13 Imaging of the Upper Airway and Larynx
Summary
This chapter presents techniques for optimizing image quality for endoscopic imaging of the larynx and surrounding structures, including still photography and videography. A standard series of photographic views is presented, followed by a discussion of standard video techniques for laryngeal imaging, and then advanced techniques including videostroboscopy, videokymography, and high-speed digital imaging. Appropriate use of these images and techniques will allow accurate and thorough documentation of the region for general otolaryngologists and laryngologists alike.
Keywords
endoscopy, high-speed digital imaging, laryngoscopy, mucosal wave, videokymography, videostroboscopy, vocal cords
Introduction
Medical imaging of the upper airway is significantly different from other head and neck imaging in that it not only requires use of endoscopic techniques, but also is highly dependent on the use of video. Similar to other endoscopic applications in the head and neck, angled rigid scopes and flexible distal-chip laryngoscopes produce the best results for most situations, and fiberoptic scopes should be avoided if possible due to their low image quality. For many patients, the increased comfort of flexible transnasal endoscopy with a distal-chip scope outweighs the slight decrease in image quality compared with rigid scopes as it also allows natural phonation not possible with per-oral techniques. However, rigid examination remains an excellent tool to visualize the laryngeal mucosa. An important concern specific to the larynx is the ability to rapidly switch between different light sources such as xenon, strobe, and narrowband imaging.
13.1
Image Series
Still photographs are best obtained as frame grabs from careful review of video, and should be used sparingly, reserving the bulk of one’s attention for the more important review of the motion of the larynx and related structures. The photographs alongside are from a single healthy volunteer using the same equipment: Olympus Visera Elite OTV-S190 video processor, the CLV-S190 Xenon light source, and ENF-VH video rhinolaryngoscope.
13.1.1 Home Position
A flexible endoscope is placed through the nose, with the tip at the level of Passavant’s ridge, also known as the velopharyngeal isthmus. In this position, upward/posterior movement of the palate will obscure the view of the larynx. This position is ideal to get a general look at the health of the posterior oropharynx and a distant look at the larynx as well as an ideal starting position for procedures done to include transoral injection of the vocal fold and fiberoptic endoscopic evaluation of swallow. Note that the vocal folds form a “V” shape with the anterior commissure at the bottom of the screen. As such, the right vocal fold appears to the left and the left vocal fold appears on the right. Protruding the tongue and/or jaw jet can improve visualization of the vallecula.
13.1.2 Larynx, Cords Adducted and Abducted, Cheek Puffed/Valsalva
This position fills the available view with the entire laryngeal structure and surrounding pharyngeal wall including the epiglottis, aryepiglottic folds, and arytenoids (Fig. 13.1). Obtain views with the vocal cords alternately fully abducted and adducted, as well as a view while the patient performs a valsalva maneuver to open the hypopharynx/pyriforms. Light intensity and gain of the capture equipment may need to be fine-tuned manually for proper exposure.
