Arytenoid Dislocation: A Diagnostic Strategy

Definition

Arytenoid dislocation, also termed arytenoid subluxation, is a rare mechanical injury of the larynx in which an arytenoid cartilage becomes displaced from its articulation with the cricoid.

Dislocation impairs vocal cord mobility and often mimics recurrent laryngeal nerve paralysis. The condition has been reported to most commonly arise after traumatic endotracheal intubation, external laryngeal trauma, or forceful instrumentation of the larynx.

Unlike neurogenic immobility, arytenoid dislocation represents a mechanical limitation of the joint’s range of motion. Early identification is said to permit possible microlaryngoscopic reduction and greater likelihood of functional recovery.

Literature Review

Arytenoid dislocation is uncommon. The literature is therefore dominated by small retrospective series. Most reported cases follow endotracheal intubation, with the remainder due to external trauma or laryngeal manipulation.

Patients typically present with hoarseness or breathiness immediately after the inciting event, accompanied by impaired vocal cord mobility resembling recurrent laryngeal nerve paralysis or paresis. Papers by Cummings and colleagues (8 patients) and Crumley (11 patients) underscored the diagnostic challenge, and they believed that laryngeal examination alone cannot reliably distinguish arytenoid dislocation from neurogenic vocal fold immobility. Sataloff’s subsequent work (7 patients), later expanded by Apostolides (6 patients), promoted the idea that laryngeal electromyography (LEMG) is instrumental in differentiating mechanical fixation from neuropathic injury by revealing preserved motor unit recruitment in an immobile cord. The largest series, by Watanabe (24 patients), says that early closed endoscopic reduction—ideally within 2 to 4 weeks—yields the highest likelihood of vocal restoration.

In aggregate, the literature suggests that early suspicion, appropriate use of LEMG, and prompt mechanical correction form the foundation of effective management.

A Personal Experience Leading to an Alternate Method of Diagnosis

1. Why dislocation is rare: the cricoarytenoid joint is extraordinarily tough.

   Near the end of Dr. Oskar Kleinsasser’s career, I had the privilege of observing him perform an endoscopic arytenoidectomy for vocal cord paralysis in Marburg, Germany. The procedure was beautifully executed yet required significant time simply to release the remarkably tough joint capsule.

2. A second experience confirming the joint’s robustness.

   Shortly afterward, I performed the same operation for bilateral vocal cord paralysis in my own practice. Again, I was struck by how exceptionally strong the cricoarytenoid joint capsule is. This was prior to developing my own posterior commissuroplasty technique, which ultimately proved to be a far better solution for bilateral vocal cord paralysis.

3. Why were there only 2–3 cases in my entire caseload?

   Early in my career, I recalled reading a case series—approximately 30 patients—from a single author. I cannot locate it now, but at the time I wondered why, despite years as the sole dedicated laryngologist in two major academic centers with extensive trauma and critical-care populations, my own incidence of true arytenoid dislocation was so low. Combined with my knowledge of the joint’s toughness, I began to suspect that some cases diagnosed as “dislocation” might have another explanation.

4. Overdiagnosis from outside referrals prompted a search for a fail-safe diagnostic test and alternate diagnoses.

   Several patients referred to me with a diagnosis of arytenoid dislocation shared similar criteria: an intubation event followed by immediate voice change, an anteriorly displaced arytenoid superstructure, and vocal fold immobility. Once I developed and applied a better diagnostic technique (described below), I found that nearly all of these cases were actually paralysis or paresis—not dislocation.

5. Anterior displacement of the arytenoid superstructure proved unreliable.

   I observed repeatedly that the arytenoid superstructure can sag anteriorly in true vocal fold paralysis and, at times, simply in the “elderly larynx.” This means that anterior displacement—often treated as a hallmark sign—is not specific to arytenoid dislocation.

6. Laryngeal EMG is not always reliable in this setting.

   A strong thyroarytenoid (TA) signal on EMG can lead to false reassurance that the vocal cord immobility is not neurological but instead due to arytenoid dislocation. But here’s the rub:  In cases where only the posterior cricoarytenoid (PCA) muscle is not functioning, for example due to bruising (muscle or nerve arborization) from intubation with blade behind the larynx—the TA and LCA innervation may remain normal despite the PCA weakness. Clinically this can mimic vocal cord immobility due to dislocation.

7. Posterior cricoid plate fractures can masquerade as arytenoid dislocation.

   If trauma fractures the portion of the cricoid that bears the joint, the displaced segment—often accompanied by PCA injury—can closely mimic the appearance of a dislocated arytenoid, even when using the more reliable diagnostic method discussed below.

8. The screening test and key finding: vocal process mismatch.

   In our clinic, we routinely topically anesthetize every patient’s larynx to create what I call a “close-clear rather than far-fuzzy” view. This allows direct visualization of the posterior commissure during both respiration and phonation. In any case of suspected paralysis, paresis, fracture, or true dislocation, we assess vocal process match. A mismatch is the essential finding that can help distinguish paralysis from structural displacement.

What Finding Effectively Rules Arytenoid Dislocation Out?

Normal Arytenoid Matching. In the normal larynx, the arytenoid cartilages should be positioned as mirror images of each other. This would mean that the vocal processes would line up precisely or nearly precisely. The cartilage is embedded in the posterior third of the cord.