Video Laryngeal Stroboscopy Why would my child need a video laryngeal stroboscopy? Video laryngeal stroboscopy VLS is a procedure done to evaluate the motion of the vocal cords. It allows the physician to tell the difference between different lesions of the vocal cords that can affect the voice. It is used when there is a complaint of a voice disorder such as hoarseness or loss of voice.
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The free edges of the vocal folds appear as a blur. Stroboscopy is a special method of examination of a vibrating or fast moving object, such as the vocal folds. By taking multiple snapshots at different phases of the vibratory cycle it is possible to see details of the change in shape of pliable surface of the vocal folds i. The flashing light from the stroboscope is passed through a flexible nasoendoscope or rigid endoscope to illuminate the vocal folds Figure 2. To do this the rate of vibration of the vocal folds or fundamental frequency needs to be measured.
This can be done by analysing one three types of signal: 1. The flashes of light from the stroboscope are synchronized to the frequency of vocal fold vibration with a slight time delay added for each flash. If the flash takes place in time with the fundamental frequency the vocal folds would appear not to move.
The slight time delay means that the vocal folds are illuminated at a slightly later point in the vibratory cycle Figure 3. The slow motion allows details of the mucosal wave of the vocal folds to be seen. This is the complex vibratory or oscillatory movement of the mucosa of the vocal fold that takes place in order to produce voice. It can be seen by observing the changing reflection of light during stroboscopy or high speed digital imaging It is particularly helpful to clinicians who want to check that there is no subtle structural abnormality of the vocal folds that could be contributing a voice problem.
If each image is shown one after the other as a movie changes in the a mucosal wave can be seen Figure 2: The Laryngograph Laryngeal Strobe system with 70 degree rigid Machida endoscope and attached digital camera head Figure 3: A screen shot of the synchronised stroboscopic images with the Laryngograph waveform taken at eight points of a vibratory cycle. You can see how the Laryngograph waveform changes with the closing and opening of the vocal folds.
The vertical red lines indicate the actual vibratory cycle and phase when each stroboscopic snapshot was taken. Note the second snapshot 2: 45 degrees was taken 23 cycles later. Written by Julian McGlashan.
J R 31 Jan 20 Not sure why all those good reviews were posted. They were very misleading and I personally can say that my experience was absolutely negative. I was seen by Dr. A nurse spray some lidocaine plus some other component inside my nostrils and told me that a test will be conducted later on by Dr. I saw Dr.
Video Laryngeal Stroboscopy
Key Glossary Terms Rigid Laryngoscopy An examination of the voice box in which a rigid telescope is used; this examination provides the clearest magnified detail of the voice box, but the patient is unable to speak or sing during the exam Flexible Laryngoscopy An examination of the voice box in which a flexible fiberoptic scope is used; this examination allows the physician to view the voice box in action i. Several methods can be used to examine the throat and voice box. Images are usually recorded on video. Also called: telescopic laryngoscopy, transoral laryngoscopy Flexible laryngoscopy: This examination allows for viewing the voice box in action.