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Recurrent laryngeal nerve paralysis: Current concepts and treatment: Part III--Surgical options.

[Editor's note: This is Part III of an article reprinted from Annales d'Otolaryngologie et de Chirurgie Cervico-Faciale [*], Part I--"Phylogenesis and physiology," appeared in the November2000 issue of Ear, Nose & Throat Journal and included the references for the entire three-part article. Part II--"Causes, diagnosis, and management" appeared in the December 2000 issue of Ear, Nose & Throat Journal.]

Indications for surgical treatment

Surgical treatment depends on the severity of symptoms, the general health of the patient, and the patient's wishes in terms of voice quality. [51] Aspiration is a major factor in initial evaluation and surgical indication. Aspiration pneumonia is life-threatening, with high mortality, especially after lung surgery. [65] Glottic insufficiency decreases the effectiveness of cough, so the treatment of URLNP in patients suffering from chronic bronchitis is aimed at preventing complications of insufficient lung clearance. Patients with poor general health unrelated to pulmonary disease may also benefit from early surgery, avoiding pulmonary complications of URLNP.

Aspiration may occur whatever the origin of the URLNP, but it seems to occur more frequently and more severely in cases of vagal nerve lesions. Sensation in the pharynx and larynx is diminished in vagal lesions by damage to the internal branch of the SLN and the pharyngeal plexus. In this case, paresis or paralysis of the pharyngeal constrictor muscles and the velum contributes to dysphagia and aspiration.

Management of aspiration in URLNP has three levels: adaptation of food, swallowing exercises, and VC medialization. First, liquids should be excluded from the diet. Water in jellified form may be consumed if little or no aspiration is detected. If general health and pulmonary function are excellent and aspiration occurs rarely (type I or rarely type II, according to Pearson's classification [66]), swallowing therapy may suffice to avoid complications. Therapy includes rotating the neck toward the paralyzed side to direct the bolus to the piriform sinus on the healthy side, partial cervical flexion during swallowing, "double swallow," and other maneuvers. [45] If aspiration presents a major health risk, if it occurs for each swallow, or if for any other reason it is poorly tolerated, surgery is indicated.

In the absence of aspiration, surgical intervention depends on the patient's profession (voice professional) and his or her wishes in terms of voice quality. The social and professional role of voice must be taken very seriously. Once surgery has been decided, the timing and the type of procedure need to be determined.

Timing of surgery

Timing relative to the onset of URLNP depends on the severity of symptoms and on the mechanism of the neural lesion. In high vagal nerve resection (in skull base surgery, for example), symptoms are often severe and chances of spontaneous recovery are extremely low. Early surgical treatment, or even immediate medialization, performed at the time of vagal resection is often recommended. [51] In this case, however, the difficulty lies in estimating the degree of medialization necessary to compensate for ulterior VC atrophy.

For resection of the RLN, symptoms vary in severity and surgical indications vary. Early surgery is justified in cases of severe aspiration or for vocal necessity (voice professionals), while awaiting an eventual spontaneous compensation or reinnervation. If the RLN was sectioned but surgical anastomosis was performed immediately, severity and evolution are unpredictable. Again, if symptoms are severe, surgery is indicated despite an eventual spontaneous reinnervation or compensation.

If the type of nerve damage is unknown or if the paralysis is well tolerated, a waiting period of 12 months is indicated to allow for spontaneous recovery of motion, favorable synkinesis, or laryngeal compensation. [37,51] Again, if the mechanism of nerve damage is unknown and the symptoms severe, early surgery is indicated. [51] A reversible procedure is recommended in cases of ulterior spontaneous recovery, favorable synkinesis, or compensation. If little or no voice improvement is noted after the 12-month waiting period, a "permanent" surgical procedure should be considered according to the patient's wishes in terms of voice quality.

Type of surgical procedure

The procedure depends on the general health of the patient, his or her needs or wishes in terms of voice quality, the glottic configuration, and the experience of the surgeon. Most medical teams recommend preoperative evaluation by a voice specialist and a speech therapist. [45,51] Voice recordings and objective acoustic and aerodynamic evaluation are performed. The speech therapist aids in evaluating the patient's vocal needs and can initiate breathing exercises.

The preoperative physical workup is designed to determine glottal configuration during phonation. Video documentation using fiberoptic or telescopic laryngoscopy and/or stroboscopy is recommended. The type of glottic gap should be noted: membranous (elliptical) or membranous and cartilaginous (triangular). [45] The relative level of the vocal folds on phonation, with a lower or higher paralyzed fold, should be evaluated. Glottic configuration must be precisely determined because the various surgical techniques address these configurations differently.

Techniques for VC medialization belong to four general categories: medialization thyroplasty, arytenoid adduction, intracord injection, and laryngeal reinnervation. Each technique has its particular indications, advantages, disadvantages, and complications.

Medialization thyroplasty

Introduction. In 1915, Payr was the first to report external VC medialization using a thyroid cartilage flap. [67] Isshiki et al in 1974 were the first to describe the technique in detail and to employ it for treating glottic incompetence. [9] The technique is now known as the Isshiki type I procedure (the other procedures described by Isshiki are not employed for treating URLNP). Thyroplasty consists of introducing an implant through a window in the thyroid cartilage to medialize the VC and the vocal process.

Technique. External thyroplasty should be performed using local anesthesia, with or without light sedation. This allows precise placement of the implant according to the intraoperative voice result. Performed under general anesthesia, the phonatory results are unpredictable, and an eventual endotracheal tube impedes correct medialization. During the procedure, fiberoptic laryngoscopy is performed, allowing intraoperative visualization of the laryngeal configuration at rest and during phonation.

A horizontal cutaneous incision 5 to 6 cm long is made at the midlevel of the thyroid cartilage on the paralyzed side. [45] The superior subplatysmal flap is raised to the superior border of the thyroid cartilage and the inferior flap to the superior border of the cricoid cartilage. The midline is incised and the strap muscles reclined laterally. The external thyroid perichondrium is then elevated from the midline laterally to the posterior border of the thyroid ala.

The VC is located midway between the thyroid notch and the inferior border of the thyroid cartilage. It is currently recommended to delineate the thyroid window in a low position, as the contralateral normal VC adducts and is lowered during phonation. [44] The risk of implanting the prosthesis in the ventricle is decreased with a low window placement as well. Tucker et al [68] advise placing the window 5 mm above the inferior border of the thyroid cartilage, while Netterville et al [69] advise 3 mm. Hoffman and McCulloch place the window at the junction between the superior two-thirds and the inferior one-third of the thyroid ala along the oblique line. [45]

The anterior border of the window should remain 5 to 10 mm from the midline to avoid damage to the anterior commissure or extrusion of the implant, the anterior VC being relatively thin. [67] The posterior limit should be 10mm from the posterior border of the thyroid ala. [68] For all the techniques, the window is located just above the inferior tubercule, an external anatomic landmark for the vocal process of the arytenoid.

The window is outlined on the thyroid cartilage using electrocautery or methylene blue. For the Montgomery thyroplasty technique, special instruments are employed to place and outline the window . [70] Incision of the cartilage is performed using a scalpel (for nonossified cartilage), a diamond burr with continuous irrigation, or with a microsaw. [70] The shape of the window depends on the type of implant: rectangular for silicone or hydroxyapatite implants, round for the Gore-Tex ribbon implants. Contrary to some initial reports, it is not necessary to retain the resected fragment of cartilage. In fact, it is not recommended due to secondary resorption or displacement of the fragment, with unpredictable vocal results. [68]

After drilling the window, the internal perichondrium is delicately raised from the internal surface of the thyroid ala 2 to 4 mm in all directions. Incision of the perichondrium is recommended by several authors; in fact, it seems to be necessary for correct implant positioning. [45,51,69,71] Netterville et al recommend perichondrial incision along the superior, posterior, and inferior borders of the window, creating an anteriorly based perichondrial flap. [69] Perichondrial incision nearly always causes bleeding in the TA muscle, which must be carefully controlled using bipolar cautery.

The implant type depends on the experience and choice of the surgeon and eventually the implant cost. The hypothetical ideal implant is biologically inert, presculpted to the adequate shape and size, easy to place, reversible, and readily available at a low cost. [45] Silastic (silicone polymer), hydroxyapatite, and Gore-Tex (expanded polytetrafluoroethylene or ePTFE [72]) are currently employed for implants. The shape varies from rectangular, to rectangular with an anterior triangular pyramid (for medialization close to the anterior commissure) or a posterior triangular pyramid (for medialization of the vocal process of the arytenoid), or both. Some implants are preshaped, [70] while others must be shaped intraoperatively. Gore-Tex is in the form of a cardiac patch that is cut into a ribbon.

A slight overcorrection is recommended to compensate for resorption of the postoperative laryngeal edema. [73] Overcorrection is also recommended in cases of early surgery due to later muscular atrophy that can cause poor voice quality despite the implant. Maximal medialization should be obtained at the posteroinferior corner of the window, corresponding to the vocal process. [69] Depth at this point is measured by pushing the vocal process (with a microelevator or with a special measuring instrument) while the patient phonates. This depth is modified until the optimal vocal result is obtained. Depth corresponds to the width of the implant. Placement of the implant should be rapid in order to adequately evaluate voice quality before the onset of laryngeal edema. [51]

Hemostasis is checked and the incision is closed in layers on a suction drain, which is maintained for 24 hours. Perioperative steroids (prednisone 1 mg/kg) is recommended by some authors. [71,73] Most authors also recommend prophylactic oral antibiotics for 5 to 7 days postoperatively. [71-73] Tucker et al [68] and Montgomery et al [71] recommend a 24-hour hospitalization postoperatively in order to diagnose and treat possible complications, especially dyspnea due to laryngeal edema or hematoma.

Advantages and disadvantages. Thyroplasty is a relatively simple technique to learn and results are rapidly reproducible, unlike Teflon injection, for example, in which results are unpredictable without considerable experience. Local anesthesia permits physiologic vocal fold motion during phonation intraoperatively, allowing precise implant positioning and shaping. [74] The technique is theoretically reversible, but fibrosis and foreign body reaction may permanently affect voice even after implant removal. [75,76]

It seems that thyroplasty does not sufficiently close the posterior glottis, and thus it may yield disappointing results if used alone in cases of a large posterior glottal gap. [45,52] The degree of medialization of the anterior glottis and the site of maximal medialization are, however, adjustable intraoperatively [74] or later in cases of voice modifications. [72]

The Montgomery implant is radiographically opaque, allowing visualization on standard neck x-ray in cases of displacement or extrusion. [70,71] The major advantages of preformed implants are their rapid placement and their secure locking system. But the drilling of the thyroid window needs to be of a precise shape and size, and the cost of these implants is high. Sculpting a Silastic block intraoperatively is difficult and increases the duration of surgery. Some have recommended partial initial carving before sterilization of the Silastic block to partially decrease sculpting time, [45] but exact sizing and shaping is still difficult. Gore-Tex is much simpler in that it requires no precise sculpting, window drilling, or specific instrumentation. [72] A 4-mm-wide ribbon is cut out of a cardiac patch and inserted little by little through around thyroplasty window, which can vary in shape and size. The biocompatibility of Gore-Tex is well known after more than 20 years of use in cardiac surgery.

All of these biomaterials provoke a local inflammatory reaction. This reaction seems to be less severe than with Teflon (see below). Extrusion or displacement of the implant is always a risk. The viscoelastic properties of these materials are radically different from those of the normal vocal fold, [77] and thus they may interfere with normal laryngeal vibration and alter voice quality. Finally, the external approach leaves a cutaneous scar.

Indications. The reversibility of thyroplasty has not yet been sufficiently demonstrated to consider it as a "temporary" treatment. For this reason, early thyroplasty does not appear to be recommended if spontaneous recovery is likely. The indisputable indication is any stable, definitive paralysis without surgical contraindications. In the case of a large posterior glottal gap, thyroplasty alone may be insufficient and may be associated with arytenoid adduction (see below). The choice of implant depends especially on the personal experience of the surgeon.

Abnormal hemostasis and allergic reaction to local anesthesia are the main contraindications to external thyroplasty. Previous laryngeal surgery (cordectomy) and external-beam radiation to the larynx are relative contraindications because of the increased risk of implant extrusion and infection. [69] Previous Teflon injection is not a contraindication, but scarring and changes in the mass and elasticity of the VC due to Teflon will influence the vocal result. [73] Thyroplasty following Teflon injection is technically difficult as well.

Complications. Laryngeal obstruction due to hematoma within the first postoperative week is the most frequent and dangerous complication of external thyroplasty, occurring in 2 to 10% of cases. [67,68,73] Several reported cases were treated by emergency surgery for hemostasis or by temporary tracheotomy. Postoperative laryngeal edema, occurring in 2 to 4% of cases, usually requires only hospitalization for surveillance and steroid treatment. [71,73,74] Displacement and extrusion of the implant are rare, [67,68] but can occur immediately postoperatively or years later, especially after laryngeal trauma. [73]

Vocal results. For most authors, voice is excellent immediately after surgery. Objective acoustic and aerodynamic parameters were significantly improved in a group of 43 patients studied by McLean-Mus et al. [78] During the first months, voice quality apparently deteriorates slowly and stabilizes after approximately 3 months. [69,79] Overcorrection is recommended to compensate for operative laryngeal edema and for later VC atrophy. Satisfactory voice is obtained in 70 to 90% of cases. [67,73,74,80] Reintervention for implant adjustment improved results to 94% for Cummings et al. [73]

Arytenoid adduction

Introduction. This technique was also first described by Isshiki et al in 1978. [44] The aim is to pull the muscular process of the arytenoid laterally, reproducing the mechanical effects of the TA and LCA muscles and allowing physiologic motion at the cricoarytenoid joint. The body of the arytenoid rocks medially and the vocal process is adducted and lowered. This technique can be used alone or, as stated above, in conjunction with external thyroplasty or vocal fold injection.

Surgical technique. Arytenoid adduction is ideally performed using local anesthesia in order to adjust adduction according to intraoperative phonation. The approach to the thyroid ala is the same as for thyroplasty, with lateral or medial retraction of the strap muscles. The goal is to expose the posterior border of the thyroid ala. The insertions of the inferior constrictor muscle on the paralyzed side are incised along the inferior one-third of the thyroid ala. The piriform sinus mucosa is elevated in order to palpate the arytenoid cartilage and its muscular process. The arytenoid is located approximately between the anterior two-thirds and the posterior one-third of the thyroid ala. Exposure can be improved by resecting a posterior band of thyroid cartilage. [45,69,81] The muscular process is identified by following the PCA muscle fibers from their cricoid insertions to the arytenoid. One or two 3-0 or 4-0 Prolene sutures are placed through the muscular process or in the pericartilaginous tissue. These su tures are passed anteriorly through two small drill holes placed 5 to 10mm from the midline in the inferior one-third of the thyroid ala with a Keith's needle. The sutures are knotted at the anterior surface of the thyroid cartilage, and the wound is closed in layers on a suction drain.

Advantages and disadvantages. Local anesthesia allows intraoperative phonatory adjustment of the sutures. In theory, arytenoid adduction is reversible if the cricoarytenoid joint remains intact. The surgical technique is rather delicate and necessitates a certain amount of training and experience. Adduction permits closure of the posterior glottal gap, but little medialization of the membranous VC is obtained. It is often necessary to associate thyroplasty or vocal fold injection. [44,45]

Indications. Glottal configuration determines the need for arytenoid adduction. Adduction addresses the posterior glottal gap (lack of contact between vocal processes) on phonation. Arytenoid adduction also lowers the vocal process on the paralyzed side, correcting vocal fold approximation in the frontal plane. [53,69]

Complications. Postoperative laryngeal edema is the most frequently occurring complication, and it generally responds favorably to steroids and hospitalization for surveillance. Laryngeal hematoma following arytenoid adduction has never been reported in the literature. Suture displacement is possible, [67] as is local wound infection and an unaesthetic scar.

Results. Some authors systematically associate arytenoid adduction and thyroplasty. [52,69] Recent studies have not shown a significant difference in objective voice results between the two techniques (jitter, shimmer, harmonics-to-noise ratio, phonatory airflow rate). [82] This may also be due to the lack of sensitivity of these objective parameters. The technique seems to have less favorable results in cases of long-standing URLNP due to muscular atrophy and fibrosis. [45] Initially, Isshiki et al opened the cricoarytenoid joint in order to more easily place the sutures and in order to stabilize the adduction by causing cricoarytenoid ankylosis. Hoffman and McCulloch, however, recommend not opening the joint because of the risk of joint destabilization and arytenoid prolapse into the laryngeal lumen. [45] They also maintain that joint opening is not necessary for proper adduction.

Vocal fold injection

Introduction. In 1910, Brunings was the first to describe the technique of endoscopic vocal fold injection. He developed a gun-like syringe still used today. [45,83] Teflon injection was first described by Arnold in 1962, and it has been widely employed ever since. [84] The injection is designed to increase vocal fold volume and, to a lesser degree, medialize the vocal process. It must be performed within the vocalis muscle so as not to traumatize the vocal ligament or the superficial lamina propria, thus preserving the vibratory characteristics of these structures.

Surgical technique. Injection methods differ essentially in the substance injected. Silicone seems to be employed more frequently in Japan, whereas Teflon (polytetrafluoroethylene [72]) is used in the U.S. and in Europe. More recently, Gelfoam, collagen (human or bovine), autologous fat, hydroxyapatite cement, and a new silicone suspension are being investigated and employed. [76] The injection is most often performed endoscopically, although transcutaneous injection has also been described. Injection via indirect mirror laryngoscopy and a curved needle is rarely performed due to the difficulty, the learning curve, and the need for a high level of patient cooperation. [45]

The ideal material for injection would be, according to Arnold, easily injected, perfectly biocompatible, and inert over the long term. Such a material does not yet exist. Teflon, for example, is easy to inject and has lasting effects in the larynx, but its biocompatibility is limited, with frequent complications with time. Autologous fat is easily injected and perfectly biocompatible, but it tends to be reabsorbed with unpredictable long-term effects in the larynx. [85]

Teflon injection. The injection is performed with the patient under general anesthesia with tracheal intubation or under simple sedation with spontaneous breathing. Sedation allows for a better evaluation of the volume to inject by asking the patient to vocalize intraoperatively. However, the natural vocal fold motion during breathing may interfere with precise placement of the needle. General anesthesia immobilizes the larynx and is more comfortable for the patient. However, the tracheal tube can interfere with needle placement and with vocal fold medialization. Jet ventilation eliminates the disadvantages of both techniques, but it is not without risk (pneumothorax and pneumomediastinum). [83]

The laryngoscope should be placed just cranial to the vocal folds so as not to artificially modify glottic configuration. The operating microscope is not employed, as it gets in the way of the injector and does not improve needle placement notably.

A Brunings' injector is filled with 3 ml of Teflon. Two injections are made on the paralyzed side. The first is done 2 to 3 mm lateral to the vocal process, while the second is placed 4 to 5 mm anterior to the first in the TA muscle. Both injections are made at a depth of 3 to 5 mm. [45] It is better to underinject Teflon, as secondary removal is extremely difficult and damaging to the vocal fold. Reinjection is always possible if the vocal result is insufficient.

Transcutaneous injection is made through the cricothyroid membrane, passes deep to the subglottic mucosa, and enters the vocal fold without penetrating into the laryngeal lumen. Correct needle placement is followed and volume evaluated using fiberoptic laryngoscopy.

Autologous fat. In 1991, Mikaelian et al were the first to report the use of autologous fat to treat glottic incompetence in URLNP. [86] Fat is harvested from the thigh or abdomen using a cutaneous incision or lipoaspiration under local or general anesthesia. If fat is harvested via a cutaneous incision, it is necessary to remove the fibrous tissue and blood vessels and to morcellate the fat. Most recommend rinsing the harvested fat in saline to remove the blood and free fatty acids. Fat harvested by an incision seems to have a longer half-life than fat harvested by lipoaspiration. In addition, lipoaspiration is impossible in some patients in poor general health with little body fat. [87] The placement and depth of injection are identical to those for Teflon. It is necessary to overcorrect when using autologous fat. [88] An injection of 6 ml is generally sufficient to obtain a medial convexity. A transcutaneous approach may also be employed.

Steroids are administered intraoperatively (1 mg/kg of intravenous prednisone). Most authors also recommend oral antibiotics for 5 to 7 days postoperatively. Oral feeding is allowed several hours postoperatively if no complication arises. Voice rest is not necessary. [86]

Advantages and disadvantages. Teflon and autologous fat are inexpensive, as compared with collagen and the new biomaterials, and their effects in tissues are well documented. Whichever implant material is used, the technique is easy and quick to perform ([less than or equal to]15 min), but it requires general anesthesia or heavy sedation for direct laryngoscopy. The injection increases the volume of the paralyzed vocal fold and, to a lesser degree, medializes the vocal process. [89,90] Intraoperative voice evaluation is generally not possible. Finally, injection may be insufficient in cases of advanced vocal fold atrophy and fibrosis. [67]

Teflon injection is essentially irreversible. Although Dedo reported removal, [46] the effects of vocal fold scarring after removal would seem to lead to a poor voice quality. Voice results are variable due to the low elasticity of Teflon and the inflammatory reaction with fibrosis that results. [76] Reproducible results seem to be attainable after much surgical experience. Laryngeal granuloma is frequent (see below), and extrusion and mucosal ulceration are possible. [74] Teflon has been shown to migrate to regional lymph nodes and even to distant organs. [76]

Autologous fat is the ideal implant in its abundance, low cost, and perfect biocompatibility. [89] Its viscosity is close to that of laryngeal mucosa, increasing the ease of phonation after injection compared with other materials. [77] Fat has been shown, however, to be resorbed to an apparently unpredictable degree. Hoffman and McCulloch have reported persistence of fat in the vocalis muscle after 5 months. [45] Others have found a persistence of vocal fold augmentation in 30 to 40% of cases after 12 months. [65,85,91] In cases of resorption with an adverse effect on voice, fat can always be reinjected, and previous fat injection does not preclude the use of other medialization techniques later. [45]

Indications. The irreversibility of Teflon and its potential complications tend to limit its use today. Teflon is indicated only when the paralysis is judged to be irreversible and favorable synkinesis has not occurred. The rapidity of injection makes it an ideal substance in case of poor general health or poor prognosis, as granuloma tends to arise after several months or years (see below). Teflon is contraindicated if spontaneous recovery or synkinesis is to be expected, as it is irreversibly injected and can lead to poor vocal outcome. Inflammatory disease of the larynx is also a contraindication, as Teflon promotes local chronic inflammation. [76,83]

Because of its potential resorption, autologous fat is especially indicated as a temporary symptomatic treatment for swallowing and voice while awaiting spontaneous recovery with synkinesis. [92] Fat injection can also be considered as a therapeutic trial before another medialization technique or injection with an irreversible material.

Complications. As stated above, granuloma is the most frequent complication of Teflon injection. It appeared after 6 months and up to several years following injection for 36% of patients in the series reported by Gardner et al. [93] Airway obstruction with stridor occurs within the first few days after injection and seems to be most often due to overinjection. [46,93] This complication can require tracheotomy or reintervention for the removal of Teflon. Teflon can be dislodged or displaced within the larynx, and it also tends to migrate to regional lymph nodes and distant sites. [45,76,90]

Injection of autologous fat seems to have few complications, the most frequent being hematoma and infection at the site of fat harvest. One case of vocal fold pseudocyst has been reported after injection superficially into the superficial lamina propria. [87]

Results. Autologous fat has been routinely employed with success in treating aspiration due to URLNP. [65,87] Excellent vocal results have also been reported. [90,91,94] Voice that is excellent initially tends to deteriorate during the first 3 months and then stabilize for the next 3 to 9 months. [91] If lasting results are not obtained, reinjection or another medialization technique is indicated. Finally, injection addresses the anterior glottis better than the posterior glottis. [94] A laryngeal configuration with a large posterior glottal gap would probably benefit from associated arytenoid adduction.

Laryngeal reinnervation techniques

Introduction. The first description of laryngeal reinnervation is attributed to Frazier and Mosser in 1926. [84] The aim of reinnervation is to increase the motor afferences to the TA muscle to maintain at least muscular tone and volume. Reinnervation can be performed by direct end-to-end anastomosis with a nerve-muscle pedicled flap (strap muscle) or by direct electrical laryngeal stimulation. Reinnervation is said to decrease the glottal gap and improve the vibratory characteristics of the paralyzed vocal fold. Most of these techniques are still experimental and are generally associated with other techniques of medialization when a predictable vocal result is necessary. [84,95]

Surgical techniques. End-to-end anastomosis is performed between the proximal end of the recurrent laryngeal nerve and the distal end of the ansa hypoglossi on the paralyzed side. The suture is a typical nerve anastomosis using epineurial microsutures (10/0 diameter, in general). Dissection and preparation of the cut recurrent nerve may be long and difficult if previous cervical surgery has been performed.

The nerve-muscle pedicled patch technique employs much the same external approach as that used for thyroplasty. The cutaneous incision is extended to the anterior border of the sternomastoid muscle. The muscle is retracted laterally, and the internal jugular vein and the ansa hypoglossi are identified. The latter is followed to its extremity in the anterior belly of the omohyoid or other strap muscle. A muscle fragment of approximately 1 [cm.sup.3] containing the nerve end is isolated. This flap is inserted into a window made in the thyroid cartilage, as for thyroplasty, with the internal perichondrium resected to expose the TA muscle. Two or three small sutures fix the flap to the muscle. Closure and postoperative course are the same as for thyroplasty. [95]

The laryngeal pacing technique is still under experimentation in animals due to several unresolved technical considerations. [96] Electrode miniaturization is necessary, but it is difficult in that the smaller the electrode, the higher the impedance, and thus the more heat produced, leading to muscular bums. [97] The ideal source for the rhythm of laryngeal pacing is still controversial; some employ the contralateral larynx, others the CT muscle, and still others the diaphragm. Complications are frequent: electrode displacement, electrical interference, software deficiencies, inflammation, infection, and laryngeal muscle damage. Reliability and tolerance as yet remain insufficient for use in humans.

Advantages and disadvantages. Nerve anastomosis and the nerve-muscle pedicled flap can be performed using local anesthesia, avoiding general anesthesia and shortening hospital stay. Both procedures can be associated with thyroplasty or arytenoid adduction in a one-step procedure. [51,98] Both techniques serve to decrease vocal fold atrophy. [98] Reinnervation seems to be less successful in cases of longstanding paralysis with onset of muscular atrophy. [98] The muscular patch has the advantage of selectively reinnervating the TA muscle, as compared with end-to-end anastomosis, in which synkinesis involving other laryngeal muscles may occur. The muscular patch also leaves the recurrent nerve intact and thus allows synkinesis to eventually occur. [69,98]

Reinnervation is not a widely employed technique. Dissection can be long and require a certain degree of experience. Vocal results are unpredictable and become apparent only after 2 to 6 months postoperatively. [84,98] In theory, there is a risk of unfavorable synkinesis for end-to-end anastomosis. Woodson attributes the variable vocal results to a competition between spontaneous reinnervation with synkinesis and the surgical reinnervation. [38] It seems, in fact, that surgical reinnervation is unsuccessful if synkinesis is already present. [84] Also, in order to obtain true abductor function, selective reinnervation of the PCA by nerve fibers active during inspiration (the phrenic nerve, for example) is necessary. The present techniques do not furnish adequate specificity for this function. [39]

Indications. Today reinnervation is essentially indicated in conjunction with other techniques for treating URLNP as a means of decreasing vocal fold atrophy. [84] The main contraindication is the surgeon's unfamiliarity with the technique.

Complications. Cervical hematoma and wound infection are the principal complications, as with any type of surgery. Goding considers an insufficient vocal result to be a complication of reinnervation when used as a sole treatment. [99]

Results. According to Goding, satisfactory voice results were obtained in 88 to 95% of patients treated with the nerve-muscle pedicled patch. [99] Objective voice measurements (cepstral peak and jitter) significantly improved in 12 patients 8 months after end-to-end anastomosis in a study by Olson et al. [100] Laryngeal mobility on the operated side is observed in 5 to 40% of cases to varying degrees. [99] Vocal fold muscle tone is preserved or improved in the majority of cases.

A summary of the advantages and disadvantages of the surgical techniques is shown in the table.

Conclusions

Unilateral laryngeal paralysis can arise from many different causes. Evolution of the paralysis is often unpredictable, inasmuch as pathophysiology is still incompletely elucidated. Indications for treatment depend on the symptoms associated with the paralysis, on the general health of the patient, and on the skills and habits of the surgeon. Thyroplasty and vocal cord injection are well known and widely employed. Aspiration and poor voice quality are successfully treated by these techniques. Arytenoid adduction and laryngeal reinnervation are less widely employed, probably due to a more difficult learning curve and possibly due to variable results, especially with reinnervation. Laryngeal pacing is still under investigation for use in humans.

Progress in diagnosis and a better understanding of laryngeal neurophysiology developed during the entire 20th century. The past two decades have seen the advent of laryngeal surgery for URLNP and a more widespread interest in objective acoustic and aerodynamic voice evaluation. The 21st century is rapidly bringing miniaturization of cameras, microphones, and aerodynamic gauges. Progress is being made daily in computerized processing of acoustic information and digital images. Oral communication and its dysfunctions are becoming an important theme in clinical and laboratory research. In this "age of communication," quality of life depends more and more on the quality of voice and speech, a challenge for today's otolaryngologists.

Laboratory of voice, biomaterials and cervicofacial oncology, CNRSUPRESA 7018, University of Paris V, Laennec Hospital, 42 rue de Sevres, 75007 Paris, France.

(*.) Reprinted from "Hartl DM, Brasnu D. Les paralysies recurrenticlles: connaissances actuelles et traitements. Annales d'Otolaryngologie et de Chirurgie Cervico-Faciale 2000;l17:60-84." [c] editions Masson.
 Summary of surgical techniques [83]
 Thyroplasty Teflon Autologaus fat
Operating time 45 to 90 min 30 min 15 to 30 min
Operating ease Easy +++ Very ++++ Very easy ++++
Reversibility Variable No Yes
Anatomic changes Yes ++ Yes ++++ Little
Complications ++ ++++ Rare
Indications Definitive URLNP Definitive URLNP Any URLNP
Cost Variable-moderate Low Low
Results Immediate Immediate Immediate
 Excellent Variable voice Excellent
 Permanent or quality resorption
 reversible Permanent
 Nerve anastomosis
Operating time 2 hr
Operating ease Unpredictable
Reversibility Yes
Anatomic changes No
Complications ++
Indications Early URLNP (use
 with another technique)
Cost High (operating time)
Results 2- to 6-month delay
 Variable vocal effect
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Comment:Recurrent laryngeal nerve paralysis: Current concepts and treatment: Part III--Surgical options.
Author:Brasnu, Daniel F.
Publication:Ear, Nose and Throat Journal
Geographic Code:4EUFR
Date:Jan 1, 2001
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Recurrent laryngeal nerve paralysis: Current concepts and treatment: Part II--Causes, diagnosis, and management.
Recurrent laryngeal nerve paralysis: Current concepts and treatment: Part III-Surgical options.
Vocal fold paralysis in painless aortic dissection (Ortner's syndrome). (Imaging Clinic).
Gelfoam injection as a treatment for temporary vocal fold paralysis. (Laryngoscopic Clinic).
Perineural invasion of the facial nerve by a cutaneous squamous cell cancer: a case report.
Unusual paratracheal masses presenting with vocal fold paralysis.
Vocal fold atrophy after resection of a parapharyngeal space sarcoma.
Current technique for resection of mediastinal goiter.
Total thyroidectomy for the treatment of thyroid diseases in an endemic area.

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