Phonosurgical vocal fold injection: Indications and techniques

PHONOSURGICAL VOCAL FOLD INJECTION: INDICATIONS AND TECHNIQUES CLARK A. ROSEN, MD

Phonosurgical vocal fold injection (VFI) is an excellent choice for elective improvement of voice quality for a variety of voice disorders. This involves injection of a material into the vocal fold to improve phonatory function. The most common injection materials at present are Teflon, Gelfoam, collagen, and fat. The appropriate selection of these materials and the techniques used for injection determine the outcome of this type of phonosurgery. VFI techniques can be divided by location of injected material either into the medial or the lateral region of the vocal fold. Medial VFI is done into a superficial location of the vocal fold (Reinke's space). VFI lateral to the vocal fold (deep) medializes the entire vocal fold. The aim of VFI is to improve the closure of the glottis, thus improving phonatory efficiency and voice quality. A new method of VFI, endoscopic VFI, is presented for lateral VFI.

Vocal fold injection (VFI) has been done since 1911, and a variety of materials, such as paraffin, silicone, and bone pate, have been used. 1,z3 These injection materials were unsuccessful over the long term because of foreign body reaction or limited survivability. Rubin suggested that the ideal material for VFI should be suitable for injection, biocompatible, and have the ability to achieve long-term survival. 4 The quest for the ideal injection material is ongoing, with new materials being developed to improve biocompatibility and to match tissue and biomechanica] properties of the medial and lateral vocal fold. PREOPERATIVE EVALUATION

Patient evaluation for VFI requires detailed diagnostic testing to determine the exact cause of the dysphonia. Historical information regarding possible recurrent laryngeal nerve or crico-arytenoid joint injury or disease should be obtained. Previous head and neck or chest surgery should be documented and surgical reports reviewed. In addition, any history of intubation and its timing with the patient's dysphonia is crucial. This can identify common causes of vocal fold immobility or injury. Information should also be obtained regarding events associated with vocal fold scar formation, vocal fold hemorrhage, radiation therapy, or previous surgical trauma to the vocal folds. A measure of the patient's self-perception of the severity of his or her voice disorder is often helpful. The Voice Handicap Index is a valid and reliable means for measuring the patient's self-perception of the severity of his or her voice disorder. 5 Objective voice analysis in the voice laboratory is also helpful for both diagnosing and establishing a baseline to subsequently monitor treatment results during and after treatment. The voice laboratory assess-

From the University of Pittsburgh Voice Center, Department of Otolaryngology, University of Pittsburgh School of Medicine, Eye and Ear Institute, Pittsburgh, PA Address reprint requests to Clark A. Rosen, MD, Director, University of Pittsburgh Voice Center, and Assistant Professor, Department of Otolaryngology, University of Pittsburgh School of Medicine, Eye and Ear Institute Bldg, Suite 500, 200 Lothrop St, Pittsburgh, PA 15213. Copyright © 1998 by W,B. Saunders Company 1043-1810/98/0904-0004510.00/0

ment includes acoustic and aerodynamic measures of phonatory production. It is essential to assess the patient's speaking technique with a special concern for compensatory behaviors that may involve muscular tension dysphonia in addition to the patient's glottal incompetence. A singing voice range profile is helpful for patients who have a history of singing voice difficulties. In preparation for phonosurgical VFI, voice therapy is often helpful both preoperatively and postoperatively. Specifically, preoperative voice therapy addresses maladaptive compensatory behavior and allows the patient and speech pathologist to establish a rapport that will be continued after the phonosurgical procedure. Several sessions of preoperative voice therapy are recommended before all phonosurgical procedures. Laryngovideostroboscopy (LVS) is essential for the evaluation of a patient's dysphonia in preparation for phonosurgical VFI. A combined laryngeal endoscopy examination of rigid videostroboscopy and flexible fiber optic laryngoscopy (with halogen and stroboscopy) helps the clinician to fully understand and appreciate all nuances of the patient's dysphonia. An understanding of the vocal fold disease a n d / o r vocal fold vibratory pattern allows the surgeon and speech pathologist to diagnose the cause(s) of the dysphonia, direct the treatment, and plan the postoperative care. Rigid LVS is specifically used to evaluate closure pattern and duration of vocal fold closure that may assist in the decision-making process regarding VFI material, technique, and placement. Glottic closure time can be studied by analysis of the proportion of stroboscopy frames that show the closed phase versus the open phase of the glottal cycle. Flexible fiberoptic laryngoscopy facilitates a functional evaluation of the patient's speaking technique, singing technique, and stroboscopy in a more natural in vivo setting. 6 If the patient undergoing preoperative evaluation for phonosurgical VFI is a singer, a singing voice evaluation by a singing voice specialist is helpful. 7 This evaluation will frequently assist the voice team in determining the amount of dysphonia and level of handicap associated with the patient's speaking demands compared to his singing demands. This information allows optimal management by the multidisciplinary voice care team. Determination of the cause and prognosis for an unilat-

OPERATIVE TECHNIQUES IN OTOLARYNGOLOGY--HEAD AND NECK SURGERY, VOL 9, NO 4 (DEC), 1998: PP 203-209

203

eral immobile vocal fold are paramount in the evaluation process. Differentiation between vocal fold paralysis and disease of the crico-arytenoid joint (dislocation or fixation) is required. This can be accomplished by history (known recurrent laryngeal nerve section), laryngeal electromyography and arytenoid palpation, the latter done during direct laryngoscopy. These investigations will determine subsequent management decisions regarding vocal fold material and timing of treatment. Laryngeal electromyography differentiates between a vocal fold paralysis and crico-arytenoid joint disease and assists with determining prognosisfor recovery of unilateral vocal fold paralysis, s Microlaryngoscopy can also be used for diagnosis in selected cases. Frequently, this technique is required for the diagnosis of sulcus vocalis and for patients who do not tolerate an office LVS. During microlaryngoscopy, arytenoid palpation assists in the differentiation of vocal fold paralysis from crico-arytenoid joint fixation. For vocal fold scar evaluation, a saline submucosal infusion is diagnostic for determining the extent and severity of the vocal fold scar. A successful saline infusion trial is a good prognostic indicator for the use of autologous collagen as a medial VFI. 9 If an autologous collagen injection is being considered as a treatment possibility, skin excision for preparation of autologous collagen can be done simultaneously with the microlaryngoscopy.

VOCAL FOLD INJECTION: LOCATION Phonosurgical VFI can be divided by the location of the injection into either medial or lateral injection techniques. Medial VFI involves the injecting of material into the superficial portion of the vocal fold, most typically Reinke's space. This phonosurgical technique requires precise VFI with a small fine injection needle (27 or 30 gauge) and high magnification microlaryngoscopy to place the injection material in specific location(s). The most common pathologic conditions treated with a medial phonosurgical VFI include vocal fold scarring and focal deficits of the lamina propria of the vocal fold. These types of disorders are frequently seen after over-aggressive laser resection of vocal fold nodules. Lateral VFI involves placing the phonosurgical injection material lateral to the membranous vocal fold in a "deep location." Lateral VFI allows global medialization of the membranous vocal fold, which is ideal for patients with vocal fold paralysis or vocal fold atrophy. The common materials used for lateral VFI include Teflon (Mentor Inc, Hingham, MA), Gelfoam (UpJohn Co, Kalamazoo, MI), and fat. With the proper position of the VFI, lateral to the membranous vocal fold, no disruption of the vibratory pattern of the lamina propria of the vocal fold is expected.

VOCAL FOLD INJECTION: MATERIAL SELECTION Teflon was the first reliable injection material to be used for the successful treatment of voice problems. 1° Teflon has been shown to be initially well tolerated with no significant decrease in volume over time. However, a foreign body reaction to the injected Teflon can lead to the formation of an inflammatory mass, named Teflon granuloma, that severely disrupts the shape and function of the injected vocal fold. Dedo and others argue that a Teflon granuloma formation occurs only when there is overinjection or misplacement of the Teflon. 11These factors clearly increase the risk of the formation of a Teflon granuloma. However, 204

patients have developed a Teflon granuloma many years after a VFI with an initial excellent postoperative voice result, suggesting that the Teflon was in the right location and not overinjected in these individuals. Therefore, Teflon is associated with a significant risk of granuloma. 12 Schramm et al introduced the use of Gelfoam VFI as a temporary treatment of vocal fold paralysisJ 3 The injection involves mixing gelatin powder with a buffered saline solution to form a paste that is used for a lateral VFI. Gelfoam is naturally degraded in the body. The medialization obtained with a Gelfoam injection of the vocal fold lasts 6 to 8 weeks, depending on the amount of saline used to make the paste and the amount of paste injected. Gelfoam injection of the vocal fold can result in improved glottic closure and is an excellent option for the treatment of dysphonia due to vocal fold paralysis when the status of the vocal fold paralysis recovery is unknown. Autologous fat injection is used as a lateral VFI material for the treatment of voice disorders. Fat is obtained from the patient at the time of the VFI via liposuction or a small incision in the abdominal skin to expose subcutaneous fat. The harvested fat is thoroughly rinsed to remove fatty acids on the lipocytes, dried of excessive moisture, and then loaded into the injection device. Another techniques for processing the fat is by centrifuge. 14The advantages of lipoinjection of the vocal fold include ease of harvest, availability of material and its autologous nature. The limiting factor of this technique is the initial absorption of 30% to 50% of the injected material within the first month after injection. This has led most surgeons to overinject the vocal fold by 30% to 50% to account for this resorption. Excellent long-term results of lipoinjection of the vocal fold have been shown in several independent studies. 15-17In my 3-year experience with over 100 lipoinjections, there has been no change in the injected volume of fat that persists 1 month after injection. The most frequently used material for medial VFI is collagen. In the past, most collagen injections have been bovine collagen, often with subsequent resorption of the injected materiaD s Recently autologous collagen has become available to the clinician. In addition, there are developments pending that may allow allogenic collagen injection for the treatment of dysphonia. The value of both autologous and allogenic collagen is still unknown. 19,2° Other materials that have been injected or proposed for medial VFI include hyaluronic acid and fat. 16

VOCAL FOLD INJECTION TECHNIQUES Different approaches to VFI include transoral (via indirect laryngoscopy or direct laryngoscopy) or percutaneous (by using transnasal fiber optic guidance). The advantage of VFI done via indirect laryngoscopy with the patient in a sitting position is the ability to titrate the injection amount and sites in the most natural position. However, some patients may not tolerate this approach. The most frequently used VFI approach is transoral via direct laryngoscop)~ with either general or local anesthesia. The advantage of the former is the improved visualization of the larynx obtained with suspension microlaryngoscopy. The disadvantage of general anesthesia for VFI is the loss of the ability of the surgeon to visualize the glottic deficit during vocal fold adduction and thus monitor the adequacy of the injection. For Teflon and Gelfoam injections, the use of local anesthesia instead of a general anesthetic allows "real-time" monitoring of the glottal deficit and its correction. For lipoinjection, the advantage of a VFI done under PHONOSURGICAL VOCAL FOLD INJECTION

local anesthesia is negligible because the vocal fold is purposely overinjected. Medial VFI is usually done with suspension microlaryngoscopy (with general anesthesia). The advantage of suspension microlaryngoscopy is a stable and magnified operative site. Standard suspension microlaryngoscopy techniques are employed for medial VFI. The largest laryngoscope is used to afford the surgeon the greatest exposure of the endolarynx and ease of performance of the phonosurgical VFI. Because medial VFI is typically used to treat very specific areas of the medial compartment of the vocal fold, reviewing the patient's preoperative LVS examination in the operating room immediately before the VFI is strongly recommended. Frequently, the LVS examination can help with respect to injection site and amount. Lateral VFI can be done via several approaches, but the injection site and goal are uniform. To perform a lateral VFI, the false vocal fold is frequently retracted (during direct laryngoscopy) to expose the border of the superior surface of the vocal fold and the laryngeal ventricle. (Figs 1 and 2). The first injection site is at the junction of the superior surface of the vocal fold and laryngeal ventricle located at the level of the vocal process in an anteroposterior dimension. (Fig 1B) The injection needle is directed laterally to ensure that the deposition of the injection material is into the paraglottic space. This prevents spread of the injected material into the more superficial aspect of the vocal fold, which can impair vocal fold vibration. The injection is placed deep into the vocal fold (approximately 4 to 5 mm), and the injection is administered in an incremental fashion with careful attention given to the vocal fold position. Typically, two to three clicks of Gelfoam or Teflon are required at this location to adequately medialize a paralyzed vocal fold. One or two additional clicks of material may have to be injected at the midpoint of the membranous vocal fold at the same depth and lateral vocal fold position (Fig 1B and 3).

ENDOSCOPIC

VOCAL FOLD INJECTION

A new VFI approach has been developed by the author and used for more than 200 procedures. A lateral VFI can be performed under local anesthesia via endoscopic, direct laryngoscopy. This technique avoids the risks and limitations of a procedure done under general anesthesia and provides magnified, well-illuminated visualization of the larynx during VFI. The endoscopic VFI technique is used in a similar manner for Gelfoam, Teflon, and fat injection into the lateral vocal fold. Before entering the operating room, the patient receives a small amount of intravenous sedation and nebulized lidocaine treatment (pontocaine for lipoinjection) to provide anesthesia to the oropharynx, larynx, and trachea. Preoperative intravenous glycopyrrolate and solumedrol are also administered. The patient is in the supine position with the neck flexed and head extended. Additional topical anesthesia of 10% lidocaine is administered via spray to the oropharynx and larynx. Direct laryngoscopy is performed by using a slotted anterior commissure laryngoscope (Piling Co, Fort Washington, PA) (see Fig 1A). The side of the laryngoscope slot (as seen from behind the laryngoscope) should be opposite to the intended vocal fold to be injected. During the initial direct laryngoscopy, additional 10% lidocaine is sprayed onto the larynx if needed, and the glottal pathologic condition is confirmed (an unilateral vocal fold paralysis, vocal fold atrophy, etc). For the diagnosis of unilateral vocal fold paralysis, the suspected paralyzed arytenoid is palpated to rule out crico-arytenoid joint fixation. Anesthesia is monitored by touching an instrument to the VFI site to ensure that there is adequate anesthesia before proceeding with the injection. The laryngoscope is then positioned over the intended vocal fold to be injected in such a manner that the distal tip of the laryngoscope retracts the false vocal fold exposing the laryngeal ventricle, the membranous vocal fold, and

Slotted Anterior Commissure )scoF A

Injection Needle

Endoscopic View FIGURE 1. (A) Zero degree endoscope and injection needle in slotted anterior commissure laryngoscope. (B) Endoscopic view during VFI. (X, typical injection sites. (*, false vocal retraction from the distal tip of the laryngoscope.)

CLARK A. ROSEN

205

FIGURE 2. Endoscopic image of right vocal fold paralysis. Note retraction of the right false vocal fold ( i ) and atrophy of the paralyzed right vocal fold (--~).

the vocal process. This position is then maintained, with the surgeon's nondominant hand suspending and positioning the laryngoscope throughout the procedure. A zerodegree rigid telescope (4-mm diameter, 30-cm length) coupled with the video camera (as used in endoscopic

sinus surgery or laparoscopy) is then passed down the laryngoscope by an assistant (see Fig 1A). The injection needle attached to the loaded Bruening injection gun (Storz, St. Louis, MO) is then passed through the laryngoscope under direct endoscopic guidance with the Sur-

FIGURE 3. Endoscopic VFI. Injection needle at right midmembranous vocal fold.

206

PHONOSURGICAL VOCAL FOLD INJECTION

FIGURE 4. (A) Surgeon and assistant performing endoscopic VFI. Short arrow shows the slotted anterior commissure laryngoscope held in the surgeon's nondominant hand. The curved arrow is at the surgeon's dominant hand, which holds the injection device. The assistant holds the video camera attached to the zero-degree endoscope long arrows. Note that the stem of the endoscope is rotated upward to avoid contact with the injection device. (B) Endoscopic Vocal Fold Injection. Note the laryngoscopy position of neck flexion and head extension.

B

Endoscope

/

Laryngoscope

Injection . Needle

\ k

%,

CLARKA. ROSEN

207

FIGURE 5. Glotticclosure immediatelyafter endoscopic right VFI.

geon's dominant hand (Fig 4). After the injection, the needle is retracted into the laryngoscope, and glottic closure during phonation is observed from the endoscopic image (Fig 5). This allows precise VFI and prevents overand underinjection complications.

PITFALLS AND COMPLICATIONS OVERINJECTION OF THE VOCAL FOLD Overinjection of the vocal fold can result in persistent dysphonia, secondary to glottal incompetence. The overinjected vocal fold typically will not allow adequate glottic closure and subsequently will not improve the patient's dysphonia. Prevention of this complication involves careful observation of the vocal fold during injection and a graduated injection technique. Management at the overinjected fold is removal of the injected material. AIRWAY OBSTRUCTION Airway obstruction is the most serious complication after VFI. Fortunatel~ this is quite rare. Airway obstruction can occur in a temporary or a permanent fashion. Temporary airway obstruction typically occurs from extensive manipulation of the larynx during the VFI procedure and subsequent significant laryngeal edema. This complication can be prevented by minimizing direct laryngoscopy manipulation of the supraglottis and administering perioperative steroid treatment. Permanent airway obstruction after VFI is extremely rare and occurs only when the contralateral vocal fold becomes immobile secondary to a recurrent laryngeal nerve paralysis, crico-arytenoid joint disease (fixation or dislocation), or extreme vocal fold overinjection. 208

RESORPTION OF FAT AFTER LIPOINJECTION Incomplete medialization of the injected vocal fold after tipoinjection is considered a complication. This resorption occurs within the first 4 weeks after surgery and not at any time beyond this period. Inadequate medialization secondary to lipoinjection resorption occurs from either insufficient lipoinjection, poor processing of the injected material or unknown reasons. This may be considered a complication because of the need for further treatment of the patient's dysphonia. A repeat lipoinjection is frequently the most reasonable course of action after this complication. However, laryngeal framework surgery to medialize the vocal fold(s) is also a reasonable treatment option. TEFLON GRANULOMAS/OVERINJECTION A Teflon granuloma is a major complication of Teflon VFI, The patient typically presents with dysphonia secondary to glottal incompetence caused by the Teflon granuloma. A Teflon granuloma can also present with airway compromise symptoms. This unfortunate condition can be remedied via endoscopic laser ablation of the Teflon granuloma. 21 This is a tedious surgical procedure that results in scarring of the vocal fold and may result in a need for alternative vocal fold medialization. This can be quite difficult because of the stiffness of the scar tissue. VFI or laryngeal framework surgery can be performed after removal of overinjected Teflon material or a Teflon granuloma. An alternative method of Teflon removal from the paraglottic space and vocal fold region has been described that uses an external approach via a thyroplasty window or from a posterior approach to the thyroid cartilage.22 Care must be taken to perform all lateral (deep) VFI at PHONOSURGICALVOCALFOLDINJECTION

the d e p t h of the t h y r o - a r y t e n o i d m u s c l e a n d n o t superficial to it. Injection of Gelfoam, Teflon, or fat into the superficial p o r t i o n of the vocal fold will result in i m p a i r e d vocal fold vibration, distortion of the m e m b r a n o u s v o c a l fold free edge, a n d t r a c k i n g of injectate into the l a r y n g e a l ventricle. The latter results in a loss of the flat c o n t o u r of the s u p e r i o r surface of the vocal fold a n d e f f a c e m e n t of the l a r y n g e a l ventricle. P r e v e n t i o n of this c o m p l i c a t i o n can be perf o r m e d b y careful o b s e r v a t i o n of the d e p t h of the injection n e e d l e a n d o b s e r v a t i o n of the r e s p o n s e of the vocal fold d u r i n g the injection. If a n y indication of l a r y n g e a l ventricle s w e l l i n g or b a l l o o n i n g of the s u p e r i o r surface of the vocal fold is o b s e r v e d d u r i n g the injection, the injection s h o u l d be s t o p p e d a n d the n e e d l e a d v a n c e d to a d e e p e r tissue plane. The a p p r o p r i a t e r e s p o n s e of the vocal fold d u r i n g injection is a m e d i a l d i s p l a c e m e n t of the free e d g e w i t h o u t c h a n g e to the c o n t o u r of the s u p e r i o r surface of the vocal fold.

CONCLUSION P h o n o s u r g i c a l VFI is a n excellent choice for the l a r y n g o l o gist in treating patients w i t h selected d y s p h o n i a s . D e t e r m i n a t i o n of the ideal VFI material is still p e n d i n g ; h o w e v e r , the recent a d v a n c e s u s i n g fat as a lateral VFI material a n d a u t o l o g o u s collagen as a m e d i a l vocal fold injection m a t e rial h a v e a l l o w e d VFI to b e c o m e a significant p h o n o s u r g e r y t r e a t m e n t option. In addition, the d e v e l o p m e n t of the e n d o s c o p i c VFI t e c h n i q u e n o w allows patients to h a v e lateral VFI p r o c e d u r e s a d m i n i s t e r e d safely a n d accurately a n d represents a n o t h e r a d v a n c e in the use of p h o n o s u r g i cal VFI for the t r e a t m e n t of d y s p h o n i a .

REFERENCES 1. Bruening W: Ubereine neue behandlungsmethode der rekurrenslahmung. Berh Dtsch Laryng 18:23, 1911 2. Arnold GE: Vocal rehabilitation of paralytic dysphonia: Cartilage injection into a paralyzed w)cal cord. Arch Otolaryngol 62:593, 1955 3. Hirano M, Mori K, Tanaka S, Fujita M: Vocal function in patients with unilateral vocal fold paralysis before and after silicone injection. Acta Oto Laryngol 115:553-5591995 4. Rubin H: Pitfalls in treatment of dysphonias by intracordal injection of synthetics. Laryngoscope 75:1381-1397, 1965 5. Jacobson BH, Johnson AF, Silbergleit AK, et ah The Voice Handicap

CLARK A. ROSEN

6. 7.

8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.

Index (VHI): Development and validation. Am J Sp Lang Pathol 6:66-70, 1997 Rosen CA, Murry T: Dynamic Voice Assessment Using Flexible Endoscopy. San Diego CA, Singular Publishing, 1997 Emerich KA, Baroody MM, Carroll LM, et ah The Singing Voice Specialist. Professional Voice:The Science and Art of Clinical Care by Sataloff RT. San Diego, CA, Singular Publishing Group, 1997, pp 735-754 Min YB, Finnegan EM, Hoffman HT, et al: A preliminary study of the prognostic role of electromyography in laryngeal paralysis. Otolaryngol Head Neck Surg 111:770-775,1994 Rosen CA, Murry T: Autologous collagen for vocal fold disorders. Pacific Voice Conference, San Francisco, CA, November 7, 1998 Dedo HH, Urrea RD, Lawson L: Intracordal injection of teflon in the treatment of 135 patients with dysphonia. Ann Otol Rhinol Laryngol 82:661-667, 1973 Dedo HH: Injection and removal of Teflon for unilateral vocal cord paralysis. Ann Otol, Rhinol Laryngol 101:81-86, 1992 Nakayama M, Ford CN, Bless DM: Teflon vocal fold augmentation: Failures and management in 28 cases. Otolaryngol Head Neck Surg 109:493-498, 1993 Schramm VL, May M, Lavorato AS: Gelfoam paste injection for vocal cord paralysis: temporary rehabilitation of glottic incompetence. Laryngoscope 88:1268-1273 1978 Mikus JL, Koufman JA, Kilpatrick SE. Fate of liposuctioned and purified autologous fat injections in the canine vocal fold. Laryngoscope 105:17-22, 1995 Brandenberg JH, Unger JM, Koschkee D: Vocal cord injection with autogenous fat: A long-term magnetic resonance imaging evaluation. Laryngoscope 106:174-180, 1996 Shaw GY, Szewczyk MA, Searle J, Woodroof J: Autologous fat injection into the vocal folds: Technical considerations and long-term follow up. Laryngoscope 107:100-186, 1997 Mikaelian DO, Lowry LD, Sataloff RT: Lipoinjection for unilateral vocal cord paralysis. Laryngoscope 101:465-468,1991 Ford CN: Histologic studies on the fate of soluble collagen injected into canine vocal folds. Laryngoscope 96:1248-1257, 1986 Ford CN, Staskowski PA, Bless DM: Autologous collagen vocal fold injection: A preliminary clinical study. Laryngoscope 105:944-948, 1995 Staskowski PA, Ford CN, Inagi K: The histologic fate of autologous collagen injected into the canine vocal fold. Otolaryngol Head Neck Surg, 118:187-190,1998 Ossoff RH, Koriwchak MJ, Netterville JL, Duncavage JA: Difficulties in endoscopic removal of teflon granulomas of the vocal fold. Ann Otol, Rhinol Laryngol 102:405-412,1993 NetterviUe JL, Coleman JR Jr, Chang Set al: Lateral laryngotomy for the removal of teflon granuloma. Ann Otol Rhinol Laryngol 107:735744, 1998

209