Arytenoid Subluxation 

Updated: Aug 06, 2020
Author: Joshua S Schindler, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Practice Essentials

Arytenoid dislocation and arytenoid subluxation (AS) are rare laryngeal injuries that are usually thought to occur as complications of upper aerodigestive tract instrumentation. The terms arytenoid dislocation and AS have been used interchangeably to describe disruption of the cricoarytenoid joint. Arytenoid dislocation refers to complete separation of the arytenoid cartilage from the joint space. It usually results from severe laryngeal trauma. AS is likely a lesser injury and refers to the partial displacement of the arytenoid within the joint. Reports in the literature suggest that AS is a more common injury than arytenoid dislocation. AS is the focus of this article.[1, 2]

The image below depicts the cartilages of the larynx.

Cartilages of the larynx, posterior view. Cartilages of the larynx, posterior view.

Workup in arytenoid subluxation

Imaging studies

Several reports have identified high-resolution computed tomography (CT) scanning as extremely helpful in diagnosing AS, with the following caveat: Although positive results from CT scanning may be helpful in confirming AS, nondiagnostic CT scanning results do not rule out AS.

Magnetic resonance imaging (MRI) has also emerged as a helpful study for the diagnosis of AS. MRI offers the benefit of direct sagittal imaging compared with the reconstructions provided by CT scanning. Generally, MRI is superior to CT scanning for imaging soft tissue interfaces.

Other tests

Videostroboscopy is also a useful study in the workup of AS, allowing the clinician to detect malalignment of the true vocal folds, which is noted in persons with AS. In addition, videostroboscopy can detect the slightest motion of the true vocal fold, arytenoid cartilage, and surrounding structures, findings that can help to distinguish AS from recurrent laryngeal paralysis.

Laryngeal electromyography (EMG) findings can help to confirm normal innervation of the larynx in patients with vocal fold immobility, thereby distinguishing AS from recurrent laryngeal nerve paralysis.

Management of arytenoid subluxation

Surgery

Surgical therapy is the treatment of choice for AS. Several treatment options are available.

Early treatment of AS includes direct laryngoscopy and closed reduction of the displaced arytenoid.

Vocal fold medialization, via a type 1 thyroplasty with silastic implantation as described by Isshiki, is the treatment of choice for late AS. Other options for medialization include Gelfoam injection, autologous fat injection, and Teflon injection into the true focal fold. Teflon has largely fallen out of favor because of the possibility of granuloma formation.

Direct laryngoscopy with attempted reduction of the displaced arytenoid, as in early AS, is another treatment option for late AS.

Voice therapy

Voice therapy is an important adjunctive treatment for all patients with AS. Proper voice use and vocal hygiene are important in the rehabilitation of cricoarytenoid joint integrity. Whenever possible, have the patient begin therapy with a trained speech and language pathologist with a background in voice disorders prior to surgery.

Voice therapy is also advocated in patients who refuse or do not require surgical intervention. Patients can be taught compensation techniques for breathiness and hoarseness, which is a common complication of tracheal intubation.[3] In addition, patients can be trained to protect their airway from aspiration.

History of the Procedure

Arytenoid dislocation and arytenoid subluxation (AS) have not been widely reported in the world literature. The conditions were first described in 1973 as rare and unusual complications of endotracheal intubation. By 1994, only about 31 cases had been reported.

Problem

Arytenoid subluxation (AS) is usually a complication of upper airway instrumentation and endotracheal intubation. The normal articulation of the arytenoid cartilage is disrupted as it contacts the cricoid cartilage, resulting in reduced mobility of the true vocal fold and incomplete glottic closure that can mimic true vocal fold paralysis.

Epidemiology

Frequency

The incidence of arytenoid subluxation (AS) is unknown. It is considered a rare injury. Now, fewer than 80 cases have been reported in worldwide literature, and these are mostly case reports or small series.

Only one case of AS was reported in a large series of 1000 intubated patients, in which 6.2% had laryngeal trauma.

Because the clinical presentation of arytenoid malposition and dysphonia are common to AS/arytenoid dislocation and vocal fold paralysis, further studies are needed to establish the incidence of arytenoid trauma.

Etiology

Intubation trauma is the most common etiologic factor for arytenoid subluxation (AS) cited in the world literature. A literature review by Frosolini et al suggested that arytenoid subluxation/dislocation (AS/AD) happens in 0.01% or more of patients who undergo endotracheal intubation.[4]

Blunt and penetrating neck trauma are less common causes. Other reported etiologies include, but are not limited to, direct laryngoscopy, whiplash injury, and idiopathic causes in rare cases.

Associated anomalies (eg, laryngomalacia, acromegaly) have been identified as possible factors that can weaken the cricoarytenoid joint. Diabetes mellitus, chronic renal failure, history of rheumatic disease, and long-term corticosteroid use have also been implicated. However, no disease process or anatomic abnormality has been linked definitively with an increased risk of AS.

No statistically significant sex or age predilections have been identified for AS.

Pathophysiology

Many mechanisms of injury to the cricoarytenoid joint have been postulated. Anterior and posterior arytenoid displacement secondary to intubation have been reported in the literature. Anterior displacement is thought to occur when the arytenoid is subluxed directly by the blade of a laryngoscope as it is inserted and lifted in an anterior direction. Another possibility is that the tip of the endotracheal tube or stylet can displace the arytenoid in the same fashion as in endotracheal tube insertion. Posterolateral force applied to the arytenoid by the convex curve of the endotracheal tube as it passes into the airway is one suggested mechanism for posterior arytenoid subluxation (AS). Another theory suggests that traumatic extubation with a partially inflated cuff displaces the arytenoid posteriorly.

A retrospective study by Tsuru et al suggested that the risk of arytenoid dislocation/subluxation following tracheal intubation is greater in patients undergoing major cardiovascular surgery (odds ratio 9.9). The study also indicated that the risk is greater in cases of difficult intubation, in which intubation with direct laryngoscopy has been unsuccessful and must instead be carried out through other means, such as flexible fiberoptic laryngoscopy (odds ratio 12.1).[5]

The proposed mechanisms of AS due to endotracheal manipulation are disputed. In an unfixed cadaveric larynx study by Paulsen et al, the authors were unable to cause arytenoid dislocation or subluxation in 36 larynges via intubation, extubation, or manual manipulation.[6] Although this study does not mimic the normal physiologic condition since all of the larynges were from cadavers and thus had no muscle tone, the study brings the diagnosis of arytenoid dislocation and AS into question. The study's authors propose that AS does not occur, but rather hemarthrosis of the cricoarytenoid joint leads to fibrosis and subsequent fixation. Other authors have proposed that what is thought clinically to be AS is actually a manifestation of paresis, either of the recurrent laryngeal or external branch of the superior laryngeal nerve.

Arytenoid injury due to external neck trauma is often accompanied by other laryngeal injuries (eg, mucosal tears, thyroid or cricoid cartilage fractures, hematoma formation). Blunt neck trauma can cause anterior AS from inward pressure applied by a medially displaced thyroid ala. Posterior AS can also result from an anterior blow to the laryngeal framework that causes lateral splaying of the thyroid cartilages, thereby forcing the arytenoid posteriorly. Injury to the recurrent laryngeal nerves or external branch of the superior laryngeal nerve is also common to such injuries and may complicate both the diagnosis and treatment.

Presentation

Upon presentation, patients with arytenoid subluxation (AS) primarily report hoarseness. Breathy voice quality, vocal fatigue, and an inability to project the voice are also common symptoms. Dysphagia, odynophagia, sore throat, and cough are less common. Respiratory compromise that necessitates airway management is uncommon. A history of recent upper aerodigestive tract instrumentation or intubation should also prompt consideration of AS.

A thorough laryngeal examination should be performed using a laryngeal mirror, flexible fiberoptic laryngoscope, or rigid telescope. Reduced vocal fold mobility and arytenoid edema with loss of arytenoid symmetry are physical signs that suggest acute AS. Poor glottic closure, posterior glottic chink, and malalignment of the true vocal folds are often noted.

Importantly, note that recurrent laryngeal nerve paralysis can also manifest with the above symptoms and physical signs. Recurrent nerve paralysis can result from (1) pressure on the nerve from the endotracheal tube cuff in intubated patients or (2) external laryngeal trauma. Differentiation between recurrent laryngeal nerve paralysis and AS can be difficult if based only on history and physical examination findings. Further studies are frequently necessary to make the correct diagnosis. Making the distinction is important because early management of AS consists of endoscopic reduction, whereas early management of vocal fold paralysis frequently consists of observation with voice therapy. The opportunity for early endoscopic reduction may be lost if AS is misdiagnosed as vocal fold paralysis. Laryngeal electromyography (EMG) may be essential to make this distinction early following the injury.

Relevant Anatomy

The arytenoid cartilage is composed of hyaline and elastic cartilages. The cartilage is pyramid-shaped and consists of an apex, base, and 2 processes. The vocal process articulates with the vocal ligament, and the muscular process is the insertion point for the muscles that move the arytenoid. The base rests on the cricoid cartilage, and the apex articulates with the aryepiglottic fold and the corniculate cartilage (Santorini cartilage).[7]

Most cricoarytenoid motion is that of rocking and, to a lesser extent, gliding. The cricoarytenoid joint is a synovial joint enclosed by a joint capsule. The capsule receives posterior support from the posterior cricoarytenoid ligament, which usually prevents posterior subluxation. The cricoarytenoid joint controls adduction and abduction of the true vocal folds, which facilitates the main laryngeal functions of airway protection, respiration, and phonation.

Contraindications

Contraindications to surgical correction of arytenoid subluxation (AS) are based on the patient's comorbidities and his or her ability to tolerate surgery. Informed consent must be obtained prior to all surgical procedures. Laryngeal electromyography (EMG) findings of recurrent or superior laryngeal nerve paralysis represent at least a relative, if not strict, contraindication to surgical manipulation. Voice therapy is sometimes advocated for patients who refuse or do not require surgical intervention.

 

Workup

Laboratory Studies

See the list below:

  • Currently, no laboratory studies help in the diagnosis of arytenoid subluxation (AS).

Imaging Studies

See the list below:

  • CT scan

    • Several reports have identified high-resolution CT scan as extremely helpful in diagnosing arytenoid subluxation (AS), with the following caveat: Although positive results from the CT scan may be helpful in confirming AS, nondiagnostic CT scan results do not rule out AS.

    • Typical findings of AS include displacement of the arytenoid body, altered angulation of the aryepiglottic fold, and widening of the ventricle on the affected side.

    • The relationship of the arytenoid to the cricoid cartilage is the imaging parameter that best distinguishes AS from vocal fold paralysis. CT scan images can demonstrate a slight rotation and displacement of the arytenoid in persons with vocal fold paralysis, but not to the degree that is evident in persons with AS.

    • CT scans may be of limited usefulness if the laryngeal cartilages are insufficiently mineralized, especially in the pediatric population.

    • Helical CT scanning has been developed in some centers as a more accurate tool in the evaluation of cricoarytenoid joint integrity.[8]

  • MRI

    • MRI has also emerged as a helpful study for the diagnosis of AS. MRI offers the benefit of direct sagittal imaging compared with the reconstructions provided by CT scan. Generally, MRI is superior to CT scan for imaging soft tissue interfaces.

    • To date, MRI has not been shown to be more effective than CT scan in the evaluation of the arytenoid-cricoid interface. MRI has not supplanted CT scan as the primary imaging modality for laryngeal structures.

Other Tests

 

Laryngeal videostroboscopy

Videostroboscopy is also a useful study in the workup of arytenoid subluxation (AS), allowing the clinician to detect malalignment of the true vocal folds, which is noted in persons with AS. Differences in vocal fold level as small as 1 mm can be detected.

Videostroboscopy can also detect the slightest motion of the true vocal fold, arytenoid cartilage, and surrounding structures. These findings can help to distinguish AS from recurrent laryngeal paralysis.

Videostroboscopy helps detect other injuries. Submucosal vocal fold hemorrhage, hemorrhagic polyps, and cysts can result in vocal fold scarring if not diagnosed and properly treated. Videostroboscopy remains invaluable in the identification of these often subtle injuries.

Laryngeal electromyography

EMG of the laryngeal musculature is very important in the diagnostic workup of suspected AS. EMG findings can help to confirm normal innervation of the larynx in patients with vocal fold immobility, thereby distinguishing AS from recurrent laryngeal nerve paralysis.

Evidence of innervation includes the presence of voluntary electrical activity in the laryngeal muscles on the immobile side and the presence of recruitment.

The aforementioned literature review by Frosolini et al found that, among the studies looked at, laryngeal EMG played a fundamental role in eliminating unilateral vocal fold paralysis as a differential.[4]

Diagnostic Procedures

See the list below:

  • Direct laryngoscopy

    • Prior to the development of imaging techniques and the application of laryngeal EMG, direct laryngoscopy was the standard diagnostic and therapeutic modality for arytenoid subluxation (AS).

    • Direct laryngoscopy under general anesthesia with palpation of the arytenoid cartilage yields valuable clinical information.

    • The cricoarytenoid joint is assessed for mobility and displacement of the arytenoid.

    • Current diagnostic aids allow the clinician to have a more accurate diagnosis before proceeding to surgery.

 

Treatment

Medical Therapy

Voice therapy is an important adjunctive treatment for all patients with arytenoid subluxation (AS). Proper voice use and vocal hygiene are important in the rehabilitation of cricoarytenoid joint integrity. Whenever possible, have the patient begin therapy with a trained speech and language pathologist with a background in voice disorders prior to surgery.

Voice therapy is also advocated in patients who refuse or do not require surgical intervention. Patients can be taught compensation techniques for breathiness and hoarseness, which is a common complication of tracheal intubation.[3] In addition, patients can be trained to protect their airway from aspiration.

Frequently, patients with AS or vocal fold paralysis develop muscle tension dysphonia that produces a strained voice quality, vocal fatigue, frequent neck pain, and a sore throat. These symptoms reflect lack of compensation for incomplete glottic closure in both processes. Voice therapy may help prevent and correct dysphonia by redirecting the patient into better compensatory techniques.

Prevention

Although it was previously indicated that a stylet can cause arytenoid displacement, a retrospective study by Wu et al suggested that utilization of an intubation stylet in endotracheal intubation reduces the risk of arytenoid dislocation. The investigators reported that among 104 intubated patients, a stylet was used in 38.5% of those in whom dislocation occurred, compared with 64.1% of those who did not suffer dislocation.[9]

Surgical Therapy

Surgical therapy is the treatment of choice for arytenoid subluxation (AS). Several treatment options are available.

A prospective study by Lee et al indicated that arytenoid dislocation (AD) can be successfully treated with closed reduction and that early surgical intervention improves outcomes in this procedure. The study involved 22 patients with arytenoid dislocation, including 16 with anterior dislocation and 6 with posterior dislocation. Patients were treated with closed reduction with or without adjunct therapy (injection laryngoplasty or botulinum toxin administration), with the exception of one patient who recovered spontaneously. Of the treated patients, 18 regained arytenoid motion, accompanied by voice improvement, with recovery sustained 6 months postsurgery. The investigators also found that patients who underwent closed reduction within 21 days after the presumed dislocation event tended to have better restoration of arytenoid motion.[10]

A study by Cao et al on patients who underwent closed reduction for arytenoid dislocation under local anesthesia, with 26 out of 33 patients (79%) classified as satisfied with the procedure’s results. These patients demonstrated significant improvement in grade, roughness, breathiness, asthenia, maximum phonation time, self-assessed Voice Handicap Index, jitter%, shimmer%, normalized noise energy, and noise-to-harmonic ratio.[11]

The aforementioned literature review by Frosolini et al reported that the “surgical relocation of AS/AD under general or local anesthesia was achieved in about 80% of patients.”[4]

Generally, the earlier the intervention in AS, the better the outcome for voice quality. Treatment of AS can be divided into early and late interventions.

Early treatment

Early treatment of AS includes direct laryngoscopy and closed reduction of the displaced arytenoid. Injection of steroid preparations (eg, triamcinolone) into the cricoarytenoid joint space at the time of reduction is preferred by some practitioners.[12]

Tracheotomy may be required in the acute period of laryngeal edema and airway compromise. Other reports in the literature advocate arytenoidectomy via an endoscopic approach or externally via laryngofissure. Arytenoidectomy has not been widely accepted and could pose a greater risk of aspiration and poor airway protection. Usually, arytenoidectomy is reserved for when the arytenoid obstructs the airway or when all other interventions have failed.

Late treatment

Vocal fold medialization, via a type 1 thyroplasty with silastic implantation as described by Isshiki, is the treatment of choice for late AS. Other options for medialization include Gelfoam injection, autologous fat injection, and Teflon injection into the true focal fold. Teflon has largely fallen out of favor because of the possibility of granuloma formation.

Gelfoam and fat are resorbed over time and are therefore considered temporary treatments. Gelfoam and fat are considered in patients who are likely to regain vocal fold mobility and closure.

Direct laryngoscopy with attempted reduction of the displaced arytenoid, as in early AS, is another treatment option for late AS. The likelihood of successful reduction is greatly reduced in delayed diagnoses of AS because of fibrous ankylosis of the cricoarytenoid joint. Canine studies have shown that even minor injury to the joint capsule can affect arytenoid mobility. Arytenoid mobility can be significantly impaired, even with successful reduction. Although one large series demonstrated phonatory improvement with reductions as late as 1 year following injury, late endoscopic reduction has not been widely accepted as the first line of treatment for late AS.

Preoperative Details

Obtain informed consent prior to all surgical procedures. Include a careful discussion with the patient regarding risks of airway compromise and the possible need for tracheotomy. If extensive supraglottic edema is coexistent, treatment with oral steroids or antireflux agents may be considered prior to surgical therapy.

Intraoperative Details

Endoscopic procedures are performed with the patient under general anesthesia or under local anesthesia with intravenous sedation.

Various instrumentation techniques have been used to reduce the subluxated cartilage. Sataloff et al recommend the Holinger laryngoscope for anterior dislocations. The tip of the scope is contacted with the joint interface; the displaced arytenoid is then lifted and reduced posterolaterally. Other authors report success with the laryngeal spatula during endoscopy.

For posterior subluxations, the Miller-3 straight intubating laryngoscope is favored for its unique curved tip. Sataloff et al describe placement of the laryngoscope in the pyriform sinus with the lip of the Miller blade in the subluxated joint. The cartilage is lifted and repositioned anteromedially. Smaller microlaryngeal instruments (ie, cups forceps) are less likely to be effective and may lacerate the mucosa.

Intraoperative steroids have also been advocated by some authors. A preparation of triamcinolone acetate (Kenalog) at 40 mg/mL, in varying amounts, can be injected into the cricoarytenoid joint using a 25-gauge butterfly needle. This has been proposed to prevent joint ankylosis and reduce edema in persons with acute injuries. However, to date, intraoperative steroid injection has not been definitively shown to improve the outcome of endoscopic reduction.

Medialization thyroplasty is performed with the patient under local anesthesia with intravenous sedation, as needed. Ensure that the patient is awake in order to assess voice quality while positioning the vocal fold implant. The optimal voice quality for each patient is obtained using this method.

Postoperative Details

Monitor all patients for airway compromise in the postsurgical period. Common signs include respiratory distress, tachypnea, and stridor. Also monitor oxygen saturation levels.

If symptoms develop, prompt fiberoptic laryngoscopy is indicated, as is intravenous steroid therapy to reduce laryngeal edema. Racemic epinephrine has also been recommended to reduce airway edema. Supportive measures, including humidified oxygen, are also useful. Close observation in an intensive care unit may be warranted. Tracheotomy may be indicated if these measures are ineffective.

The use of postoperative antibiotics, antireflux medications, and tapered oral steroid therapy for patients to complete at home are often advocated. Oral narcotic analgesics may be necessary.

Follow-up

Most patients who have endoscopic arytenoid reductions are scheduled for a follow-up visit within 2-4 weeks. A period of voice rest may be recommended to allow the cricoarytenoid joint to stabilize.

Patients who undergo medialization thyroplasty are usually scheduled for a follow-up visit within 1-2 weeks. A period of voice rest, from 3 days to 1 week, may also be advocated.

All patients require voice therapy for speaking; when applicable, voice therapy is required for singing. Whenever possible, have the patient begin speaking voice therapy prior to surgical intervention.

Complications

Failure to reduce the arytenoid is the most common complication of endoscopic reduction of arytenoid subluxation (AS). Histologic studies have shown that fibrosis of the cricoarytenoid joint can occur as early as 24 hours following injury.

Recurrence of subluxation after successful reduction is a related complication of the endoscopic approach. This complication is likely due to laxity of the ligamentous support of the cricoarytenoid joint following injury.

Iatrogenic disruption of the laryngeal mucosa can occur during attempts to reduce the arytenoid, thereby increasing the risk of infection.

Instrumentation of the airway can result in supraglottic edema, glottic edema, or both, thereby causing airway compromise.

Possible complications of medialization thyroplasty include the following: bleeding, infection, or hematoma of the surgical site; malpositioning of the implant, causing airway compromise or poor voice quality; extrusion of the implant; and chondritis.

Outcome and Prognosis

Early diagnosis and intervention is the best hope for a favorable outcome in the treatment of arytenoid subluxation (AS).

Some patients are able to compensate for the immobile vocal fold and return to near-normal voice quality without surgical intervention. However, most patients require either endoscopic reduction in the early period or medialization procedures in the late period to achieve subjective and objective improvement in voice quality. Outcomes for both procedures have been favorable, although not uniformly successful.

Future and Controversies

Arytenoid subluxation (AS) continues to be a rare, but challenging, problem for the laryngologist. Future management of AS will be directed toward developing more effective means of restoring cricoarytenoid joint structure and mobility, thereby improving phonatory outcomes for patients with this injury. Newer concepts that may add more treatment options for patients with AS are evolving.

The use of botulinum toxin as an adjunct to endoscopic reduction for anteromedial AS has been reported in a recent study. The study proposes that reduction of the arytenoid alone often fails because the surgeon cannot control unbalanced forces placed on the arytenoid by the intrinsic laryngeal musculature. Injection of botulinum toxin into the laryngeal adductor muscles on the affected side weakens these forces and allows the arytenoid to remain in the reduced position. Ten patients were studied, and results were favorable.

Some controversy exists in the literature over the timing of endoscopic reduction. One retrospective series reported favorable voice outcomes in patients who had endoscopic reduction as long as 1 year following injury. This finding challenges the dictum that medialization techniques are the best intervention for late treatment of AS. However, the overall consensus seems to be that, beyond 1 month following injury, the best voice outcomes will likely be obtained using medialization.