Vocal Cord Function and the Early Detection of Voice and Swallowing Changes
Understanding the vital role of the function of vocal cords can lead to early detection and treatment of voice and swallowing problems. Statistics tell us that nearly 75-89% of PwP will acquire a voice disorder while 95% will develop a swallowing disorder. These disorders may occur independently or concurrently, making it sometimes a challenge to differentiate. Most commonly we identify the vocal cords as the means of producing sound, however they also play an important role in the physiology of swallowing. Therefore, subtle changes to the vocal cords can serve as an indicator for future voice and swallowing difficulties.
The intricate subsystems of voice production involve a coordinated effort between respiration, phonation, and resonance. In other words, to communicate we must have adequate air intake which flows upward into our trachea and subsequently begins the process of vocal cord vibration. We then shape the vibration using our articulators to form speech. In order to produce sufficient vocal cord vibration, rapid successive periods of opening and closing of the vocal cords must occur. This provides regulation of airflow and allows for adequate subglottic air pressure required for vocal cord vibration. In cooperation with nearly 30 muscles in and around the larynx, the phenomenon of voice occurs. Oftentimes people with Parkinson’s have inadequate adduction of their vocal cords which interrupts this process and results in a breathy voice with reduced vocal intensity. The Voice Handicap Index-30 (VHI) is a questionnaire that can reveal physical, functional, and emotional changes resulting from poor vocal function. To determine whether voice quality has an impact on your communication, the shorter VHI-10 serves as a screening device that can be obtained online and completed. A score of 11 or more indicates a voice change that negatively impacts communication in everyday situations.
Swallowing involves several stages including the closing of the vocal cords and squeezing of the arytenoids which helps seal the airway, serving to protect from food or liquids entering into the trachea. The third layer of protection involves the epiglottis which swings down and covers the laryngeal vestibule. Symptoms indicating that food and/or liquids are passing beneath the vocal cords include coughing during or right after eating or drinking, throat clearing, and a wet and gurgly sounding voice during or after eating or drinking. The Eating Assessment Tool-10 is a quick questionnaire also easy to download online that can be used to measure swallowing difficulties. A score of 3 or more indicates a swallowing problem.
During the process of communication and swallowing, the vocal cords do not act alone but in coordination with many other structures, therefore it is important to discuss potential voice and swallowing problems with a professional. If your score on the VHI-10 or EAT-10 indicates a problem, you should share your score and speak to your physician. They may choose to refer you to a licensed, certified Speech-Language Pathologist (SLP) to receive additional evaluations. Using specialized equipment, a SLP gathers objective data that describes the efficiency of voice and airflow known as laryngeal function studies. A more comprehensive evaluation called videostroboscopy is known as the gold-standard technology used to view the larynx and the movement of the vocal cords. A modified barium swallow study (MBS), also known as videofluoroscopic swallow study, or fiberoptic endoscopic evaluation of swallowing (FEES) may be used to detect penetration and/or aspiration of food or liquid entering the lungs. The MBS is a fluoroscopic procedure whereas the FEES is performed in a clinic where a flexible scope is passed through the nose. These diagnostic procedures performed at the first sign of change or at the time of diagnosis can serve to guide you and your physician in developing a plan of care to help maintain your voice and swallowing throughout the course of the disease.
Resources:
Belafsky PC, Mouadeb DA, Rees CJ, Pryor JC, Postma GN, Allen J, and Leonard RJ. Validity and reliability of the Eating Assessment Tool (EAT-10). Ann Otol Rhinol Laryngol 117: 919-924, 2008.
Rosen, C, Lee, A, Osborne, J, Zullo, T, and Murry, T. Development and Validation of the Voice Handicap Index10. Laryngoscope: 114(9): 1549-1556, 2004
American Speech-Language-Hearing Association Adult Dysphagia: https://www.asha.org/PRPSpecificTopic.aspx?folderid=8589942550§ion=Assessment
Darla Freeman, M.A. CCC-SLP presented at the 5th World Parkinson Congress in Kyoto, Japan. She currently works as a licensed speech-language pathologist at the Florida Center for Voice and Swallowing in Tampa, and she is working towards her doctoral degree in Speech-Language Pathology at Northwestern University.
Ideas and opinions expressed in this post reflect that of the authors solely. They do not reflect the opinions or positions of the World Parkinson Coalition®