Transcervical Vocal Fold Injection (In-Office)

Vocal fold injection (VFI) is a treatment modality applicable to various laryngeal diseases and is successfully used as an alternative to laryngeal framework surgery. The indications for in-office VFI include vocal fold paralysis, paresis, atrophy, and scarring along with their sequelae.¹

This video is a detailed demonstration of office-based VFI in a patient with unilateral vocal fold paralysis (UVFP), which is the most common neurologic disorder affecting the larynx. It is secondary to damage to the recurrent laryngeal nerve, which usually results from cancer, trauma, or surgery. Although the majority of cases can be attributed to a known etiology, one-fourth of patients present without a clear precipitating event.² UVFP presents with dysphonia, dyspnea, and dysphagia. The effects on voice and swallowing can have a significant negative impact on the patient's quality of life. Among the options of voice therapy, laser treatment, surgical intervention, and office-based VFI, the latter emerges as a treatment of choice in this particular patient, offering immediate results and higher cost-effectiveness compared to the surgical approach.³ The aim of this procedure in UVFP is "medialization" of the affected cord to improve voice quality by injecting a filler material into the depth of the affected vocal fold.

Careful patient selection is pivotal when choosing office-based VFI as a treatment option. An optimal candidate has minimal gag reflex, given that a hyper-responsive gag reflex may render the visualization with a flexible endoscope—and hence the procedure in itself—impossible. Additionally, it is necessary to have a reasonable threshold for pain, a minimal level of anxiety, and an ability to remain still for a duration of up to 30 minutes. Additionally, the patient must have a clear nasal airway to pass the flexible scope. Patients with severe head tremor may pose challenges during the examination. In-office VFI is performed under local anesthesia, and if adequate anesthesia is not achieved, the patient may experience severe discomfort, anxiety, elevated sensitivity, and is unlikely to be able to tolerate a procedure performed in office settings. Informing the patient of each upcoming step during the procedure may help ameliorate some of the anxiety.⁴

In-office VFI encompasses transcervical, so-called percutaneous (trans-cricothyroid membrane, trans-thyroid cartilage, and trans-thyrohyoid membrane), trans-nasal, and per-oral endoscopic approaches. Many materials have been used for injection, such as autologous fat, cadaveric dermis, methyl-cellulose, and hyaluronic acid; however, more evidence is needed to establish the ideal material. Moreover, every substance tends to induce some level of tissue reactivity. In the case of transient injectables, this reactivity is likely to disappear with the material gone over time. The greater the thickness of the soft tissue separating the injectable from the membranous vocal fold, the lower the likelihood of adverse effects on vocal fold vibration caused by either the injectable itself or the ensuing inflammatory response.¹ In this clinical case, micronized particulate cadaveric human acellular dermis (Cymetra) was selected as the filler material.

The patient's preparation begins with the application of local anesthesia: tetracaine 2% spray is used to desensitize the nasal cavities. Subsequently, the patient is instructed to refrain from speaking, swallowing, and coughing, unless requested. The thyroid cartilage is palpated in the middle and traced downward until a dip and a firm ring of tissue are felt. These are the cricoid groove and the cricoid cartilage, respectively. The cricothyroid membrane is located immediately above the groove of the cricoid. With the patient in a sitting position and head straight, lidocaine solution is injected through the cricothyroid membrane, and verification of correct tracheal placement is ensured by aspirating air. The injection is made from a higher level, which allows the lidocaine to pass through the vocal folds and descend along the anatomical structures, enveloping the larynx. Before the injection, the patient is prepared for the experience, being informed that they may feel a pinch, followed by a brief period of coughing.

While waiting for the lidocaine to take effect, the practitioner takes the opportunity to prepare and ensure that all elements are ready for the subsequent steps. The compatibility of the 1.5-inch long 23-gauge needle with the Cymetra substance is confirmed. Normal saline is mixed with Cymetra in the syringe, which is manipulated back and forth to ensure an even and clump-free mixture. The final step involves removing air from the syringe by moving it back and forth, allowing air to re-enter, and eventually expelling all air.¹

Next, a flexible laryngoscope is positioned in the left nostril. Given that the right side of the larynx is being addressed, the left nostril is chosen to provide an optimal view. In the trans-cricothyroid membrane approach, the slightly angled 23-gauge needle is inserted just below the lower edge of the thyroid cartilage, about 3–7 mm to the right of the midline. The needle is then moved upwards and sideways with gentle pressure. This motion helps ensure the needle is beneath the surface layer, preventing any accidental puncture of the mucosa. The patient is guided through vocalizations such as "Eee" with additional instructions to swallow, as the initial condition of the vocal folds are evaluated on the display. Next, the filler is injected, seen as an increase in the thickness of the fold on the monitor. The patient is then prompted once again to voice "Eee," illustrating the effect of the injection on vocal cord function. In case the injected material is distributed unevenly, resulting in an irregular vocal fold contour, the patient may be instructed to clear their throat or produce a sharp cough to help attain a more uniform distribution.

It is important not to overcorrect the paralyzed vocal fold and to avoid subglottic disposition of the filler material. The infiltration of the filler material should be stopped as soon as the vocal fold is at midline. The subglottic region should be inspected with the laryngoscope to avoid subglottic disposition. Moreover, in order to avoid extravasation of the filler material it is advised to insert the needle in “stair step” fashion: entering mucosa; moving the needle 1–2 mm lateral; pushing the needle in 1–3 mm further.⁶

Following the procedure, due to the effects of the anesthetic used during the intervention, the patient is advised to refrain from eating or drinking for two hours until full sensation returns to the larynx. However, the patient is allowed to talk after the procedure. The patient is monitored for a period of 15–30 minutes to ensure effective control of bleeding and absence of dyspnea.⁶

The use of VFI in awake patients without sedation has become increasingly popular, presenting a notable trend in recent years. VFI is recognized as a safe, effective, and clinically feasible treatment with a high success rate. This video serves as an invaluable resource for medical practitioners, highlighting the growing utilization of VFI. Medialization of the paralyzed vocal fold not only enhances vocal quality by restoring glottal competence but also contributes to improved swallowing function.⁵ The negligible complication rates associated with this procedure make it a compelling choice, comparable to surgery requiring general anesthesia. Notably, recent advancements in material engineering and digital imaging technology have elevated this method as an attractive alternative to traditional laryngeal framework surgery in carefully selected patients.¹

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.