.4 million research grant to fund this work. The surgical planning tool could help surgeons develop customized implants for patients.
“By simulating the dynamics of glottal airflow, the mechanics of the vocal fold tissue, and their interaction after incorporating a surgically placed implant, the computer software will predict how the implant will affect the vibration prior to the surgery,” Haoxiang Luo, PhD, who specializes in computational modeling of fluid-structure interaction (FSI) for biological systems, said in a statement. “It will also help figure out the optimal parameters of the implant such as its shape, size and placement in the voice box.”
Vocal folds are located on both sides of the larynx and come together and vibrate to produce sound.
“Vocal folds are extremely delicate tissue, and the glottal airflow when we speak produces considerable vortices, or swirls, that are hard to describe mathematically or to capture in a computer simulation,” said Luo. “We had to design high-fidelity and yet efficient computational tools to simulate the vocal folds and airflow.”
The researchers focused on unilateral vocal fold paralysis, which is when one of the vocal folds does not close completely against the other, causing people to have a hoarse voice and require more effort to produce sound. They often also experience vocal fatigue and become winded during everyday activities and can lead to a loss of productivity at work and long-term disability.
Type 1 laryngoplasty involves stabilizing the paralyzed vocal fold with a small implant that helps a person produce voice and breathe more easily.
“Currently, this surgery depends on recreating a three-dimensional structure with only two-dimensional data,” Dr. Gaelyn Garrett, a professor and Vice Chair of Otolaryngology, who is also senior executive medical director of the Vanderbilt Voice Center, said in a statement. “The symmetry of vibration provided by the new 3D planned, patient-specific implant should give more consistent and optimal voice outcomes.”
