Vocal tract visualization and imaging is the collection of procedures for performing a detailed visual examination of the vocal tract and laryngeal and velopharyngeal structures and gross function, including vocal fold vibration. These procedures enable a speech-language pathologist (SLP) to further assess and plan treatment strategies for
These procedures use either a constant or a stroboscopic light source for indirect laryngoscopy, rigid fiberoptic oral endoscopy (RFOE), or flexible fiberoptic nasendoscopy (FFN). Images and/or videos can be made using any of these techniques and can be stored on digital media. Physicians are the only professionals qualified and licensed to render medical diagnoses related to the identification of laryngeal pathology as it affects voice. Imaging should be viewed and interpreted by an otolaryngologist with training in this procedure when used for medical diagnostic purposes. SLPs trained in stroboscopy view and interpret imaging for SLP diagnosis (e.g., dysphagia) and to establish/modify treatment plans. Videofluoroscopy, ultrasound, and video images can also be used to view all or part of the vocal tract and oral structures. However, this is not the focus of this page.
Please see ASHA’s resource on Flexible Endoscopic Evaluation of Swallowing (FEES) for further information on imaging for deglutition.
Although there is typically some variation between procedures, an effort has been made to standardize protocols for instrumental assessment of voice, including recommendations for laryngeal endoscopic imaging (Patel et al., 2018).
FFN is performed with a flexible nasendoscope inserted through the nasal passage. A fiberoptic bundle transmits high-intensity light to illuminate structures, which are then viewed and/or recorded. Distal-chip flexible endoscopes allow for assessment of vibratory motion similar to that of a rigid endoscope with stroboscopy (Patel, 2012). A nasendoscope with a smaller diameter may be used for pediatric populations.
Please see ASHA’s resource on Flexible Endoscopic Evaluation of Swallowing (FEES) for related information.
RFOE is performed with a rigid tube inserted into the oral or pharyngeal cavity. A prism optic system projects high-intensity light at a predetermined angle to illuminate the structures to be observed and recorded.
Videolaryngoendoscopy is used to assess the following (Patel et al., 2018):
Videostroboscopy is performed with either a flexible or a rigid endoscope combined with a strobe light correlated to vocal fold vibration via a laryngeal microphone. This combination permits vocal tract structures to be seen in an apparent “slow motion” format.
Videostroboscopy is used to assess the following (Patel et al., 2018):
For many clinicians, it will be necessary to seek training in visualization and imaging after completion of the requirements for the ASHA Certificate of Clinical Competence through intensive continuing education, pre-service, or in-service training programs. Education and training may vary for each of these procedures. The training and mentorship should take place in a clinical setting, allowing the professional to work with more experienced professionals and a number and variety of patients. Practitioners must determine if they have obtained a sufficient degree of education and training to be competent to perform vocal tract visualization and imaging. The safety of the patient is paramount when considering any procedure. Please see ASHA’s Vocal Tract Visualization and Imaging: Position Statement and ASHA’s States with Specific Instrumental Assessment Requirements for further information.
Before undertaking these procedures, practitioners should take the following precautions:
Aryepiglottic fold—composed of the mucous membrane, not typically used in voice production (Figure 2-4)
Corniculate cartilage—paired cartilaginous structures that sit atop the arytenoid cartilage, not directly implicated in voice production (Figure 2-4)
Cuneiform cartilage—cartilage embedded in the aryepiglottic muscle/fold that serves as a supportive framework for the larynx (Figure 2-3)
Epiglottis—cartilage covered with a mucous membrane, does not serve a function in voice production (Figures 2-3 and 2-4)
Esophageal sphincter—a muscular ring that opens into the esophagus, does not serve a function in typical voice production (Figures 2-3 and 2-4)
Posterior pharyngeal wall—the muscular wall of the posterior pharynx used in swallowing, not used in voice production (Figure 2-4)
Tracheal rings—cartilaginous rings of the trachea, do not serve a function in voice production (Figure 2-3)
True vocal folds—muscularized mucous membranes used for sound production (Figures 2-3 and 2-4)
Ventricular folds—ligaments covered by a mucous membrane that lie superior to the true vocal folds, also called “false vocal folds” (Figure 2-4)
Patel, R. R. (2012). Updates on endoscopic laryngeal imaging. Perspectives on Voice and Voice Disorders, 22(2), 64–71. https://doi.org/10.1044/vvd22.2.64
Patel, R. R., Awan, S. N., Barkmeier-Kraemer, J., Courey, M., Deliyski, D., Eadie, T., Paul, D., Švec, J. G., & Hillman, R. (2018). Recommended protocols for instrumental assessment of voice: American Speech-Language-Hearing Association Expert Panel to Develop a Protocol for Instrumental Assessment of Vocal Function. American Journal of Speech-Language Pathology, 27(3), 887–905. https://doi.org/10.1044/2018_AJSLP-17-0009
Roy, N., Barkmeier-Kraemer, J., Eadie, T., Sivasankar, M. P., Mehta, D., Paul, D., & Hillman, R. (2013). Evidence-based clinical voice assessment: A systematic review. American Journal of Speech-Language Pathology, 22(2), 212–226. https://doi.org/10.1044/1058-0360(2012/12-0014)