Flexible Laryngoscopy

Underneath the umbrella term “flexible laryngoscopy”, various technologies can be specified to describe the scope in more detail.  Flexible fiberoptic laryngoscopy refers to a scope where fiberoptic technology is used to deliver both light and visualization, often with the naked eye looking through an eyepiece. 

Flexible video laryngoscopy refers to the addition of a recording modality to save a video of what was seen by the laryngoscope.  Recording capabilities can be achieved with either a separate camera attached over the eyepiece of a flexible fiberoptic laryngoscope or a self-contained scope with no eyepiece but rather a distal chip camera (“CCD”, charge coupled device) in the tip of a scope that then send their images to a processor and are digitally recorded.  Distal chip scopes are becoming the standard of care because of their sharp, if not high-definition, images. 

Regardless of the technology of the scope, if the software supports it, the image can be processed using stroboscopy technology to see vocal folds in pseudo-slow motion while vibrating. 

High definition, chip tip, flexible laryngovideostroboscopy is the preferred technology for most professionals who care for patients with voice and other laryngeal disorders. 

The nose is often topically anesthetized and decongested before the exam is performed (i.e., oxymetazoline or phenylephrine mixed with 2% lidocaine that is allowed to sit for a few minutes for maximal decongestion) for patient comfort and tolerance of what can be a lengthy exam. 

For example, continuous flexible laryngoscopy during exercise testing can require more than 10 minutes. For some indications (i.e., flexible (historically fiberoptic) endoscopic evaluation of swallowing or FEES) however, care must be taken not to anesthetize the pharynx with nasal sprays as swallowing sensation, and subsequent FEES outcome can be affected. 

With the patient seated deep in the chair and leaning forward from the waist with the neck flexed and head extended (“leading with the chin” , aka the “sniffing position”, see below) the scope is placed in the nasal cavity and the clinician can visually guide the scope into the nasopharynx, preferably with the scope on the floor (inferior meatus) of the nose and against the inferior turbinate rather than the nasal septum.

The middle meatus of the nasal cavity is often the path of least resistance for entering the nasal cavity, but arguably much more uncomfortable for the patient and often changes/rotates the angle of visualization of the larynx as the endoscopist advances.

If performing a complete pharyngeal and laryngeal physical examination, assessment of the nasal passages, nasopharynx (including Eustachian tube orifices and Fossae of Rosenmueller) and velopharyngeal closure are performed. 

With the tip of the scope resting on the floor of the nose near the choanae, the patient is first asked to say /i/. Any significant tremor of the palate or pharynx will often be demonstrated here.  Subsequently the patient should say something akin to “Coca-Cola” or “Puh-Tuh- Kuh” and then hold out a long “S” sound to evaluate for air or mucus escape (up) into the nasopharynx. 

The scope is then passed to the oropharynx where the base of tongue and vallecula are examined with the patient protruding their tongue.  The hypopharynx is examined with the patient performing a Valsalva maneuver while their cheeks are inflated against closed lips and velopharynx.  Pooling of saliva in the hypopharynx or vallecula may be an indication of dysphagia due to pharyngeal motor or sensory weakness, cricopharyngeal dysfunction or esophageal dysmotility.

Attention is then turned to the neurolaryngeal exam. This begins with the patient saying /i/.  This orients the endoscopist to the natural phonatory position of the larynx.  When visualization of the TVFs during /i/ is difficult, it is a good time to re-position the patient’s head and chin into the “sniffing position”.  It is advantageous to watch the patient breathing at rest to look for any unexpected spontaneous or “twitchy” movements, especially in cases of suspected intermittent laryngeal obstruction.

Next, an alternating /i/ and sniff is performed 3 or more times to look for asymmetries in gross abduction and adduction of the TVFs.  The endoscopist should focus on the vocal processes of the arytenoid cartilages and ignore the often asymmetric, non-pathologic movements of the arytenoid suprastructures (cuneiform and corniculate cartilages under mucosa) when looking for motion abnormalities. 

The patient is then asked to sniff three times without the /i/.  This offers a second look for abduction asymmetry.  A glide from low to high pitch and then from high to low pitch on /i/ follows to offer insight into cricothyroid (CT) muscle (and therefore SLN) function.  Traditionally, when looking for CT muscle weakness, the posterior glottis and petiole of the epiglottis are expected to rotate towards the affected side. 

Laryngeal diadochokinesis (LDDK) is then performed by asking the patient alternate between /i/ and /hi/ or repeating “puh-tuh-kuh” as quickly as they can.  This may demonstrate a weak side during the task which helps determine sidedness of a TVF motion.  

Finally, the patient is asked to say a sentence to evaluate connected speech such as “We were away a year ago” which may demonstrate different patterns of supraglottic hyperfunction as compared to a held /i/.  After completion of the neurolaryngeal exam using flexible laryngoscopy, adjunctive tests such as stroboscopy and FEES can be performed.