Disclosure
Indirect mirror laryngoscopy is the traditional modality used to perform laryngeal examinations on dysphonic patients. It may be inadequate for the diagnosis of mass lesions when patient gagging does not permit adequate visualization. Because of the gagging and the unnatural position of the larynx during the examination, mirror laryngoscopy is not practical for the diagnosis of voice disorders that relate to physiologic and functional pathology. The rod lens telescope, introduced by Hopkins, has several advantages over the traditional indirect laryngoscope. It produces a magnified, recordable image of the larynx that is superior for the diagnosis of mass lesions and mucosal wave abnormalities, especially when performing stroboscopy. However, its use requires one to grasp the tongue and leads to a variable degree of gagging, thereby preventing visualization of the larynx in its normal position. These factors decrease its utility for the diagnosis of functional and movement disorders of the larynx. The flexible fiberoptic laryngoscope, introduced by Sawashima and Hirose in 1968, allows visualization of the larynx with the patient in a comfortable, natural position. Therefore, it is preferable to indirect laryngoscopy and the rod lens telescope for dynamic voice evaluation. This article describes a unique method of performing a comprehensive dynamic voice evaluation using flexible laryngoscopy.
Following equipment should be available for this examination:
The procedure should be explained, and the patient should be seated comfortably prior to commencing the examination. Gentle reassurance is often necessary. Anterior rhinoscopy is performed, and then a topical decongestant is applied to the more widely patent side of the nasal cavity. Several choices of topical decongestants are available (eg, phenylephrine hydrochloride [Neo-Synephrine], ephedrine, oxymetazoline, epinephrine). Following or concurrently with decongestion, topical anesthesia is applied. Once again, several choices are available, including 4% lidocaine and 2% tetracaine. The preferred practice is to wait for several minutes after the application of topical medicines to allow for maximum effect.
Nasal cavity With the patient seated upright, pass a flexible laryngoscope into the nasal cavity. Examine the nasal cavity for nasal septal deviation, polyposis, and other causes of nasal obstruction that could contribute to the voice disorder. Two areas that often allow for easy passage through the nasal cavity are found (1) along the floor and (2) between the inferior and middle turbinates. Nasopharynx After passage through the nasal cavity, visualize the nasopharynx. Examine the nasopharynx for evidence of adenoid hypertrophy or other obstructive masses. At this time, direct attention to the soft palate. First, ask the patient to produce a prolonged "EE" sound. During this sustained phonation, observe the soft palate for evidence of tremor. The differential diagnosis of such a tremor includes a variety of neurologic conditions, including Parkinson disease, essential tremor, and pseudobulbar palsy. Observe the free edge of the soft palate for adequacy of contact with the Passavant ridge along the posterior wall of the nasopharynx. A gap between them is diagnostic of velopharyngeal insufficiency (VPI). The differential diagnosis for VPI includes cleft palate (both overt and submucous), stroke, and iatrogenic injury from a previous soft palate or tonsil surgery. Subtler VPI can be diagnosed during sustained phonation based on the presence of bubbling, which results from air leakage across the velopharyngeal junction. Perform a further evaluation of velopharyngeal closure by having the patient say "Coca Cola" or "KAY KAY KAY." Once again, carefully observe the soft palate for gross velopharyngeal incompetence and bubbling of secretions. Oropharynx Upon completion of the nasopharyngeal examination, ask the patient to breathe slowly through the nose. As the soft palate pulls away from the Passavant ridge, advance the tip of the flexible laryngoscope into the oropharynx. Instruct the patient to protrude the tongue. At this point, examine the base of the tongue for evidence of tremor, weakness, or pooling of secretions. Also observe for neoplasms, retention cysts, or lingual tonsillitis. Hypopharynx Ask the patient to perform the Valsalva maneuver, which allows examination of piriform sinuses for pooling of secretions or a neoplasm. Larynx Position the tip of the laryngoscope just above the level of the epiglottis. If the glottis is not clearly visualized because of posterior displacement of the epiglottis, have the patient lean forward and protrude the chin. Often, this is helpful. Instruct the patient to breathe quietly. Observe the glottis for evidence of inappropriate adduction during inspiration or expiration, which would be consistent with paradoxical vocal fold movement disorder. Ask the patient to produce a sustained "EE" sound. Carefully examine the glottis for lesions, vocal fold mobility, and vocal fold atrophy. Common glottic lesions include nodules, cysts, papilloma, leukoplakia, and neoplasms. Common vocal cord movement abnormalities include paresis (reduced vocal fold motion), paralysis, tremor, and hyperfunctional voice disorders (eg, muscle tension dysphonia [MTD]). Atrophic vocal folds are associated with a prominence of the vocal process of the arytenoid due to a loss of the muscle bulk of the membranous portion of the vocal fold and deepening of the laryngeal ventricle. Ask the patient to phonate continuously from a low-pitch "EE" sound to a high-pitch "EE" sound. The vocal folds should lengthen symmetrically. An inability of the vocal folds to lengthen is indicative of bilateral superior laryngeal nerve paralysis. Unilateral paralysis manifests as an inability to lengthen the ipsilateral vocal cord. In patients with vocal fold paralysis, the atrophic paralyzed vocal fold may lie caudal to the healthy vocal cord. The detection of such a level of mismatch may be important in optimizing the results of vocal fold medialization. An evaluation of vocal fold paralysis should include vocal fold position, bulk, and length/tension. Perform further assessment of vocal fold mobility by requesting the patient to say "HEE - HEE - HEE" with a breath between each "HEE” sound. This produces alternating maximal adduction and abduction of the vocal folds, which allows for the detection of subtle movement abnormalities. For example, a person with recovered vocal fold paralysis may demonstrate a subtle decrease in abduction that could otherwise be missed. In situations in which a lack of vocal fold movement is observed during attempts at phonation and a functional etiology is suggested, ask the patient to cough. Alternately, the tip of the laryngoscope may be used to touch the tip of epiglottis in order to stimulate the cough reflex. Adduction of the vocal folds in this situation confirms a functional etiology. Hyperfunctional speech (eg, MTD) is accentuated through the production of "EE" and "OO" sounds. Ask the patient to repeat one (or more) of the following sentences: "We see 3 green trees," "You should use new blue shoes," or "You could need 2 new shoes if these don't fit." MTD is characterized by an inappropriate adduction of false vocal cords or the anteroposterior shortening of the larynx during connected speech production. The voice is generally rough. MTD, among the most common causes of dysphonia, is often associated with organic pathology such as benign laryngeal lesions or vocal cord atrophy. In certain cases, subtle MTD missed with the above exercises may be demonstrated by having the patient engage in normal daily speech. For example, a teacher may be asked to start a lecture or a salesperson asked to start a sales talk. This exercise is particularly useful for planning speech therapy and for evaluating progress in those patients who are already undergoing therapy. Sometimes, having the patients sing is useful. In a patient without professional voice training, singing a simple song, such as "Happy Birthday," may produce useful information regarding the ability of the patient to change pitch and may demonstrate spasms or tremors. In a patient who has professional voice training, singing under laryngoscopic visualization often elucidates findings useful for guiding voice therapy. At this point, advance the tip of the flexible laryngoscope past the tip of the epiglottis so that it lies just above the false vocal folds. Perform video stroboscopy as the patient produces a prolonged "EE" sound. Abnormalities in the mucosal wave and the vocal fold vibration may be detected. Subtle lesions also may be noted. If a subtle mucosal lesion is detected that requires further characterization, a rod lens telescope, which yields a clearer, larger view of the glottis, may be used. |
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Muscle tension dysphonia
Spasmodic dysphonia
Paradoxical vocal fold movement
Atrophic vocal cords
Unilateral vocal fold paralysis/paresis
Functional voice disorder
Essential tremor
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