Vocal fold augmentation is a well-established, effective treatment option in the management of various voice disorders and laryngeal symptoms due to underlying glottic insufficiency (GI). The treatment of GI can be accomplished either through vocal fold injection augmentation (VFIA, also known as injection laryngoplasty) or laryngeal framework techniques (medialization laryngoplasty, arytenoid adduction, and cricothyroid subluxation). There are no hard and fast indications for choosing either of these surgical approaches over another in the treatment of GI. The appeal of VFIA is its ability to be performed in the outpatient office setting. The factors underlying the shift in practice to more office-based TVF augmentation procedures include improved “off-the-shelf” injectables with both short and long-term augmentation benefit, established safety profiles, more options for material delivery, and novel injectable agents with anticipated permanent effect ^, in the setting of ever more valuable operating room time. This chapter will provide an overview of VFIA, with a dedicated focus on surgical techniques in the outpatient setting.

GI results from the unintended loss of expired air from the glottis during phonation and can be caused by a variety of vocal pathologies. It can manifest with a weak and breathy vocal quality accompanied by dyspnea with speaking, especially when the air loss is significant, as is seen in TVF paralysis. However, GI can be more subtle, and symptoms of vocal fatigue, strain, and increased vocal effort can also predominate. Other nonspecific laryngeal symptoms that present without voice or swallowing complaints have also been described as indications for vocal fold augmentation when GI is present. These include chronic cough, globus pharyngeus, throat discomfort, throat clearing, and a sensation of phlegm in the throat. ^,

Traditionally, VFIA with a temporary substance to augment the vocal folds and reestablish glottic competence has been advocated when the prognosis for recovery is unclear. This most commonly applies to cases of acute UVFP and symptomatic paresis. Temporary augmentation allows for transient rehabilitation of voice, improved cough strength, and reduction of aspiration risk while time is allowed for spontaneous vocal fold motion recovery. Repeat injection can be performed if the clinical effect of the injectable is lost before the recommended time point of considering a more permanent or durable intervention. Short-acting VFIA materials, typically carboxymethylcellulose or hyaluronic acid, can also be employed as a diagnostic tool. Diagnostic (also known as “trial” VFIA) involves the injection of a temporary material into the deep vocal fold when anticipated outcomes are unclear. Unclear outcomes may be due to primary pathology (e.g., vocal fold paresis, scar, atrophy), concomitant pathologies (i.e., dysarthria or velopharyngeal insufficiency), or unrealistic patient expectations. Diagnostic VFIA provides an opportunity for both the patient and provider to assess the effects of medialization on specific voice-related measures (e.g., quality, effort, and volume) and other laryngeal symptoms (e.g., cough, dysphagia, throat clearing). Permanent causes of GI can also be effectively managed with vocal fold augmentation procedures. Augmentation procedures intended to give a lasting result include type I thyroplasty (medialization thyroplasty) and VFIA with more durable injectable substances. Currently, more durable “off-the-shelf” injectable materials with established safety profiles include calcium hydroxyapatite, polydimethylsiloxane (not available in the United States), and silk-hyaluronic acid. Table 41.1 summarizes the available injectable products, availability in the US, and anticipated duration of action.

Because VFIA materials have become more durable, the risk of inappropriate superficial injection into the lamina propria has become important for the surgeon to be aware of. While no VFIA is without risk of this possibility, the most common and unfortunate outcome remains superficial injection of a material that causes significant stiffness of vibration and is not quick to resorb. ^, Overaugmentation, underaugmentation, and overly anterior injection are also problematic for reasons of the need for further procedures and initial poor outcomes. Additionally, inflammatory reactions have been reported in patients having undergone VFIA with calcium hydroxylapatite, hyaluronic acid, and silk-hyaluronic acid. ^, Patient counseling should reflect this small but real possibility, as it can have serious implications for impairment of laryngeal function.

VFIA is performed in the deep (or lateral) aspect of the vocal folds. The material is injected within the thyroarytenoid/lateral cricoarytenoid muscle complex or the paraglottic space to provide global augmentation and medialization of the overlying vocal fold layers. The desired result parallels that of medialization laryngoplasty (aka Type I thyroplasty). This technique can be used for all types of vocal fold pathology resulting in GI; it is typically used to treat cases of mild-moderate GI with a transglottal, elliptical, or short but complete phase closure pattern—all typically accompanied by secondary, compensatory muscle tension dysphonia.

In the operating room, VFIA is often performed via direct laryngoscopy with microscopic or telescopic assistance. VFIA performed in the awake or sedated state typically utilizes an assistant performing simultaneous indirect laryngoscopy to afford accuracy of material placement via one of three primary routes of injection by the surgeon: per-oral, transnasal, and percutaneous. The percutaneous approaches are further categorized into transthyrohyoid, transcricothyroid, and trans-thyroid cartilage. Ultimately, the technique chosen is based on surgeon preference but considers patient anatomy, patient tolerance, material being injected, and where the procedure will take place (operating room, endoscopy/procedure suite, office, or bedside).

Injection augmentation via direct laryngoscopy under general anesthesia affords the surgeon a magnified, detailed view of the vocal folds and also allows for direct examination and palpation to confirm suspected pathology. However, the surgeon must make an educated estimate of the amount of augmentation needed without a defined endpoint, given that the patient is asleep and that overaugmentation is required for most injectables.

With the patient supine, general anesthesia is induced, followed by muscle relaxation and intubation with a small endotracheal tube (typically 5-0 or 5-5). Other methods to oxygenate are available but beyond the scope of this chapter (i.e., jet ventilation and high flow nasal cannula). A rigid laryngoscope is placed with the distal end just proximal to the true vocal folds, lateralizing the false vocal folds, and the laryngoscope is then placed into suspension to afford the surgeon freedom of both hands. Telescopes are also useful for cases under direct laryngoscopy where exposure of the glottis is challenging and a line of sight through the laryngoscope is unachievable. Depending on the material being injected, either a malleable, disposable needle or a reusable injection device is employed. The traditionally recommended needle insertion site is located lateral to the vocal process along the superior arcuate line ( Fig. 41.1 ), approximately 3–5 mm deep to the mucosa. Optimal needle placement can be appreciated when the initial delivered injectable provides augmentation at the level of the infraglottic vocal fold ( Fig. 41.1 ). Augmentation is performed gradually, concurrently assessing the degree of global augmentation, ensuring no focal enlargement or superficial “blebs” of injection occur, and injecting until the medial edge of the vocal fold appears medialized and oftentimes overaugmented by approximately 20%, depending on the material being used. If inadequate anterior medialization is occurring while using the first injection site, the needle can be repositioned to a second, separate injection site along the superior arcuate line in the more anterior region of the mid-membranous vocal fold. Multiple pokes with the needle are not usually needed or recommended to prevent extrusion.

Deep vocal fold augmentation locations via suspension microlaryngoscopy.

(A) Planned injection locations along the left vocal fold arcuate line. Injection is initially planned just anterior and lateral to the vocal process. An additional injection site more anteriorly at the midmembranous portion of the vocal fold can be performed if there is inadequate augmentation/medialization of this portion of the vocal fold with the initial injection site.

(B) Note the infraglottic bulge that can be visualized, representing appropriate depth and desired augmentation appearance.

(C) Planned injection locations into the left vocal fold in an elderly patient with left vocal fold paralysis and bilateral atrophy. Note the prominent ventricles upon exposure with the laryngoscope, with care to inject into the true vocal fold and not too laterally within the ventricle.

(D) View of augmented left true vocal fold using Silk-hyaluronic acid.

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