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The Importance of Strobovideolaryngoscopy in the Evaluation of Sudden Voice Change.

THE PURSUIT OF ACCURATE IMAGING of the normal and abnormal vocal fold has occupied laryngologists for decades. Strobovideolaryngoscopy has been and continues to be the single most important tool in diagnostic laryngology, with the possible exception of the flexible laryngoscope.

Developed by German physician Max Joseph Oertel in 1878, stroboscopic light examination allows routine, slow motion evaluation of the mucosal cover layer of the leading edge of the vocal fold. (1) Vocal fold vibration occurs at a rate anywhere between 80 to 1,000 cycles per second, significantly beyond the processing capacity of the brain's visual cortex. By using a spinning disk to create the strobe effect, Oertel discovered that using pulsed light at a rate slightly different from the frequency of vocal fold vibration would capture images at slightly different points in the glottic cycle. Due to the persistence of images on the retina, these images are fused by the brain into what appears to be a slow-motion image, allowing evaluation of the vibratory margin of the vocal fold. (2) This phenomenon is known as the persistence of vision, and it is the principle behind film projection.

For many years following its discovery, cumbersome equipment and cost prevented most practitioners from adopting stroboscopy. It was not until the 1980s, with the development of a pulsed xenon light source and low light camera, that stroboscopy became a much more practicable technique to use in the office. Today, stroboscopy is utilized in the laryngologist's office by way of either a flexible examination or rigid telescope--though the latter remains a more accurate diagnostic tool. (3) In addition, technology has allowed modern laryngologists to digitally record and preserve their findings.

Stroboscopy allows an improved physical examination which permits detection of vibratory asymmetries, structural abnormalities, small masses, submucosal scars, and other conditions that are invisible under ordinary light. (4) For example, in a patient with a poor voice following laryngeal surgery and a "normal looking larynx," stroboscopic light reveals adynamic segments that explain the problem even to an untrained observer (such as the patient). In addition, it permits differentiation between cysts, nodules, and other masses, allowing better treatment planning and prognostic predictions.

Strobovideolaryngoscopy is the most common technique for assessing vocal fold vibration in clinical use, but it has limitations. It works well with patients whose vocal folds vibrate in a periodic or pseudoperiodic fashion; however, it is not optimal for assessment of aperiodic vibration because the frequency detection system of the stroboscope cannot track rapid, irregular changes effectively. Stroboscopy also can give an incorrect impression when the vocal folds are producing more than one periodic source, as in some cases of diplophonia. Because of these limitations that are based in the technology of strobovideolaryngoscopy, stroboscopic examination of some voice problems is troublesome. These include some cases of severe hoarseness, diplophonia, voice breaks, vocal tremor, and other problems. It is also difficult to examine the vocal folds in patients who have very short phonation times. Because of the tracking problems that impair the ability of stroboscopy to image voice breaks clearly, register transitions cannot be assessed definitively using strobovideolaryngoscopy.

Sudden voice change is a chief complaint that is caused by benign etiologies related to trauma from vocal overuse or misuse, inflammation, or benign vocal fold lesions, and it may represent a laryngologic emergency. For example, one particular case that illustrates the utility of a full laryngologic workup utilizing strobovideolaryngoscopy involves a 30-year-old male professional opera singer who presented with a one-week history of increased vocal effort, loss of range, and sore throat associated with singing. Past medical history was significant for laryngopharyngeal reflux controlled with lansoprazole and ranitidine. Flexible laryngoscopy was performed, and failed to reveal any positive clinical findings. Rigid strobovideolaryngoscopy was performed next following a standard assessment protocol. (5) First, the patient was examined during abduction (Figure 1). Next, the patient was instructed to phonate at high pitch (Figure 2). Finally, the patient was instructed to phonate at a low pitch, causing a left physiological sulcus containing a vocal fold hemorrhage to be delivered superiorly by the mucosal wave (Figure 3).

Absolute voice rest with weekly examinations was recommended, and limited speaking was instituted at one week. Follow-up approximately three weeks later showed complete resolution of the hemorrhage; vocal function had returned to his baseline. Due to a busy international performance schedule, follow-up video-stroboscopic exam was delayed for four months, but demonstrated continued complete resolution.

In a review of 343 patients during a two-year period, information gathered on stroboscopic examination was found to influence diagnosis or treatment in approximately one-third of the entities diagnosed. (6) In regard to hemorrhages, stroboscopy either established or altered diagnosis in roughly 88% (22/25) of cases in that study. Videostroboscopy is an indispensable tool in evaluating patients with vocal complaints. It permits an adequate physical examination that cannot be performed under continuous light, and it can help elucidate underlying pathology missed on standard flexible laryngoscopy. (7) Stroboscopic analysis may identify injuries that would be missed and, without intervention, might cause permanent dysphonia. Strobovideolaryngoscopy is an absolutely essential component of the evaluation of dysphonia and voice change; and singing teachers should be certain that their students with medical voice problems obtain care from a specialist who has state-of-the-art technology so that important disorders will not be missed.

NOTES

(1.) Max Joseph Oertel, "Das laryngoskopische Untersuchung," Archives of Oto-Rhino-Laryngology, no. 3 (1895): 1-16.

(2.) Robert T. Sataloff, Professional Voice: The Science and Art of Clinical Care, 4th ed. (San Diego: Plural Publishing, 2017); Clark A.Rosen, Milan R. Amin, Lucian Sulica, C. Blake Simpson, Albert L. Merati, Mark S. Courey, Michael M. Johns, and Gregory N. Postma, "Advances in Office-Based Diagnosis and Treatment in Laryngology," Laryngoscope 119, Suppl. 2 (November 2009): 185-212.

(3.) Robert Eller, Mark Ginsburg, Deborah Lurie, Yolanda Heman-Ackah, Karen Lyons, and Robert T. Sataloff, "Flexible Laryngoscopy: A Comparison of Fiber Optic and Distal Chip Technologies. Part 1: Vocal Fold Masses," Journal of Voice 22, no. 6 (November 2008): 746-750; Robert Eller, Mark Ginsburg, Deborah Lurie, Yolanda Heman-Ackah, Karen Lyons, and Robert T. Sataloff, "Flexible Laryngoscopy: A Comparison of Fiber Optic and Distal Chip Technologies. Part 2: Laryngopharyngeal Reflux," Journal of Voice 23, no. 3 (May 2009): 389-395; Swapna Chandran, John Hanna, Deborah Lurie, and Robert T. Sataloff, "Differences Between Flexible and Rigid Endoscopy in Assessing the Posterior Glottic Chink," Journal of Voice 25, no. 5 (September 2011): 591-595.

(4.) Robert T. Sataloff, Joseph R. Spiegel, Linda M. Carroll, Barbara-Ruth Schiebel, Kathe S. Darby, and Rhonda Rulnick, "Strobovideolaryngoscopy in Professional Voice Users: Results, Findings and Clinical Value," Journal of Voice 1, no. 4 (June 1987): 359-364; Robert T. Sataloff, "Strobovideolaryngoscopy in Professional Voice Users: Results and Clinical Value," Annals of Otology, Rhinology & Laryngology 100, no. 9, Pt. 1 (September 1991): 725-727; John S. Rubin, Robert T. Sataloff, and Gwen S. Korovin, Diagnosis and Treatment of Voice Disorders (San Diego: Plural Publishing, 2014), 215-216.

(5.) Satoloff, Professional Voice.

(6.) Sataloff, Spiegel, et al.

(7.) Ibid.

Daniel Benito is a fourth-year medical student at Drexel University College of Medicine in Philadelphia, PA. He is originally from Miami, Florida, and completed his Bachelors of Science in Biology at Florida International University.

Dr. Romak graduated from the University of Connecticut School of Medicine, received his residency training in Otolaryngology--Head and Neck Surgery at Mayo Clinic in Minnesota, and completed a fellowship in Laryngology and Care of the Professional Voice at the American Institute for Voice and Ear Research. He practices laryngology and otolaryngology in Wilmington, Delaware.
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Title Annotation:CARE OF THE PROFESSIONAL VOICE
Author:Benito, Daniel A.; Romak, Jonathan J.; Sataloff, Robert T.
Publication:Journal of Singing
Geographic Code:1USA
Date:Nov 1, 2017
Words:1246
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