Saturday, June 15, 2024

Stroboscopy

Overview

Over the past 3 decades, expanding knowledge of vocal fold anatomy and physiology has revolutionized the clinical and surgical practice of laryngology. Since Hirano’s original description of the layered microstructure of the human vocal fold in the 1970s,
increasingly sophisticated diagnostic and surgical techniques have evolved to more precisely address and preserve vocal production. Innovative diagnostic modalities have grown out of an improved understanding of the critical importance of vocal-fold pliability to voice production. Videostroboscopy has evolved as the most practical and useful technique for the clinical evaluation of the visco-elastic properties of the phonatory mucosa.

Video documentation of laryngeal anatomy along with its mechanical function is a painless, office-based procedure done with topical anesthesia and is essential for state-of-the-art management of human voice disorders. Videolaryngoscopy with stroboscopy is the essential diagnostic procedure for the evaluation of laryngeal mucosa, vocal fold motion biomechanics, and mucosal vibration.
These are the key elements for detecting and assessing pathology as well as determining the impact on voice and airway function.

Stroboscopy is a special method used to visualize vocal fold vibration.
It uses a synchronized, flashing light passed through a flexible or rigid telescope. The flashes of light from the stroboscope are synchronized to the vocal fold vibration at a slightly slower speed, allowing the examiner to observe vocal fold vibration during sound production in what appears to be slow motion.

This slow motion picture is an illusion, as the speed of actual vocal fold vibration is not changed by stroboscopy. This special viewing allows the voice care team to evaluate each vocal fold’s vibration properties during the different phases of the vocal fold’s vibration cycle. Because vocal fold vibration is so fast, the slow motion view is actually derived from many successive vibration cycles. The information acquired from the stroboscopic examination of the vocal folds is essential for planning effective phonomicrosurgery (endoscopic surgery to enhance vocal function). Optimal human voice production is dependent on optimal vocal fold vibration. This requires aerodynamically competent closure of vocal folds along with pliable phonatory mucosa.

Videostroboscopy fulfills several important requirements of a complete office voice examination. It provides useful, real-time information concerning the nature of vibration, an image to detect vocal pathology, and a permanent video record of the examination. As important as any of these aspects, stroboscopy substantially improves the sensitivity of subtle laryngeal diagnoses over techniques with continuous nonstroboscopic light sources (eg, rigid or flexible transnasal laryngoscopy).

Relevant Anatomy

The vocal folds, also known as vocal cords, are located within the larynx (also colloquially known as the voice box) at the top of the trachea. They are open during inhalation and come together to close during swallowing and phonation. When closed, the vocal folds may vibrate and modulate the expelled airflow from the lungs to produce speech and singing. For more information about the relevant anatomy, see Vocal Cord and Voice Box Anatomy and Larynx Anatomy.

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