INVITED REVIEW ARTICLES


https://doi.org/10.5005/jp-journals-10001-1516
International Journal of Head and Neck Surgery
Volume 12 | Issue 4 | Year 2021

Management of Vocal Fold Paralysis II: Role of Injection Medialization


Seth E Kaplan1, Sana H Siddiqui2, Joseph R Spiegel3

1Department of Otolaryngology, Zucker School of Medicine at Hofstra/Northwell; Otolaryngology–Head and Neck Surgery, Lenox Hill and Manhattan Eye, Ear & Throat Hospital, New York, USA

2,3Jefferson Voice and Swallowing Center, Otolaryngology–Head and Neck Surgery, Thomas Jefferson University Hospital, Otolaryngology (ENT); Otolaryngology-Head & Neck Surgery, Philadelphia, Pennsylvania, USA

Corresponding Author: Sana H Siddiqui, Jefferson Voice and Swallowing Center, Otolaryngology–Head and Neck Surgery, Thomas Jefferson University Hospital, Otolaryngology (ENT); Otolaryngology–Head & Neck Surgery, Philadelphia, Pennsylvania, USA

How to cite this article: Kaplan SE, Siddiqui SH, Spiegel JR. Management of Vocal Fold Paralysis II: Role of Injection Medialization. Int J Head Neck Surg 2021;12(4):161–165.

Source of support: Nil

Conflict of interest: None

INTRODUCTION

Unilateral vocal fold paralysis (UVFP) is defined as the inability for the vocal fold to function due to insult at the peripheral efferent motor nerve input.1 This is a subset of the broader condition of vocal cord immobility, which includes mechanical causes such as trauma, joint fixation, or neoplasm. The incidence of this condition is difficult to ascertain. Idiopathic VFP has been reported to affect 1.04 per 100,000 persons.2 It is a condition frequently encountered in otolaryngology practices. Patients typically present with hoarseness or aspiration. The dysphonia caused by VPF is most commonly characterized by a weak, breathy voice, often with the inability to raise vocal volume and dyspnea with voice use.3 Patients also describe a weakened ability to clear the airway and coughing or choking with oral intake, particularly liquids. Diagnosis is confirmed by laryngoscopy with or without videostroboscopy showing immobility of the affected vocal cord.

Initial presentation may require workup to rule out extrinsic causes of VFP. These can be generally defined into two groups, iatrogenic and pathologic. Iatrogenic sources of injury can include stretch, thermal damage, or transection of the recurrent laryngeal nerve. These are typically caused by surgical interventions including thyroidectomy, repair of Zenker’s diverticulum, cardiothoracic procedures, anterior cervical spine surgery, and repair of vascular anomalies.4 The effect of radiation treatments, cerebrovascular insult, and trauma are also cited as sources of injury to the recurrent laryngeal nerve.4,5 Pathologic causes include those that compress or infringe on the recurrent laryngeal nerve including; thoracic cancers of the lung and esophagus, thyroid cancer, cervical and hilar lymphadenopathy, and hypertrophic cardiomyopathy. There is some thought that idiopathic VFP may be caused by a viral infection but with limited evidence.

In cases of idiopathic UVFP, a cross-sectional contrast-enhanced imaging study such as CT or MRI surveying the course of the recurrent laryngeal nerve (from the skull base to the aortic arch) should be performed to rule out a compressive mass lesion. In one study, approximately half of patients were found to have a cause for UVFP on CT imaging.6 Ultrasound was also found to be a useful alternative to evaluate cervical pathologies. Clinical signs that may suggest a brainstem lesion such as multiple cranial nerve palsies or bilateral cord paralysis warrants magnetic resonance imaging to better characterize the brainstem and skull base.7 Electromyography may be considered in cases where the status of the nerve function is unclear, or to help in predicting spontaneous vocal fold recovery.8 In cases that present as idiopathic vocal fold paresis, radiologic workup can be deferred if the patient can be monitored for early spontaneous recovery.

Treatment

The goal of treatment is to ensure glottic competency, therefore improving voice and preventing aspiration. A consultation with speech and language pathology is useful in the perioperative setting, but also for the subset of patients without aspiration risk and who do not desire operative intervention. Surgical treatment is generally divided into medialization and reinnervation procedures.1 Medialization is achieved through injection laryngoplasty and laryngeal framework surgery (i.e., medialization thyroplasty). Reinnervation surgery utilizes adjacent nerves such as ansa cervicalis or phrenic nerve with the goal to prevent atrophy of laryngeal structures either through nerve-to-nerve or nerve-to-muscle techniques. While this technique does not restore movement, it may help retain muscle tone and bulk.

The decision for surgical intervention depends on patient symptomology, the cause of UVFP, and timing since onset. If there is a reasonable prognosis for recovery, patients may elect to wait and observe for improvement, or use injection laryngoplasty for temporary relief of symptoms. If known transection has occurred, or no improvement in symptoms is seen within 6 months, then permanent measures such as thyroplasty or reinnervation techniques may be pursued. In one study of iatrogenic VFP, approximately 89% of patients recovered vocal cord function with 31% showing return of vocal cord motion.9 Mean recovery time was similar to that of idiopathic VFP at around 6 months and recovery was seen up to over 1 year in this population. Thus, permanent procedures are often not necessary initially in a patient with new-onset UVFP where transection of the nerve has not occurred. Injection medialization procedures should be offered to reduce the risk of aspiration and improve voice while observing for recovery of cord function. Early injection medialization has also been shown to reduce the need for subsequent open phonosurgery, possibly by placing the paralyzed cord in a more favorable position during the time of synkinetic reinnervation.10

Injection Material

If vocal fold injection medialization is advised, the surgeon along with the patient must make decisions regarding the type of material to be injected and location of the procedure. Injectable material may be classified into the short and long term. Short-term materials most commonly include cellulose gel, hyaluronic acid, and collagen-based products. Long-term materials, lasting for a minimum of 1 year, include autologous fat and calcium hydroxyapatite.

Autologous fat lasts several years eliminates the concern for hypersensitivity reactions and is readily available.11 Up to two-thirds of the implanted fat can be expected to reabsorb, so many advocates for overinjection. Calcium hydroxylapatite has an average duration of 18 months and maybe present for up to 2 years. In a multicenter, prospective trial, 81% of patients reported at least a moderate improvement in voice at the 12-month mark.12 No significant short-term differences have been reported comparing the use of autologous fat to calcium hydroxyapatite injections,13 and both have been shown to comparatively yield good results after a few years.14

Hyaluronic acid (i.e., Restylane, Hylaform) typically lasts 3–9 months. One study showed a subjective decline in function at an average of 4.7 months, with some augmentation of voice seen up to 12 months.15 Another paper found the benefit of Restylane to last an average of 3 months, and notably, no hypersensitivity or granulomatous reactions were seen with a 2-year follow-up.16 As such, it is an ideal substance to use in patients who are expected to have spontaneous recovery of voice. Carboxymethylcellulose, sold as Prolaryn gel or Radiesse Voice gel, may last up to 2–3 months after injection.11 In our experience, the timeframe may be much shorter in some cases, lasting only a few weeks. Carboxymethylcellulose requires no preparation and may be utilized to trial injection medialization in patients. Collagen, either human-based (Cymetra) or bovine-based (i.e., Zyplast), will last approximately 2–4 months. There is a small potential for hypersensitivity to bovine-based collagen and the FDA recommends allergy/hypersensitivity testing prior to its use, which may delay treatment. However, it has been previously demonstrated to be safe without the apparent need for testing.17

Location

Injection medialization of the vocal folds can be accomplished in an operating room setting or awake in an office-based setting. Awake office-based procedures have been growing in popularity for the past several years.18 Injection medialization of the vocal folds is no exception. Awake office-based injections require less overall time to perform, they are less costly, and they are safe even with patients on anticoagulation therapy.19-21 Most importantly, these procedures do not require general anesthesia and the associated risks. After the procedure concludes, patients do not need recovery, and after a short-period of observation, patients are able to drive themselves home under their own volition.

Other benefits include that the person injecting may receive real-time feedback in terms of the augmentation and the patient’s voice outcome. It provides the ability to modify or further augment if need be. Awake in-office injection also avoids possible complications of suspension laryngoscopy including chipped teeth, tongue numbness, and taste disturbance. Additionally, there is no concern for leakage of the injectable from an injection site during removal of an endotracheal tube, due to the compressive nature of the cuff while extubating through the glottis.

Awake injection medialization procedures may also be indicated for patients who are too high risk to undergo general anesthesia or are considered a difficult exposure from an airway perspective. These patients include those with severe trismus from facial reconstruction or radiation therapy for example. On the contrary, some patients are poor candidates for office-based awake techniques. These include patients with a neuromotor disorder or tremor who cannot hold still long enough for an accurate awake injection, patients who despite topical anesthesia continue to have strong gag reflux preventing injection, and patients with oropharyngeal dysphagia resulting in pooling of saliva in the pharynx and decreased visualization. These factors have been shown to make procedure completion in the office less likely.22 Patients also require general anesthesia if they are unable to cooperate or follow directions due to mental status issues or young age.

In-office

In the office-based setting there are two forms of injection medialization, transoral, and transcervical. The transoral approach is used for patients with thick or obese necks making a transcervical approach more difficult, or if there is a reason not to place a needle in the neck; for example, the possibly endangering the pedicle of a flap reconstructing the pharynx.

In order to perform an awake in-office injection medialization, the patient is positioned sitting upright in an otolaryngology procedure chair in the sniffing position. Sometimes we will place a pillow between the chair and the patient’s shoulder blades to keep them sitting upright and forward. The patient is anesthetized trans-nasally using an aerosolized mixture of a decongestant and 2% lidocaine. The patient is then anesthetized transorally. The author first will have the patient swish and swallow viscous lidocaine. Next, aerosolized 4% lidocaine is used to coat the patient’s tongue, buccal mucosa, soft palate, oropharynx, pharynx, and larynx. The patient is asked to inspire during nebulization to hopefully anesthetize the glottis as well (Fig. 1). Next an assistant will perform flexible laryngoscopy with the image on a monitor placed adjacent to the patient.

Fig. 1: Material setup for transoral injection medialization. In the top half of the picture, the various forms of lidocaine and aerosolized decongestant as used for topical anesthesia are shown. The unassembled curved cannula utilized for injection is seen at the bottom right

For a transoral approach the patient is asked to extrude their tongue and the person performing the procedure will grab and stabilize it with gauze. The patient is then asked not to phonate, but rather keep their mouth open and focus on breathing via a slow pant. A curved injection cannula is placed transorally passing the tongue and soft palate until seen in the pharynx via laryngoscopy. The tip of the cannula is then placed above the glottis. At this point the patient is asked to phonate as 1–2 cc of 4% Lidocaine is dripped onto the epiglottis, aryepiglottic folds, and true vocal folds bilaterally. The cannula is then withdrawn and at this point the patient should be maximally anesthetized (Fig. 2).

Fig. 2: An assistant performs flexible laryngoscopy while the clinician administers topical anesthesia to the visualized larynx

The cannula is now loaded with the chosen injectable used for augmentation and a 28-gauge needle is attached to the tip of the cannula (Fig. 3). The curved cannula is again passed through the oral cavity. Once the needle is visualized above the glottis, the tip of the needle is advanced into the paraglottic space (lateral to the thyroarytenoid muscle) of the affected side (Fig. 4). As the injectable fills the paraglottic space, the vocal fold will slowly fill in and medialize. Generally, it is a good idea to over-inject and correct for leakage or softening over time. One must also avoid injecting Reinke's space as this can cause stiffening of the vocal fold and subsequent dysphonia. The injection needle is then removed and the cannula retracted. Typically, the author will have the patient read aloud for 5 minutes along with some vocal exercises to allow the injectable to mold into place. After 45 minutes of observation, the patient can resume a diet, and be discharged home of their own volition.

Figs 3A and B: (A) An unassembled curved cannula with a 1cc Tuberculin Syringe and 28 gauge needle. (B) An assembled curved cannula

Figs 4A and B: Injection medialization is performed. The assistant holds the laryngoscope over the larynx and the clinician stabilizes the tongue with gauze. (A) The needle is visualized over the larynx and (B) Subsequently advanced into the paraglottic space

A modification to perform a transoral approach without an assistant is possible. In this scenario, the patient holds their own tongue with the person performing the procedure holding both a rigid laryngoscope for visualization in one hand and the injection cannula in the other hand.

There are three variations of the transcervical approach. Patients are anesthetized in a manner similar to the trans-oral approach. This approach makes use of additional cutaneous injection of 1 cc 2% lidocaine with epinephrine 1:100,000 at the site wherein the filler injection needle is to be placed. All three approaches are done using tactile sensation as well as visualization via laryngoscopy.

Using the trans-cricothyroid membrane approach, a 25-gauge needle bent at 45-degrees is placed through the cricothyroid membrane and passes cephalad and laterally until it enters the paraglottic space. The transthyroid cartilage approach uses a 24-guage needle that is inserted into the skin at the level of the thyroid cartilage perpendicular to the thyroid cartilage ala. The needle is passed through the cartilage until it reaches the paraglottic space. The thyroid cartilage can be difficult to pass through if calcified in older patients. Care must be taken to not puncture the mucosa of the vocal fold if passed too deep. The trans-thyrohyoid membrane approach has a 25-gauge needle placed through the thryo-hyoid membrane at the thyroid notch and directed inferiorly until it pierces through the petiole of the epiglottis. From there the needle is directed caudally and lateral, until it advances into the paraglottic space. In each of these scenarios, the injectable fills the paraglottic space until the vocal fold medialized. Just as in the perioral approach, it is a good idea to over-inject to correct for leakage, or softening over time as well as avoid injecting into Reinkes space. Again, the author will have the patient read aloud for 5 minutes along with some vocal exercises to allow the injectable to mold into place. After 45 minutes of observation, the patient can resume a diet, and be discharged home of their own volition.

Operating Room

Injection medialization may be performed in the operating room to provide general anesthesia or conscious sedation. The operating room setting is also used when combined with other surgical procedures as well. For example, when dysphagia and aspiration are primary indications for medialization, the injection may be performed with esophagoscopy, esophageal dilatation, or feeding tube placement. The operating room can also be used to perform medialization using similar office techniques in patients that are hospitalized or in patients that require some sedation or vital sign monitoring.

Medialization injection under general anesthesia is limited by endotracheal intubation, but can be effectively performed with a small endotracheal tube in place. The simplest technique is to hold a laryngoscope and inject it directly into the body of the true vocal fold. The most accurate technique is to visualize the larynx with suspension laryngoscopy and some magnification by microscope or rigid endoscope (Fig. 5). It is best to have a video system to monitor the larynx if using a transcutaneous injection technique. Injections through the thyroid cartilage, or performed submucosally through the cricothyroid membrane are preferred as there is less likelihood of early extrusion of the implant material. As with office-based procedures, it is often recommended to over-inject to correct for leakage or softening over time and to avoid injection into Reinke's space.

Figs 5A to C: (A) Preinjection view of the glottis via suspension microdirect laryngology. (B) Injection medialization of the left vocal fold. (C) Postinjection view of the glottis

Any material that is utilized for office injection can be used in the operating room. Calcium hydroxyapatite has been shown to be more likely to be injected in the operating room setting.18 Many laryngologists prefer suspension laryngoscopy under general anesthesia when injecting calcium hydroxyapatite suspensions because of the need to place that substance exclusively in a deep plane or when injecting into a scarred vocal fold. Medialization with implants of high viscosity, especially autologous fat, is routinely performed under general anesthesia because of the need to harvest the autologous fat as well as the difficulty of transcutaneous or transoral techniques with a large needle or the need for forceful injection with a straight rigid Bruning syringe.

SUMMARY

Injection medialization is an important treatment option in the treatment of UVFP because of the natural history of both iatrogenic and idiopathic UVFP and the quality of life issues with voice loss and aspiration. The option of awake, office-based treatment for many patients improves the availability and acceptance of this procedure. Comprehensive management of UVFP should include a range of options including awake, office-based techniques, and operating room-based interventions to provide care to the entire patient population.

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