Unilateral vocal fold paralysis (UVFP) occurs from a dysfunction of the recurrent laryngeal or vagus nerve innervating the larynx. It causes a characteristic breathy voice often accompanied by swallowing disabilty, a weak cough, and the sensation of shortness of breath. This is a common cause of neurogenic hoarseness. When this paralysis is properly evaluated and treated, normal speaking voice is typically restored.
Examples of vocal fold paralysis can be seen in the image and video below.
Preoperatively, the arrow demonstrates the paralyzed vocal fold, which is characteristically foreshortened, lateralized, and flaccid.
This patient was evaluated for hoarseness. One can appreciate immobility of the left true vocal fold. Stroboscopy in the second portion of the video shows the mucosal wave only with patient effort. Video courtesy of Vijay R Ramakrishnan, MD.
Unilateral vocal fold paralysis (UVFP) most commonly occurs following a surgical iatrogenic injury to the vagus or recurrent laryngeal nerve. Thus, a history of head and neck, skull base, brainstem or chest surgery should be obtained. Specifically, thyroidectomy, carotid endarterectomy, anterior cervical spine surgery, thoracic, or mediastinal surgery most often result in a presentation of UVFP. In a study of 100 children, the incidence of vocal fold immobility after cardiothoracic surgery was 8%. These 8 patients were younger and weighed less than patients with normal vocal fold movement.
The differential diagnosis for an acute UVFP should always include recent upper respiratory tract or viral infection and recent intubation for any surgical procedure. Procedures aimed at restoring glottic competence include permanent and temporary vocal fold injections, as well as laryngeal framework surgery, including medialization laryngoplasty (type 1 thyroplasty) and arytenoid adduction or arytenopexy.
Normal vocal fold function is reliant on vocal fold glottal closure that results from bilateral adduction of the vocal folds. Normally, this vocal fold adduction behavior, in combination with subglottic airflow, induces vocal fold vibration. Unilateral vocal fold paralysis (UVFP) results in glottal incompetence, either partial or complete, resulting in a weak or absent vocal fold vibration that leads to dysphonia. Significant muscle tension is often seen in the larynx as a compensatory mechanism for the glottal gap. Patients with UVFP often describe pain in the throat or neck after voice use, which is likely due to the excessive muscle tension.
The recurrent laryngeal nerve is responsible for both abduction and adduction of the vocal fold. The recurrent laryngeal nerve originates from the vagus nerve, which originates from the brainstem (nucleus ambiguous in the medulla) and travels along the carotid sheath (with the jugular vein and internal carotid artery). The left vagus nerve gives rise to the left recurrent laryngeal nerve as the vagus crosses the arch of the aorta. The left recurrent laryngeal nerve then loops under the ligamentum arteriosum and travels cephalad in the tracheoesophageal groove until it penetrates the larynx to innervate the intrinsic muscles of the larynx. The right vagus nerve delivers the recurrent laryngeal nerve branch at the level of the subclavian artery. The right recurrent laryngeal nerve loops around the subclavian artery and proceeds cephalad to the larynx.
The recurrent laryngeal nerve, just prior to its entrance into the larynx, runs deep to the inferior cornu of the thyroid cartilage. For a short section, the nerve is in a space between the cricoid and thyroid cartilage. This is thought to be the space where the nerve is vulnerable to compression from the cuff on an endotracheal tube that is either overinflated or positioned too far cephalad. Because of the circuitous nature of the recurrent laryngeal nerve, multiple disease processes and operative procedures put these important nerves at risk, often resulting in vocal fold paralysis.
Patients with unilateral vocal fold paralysis (UVFP) typically present with a fairly sudden onset of breathy, weak, low-pitched dysphonia. In some cases, however, the dysphonia can be high-pitched because of a compensated lengthening of the vocal folds to achieve better glottic closure. Often, UVFP is associated with dysphagia, specifically with liquids, because the resultant glottal incompetence can lead to aspiration. This is especially true if the UVFP is due to a high vagal lesion that results in both a recurrent laryngeal nerve and superior laryngeal nerve palsy. The latter results in significant anesthesia of the pharynx, contributing to the patient's dysphagia and increased risk for aspiration.
Patients with UVFP often report shortness of breath or a feeling of running out of air. Very little negative physiological impact upon pulmonary function actually occurs in patients with UVFP; however, because of the glottal incompetence, they experience significant air wasting and, thus, experience the sensation of shortness of breath and running out of air during speech. In addition, glottal closure is required for individuals to create positive end expiratory pressure (PEEP). Thus, some patients with an immediate postoperative UVFP can experience decreased pulmonary function because of loss of the natural PEEP that occurs with glottal closure. The glottic closure that allows a forceful cough is also compromised and thus a weak, unsuccessful cough is often reported by patients.
The indications for treatment of unilateral vocal fold paralysis (UVFP) are usually the resultant dysphonia or an ineffective cough in a patient at risk for aspiration or pulmonary compromise. If patients experience dysphagia, then they are at risk for aspiration pneumonia and treatment should be implemented as soon as possible. Improving glottic closure in the setting of UVFP and dysphagia often strengthens the voice and cough; however, it does not always correct the swallowing issue. Other sensory branches affecting the laryngopharynx may also be affected by the injury that caused the UVFP in the first place. Thus, patients should not be guaranteed improvement in their swallowing after augmentation of their vocal fold.
For dysphonia related to UVFP, treatment should be determined based on the patient's functional needs and demands, as well as on a new body of evidence that suggests early augmentation of an immobile vocal fold leads to better long-term voice outcomes (with or without return of physiologic function).
Some patients do not notice any significant functional limitation related to their UVFP. This minimal functional limitation results because of the person's minimal voice demands or comorbidities that occur during postoperative recovery. A temporary injection is often given to allow for an immediate return of glottic competence while the nerve potentially recovers.
Electromyelography (EMG) can be used to determine the prognosis of RLN recovery, even if a temporary injection has occurred. If motion does not return and serial laryngeal electromyography shows no chance for meaningful recovery of vocal fold motion, then a permanent injection of fat, a semipermanent injection of calcium hydroxylapatite, or a medialization laryngoplasty can be offered.
In addition to patient history regarding functional aspects of voice use and voice demands, a standardized voice-related outcome measure can be used to assess the patient's vocal limitations and disability. The voice handicap index has been shown to be a reliable and useful patient-based survey instrument, quantifying the patient's voice handicap due to their voice disorder.
Nonsurgical treatment can be offered to patients with UVFP, especially those who are unwilling or unable to proceed with surgical treatment. However, with more evidence demonstrating better long-term voice outcomes when early temporary augmentation is given, it may be best to offer this to all patients with a vocal fold immobility less than 6 months in duration.
The anatomy of the vagus/recurrent laryngeal nerve has been outlined above (see Pathophysiology), and its understanding is crucial to the evaluation of the potential etiology for patients who present with unilateral vocal fold paralysis (UVFP).
An understanding of both the internal and external laryngeal anatomy is important for the surgical treatment of UVFP. For patients who receive a vocal fold injection, an appreciation and thorough understanding of the anatomy of the membranous vocal fold, vocal process of the arytenoid cartilage, and paraglottic space is crucial for successful treatment.
Laryngeal framework surgery for the treatment of UVFP requires an understanding of the relationship and anatomy of the thyroid cartilage and cricoid cartilage. This is especially true regarding the relationship of the membranous vocal fold and paraglottic space to the external landmarks of the thyroid cartilage. For the more advanced laryngeal framework surgery techniques (eg, arytenoid adduction, cricothyroid subluxation), thorough knowledge of the anatomy of the cricothyroid joint and cricoarytenoid joint are required to be successful.
No contraindications exist for the nonsurgical treatment of unilateral vocal fold paralysis (UVFP) other than the patient not indicating or realizing the need for treatment. Contraindications for the surgical treatment of UVFP can include medical problems, such as severe cardiac or pulmonary limitations, or anticoagulation therapy. Although it carries a higher risk of non–life-threatening bleeding, injection of an anticoagulated patient has been routinely performed successfully in the author’s practice. Performing injections on a patient via a transoral or transcutaneous route under local or MAC anesthesia can also be done routinely in the riskier patient.
A careful and detailed medical history and evaluation are required prior to deciding on surgical treatment for UVFP. Often, the most complete history is obtained in conjunction with an internal medicine physician and an anesthesiologist. A poorly abducting contralateral vocal fold is a relative contraindication for surgical treatment of UVFP because of the airway reduction that occurs with surgical medialization of the paralyzed vocal fold.
Although rarely obtained today for the workup of unilateral vocal fold paralysis (UVFP), chest radiography is sometimes the first screening evaluation for a patient with UVFP of unknown etiology, ordered by a physician for other comorbid chest symptoms. This may reveal a chest malignancy as the cause of the UVFP. A Pancoast tumor, mediastinal mass, or even massive cardiomegaly may be found. The latter has rarely been shown to be a cause of UVFP when enlargement of the left atrium that causes a stretch injury to the left recurrent laryngeal nerve is present (Ortner syndrome).
CT scanning or MRI of the path of the vagus/recurrent laryngeal nerve should be performed as part of a workup for a UVFP of unknown etiology. The imaging should include the entire path of the vagus/recurrent laryngeal nerve involved. A left UVFP involves imaging from the base of skull to the mid chest (through the arch of the aorta). The right UVFP evaluation should extend from the base of the skull through the clavicle. Although CT is usually the test of choice, the decision between CT scanning and MRI is personal and can be decided by the otolaryngologist and radiologist.
Multiple surgeries are available for the treatment of unilateral vocal fold paralysis (UVFP), and they can be broadly categorized into temporary and permanent procedures. Temporary treatment involves endoscopic injection of a resorbable material into the affected vocal fold, lateral to the thyroarytenoid muscle in the paraglottic space. The resultant medialization of the paralyzed vocal fold improves vocal quality by restoring glottal competence and may improve swallowing function. Temporary vocal fold injection can be used when return of recurrent laryngeal nerve function is expected or when the prognosis for recovery is unknown during the first 6 months after onset of paralysis (especially when a favorable prognosis is found on LEMG).
There is also recent evidence to suggest that patients who received a temporary vocal fold injectable for a newly diagnosed vocal fold immobility are statistically significantly less likely to undergo permanent medialization laryngoplasty (thyroplasty) compared with those patients who are treated with conservative management (watch and wait) alone.
Many temporary injection materials are available. Radiesse voice gel is composed of water, glycerin, and sodium carboxymethylcellulose (an organic polymer used as a carrier in other injectable pharmaceutical products and an additive in gelatinous foods). Radiesse voice gel effectively medializes the paralyzed vocal fold for 1-3 months and does not require extra time to harvest, prepare, or reconstitute, which is common with other injectable materials.
Hyaluronic acid is a polysaccharide ubiquitous in the extracellular matrix of most species and, therefore, is nonimmunogenic. Widely used as a filler by facial plastic surgeons, hyaluronic acid also can be used as a temporary injection material to medialize the paralyzed vocal fold, although it has a limited track record in laryngology.
Cymetra, a freeze-dried micronized acellular human cadaveric dermis, can also be used to augment the paralyzed vocal fold for 1-3 months. It has the slight disadvantage of requiring extra time for reconstituting and preparing the material for injection. Because this material is derived from humans, infectious disease is a risk, although insignificant.
Gelfoam is a bovine gelatin agent with a long history of safety, efficacy, and predictability, and, therefore, remains the most common injectable material today. Nevertheless, its disadvantages, such as a large (18 gauge) needle requirement and a short duration of effect (4-6 weeks), have prompted a shift toward newer, longer-lasting materials.
Permanent vocal fold surgical treatment can be divided into vocal fold injection and laryngeal framework surgery. Injection technique is similar to that with temporary materials: however, more permanent substances such as fat, fascia, or the semipermanent calcium hydroxylapatite (CaHA) are used.
Autologous fat is typically harvested from the patient's abdomen with liposuction technique. Variability in resorption somewhat limits the predictability of long-term voice outcomes and repeat lipoinjection may be necessary to achieve the desired results.
CaHA consists of calcium phosphorus in the form of microspheres in a gel carrier. The gel carrier resorbs, so slight overinjection (10-15%) is necessary; however, the microspheres have shown resorption on average over 18 months in a recent study.
Teflon is acceptable only in patients with UVFP due to a terminal disease because of the significant long-term complication rate of Teflon granuloma formation. The incidence of Teflon granuloma formation is estimated to be over 50% with long-term follow-up, and the treatment of this complication usually requires surgery (often several) and permanent diminution in vocal function. With other options available, Teflon is rarely used today.
Both temporary and long-acting vocal fold injections are performed more frequently in an office-based outpatient setting. Newer injection materials with fine-gauge needles and chip-tip flexible endoscopes have facilitated this transition from the operating room to the office. The patient is seated in the sniffing position and the airway is topically anesthetized. Under endoscopic guidance, the paralyzed vocal fold can be injected via peroral or transcutaneous (thyrohyoid, transthyroid, or cricothyroid) routes. Advantages of office-based injections include patient convenience, cost savings, real-time monitoring of voice quality, and avoidance of general anesthesia.
Despite the increasing popularity and availability of long-acting injection materials, laryngeal framework surgery remains the criterion standard for long-term treatment of UVFP. Isshiki reintroduced laryngeal framework surgery for the treatment of UVFP to the world in 1974 when he described a type I thyroplasty. This was a concept that Payr initially described. The concept of medialization laryngoplasty is to medialize the paralyzed vocal fold from an external approach and work through the thyroid cartilage. A small window is incised and removed from the thyroid cartilage, and an implant is placed through the window to medialize the paralyzed vocal fold. See the images below.
Preoperatively, the arrow demonstrates the paralyzed vocal fold, which is characteristically foreshortened, lateralized, and flaccid.
Postoperatively, the image shows the same vocal fold as the image above following laryngeal framework surgery (arytenoids adduction and medialization ....
The most common implant used is a silastic block that is either sized from a variety of prefabricated implants or custom carved to address the 3-dimensional nature of the patient's UVFP. Gore-Tex is another implant option for medialization laryngoplasty and has been long regarded as a safe, well-tolerated implant in other parts of the body. Gore-Tex has dramatically increased in popularity in recent years because of its ability to be finely adjusted easily during surgery.
This operation has recently been widely accepted, and from a conceptual perspective, appears quite simple. A national survey found that complication rates with this procedure are higher in surgeons with inexperience or infrequent use of this operation. This most likely is related to the complex 3-dimensional anatomy of the vocal fold, paraglottic space, and implant design. Note that the implant design using medialization laryngoplasty must simultaneously address the treatment of the paralyzed vocal fold in the medial-lateral, superior-inferior, and anterior-posterior dimensions. Optimal voice results from medialization laryngoplasty involve appropriate consideration and treatment of the paralyzed vocal fold in all 3 of these dimensions with the implanted material.
More advanced and recent techniques for surgical treatment of UVFP using laryngeal framework surgery have involved manipulation of the arytenoid cartilage, namely arytenoid adduction. Isshiki also pioneered arytenoid adduction, an operation that places the arytenoid cartilage in the most favorable position for rehabilitation of the paralyzed vocal fold. Isshiki described placing a suture through the muscular process of the arytenoid cartilage and drawing the suture anteriorly into the larynx (arytenoid adduction). Woodson and Zeitels have proposed modifications to the Isshiki procedure to enhance the arytenoid repositioning. The former suggests the placement of a second suture on the muscular process of the arytenoid and securing it to the lateral-inferior aspect of the cricoid to simulate the pull of the vertical belly of the posterior cricoarytenoid muscle.
Surgical treatment of the arytenoid cartilage for UVFP is important to restore optimal length/tension of the paralyzed vocal fold and to medialize the posterior glottis. The latter has become an indication for patients with severe dysphagia, especially those patients who have been identified to have aspiration pneumonia due to incompetence of the posterior glottis.
These operations are more technically challenging than a medialization laryngoplasty and are not required for every patient with UVFP; however, combined surgical treatment of UVFP with both an adduction procedure involving the arytenoid cartilage and medialization laryngoplasty has been found to yield maximal vocal rehabilitation by many leading surgeons. This is a reasonable conclusion because medialization laryngoplasty addresses the position and bulk of the membranous vocal fold while operations on the arytenoid address tension and length of the paralyzed vocal fold. Addressing all of the distinct and important features of the paralyzed vocal fold yields the best surgical result for this condition.
In 1999, Zeitels described a new laryngeal framework procedure for UVFP called cricothyroid subluxation. This procedure involves anteriorly displacing the ipsilateral inferior cornu of the thyroid cartilage. This is performed by placement of a suture that runs from the inferior cornu of the thyroid cartilage to the midline of the cricoid cartilage. This effectively rotates the thyroid cartilage on the cricoid cartilage, providing additional length to the paralyzed vocal fold.
See the videos below.
Vocal fold paralysis, presurgery.
Vocal fold paralysis, postsurgery.
A retrospective study by Sanuki et al suggested that nerve-muscle pedicle (NMP) flap implantation may lead to reinnervation of the laryngeal muscles in patients with UVFP. In the study, 12 patients with the condition underwent a combination of refined NMP flap implantation and arytenoid adduction. Postoperatively, patients demonstrated improved phonatory function, while LEMG showed improved motor unit recruitment.
See use of LEMG in Other Tests for diagnosis and prognosis.
During both in-office vocal fold injections and laryngeal framework surgery (thyroplasty and arytenoid adduction), voice is monitored. Voice quality is observed both perceptually and with laryngeal examination via flexible fiberoptic nasolaryngoscopy. This allows the surgeon to control or adjust the surgery to optimize the voice quality at the end of the procedure. This is an essential to high-quality phonosurgery and is the reason these procedures in general should not be conducted under general anesthesia. Today, vocal fold injections are commonly performed as office-based outpatient procedures with topical anesthesia.
After lipoinjection, patients are placed on voice rest to enhance the survival of the transplanted fat. This is typically for 5-7 days in duration. One or 2 days of voice rest are usually sufficient for other injectable materials, particularly those that use small (25- or 27-gauge) needles. No rest or minimal voice rest is necessary after laryngeal framework procedures.
A voice evaluation is indicated following surgical treatment of a unilateral vocal fold paralysis (UVFP). This evaluation should include a patient-based assessment of the voice function and head and neck examination, including indirect laryngoscopy and voice evaluation by a speech pathologist. The latter is important to assist in deciding whether the patient would be best served with postoperative voice therapy.
Complications of surgical treatment for unilateral vocal fold paralysis (UVFP) include poor voice outcome, airway difficulties, and migration of the medialization implant. Given that surgical treatment for UVFP involves manipulation of the airway, factors such as swelling or a hematoma from either laryngeal framework surgery or vocal fold injection can cause airway difficulties. Prevention of this complication involves meticulous and precise surgical technique and the use of preoperative and postoperative steroids. A greater risk exists for airway compromise and difficulties when a bilateral procedure is performed, such as bilateral medialization laryngoplasty or bilateral vocal fold injection (for UVFP or contralateral vocal fold atrophy).
Unless the surgery is performed strictly for dysphagia or pulmonary toilet/cough improvement, most surgical procedures for UVFP are elective in nature and are aimed at improving voice quality; if voice quality does not improve, this should be considered a complication of the procedure. Often, poor voice quality or the inability to improve the voice following laryngeal framework surgery can be rectified with revision medialization laryngoplasty, with or without an arytenoid adduction procedure.
The most common reason for poor voice quality following medialization laryngoplasty is improper placement of the thyroplasty implant in a too anterior and/or too superior direction. In addition, the implant size can be either too large or too small. Often, the implant is made too small because of a false sense of adequate medialization that occurs intraoperatively as a result of perioperative edema prior to implant placement of the thyroplasty implant. This can be prevented by the use of preoperative steroids, as well as expedient surgery, to minimize paraglottic edema prior to placement and sizing of the thyroplasty implant.
Thyroplasty implant migration can occur postoperatively, either medially into the airway or laterally into the neck. The former obviously is of great concern but appears to be rare. A single case report exists of complication of medialization laryngoplasty (silastic) caused by a delayed allergic response to the silastic implant.
Expected voice outcome following the treatment for unilateral vocal fold paralysis (UVFP) is excellent. Most patients resume normal speaking activities and functions and are able to meet all normal voice demands. Singing is a higher demand than speaking and may not be restored to its premorbid condition. The ability to project one's voice over a large area in a loud manner is also often never fully restored despite optimal medical, behavioral, and surgical treatment. Most patients should have a normal or near-normal speaking voice ability with minimal to no functional limitations of their everyday voice use following successful treatment.
Understand that present surgical treatments only provide static improvement to the vocal fold and cannot provide the dynamic activity of the vocal fold to voice production that was present in the premorbid state.
Thus, the future goal of laryngology research is to create a method of dynamic rehabilitation of the paralyzed vocal fold. This goal has been present for decades, and much work has been devoted to the concept of reinnervation of the vocal fold. In humans, the optimal result from reinnervation is a static vocal fold but one that has tone. Often, laryngeal reinnervation is performed simultaneously or sequentially with medialization laryngoplasty. The future of laryngeal reinnervation is unknown but serves as a vast area for research and progress.