You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > LARYNGOLOGY Vocal Fold Paralysis, UnilateralArticle Last Updated: Jun 16, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Clark A Rosen, MD, Director, University of Pittsburgh Voice Center; Associate Professor, Department of Otolaryngology and Communication Science and Disorders, University of Pittsburgh School of Medicine Clark A Rosen is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American College of Surgeons, American Medical Association, and Pennsylvania Medical Society Coauthor(s): Ryan J Soose, MD, Staff Physician, Department of Otolaryngology, University of Pittsburgh Medical Center Editors: John Schweinfurth, MD, Associate Professor, Department of Otolaryngology, University of Mississippi Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Robert M Kellman, MD, Professor and Chair, Department of Otolaryngology and Communication Sciences, State University of New York Upstate Medical University; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: unilateral vocal fold paralysis, UVFP, vocal cord paralysis, neurogenic hoarseness INTRODUCTIONSection 2 of 12
  Unilateral vocal fold paralysis (UVFP) occurs from a dysfunction of the recurrent or vagus nerve innervating the larynx and causes a characteristic breathy voice. This is a common cause of neurogenic hoarseness. When this paralysis is properly evaluated and treated, normal speaking voice is typically restored. History of the ProcedureUVFP most commonly occurs following a surgical iatrogenic injury to the vagus or recurrent laryngeal nerve. Thus, a history of recent head, neck, or chest surgery should be obtained. Specifically, thyroidectomy, carotid endartectomy, anterior spine surgery, and thoracic or mediastinal surgery can lead to a UVFP. In addition, UVFP can occur following an upper respiratory or viral infection. ProblemUVFP causes a breathy weak dysphonia because of glottal incompetence that has resulted from the vocal fold paralysis. Normal vocal fold function is reliant on vocal fold glottal closure that results from bilateral adduction of the vocal folds. This vocal fold adduction behavior, in combination with subglottic airflow, induces vocal fold vibration. UVFP results in glottal incompetence, either partial or complete, because of the poor or reduced vocal fold closure resulting in a weak and uncoordinated vocal fold vibration that leads to dysphonia. Etiology
PathophysiologyThe 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 wraps around the subclavian artery and proceeds cephalad to the larynx. 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. ClinicalPatients with 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 falsetto. 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. INDICATIONSSection 3 of 12
The indications for treatment of UVFP are usually the resultant dysphonia. Treatment may be more imperative if severe dysphagia is present. If patients experience dysphagia, then they are at risk for aspiration pneumonia and treatment should be implemented immediately. For dysphonia related to UVFP, treatment should be determined based on the patient's functional needs and demands. 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 coexisting morbidities that occur during postoperative recovery. 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 inventory has been shown to be a reliable and useful patient-based survey instrument, quantifying the patient's voice handicap due to their voice disorder. Note that the indications for treatment are related to the patient's function and limitations. Nonsurgical treatment can be offered to patients with UVFP, especially those who are unwilling or unable to proceed with surgical treatment. RELEVANT ANATOMYSection 4 of 12
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 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, 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. CONTRAINDICATIONSSection 5 of 12
No contraindications exist for the nonsurgical treatment of UVFP other than the patient not indicating or realizing the need for treatment. Thus, if voice therapy is recommended for the patient but the patient sees no need for treatment, obviously, treatment is not undertaken. Contraindications for the surgical treatment of UVFP include medical problems, such as severe cardiac or pulmonary limitations or anticoagulation therapy. 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. WORKUPSection 6 of 12
Imaging Studies
Other Tests
TREATMENTSection 7 of 12
Medical therapy
Surgical therapyMultiple surgeries are available for the treatment of 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). 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. Cross-linked bovine collagen (Zyplast/Zyderm) is another effective injection material. The primary drawback is the need for allergy skin testing before use (14 d). 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 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 no resorption over the 2 years since it has been used clinically. 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. Both temporary and permanent 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 permanent 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 working 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. 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 thyroplasty implant option 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 recently 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 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. Preoperative detailsSee use of LEMG in Other Tests for diagnosis and prognosis. Intraoperative detailsDuring both vocal fold injection and laryngeal framework surgery (thyroplasty and arytenoid adduction), voice is monitored. Voice quality is observed both perceptually and with laryngeal examination via flexible fiberoptic nasopharyngoscopy. 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. Postoperative detailsPatients after lipoinjection are placed on voice rest to enhance the survival of the transplanted fat. This is typically for 6-7 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. Follow-upA voice evaluation is indicated following surgical treatment of a 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. COMPLICATIONSSection 8 of 12
Complications of surgical treatment for 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, 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. OUTCOME AND PROGNOSISSection 9 of 12
Expected voice outcome following the treatment for 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. FUTURE AND CONTROVERSIESSection 10 of 12
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. Unfortunately, this type of work has been unsuccessful for most surgeons, and much research is required to better understand the delicate innervation of the muscles of the larynx and their coordination. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Vocal Fold Paralysis, Unilateral excerpt Article Last Updated: Jun 16, 2006 | |||||||||||||||||||
