Description/Background 
The recurrent laryngeal nerves of the vagus nerves are the primary innervators of the abductors and adductors of the vocal folds. Isolated injury of the recurrent laryngeal nerve results in paralysis of the vocal cord in the para-median position on one side, 2 to 3 mm lateral to the laryngeal midline. Combined injury of the recurrent and superior laryngeal nerves paralyzes the vocal cord in the intermediate position, several millimeters lateral to the para-median position.

Vocal cord paralysis may be unilateral or bilateral, central or peripheral.  Unilateral left vocal cord paralysis is most common. Less than 20% of cases are bilateral. Thyroidectomy is by far the most common cause of bilateral vocal cord paralysis. Central causes include brain stem and supranuclear lesions and account for only 5% of all cases. Supranuclear or cortical causes of vocal cord paralysis are exceedingly rare, owing to the bilateral crossed neural innervation to the brain stem medullary centers in the nucleus ambiguus. The most frequent central cause is vascular insufficiency or a stroke affecting the brain stem. Congenital central lesions are usually secondary to Arnold-Chiari malformation or brain stem dysgenesis and are often associated with additional cranial neuropathies.

Most cases of peripheral vocal cord paralysis are secondary to thyroidectomy or non-laryngeal neoplasms, including bronchogenic, esophageal and thyroid carcinoma. Other less common lesions causing paralysis of the vocal cord include tumors of the deep lobe of the parotid gland, carotid body tumors, glomus jugulare and vagale tumors and neurogenic neoplasms of the tenth nerve and jugular foramen. External penetrating wounds to the neck or prolonged endotracheal intubation may also traumatize the recurrent laryngeal nerve, producing vocal cord paralysis. Finally, toxic neuropathy and idiopathic causes account for a few cases.

In adults, unilateral recurrent laryngeal nerve paralysis generally produces hoarseness and a weak, breathy voice with varying amounts of aspiration. The normal vocal cord may cross the midline to approximate the paralyzed vocal cord in the para-median position. In children, varying degrees of inspiratory stridor may also be present. Bilateral vocal cord paralysis is commonly associated with inspiratory stridor, shortness of breath and dyspnea on exertion.

Policy
Injections of bulking agents is considered MEDICALLY NECESSARY for members with unilateral vocal cord paralysis using agents that are cleared by the U.S. Food and Drug Administration for this indication. This procedure has been shown to improve vocal quality and prevent recurrent aspiration pneumonia in individuals with unilateral vocal cord paralysis.

Injections of bulking agents into the vocal cords is considered investigational and /or unproven and therefore considered NOT MEDICALLY NECESSARY for all other indications because their effectiveness for indications other than the one listed above has not been established.

Rationale
Management of unilateral vocal cord paralysis due to lesions of the recurrent laryngeal nerve includes the injection of Teflon paste or Gelfoam under local anesthesia into the paralyzed vocal cord, mobilizing it medially. Medialization is valuable in the therapy of aspiration and results in dramatic improvement in voice quality. Other injection options for glottic insufficiency include bovine collagen, calcium hydroxylapatite, injectable fat and Gelfoam. An assessment by the National Institute for Clinical Excellence (NICE, 2005) concluded that there are no major safety concerns regarding collagen injections for vocal cord augmentation and that they provide short-term symptom relief. However, evidence on long-term efficacy is lacking. Belafsky and Postma (2004) stated that initial experience with vocal fold augmentation using calcium hydroxylapatite is promising. However, its long-term safety and effectiveness needs to be established. Medialization of the paralyzed cord may also be accomplished externally via a thyroidotomy and placement of a Silastic wedge implant inside the thyroid cartilage in a small pocket deep to the paralyzed vocal cord.

Lee and colleagues (2010) investigated the effectiveness of IL in the management of post-thyroidectomy vocal cord paralysis (VCP). From March 2005 to December 2008, a total of 174 consecutive injection laryngoplasties were performed in patients with unilateral glottic insufficiency. This included 34 patients with post-thyroidectomy VCP: 15 with temporary VCP and 19 with permanent VCP. Percutaneous injection was performed under local anesthesia into the vocalis muscle, using disposable 25G-long needles through the cricothyroid membrane or directly through the thyroid cartilage. Patients completed the acoustic, aerodynamic, perceptual, stroboscopic and voice handicap index evaluations before and at 3 and 6 months after the injection. All IL could be performed under local anesthesia without morbidity. Acoustic and perceptual parameters (overall grade of hoarseness, roughness, breathiness, asthenia and strain), maximum phonation time, jitter, and shimmer, voice handicap index and grades of mucosal waves and glottic closure were significantly improved after the injection and they remained stable over 6 months in both the temporary VCP and permanent groups (p < 0.05). The authors concluded that based on these results, IL improved the voice and voice-related quality of life in patients with post-thyroidectomy VCP. It is a simple, safe and useful method for rehabilitating post-thyroidectomy VCP patients.

Lau et al. (2010) (i) determined the correlation between voice handicap index and quantitative videostroboscopy for patients undergoing IL for UVFP; and (ii) evaluated which videostroboscopy measurements correlate best with voice handicap index in patients demonstrating progressive improvement beyond 6 months following IL. Patients underwent outpatient injection laryngoplasty with hyaluronic acid between 2005 and 2007. A total of 28 patients were assessed pre-operatively and post-operatively using voice handicap index and videostroboscopy. Various videostroboscopy measurements were quantified: glottic open area (ratio of open to total glottic area during closed phase of phonation), glottic closed phase (frame ratio of closed phase to total glottic cycle), supraglottic compression (percent encroachment of supraglottis onto best-fit ellipse around glottis), wave amplitude (difference in glottic open area between open and closed phases) and wave duration (number of frames per glottic cycle). Correlation coefficients were calculated using Spearman's r. A total of 117 separate recordings were analyzed. Correlation coefficients between voice handicap index (normalized to preoperative values) and glottic closed phase showed moderate-strong correlation (r = -0.733, p < 0.001), while glottic open area and wave duration showed weak-moderate correlation (r = 0.465, p < 0.001 and r = -0.404, p < 0.001 respectively). Other parameters showed poor correlation.  A subset of 25 recordings from 8 patients with progressive voice handicap index improvement beyond 6 months showed highest correlation with supraglottic compression (r = 0.504, p < 0.05). The authors concluded that voice handicap index correlates best with glottic closed phase, suggesting duration of vocal fold closure during the glottic cycle best represents patients' subjective outcome post-procedure. Progressive improvement in voice handicap index beyond 6 months may relate to gradual reduction in compensatory supraglottic compression, with moderate correlation.

Furthermore, an UpToDate review on “Hoarseness in adults” (Bruch and Kamani, 2015) states that “Unilateral paralysis — Surgical procedures are available for unilateral fold paralysis to reposition (medialize) the immobile vocal fold in order to achieve adequate glottal closure and improve voice, as well as swallowing and cough. Techniques include transoral or transcervical injection (injection laryngoplasty) of permanent or resorbable material, such as autologous fat, collagen, hyaluronic acid or hydroxylapatite, lateral to the vocal fold. Medialization thyroplasty involves transcervical placement of an implant (usually silicone or Gortex) through a surgically created window in the thyroid cartilage.”

In a multi-institutional retrospective review, Sulica et al. (2010) identified contemporary indications, treatment principles, technique, injection materials, complications and success rates of vocal fold injection augmentation. Records of patients undergoing injection augmentation at 7 university medical centers from July 2007 through June 2008 were reviewed for information regarding diagnosis, unilateral or bilateral injection, route of injection, anesthesia, treatment site (office or operating room), material used, reason for technique selected and technical success. In 12 months, 460 injections were performed, 236 (51%) in awake, unsedated patients, and 224 (49%) under general anesthesia.  Indications included vocal fold paralysis (248; 54%), paresis (97; 21%), atrophy (68; 15%) and scar (47; 10%). Scar was more likely to be treated in the operating room (p = 0.000052).  In awake patients, 112 (47%) injections were performed by transcricothyroid approach, 55 (23%) by peroral approach, 49 (21%) by trans-thyrohyoid membrane approach and 20 (8%) by trans-thyroid cartilage approach. Neither technical success rate (99% versus 97%) nor complication rate (3% versus 2%) differed between awake and asleep techniques. The most common materials in the clinic setting were methylcellulose (35%), bovine collagen (28%) and CaHA (26%); in the operating room, these were CaHA (36%) and methylcellulose (35%). Calcium hydroxylapatite was more likely to be used under general anesthesia (p = 0.019). Five-year data show that the use of injection in the awake patient rose from 11% to 43% from 2003 to 2008. The authors concluded that injection augmentation remains a safe, effective and clinically practical treatment with a high rate of success, whether performed in the awake or asleep patient. The rapid adoption of awake injection over the past 5 years speaks to its clinical utility. Complication rates are low and equivalent to those under general anesthesia.

In a Cochrane review, Lakhani et al. (2012) evaluated the effectiveness of alternative injection materials in the treatment of UVFP. These investigators searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register; the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; EMBASE; CINAHL; Web of Science; BIOSIS Previews; Cambridge Scientific Abstracts; ICTRP; and additional sources for published and unpublished trials. The date of the most recent search was March 23, 2012. Randomized controlled trials (RCTs) of injectable materials in patients with UVFP were selected for analysis. The outcomes of interest were patient and clinician-reported improvement, and adverse events. Two authors independently selected studies from the search results and extracted data. They used the Cochrane "Risk of bias" tool to assess study quality. These researchers identified no RCTs that met the inclusion criteria for this review. They excluded 18 studies on methodological grounds: 16 non-randomized studies; 1 RCT due to inadequate randomization and inclusion of non-UVFP patients; and 1 RCT that compared 2 different particle sizes of the same injectable material. The authors concluded that there is currently insufficient high-quality evidence for or against specific injectable materials for patients with UVFP. They stated that future RCTs should aim to provide a direct comparison of the alternative materials currently available for injection medialization.

The consensus report on “Vocal fold scars” by the Phonosurgery Committee of the European Laryngological Society (Friedrich et al., 2013) stated that scarring of the vocal folds leads to a deterioration of the highly complex micro-structure with consecutively impaired vibratory pattern and glottic insufficiency. The resulting dysphonia is predominantly characterized by a reduced vocal capacity. Despite the considerable progress in understanding of the underlying pathophysiology, the treatment of scarred vocal folds is still an unresolved chapter in laryngology and phonosurgery. Essential for a successful treatment is an individual, multi-dimensional concept that comprises the whole armamentarium of surgical and non-surgical (e.g., voice therapy) modalities. An ideal approach would be to soften the scar, because the reduced pliability and, consequently, the increased vibratory rigidity impede the easiness of vibration. The chosen phonosurgical method is determined by the main clinical feature: Medialization techniques for the treatment of glottic gap, or epithelium-freeing techniques for improvement of vibration characteristics often combined with injection augmentation or implantation. In severe cases, buccal mucosa grafting can be an option. New developments include treatment with anxiolytic lasers (e.g., pulse dye laser [PDL]; potassium titanyl phosphate [KTP] laser), laser technology with ultrafine excision/ablation properties avoiding coagulation (Picosecond infrared laser, PIRL) or techniques of tissue engineering. However, the authors concluded that despite the promising results by in-vitro experiments, animal studies and first clinical trials, the step into clinical routine application has yet to be taken.

References

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10. Sagawa M, Sato M, Fujimura S, et al. Vocal fold injection of collagen for unilateral vocal fold paralysis caused by chest diseases. J Cardiovasc Surg. 1999;40(4):603-605.
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20. Sclafani AP, Romo T 3rd, Jacono AA, et al. Evaluation of acellular dermal graft in sheet (AlloDerm) and injectable (micronized AlloDerm) forms for soft tissue augmentation. Clinical observations and histological analysis. Arch Facial Plast Surg. 2000;2(2):130-136.
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Coding Section

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.

This medical policy was developed through consideration of peer-reviewed medical literature generally recognized by the relevant medical community, U.S. FDA approval status, nationally accepted standards of medical practice and accepted standards of medical practice in this community,  and other nonaffiliated technology evaluation centers, reference to federal regulations, other plan medical policies and accredited national guidelines.

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