Iatrogenic Vocal Fold Scar 

Updated: Feb 20, 2020
Author: John Schweinfurth, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Background

Dysphonia associated with vocal fold scar is one of the most challenging voice disorders to both patients and clinicians. The best treatment of vocal fold scar is prevention. In no medical procedure is the phrase primum non nocere ("first do no harm") more applicable than in surgery of the larynx. Certainly, improperly performed or timed surgical intervention can result in irreversible dysfunction and dysphonia. Benign vocal lesions should be approached conservatively whenever possible; surgery should be reserved for unresolving lesions that result in dysphonia. This requires precise and conservative phonomicrosurgery with proper postoperative voice care. New techniques to prevent or reduce scarring are becoming more widespread; nevertheless, vocal fold scarring following surgery is not uncommon.[1]

This article focuses on surgical and nonsurgical treatment of vocal fold scars. No proven treatment currently exists for every case of vocal fold scarring. Conservative treatment therefore should be exhausted before considering surgical intervention, which then should be based on the modern concepts of the vocal fold microanatomy and histology of the vocal fold physiology.

The image below depicts vocal fold scarring.

This patient underwent right mucosal stripping for This patient underwent right mucosal stripping for nodules. Note the thickened and irregular right cord. On videostroboscopy, the cord was immobile.

Problem

Iatrogenic injury to vocal cords typically consists of scarring, fibrosis, webbing, or sulcus formation. The term sulcus vocalis is used to describe a depression or groove in the surface of the vocal fold mucosa that typically is found on the leading edge of the vibratory surface. Along the sulcus, the mucosal cover is scarred down to the underlying vocal ligament and therefore is tethered with limited mobility.[2]

Epidemiology

Frequency

Iatrogenic injury is likely underreported, and its true incidence is difficult to estimate. The incidence of sulcus vocalis is impossible to determine because of the variation in presentation, etiology, and diagnosis.[3] Most cases of sulcus are undiagnosed because of subclinical symptoms, lack of awareness, and difficulty in identification because of the relative rarity of videostroboscopy.

Etiology

Surgical causes include an overresection of the superficial layer of the lamina propria, which results in remucosalization over the deficient area and damage to the vocal ligament and deep layers of the lamina propria. Surgical incisions or abrasions on both true vocal folds can lead to webbing and scarring between the vocal cords. In particular, damage to the anterior commissure may result in scarring and web formation, especially if surgery is performed on the anterior portion of both true cords. With respect to surgical incisions, the depth of injury and the damage to surrounding tissues are the most important predictors of scar formation. Surgical dissection or laser ablation into the zone of the vocal ligament can result in significant fibrosis and scar formation. Injudicious use of the laser may result in vaporization of the mucosa or thermal injury with a zone of damage extending through the mucosa into the vocal ligament or vocalis muscle and surrounding tissue.

Pathophysiology

A defect in the medial surface of the true vocal fold along the sulcus may produce a glottic gap. More importantly, the vocal cover fibroses to the vocal ligament and the resulting mucosal wave may be significantly diminished or absent. This decreased pliability restricts the Bernoulli and myoelastic effects whereby transglottic airflow medializes the leading edge of the vocal fold. The overall effect is a higher fundamental frequency with significantly reduced harmonics and a harsher voice quality. At the extremes of scarring, glottic closure is impaired, which may lead to a very weak breathy voice and possibly aspiration of liquids.

Presentation

Patients may have had past vocal cord mucosal stripping or laser surgery. Typically, the patient has a history of surgery for nodules and developed hoarseness postoperatively that never improved. Patients complain of hoarseness and may complain of dysphonia or a higher-pitched, thin voice. Patients often have symptoms of glottal insufficiency, including vocal fatigue, breathiness, and poor volume and projection. The voice may be thin and exhibit a higher fundamental frequency. Patients also may revert to use of the false vocal folds, which results in a strained, low-pitched, dysphonic voice. If vocal fold scarring is severe, patients may complain of shortness of breath caused by excessive loss of air with phonation. In severe cases of glottic insufficiency, patients may experience aspiration of thin liquids or dysphagia.

Examination of the glottis may reveal an anterior web and/or an irregular, fibrotic, and sometimes atrophic vocal fold with mucosal hypertrophy. Videostroboscopy reveals a decreased or absent mucosal wave, and often the medial edge of the injured cord does not approximate the other during phonation. In addition, the cords may be at different levels, leading to incomplete closure. In sulcus vocalis, examination of the true vocal fold reveals a linear depression or an area of incomplete closure. Videostroboscopy reveals an area of decreased mucosal wave corresponding to the sulcus and may demonstrate associated incomplete closure.

Indications

Indications for surgical intervention include impaired function secondary to troublesome dysphonia, severe breathiness with vocal fatigue, aspiration, and uncertainty as to the diagnosis.

Relevant Anatomy

Awareness of the body-cover principle of vocal fold vibration is essential to the understanding of vocal fold scarring. The vocal fold is composed of a muscle covered by a free mucosal edge that vibrates and can be separated into discrete layers. Each layer has distinct mechanical properties and can be differentiated by the concentration of elastin and collagen fibers that run parallel to the leading edge. The delicate arrangement of the extracellular matrix proteins within the lamina propria permits passive movement of the vocal cover over the body, resulting in the formation of the mucosal wave as air is passed through the glottis as a release of building subglottic pressure.

Fibroblasts are found in high concentrations in the deep layers of the lamina propria and in the vicinity of the vocal ligament. Violation of these layers stimulates fibroblastic activity, which promotes scar and sulcus formation.

 

Workup

Other Tests

Videostroboscopy

See the list below:

  • Videostroboscopy reveals a decreased or absent mucosal wave, and often the medial edge of the injured cord does not approximate to the other during phonation. In addition, the cords may be at different levels, leading to incomplete closure.[4, 5]

  • In sulcus vocalis, videostroboscopy reveals an area of decreased mucosal wave corresponding to the sulcus and more clearly shows associated incomplete closure.

Histologic Findings

Obtaining pathology slides from the original surgery may be helpful. The size of the resected specimen and the presence of muscle or dense collagen and elastin fibers indicate a deep dissection, which is more likely to involve scar formation.

 

Treatment

Medical Therapy

An anatomic change in the vocal fold, such as scarring and sulcus vocalis, is difficult to treat medically. The use of oral corticosteroids (not inhaled) at any point within 1 year of the original injury may reduce or arrest any ongoing fibrosis. Evaluate and treat any intercurrent medical conditions affecting the voice (eg, reflux laryngitis, allergic rhinitis). All known sources of mechanical trauma are maximally reduced before considering surgical therapy to ensure the best possible postoperative result. This is accomplished in part by medical and speech therapy directed at reducing vocal trauma through improved technique and vocal hygiene. Some improvement in fluency and volume can be expected with speech therapy directed at voice building; however, vocal range is unlikely to recover significantly (see the Medscape Reference article Voice Therapy).

Surgical Therapy

Surgical treatment of scarring is directed at (1) medialization of the affected cord through bulking or framework surgery and/or (2) attempting to restore the sliding motion of the affected mucosal cover over the underlying vocalis muscle.

Vocal fold augmentation can be performed via lipoinjection of the vocal folds or by type I thyroplasty (medialization laryngoplasty). These procedures are reliable in medializing the vocal folds, and when used for vocal fold scar, they often result in reduced glottal incompetence during phonation. The clinical results that the patient experiences are reduced effort for phonation and increased volume to the voice. However, voice quality is not improved because the scar has not been directly addressed.[6, 7]

The vocal cord may also be approached through a minithyrotomy.[8] Fat may be implanted submucosally through a small window through the anterior thyroid cartilage without incising the epithelium.[9] Paniello (2008) reported good results with improved pliability and glottal closure in the majority of patients.[10]

Medialization laryngoplasty may be effective in patients in whom arytenoid mobility is good but the cord is thin, lateralized, fibrotic, and adynamic. Benninger et al recommend medialization for glottic gaps of at least 1.5 mm.[11] This procedure may be combined with lipoinjection in an attempt to reestablish the mucosal wave.

The second approach to vocal fold scar is to alter or reconstruct the lamina propria. Current opinion holds that a biocompatible material placed between the vocal ligament and cover, ie, within the layers of the lamina propria, potentially could make up for lost tissue and restore the sliding movement of the mucosal cover. If a thick scar band is associated with a sulcus, removing the scar band through a microflap approach is sometimes useful, although this step may further thin the cord.

The ideal implant material would assume the function of the intermediate layer of the lamina propria, which is composed of elastin, hyaluronic acid, and fibromodulin. It would be placed so that it augments the infraglottis and the free edge of the vocal fold. Therefore, the ideal implant would have a low viscosity, low resorption, and would be injectable.

If the goal of implantation is to reproduce normal lamina propria, then fat is the closest material available in viscosity (4 Pa/s), whereas the commercially available bovine collagen is much higher (10 Pa/s). Autologous fat is probably the best augmentation material currently in widespread use. Allogenic human collagen and other biologic materials (fascia) also are presently being investigated for this purpose.

Injectable hyaluronic acid may also have an application in the treatment of patients with sulcus vocalis. Because hyaluronic acid makes up the gel-like space of the superficial lamina propria, replacing it has long been considered the holy grail of therapy for vocal scarring. Although the usefulness of hyaluronic acid is unknown, early reports suggest that maintaining sufficient volume of material in the desired location is problematic. Studies into the use of this material are ongoing.

Preoperative Details

Patients presenting with dysphonia caused by vocal fold scar are evaluated by indirect laryngoscopy and videostroboscopy, with particular attention paid to vocal fold mobility, glottic closure, and the presence, amplitude, and symmetry of the mucosal wave. Any medical conditions affecting the voice (eg, reflux laryngitis, allergic rhinitis) are evaluated and treated. All known sources of mechanical trauma are maximally reduced before considering surgery. This is accomplished in part by medical and speech therapy directed at reducing vocal trauma through improved technique and vocal hygiene. Surgical candidates must be willing to postpone speaking and singing engagements for at least 2-3 months postoperatively.

Intraoperative Details

After adequate exposure of the larynx is obtained, the microscope is brought into position. Obvious scar tissue and bands of fibrosis should be removed in an atraumatic fashion whenever possible, preferably through a microflap approach. Often, once the vocal folds are exposed via high-power magnification, hydrodissection is performed to assess the severity and extent of the vocal fold scar. This assists in the decision-making process. If the area of vocal fold scar is so severe that hydrodissection is impossible or very difficult, then collagen injection will not be successful and the treatment options are vocal fold augmentation or fat graft reconstruction.

For vocal fold augmentation of the scarred vocal fold(s) with lipoinjection, endoscopic injection is the most convenient method of implant delivery. Some use the current technique of harvesting fat via a large 8-mm liposuction cannula and injecting it into the thyroarytenoid muscle. Anecdotal reports support rinsing the harvested fat in insulin to support adipocyte cell membrane stabilization. A moderate decrease in volume in the early postoperative period should be expected; therefore, the vocal fold should be overcorrected at surgery by approximately 30%. The augmentation gains found 1 month postsurgery are typically stable and permanent.

Fat graft reconstruction is a surgery designed to reconstruct the damaged lamina propria by implanting small pieces of fat into the vocal fold between the mucosa and the vocal ligament. This technique requires elevation of the mucosa off the vocal ligament in the region of the scar via either a lateral cordotomy or microflap in the area of the vocal fold. If the latter approach is used, then after the implantation of the fat, the microflap is laid back into position with a suture to secure the fat grafts into place during the postoperative period. When the fat grafts are placed into the pocket via a lateral cordotomy and tunnel approach, a suture typically is not required. The fat grafts can be harvested from several locations, including ear lobule, axilla, or abdomen. This is a new procedure that requires great technical ability and has not yet gained widespread acceptance.

Postoperative Details

The patient is placed on strict voice rest for 2 weeks after microflap surgery and for 1 week after injection. Patients with more extensive dissections may be placed on a short course of oral corticosteroids. All patients receive antibiotics for 7 days and a mild narcotic for pain relief. Patients with symptoms or findings of laryngopharyngeal reflux are medically treated with a proton pump–inhibiting agent.

Follow-up

Patients are reexamined at 2, 4, 8, and 12 weeks postoperatively. At the 2-week postoperative visit, videostroboscopy is performed and the patient resumes therapy with the speech pathologist. Return to voice use over the first few weeks is gradual, increasing by 5-minute intervals twice daily. Singers may begin to work with the vocal pedagogue at 1 month but are cautioned to decrease work if they feel any discomfort or if singing feels effortful. Most patients can expect to be 90% recovered from the effects of surgery at 3 months.

Complications

Surgical complications are related to the laryngoscopy, vocal cord incision, or implantation of material for medialization. Complications of laryngoscopy include damage to or avulsion of teeth, oral mucosal laceration, and pressure damage to the tongue (eg, numbness, altered taste). Foreign body placement can result in infection, inflammation, and extrusion. This may result in further scar formation. An implant that impinges on the vocal process of the arytenoid may lead to arytenoid immobility and fibrosis of the cricoarytenoid joint. Overmedialization of the vocal cord may affect airway patency resulting in a strained vocal quality, shortness of breath, and dyspnea on exertion. Any incision into the vocal fold can result in further scar formation with recurrence of the sulcus.

Outcome and Prognosis

Studies by Ford et al and Pontes and Behlau used microsurgical techniques on 30 patients with pathologic sulcus.[12, 13] Both studies, based on objective measures, reported voice improvement in most patients. Sataloff et al described voice improvement and limited return of mucosal wave using fat implantation methods.[14]  Most patients can expect significant voice improvement from either technique, but improvement is not equal to premorbid conditions in most individuals. In addition, insufficient data are available on the longevity of the improvement.

Future and Controversies

Future injectable materials may more closely simulate the composition of the intermediate layer and hyaluronic acid, but difficulty remains regarding consistent placement and long-term positional stability. Certainly, the best way to treat scarring is to prevent it. Improperly performed or timed surgical intervention can result in irreversible dysfunction and dysphonia. Conservative treatment should be exhausted before surgical intervention is considered. Base surgery on the modern concept of the microanatomy and histology of the vocal fold. Using microflap techniques avoids a raw mucosal surface that heals by secondary intention and may subsequently result in a sulcus.