Sulcus Vocalis 

Updated: Aug 10, 2018
Author: John Schweinfurth, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Background

The term sulcus vocalis is used specifically to describe a groove or infolding of mucosa along the surface of the vocal fold. In the area of the sulcus, the mucosa is scarred down to the underlying vocal ligament, giving it a retracted appearance.

Essentially, no differences exist between vocal fold scarring where an identifiable sulcus is present and scarring where an identifiable sulcus is not present. In either case, an alteration in the normal physiology of vocal fold vibration exists, which affects voice production. Therefore, this chapter will focus on vocal fold scarring and its effect on vocal physiology.

Most clinicians agree that presentation of sulcus vocalis is hoarseness, vocal fatigue, voice weakness, and increased effort. However, clinicians may disagree on terminology, diagnosis, and treatment of this disorder. Certainly, widespread acceptance of videostroboscopy has allowed more clinicians to recognize the disorder. This has spurred new interest in its diagnosis and treatment.

History of the Procedure

Patients may experience hoarseness but more often have symptoms of glottal insufficiency, including fatigue, poor volume, and poor projection. However, the voice may be normal with more subtle symptoms (eg, fatigue, decreased vocal range with singing).

Problem

The term sulcus vocalis is used to describe a depression or groove in the surface of vocal fold mucosa that is typically 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. A linear sulcus, nearly the length of the true vocal fold, can be seen in the image below.

Linear sulcus nearly the length of the true vocal Linear sulcus nearly the length of the true vocal fold.

A mucosal bridge is a variation on the simple sulcus and is formed when 2 parallel sulci simultaneously appear on the medial and superior surface of the true vocal fold. This creates an area of normal-appearing mucosa between 2 mucosal defects. These lesions are more difficult to treat than single sulci but fortunately are very rare.

Epidemiology

Frequency

The incidence of sulcus vocalis is impossible to determine due to variation in presentation and diagnosis. Most sulci are undiagnosed because of subclinical symptoms, lack of clinician awareness, and difficulty in identification due to limited availability of laryngeal videostroboscopy. In a study of autopsy specimens by Nakayama et al, sulci were identified in 20% of specimens.[1, 2]

Etiology

Sulcus vocalis may be congenital or secondary to vocal trauma, infection, degeneration of benign lesions, or surgery.[3] In addition, Bouchayer et al proposed a relationship with ruptured congenital epidermoid cysts and also suggested that the disorder may demonstrate familial patterns.[4] Typically, patients with congenital sulci have a lifelong history of disordered voice.

Presence of parallel sulci associated with a mucosal bridge is consistent with ruptured cyst etiology. Surgical causes include overresection of the superficial layer of the lamina propria, resulting in remucosalization over the deficient area and damage to the vocal ligament and deep layers of the lamina propria. Nonsurgical causes include untreated benign lesions, chronic vocal abuse, and repeated intracordal hemorrhage. Microvascular lesions (ie, varices, capillary ectasias) also may result in scarring secondary to hemorrhage and fibrosis.

A retrospective study by Lee et al indicated that epithelial pathology plays a significant role in sulcus vocalis, with the prevalence of parakeratosis, dyskeratosis, and epithelial thickening found to be particularly high in sulcus vocalis. The investigators suggested that epithelial changes cause perilesional inflammation, which in turn produces clinical changes.[5]

Pathophysiology

A defect in the medial surface of the true vocal fold along the sulcus may produce a glottic gap. More importantly, the cover may fibrose to the vocal ligament and result in a diminished or absent vocal mucosal wave. This decreased pliability restricts the Bernoulli and myoelastic effects, whereby transglottic airflow medializes the leading edge of the vocal fold. The overall effect is usually a higher fundamental frequency with significantly reduced harmonics and harsher voice quality.

Presentation

Patients experience hoarseness and often have symptoms and signs of glottal insufficiency, including poor volume, poor projection, and vocal fatigue. On initial interview, the voice may be hoarse and breathy or acceptable, but most patients have an overall decrease in vocal performance.

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 more clearly demonstrates the associated incomplete closure.

Relevant Anatomy

Awareness of the body-cover principle of vocal fold vibration is essential to the understanding of sulcus vocalis. The vocal fold is composed of a muscle covered by a free mucosal edge that vibrates and can be separated into discrete layers in which various types of pathology may develop. 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.

Histologically, the vocal fold is a complex structure. The delicate arrangement of extracellular matrix proteins within the lamina propria permits passive movement of the vocal cover over the vocal ligament and muscle, or body. This results in formation of the mucosal wave as air is passed through the glottis as a release of building subglottic pressure. Violation of deeper layers of the lamina propria and vocal ligament, as was once common with stripping procedures, is now known to be associated with scar and sulcus formation.

 

Workup

Other Tests

Refer patients with symptoms of hoarseness, loss of range, or voice fatigue with no obvious laryngeal pathology to a laryngologist for further evaluation, preferably to an otolaryngologist with special interest and training in diagnosis and treatment of voice disorders. Sulcus vocalis is a challenging rare disorder and often is best treated by a subspecialist.

A laryngologist usually employs a team approach to the diagnosis and treatment of voice disorders (eg, speech pathologist, singing voice specialist) and has a variety of specialized endoscopes that allow for detailed examination of the larynx.

Videostroboscopy is an important tool used by the laryngologist. This imaging system is controlled in part by the patient's vocal pitch, allowing for slow-motion video recording of vocal fold vibration. 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 more clearly shows associated incomplete closure.

Other diagnostic studies commonly employed by the laryngologist include acoustic and airflow measurements.

  • Acoustic analysis reveals some information about vocal production efficiency and voice strength.

  • Airflow measurements are useful in gauging vocal support and glottic constriction.

 

Treatment

Medical Therapy

Anatomic change in the vocal fold (eg, sulcus vocalis) is difficult to treat medically. Any intercurrent medical conditions affecting the voice (eg, reflux laryngitis, allergic rhinitis) are evaluated and treated. Prior to considering surgical therapy, all known sources of mechanical trauma are maximally reduced to determine reversibility and hopefully prevent a postoperative recurrence. This is accomplished in part by medical and speech therapy to reduce vocal trauma through improved phonatory technique and vocal hygiene.

The primary goal of speech therapy is to improve vocal efficiency. The method most commonly employed is direct speech therapy, which is covered in the Medscape Reference article Voice Therapy. When voice therapy is combined with external measures (eg, amplification) and behavioral alterations (eg, scheduling vocal rest periods), vocal fatigue may dissipate.

Surgery is reserved for unresolving lesions that have resulted in persistent troublesome dysphonia.

Surgical Therapy

Patients with sulcus vocalis may complain of vocal insufficiency, loss of quality, or both. When low volume and loss of projection are major complaints, medialization of the scarred vocal fold may significantly improve vocal performance while decreasing effort and fatigue.[6]

Medialization alone may not significantly impact vocal quality. An attempt to reconstitute the lamina propria may be considered for patients who have adequate volume but poor vocal quality.[7]

Current opinion holds that placing a biocompatible material between the vocal ligament and cover or within the layers of the lamina propria could compensate for lost tissue and restore sliding movement of the mucosal cover. This additional layer also may prevent fibroblast migration from deeper layers and further scar formation. A thick scar band associated with the sulcus may be removed through a microflap approach. However, this maneuver carries the risk of further fold thinning. The ideal implant material assumes the function of the intermediate layer of the lamina propria, which is composed of elastin, hyaluronic acid, and fibromodulin. Implant material is placed to augment the infraglottics and free edge of the vocal fold. Phonation threshold pressure (ie, amount of pressure required to initiate voice) is decreased by improved closure, increased fold thickness, and lower viscous damping (ie, tissue inertia). Therefore, the ideal implant has low viscosity and resorption and is injectable.

Injectable collagen gained interest early because of its ability to soften scar tissue when used in the face. Irradiated cadaveric collagen is readily available in a powder form, which can be reconstituted and injected through a narrow-gauge needle. This can be safely used without sensitivity testing and has a duration of up to 3 years. When normal lamina propria reproduction is the goal of implantation, fat is the available material most similar in viscosity (4 pascal seconds [Pa-s]) to the lamina propria. In contrast, collagen has a much higher viscosity (10 Pa-s). However, collagen is much easier to inject and is more readily obtained. Furthermore, collagen can be injected transcutaneously in a clinic setting.

Autologous fat probably is the best augmentation material in widespread use.[8] More forgiving placement of autologous fat within the larger muscle bed is possible, and longevity has improved through development of viable adipocytes. Archer and Banks demonstrated maintenance of viable adipocytes and bulk for up to 1 year in an animal model.

Fat may be implanted into the vocal fold through an endoscopic approach but may also be implanted through a surgically created window in the thyroid cartilage, or "minithyrotomy."[9] Paniello (2008) reported good results in 2 patients treated specifically for sulcus vocalis with this approach.[10]

A study by Karle et al indicated that treatment of sulcus vocalis and vocal fold scars with autologous transplantation of temporalis fascia into the vocal fold can produce good long-term results. The investigators reported that at 6-month follow-up, patients who underwent the procedure experienced a mean reduction in Voice Handicap Index–10 (VHI-10) scores of 8.35, while at an average follow-up of 44 months, VHI-10 scores had decreased by 13.53 from their preoperative values. One complication occurred among the study’s 21 patients, and it was minor and self-limited.[11]

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.

A study by Hwang et al suggested that pulsed dye lasers can effectively be used to treat sulcus vocalis. Each treatment in the study, which involved 25 patients with the condition, consisted of 60-100 laser pulses (0.75 Joules per pulse) on each vocal fold. The procedures appeared to decrease vocal fold stiffness, improve mucosal wave properties, and reduce dysphonia. Moreover, in most patients, improvement was demonstrated in several postoperative voice analysis indices.[12]

The aforementioned study by Lee et al, which indicated that epithelial pathology plays an important part in sulcus vocalis, suggested that surgical treatment should involve the removal of pathologic epithelium, as a means of treating inflammation.[5]

Preoperative Details

Surgical candidates must be willing to postpone speaking and singing engagements for at least 3 months postoperatively. Patients presenting with dysphonia are evaluated by indirect laryngoscopy (as seen in the image below) and videostroboscopy (as seen in the image below), with particular attention to vocal fold mobility; glottic closure; and the presence, amplitude, and symmetry of the mucosal wave.

Sulcus under normal light indirect laryngoscopy: N Sulcus under normal light indirect laryngoscopy: Note the very subtle appearance.
Sulcus under stroboscopy: Note the defect in the v Sulcus under stroboscopy: Note the defect in the vibratory surface caused by the sulcus.

Diagnostic laryngoscopy may be necessary prior to invasive procedures aimed at altering laryngeal anatomy in order to have a more complete understanding of vocal fold pathology and potential for surgical treatment. Specifically, the ability of the surgeon to adequately expose the larynx may affect the surgical approach chosen. The area of vocal scarring may be more closely estimated by palpation. Some surgeons employ a diagnostic infusion of saline under the mucosa to assess the feasibility of injecting or implanting biocompatible material.

Intraoperative Details

Bring the microscope into position after the larynx is adequately exposed. Remove obvious scar tissue and bands of fibrosis whenever possible, preferably through a microflap approach. Endoscopic or transcutaneous injection is the most convenient method of implant delivery, but anecdotal reports suggest that sufficient bulk cannot be obtained through injection alone; passage through a needle barrel is too traumatic to the adipocytes; and the implants may extrude out of the injection site. On the other hand, implanted fat tends to migrate superiorly in the pocket. The authors' current technique is to harvest fat via a large 8-mm liposuction cannula and inject it into the thyroarytenoid muscle with a Breunig syringe. Anecdotal reports support rinsing harvested fat in insulin to support adipocyte cell membrane stabilization. A moderate decrease in volume in the early postoperative period should be expected. Therefore, overcorrect the vocal fold at the time of surgery.

Postoperative Details

Patients are placed on strict voice rest for 2 weeks following microflap surgery. Patients with more extensive dissections may be placed on a short course of 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 re-examined 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. Gradual return to voice use over the first few weeks is recommended, increasing by 5-minute intervals twice daily. Singers may begin work with the vocal pedagogue at 1 month but are cautioned to back off if they feel any discomfort or strain. Most patients can expect to see 90% of the functional surgical result at about 3 months.

Complications

Surgical complications are related to laryngoscopy, vocal cord incision, and implantation of material for medialization. Complications of laryngoscopy include damage to or avulsion of teeth; oral mucosal laceration; and pressure damage to the tongue, including numbness or altered taste. Any vocal fold incision can result in further scar formation with recurrence of the sulcus.

Outcome and Prognosis

In 2 studies, microsurgical techniques were used on 30 patients with pathologic sulcus. Voice improvement was reported in the majority of subjects using objective measures. Using fat implantation methods, Sataloff et al described voice improvement and limited return of mucosal wave.[13] Most patients can expect significant voice improvement from either technique, but results are not equal to premorbid conditions in most cases. Additionally, insufficient data exists on the longevity of improvement.[14]

Future and Controversies

Future injectable materials may more closely simulate composition of the intermediate layer and hyaluronic acid, but consistent placement and long-term positional stability remain difficult. 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, which should be based on the modern concept of vocal fold microanatomy and histology. Use of microflap techniques avoids a raw mucosal surface that heals by secondary intention and may result in a sulcus.