Учебники / Operative Techniques in Laryngology Rosen 2008

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eratively. If more than 30–45 min elapse between the opening of the cartilaginous window and placement of the implant, then significant vocal fold edema may have developed. Clues that vocal fold edema has developed include:

■The patient’s baseline voice (nonmedialized) sounds significantly better than it did before the case began.

■Good voice quality is obtained during medialization with depth gauge immediately after opening the

window, but cannot be replicated later (30 + min) in the case.

When vocal fold edema is suspected, one must rely on visual clues more than auditory clues in determining the correct amount of medialization. In other words, it is more important to confirm a well-medialized vocal fold (using an indwelling flexible laryngoscope) in a patient with a mildly stained voice, rather than settling for a normal voice with a slightly undercorrected vocal fold.

A subset of patients may be noted to have voice deterioration months to years after surgery. This is probably best explained by continued atrophy of the vocal fold musculature from prolonged denervation, or bilateral age-related atrophy.

Implant malposition of the implant generally accounts for the balance of revisions. Netterville and Billante have identified placing the implant too far superior, which results in medialization of the ventricular mucosa or the false vocal fold, as the most common overall cause for revision. This can be avoided by placing the window no more than 3 mm above the inferior border of the thyroid ala, or as low as possible while maintaining a stable inferior frame of cartilage below the window. Also, one should carefully probe within the window to confirm the

Fig. 37.3  Flexible laryngoscopy demonstrating excessive medialization of the anterior third of the left vocal fold after medialization laryngoplasty

plane of the true vocal fold prior to attempting the use of any depth-measuring devices. The image from an indwelling flexible laryngoscope is extremely useful to confirm the correct medialization plane; a bulging ventricular fold or everted ventricular mucosa (or, more rarely, subglottis) indicates an incorrect medialization plane (Fig. 37.2). Overmedialization of the anterior vocal fold, caused by too anterior a placement of the medialization implant, results in a distinctive pressed or strained vocal quality from early contact and “overclosure” of the anterior part of the membranous vocal fold during phonation (Fig. 37.3). To prevent this, glottic tissues overlying the anterior third of the window are generally not medialized. This is especially true in men, in whom the extremely thin glottic tissue overlying this area is prone to overmedialization from even small amounts medial displacement. It is not uncommon for a well-carved implant to cause a slight amount of unintended anterior medial displacement. If a pressed voice is noted after implant placement, forceps can be used to pull the anterior portion of the implant partially out of the window, and retest the voice. If the voice improves with this maneuver, reshaping of the anterior portion of the implant is necessary.

37.4.1 Revision Surgery

The approach for revision surgery does not deviate much from that taken with primary surgery. The location of the original cartilaginous window from the previous surgery is not taken into consideration when planning the location of the revision window. The same meticulous exposure of the thyroid ala and precise measurements should be used to establish the “new” window location. The new window is then created, even if there is some overlap between this and the original window. In some cases, this may result in a larger window, or one with an irregular shape. As long as the revision implant occupies the new window location, and is secured within this space, the unusual window dimensions do not present a problem (Figs. 37.4, 37.5).

Most implants can be removed easily as the new window is opened, using two single-prong hooks. Once the revised window is created, the fibrous capsule that has formed deep to the implant must be incised (Fig. 37.6). This fibrous tissue creates tethering of the thyroarytenoid muscle and must be incised along the perimeter of the window (Fig. 37.7). Finally, the paraglottic space is entered and undermined, similar to primary medialization techniques, to permit unencumbered medial displacement of the vocal fold. This is similar to the release of the internal perichondrium that is performed in most medialization surgery. The remainder of the surgical case proceeds in a similar fashion to primary medialization laryngoplasty.

In many cases, the reason for failure may be related to vocal fold height differences, or lack of posterior glottic closure conditions that medialization surgery cannot correct. Therefore, it is not surprising that substantial number of medialization revisions require arytenoid adduction. If an adequate voice quality cannot be obtained by medial displacement of the vocal fold intraoperatively, then arytenoid adduction should be performed in conjunction with medialization.

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Fig. 37.4  Original window/implant and the outline of the “new” ideal window dimension superimposed

Fig. 37.5  Combined revision window that is created. Note the secure position of the implant

Fig. 37.6  Fibrous capsule within the paraglottic space after implant removal. Note adherence of the capsule along the inner aspect of the thyroid lamina

Fig. 37.7  Sharp incision through the fibrous capsule along the margin of the window

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37.5 Long-Term Surgical Issues	Selected Bibliography

Patients who have undergone successful medialization laryngoplasty, with or without arytenoid adduction often express concerns about the safety of endotracheal intubation for surgical procedures in the future. A waiting period of 6 months postsurgery (if the proposed surgery is elective) is advised. The anesthesiologist should place the smallest endotracheal tube that he or she feels is safe—ideally, size 6.0 or smaller—prin- cipally to avoid inducing laryngeal edema from a slightly constricted glottic aperture.

Key Points

■Corticosteroids should be given in the preoperative and immediate postoperative period to help minimize potential complications.

■Major complications/ risk factors of framework surgery include:

Complication	Risk factor(s)
Airway compromise/	Arytenoid adduction
obstruction	Bilateral medialization
	Prior history of neck irradiation
Implant extrusion/exposure	Violation of airway mucosa

■Suboptimal results with framework surgery are usually due to one or more of the following:

■Persistent posterior glottic gap

■Undermedialization

■Implant malposition:

■Anteriorly

■Superiorly

■Vocal fold height mismatch

■A good voice after framework surgery that begins to “fade” or weaken 1–2 weeks postoperatively suggests undercorrection.

■Revision surgery for medialization laryngoplasty failures often requires arytenoid adduction to achieve maximal voice results.

■Endotracheal intubation is safe in patients who have undergone framework surgery in the past, but should be delayed until 6 months postoperatively, if possible. A smaller diameter ETT (6.0 or smaller) is recommended.

1Anderson TD, Spiegel JR, Sataloff RT (2003) Thyroplasty revision: frequency and predictive factors. J Voice 17:442–448

2Cohen JT, Bates DD, Postma GN (2004) Revision Gore-Tex medialization laryngoplasty. Otolaryngol Head Neck Surg 131:236–240

3Cotter CS, Avidano MA, Crary MA, Cassisi NJ, Gorham MM (1995) Laryngeal complications after type 1 thyroplasty. Otolaryngol Head Neck Surg 113:671–673

4Hong KH, Jung KS (2001) Arytenoid appearance and vertical height difference between the paralyzed and innervated vocal folds. Laryngoscope 111:227–232

5Maragos NE (2001) Revision thyroplasty. Ann Otol Rhinol Laryngol 110:1087–1092

6Netterville JL, Stone RE, Luken ES, Civantos FJ, Ossoff RH. Silastic medialization and arytenoid adduction: the Vanderbilt experience. A review of 116 phonosurgical procedures. Ann Otol Rhinol Laryngol 102:413–424

7Rosen CA (1998) Complications of phonosurgery: results of a national survey. Laryngoscope 108:1697–1703

8Weinman EC, Maragos NE (2000) Airway compromise in thyroplasty surgery. Laryngoscope 110:1082–1085

9Woo P, Pearl AW, Hsiung MW, Som P (2001) Failed medialization laryngoplasty: management by revision surgery. Otolaryngol Head Neck Surg 124:615–621

Chapter 38
Silastic Medialization Laryngoplasty	38
for Unilateral Vocal Fold Paralysis

38.1Fundamental and Related Chapters

Please see Chaps. 1, 5, 9, 14, 36, 37, 39, 40, and 41 for further information.

38.2Disease Characteristics and Differential Diagnosis

Patients with unilateral vocal fold paralysis (UVFP) typically complain of breathy dysphonia, vocal fatigue, and aspiration of liquids. The etiology of the paralysis is frequently vagal/recurrent laryngeal nerve injury secondary to iatrogenic causes or nonlaryngeal malignancy. Laryngoscopy generally shows an immobile vocal fold, although a slight amount of adduction can be present due to contralateral innervation of the interarytenoid muscle. The position of the paralyzed vocal fold can vary from median position to lateralized, and the height from slightly above to below the contralateral vocal fold. This variation of the position of the vocal fold is probably related to the degree of reinnervation that has occurred subsequent to the nerve injury, as well as the differing anastomotic connections between the RLN and SLN that are variable from patient to patient.

Differential diagnosis of an immobile vocal fold includes vocal fold paralysis, cricoarytenoid joint fixation (usually due to trauma or rheumatologic disease), and cricoarytenoid dislocation (very rare, and almost exclusively related to severe external trauma—not intubation). Cricoarytenoid joint abnormalities can be differentiated from vocal fold paralysis using laryngeal electromyography and vocal fold palpation.

38.3Surgery Indications and Contraindications

It is important to note that Silastic medialization laryngoplasty (ML) is designed to be a long-term treatment for symptomatic UVFP. Experimental and clinical evidence supports the efficacy of Silastic ML over a prolonged period. However, it should be noted that Silastic ML is fully reversible—that is, the implant can be removed if return of vocal fold mobility occurs, or if a revision surgery needs to be performed later. There is minimal tissue reactivity to Silastic over time; generally, a thin fibrous capsule surrounding the implant is all that is seen months to years after ML. Even though the implant can be removed, this

procedure should be used as a permanent treatment not a temporary method of medialization.

Indications comprise:

■Symptomatic glottic insufficiency (dysphonia, aspiration), especially if there is little to no chance of return of vocal fold motion

Contraindications include:

■Previous history of radiation therapy to the larynx (relative)

■Malignant disease overlying the laryngotracheal complex

■Poor abduction of the contralateral vocal fold (due to airway concerns)

■Presence of lesion on the vocal folds

38.4Surgical Equipment

No single implant material is superior to the others for performing ML. It is really a matter of surgeon preference and experience. We advocate hand carving of a medium-grade Silastic block (available from Medtronic ENT, Jacksonville, Fla.), using the surgical technique described by Netterville. This leads to precise medialization, superior voice results, and a better understanding of the dynamics of vocal fold medialization. However, other systems (such as the preformed implants in the Montgomery Thyroplasty Implant System (Boston Medical Products, Westborough, Mass.) or strip GORE-TEX® (W.L. Gore and Associates, Flagstaff, Ariz.) and VoCoM hydroxylapatite (Smith and Nephew, Bartlett, Tenn.) can be employed successfully as well.

■Netterville Medialization Tray (Medtronic ENT)

■Drill with 2- or 3-mm cutting burr

■Kerrison rongeurs tray (1- to 3-mm-sized tips)

■Medium-grade Silastic block (Medtronic ENT)

■Partially preformed blocks are used in this procedure, referred to as “silicone strips” by the manufacturer

■Ruler (15-mm section of plastic ruler at tip of hemostat)

■Flexible laryngoscope

■C-mount camera with videocart/monitor

■Clear overdrape for laryngoscope (1010 drape)

■Local anesthetic (nasal and subcutaneous)

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Fig. 38.2  Horizontal skin incision: typically midthyroid cartilage and 5 cm in length

38.5Surgical Procedure

1.The surgical region is liberally infiltrated with 1% lidocaine with 1:100,000 epinephrine, from the hyoid down to the cricoid cartilage, on the side of the intended surgery. Typically, 15 ml are used. Preoperative intravenous Decadron (10 mg) is administered.

2.Four percent lidocaine and oxymetazoline nasal spray is applied to the most patent nasal cavity.

3.Placement of an indwelling flexible laryngoscope with videomonitoring of the larynx during the entire surgical case. The visual feedback of the larynx is invaluable when performing this surgery. One-inch tape is used to secure the flexible scope to a modified i.v. pole hanging above

Fig. 38.1  Diagram of typical prep/drape for medialization laryngoplasty

the patient’s head. The neck is then prepped and draped, including a clear overdrape to allow manipulation of the flexible laryngoscope during the case (Fig. 38.1).

4.A horizontal incision is placed in a skin crease at the level

of the midthyroid cartilage, typically 5–6 cm in length (Fig. 38.2).

4.Subplatysmal flaps are raised to the hyoid superiorly and the upper portion of the cricoid below; retention hooks are used to secure the flaps out of the way.

5.The midline raphae is divided between the strap muscles with cautery, exposing the laryngeal cartilage (Fig. 38.3).

6.A single-prong hook is placed under the thyroid notch, and the larynx is retracted towards the side opposite the paralysis, bringing the entire hemilaryngeal cartilage into view (Fig.38.4).

7.The outer perichondrium of the thyroid cartilage is then incised with a 15 blade, and a posteriorly-based flap is raised with a cottle or freer elevator. This requires serial release of the perichondrium superiorly and inferiorly (Fig. 38.5).

8.The inferior border of the thyroid ala has muscle fibers from the cricothyroid muscle inserting onto it, so these must be divided (typically with bipolar cautery followed by 15-blade division). This exposes the inferior border, so that the correct orientation of the window can be properly determined (Fig. 38.6).

9.The exposure of the inferior thyroid cartilage border must extend posterior to the muscular tubercle (an inferiorprojecting extension of the thyroid ala), as the angulation of this process can cause mistaken orientation of the medialization window. The downward projection of the muscular tubercle must be ignored when determining the horizontal plane of the inferior border of the thyroid cartilage (Fig. 38.7).

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Fig. 38.3  Division of midline raphae of the strap muscles

Fig. 38.5  Posteriorly based outer perichondrial flap elevation

10.A window is outlined in the thyroid cartilage, measuring 6 × 13 mm, using the window-size gauge instrument. The window is placed 3 mm above the inferior border of the thyroid cartilage. Placement of the window any higher (superior) may result in medialization of the false vocal fold or ventricular mucosa, with poor voice results. The window is “set back” from the midline of the thyroid cartilage by a distance of 5 mm in women and 7 mm in men. This setback helps avoid medialization of the anterior vo-

Fig. 38.4  Single-prong hook under the thyroid notch to gain exposure to thyroid ala

Fig. 38.6  Bipolar cautery and sharp dissection are used to expose the inferior border of the thyroid ala

cal fold, which may result in “pressed” voice (Fig. 38.8). After the window is outlined, one can pass a needle (21 gauge) through the anterior-superior corner of the proposed ML window during simultaneous flexible laryngoscopy. Care is taken to not “pass point” with the needle as it goes through the cartilage, thus avoiding the airway. The needle can usually be seen immediately or can be rapidly jostled to aid the identification of the needle location. The needle location can aid in optimal window localization. If

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Fig. 38.8  Correct placement of the medialization window, 5–7 mm from the midline of the thyroid ala (5 mm in females, 7 mm males), and 3 mm above the inferior border. The window-size gauge instrument is 6 × 13 mm in area

the needle is seen too anteriorly or superiorly, the planned ML window can be adjusted appropriately.

11.The window of cartilage is then removed (with a 15 blade, Kerrison rongeur, or drill, depending on laryngeal calcification). In younger patients, the cartilage is soft, and can be removed with a 15 blade, being cautious to avoid penetration of the cartilage with resultant paraglottic bleeding. Often, a triangle of cartilage can be incised and then removed from the posterior superior aspect of the window using a Woodson elevator (Fig. 38.9). Once an entry point through the thyroid cartilage is established, a Kerrison rongeur can be used to complete the window (Fig. 38.10). When drilling the window, a 2- to 3-mm cutting burr is used, first outlining the perimeter of the window. Once the entire rectangular section of cartilage is thinned, a Woodson elevator can be used to gain entry into the paraglottic space (Figs. 38.11, 38.12).

 

Fig. 38.7  Diagram showing the incorrect (left) and correct (right) method of exposing the inferior thyroid ala. On the left, the cricothyroid fibers have not been divided from the inferior border, and an incorrect, downwardly sloping line is used to trace the proposed horizontal plane of the vocal fold. On the right, a through dissection of the inferior thyroid ala allows the true horizontal plane of the vocal fold to be outlined, insuring correct window placement. In this case, the inferior muscular tubercle (arrow) is ignored when determining the plane

Fig. 38.9  A small triangle of cartilage is removed from the posterior window using a 15 blade and a Woodson elevator

12.The inner perichondrium that lies deep to the window is removed, exposing the thyroarytenoid muscle fascia. Often this inner perichondrium is removed piecemeal with the Kerrison rongeur during primary cartilage removal of the window. However if it is intact, then it may be incised superiorly, posteriorly, and inferiorly (Fig. 38.13). A surgical plane is then developed, with the right-angle elevator within the paraglottic space (just superficial to the TA fascia) in all directions around the window except anterior (Fig. 38.14). Dissection anterior to the window may result in perforation into the airway through the very thin (and closely adherent) ventricular mucosa and should be avoided. Incising the inner perichondrium and establishing a surgical plane in the paraglottic space is important to successful medialization. An intact perichondrium remains tightly bound to the thyroid cartilage (even with undermining) and often provides great resistance to medialization; it is analogous to trying to displace a trampoline. In contrast, the paraglottic space allows for unencumbered medialization, once the inner perichondrium is incised.

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38.10  Kerrison rongeur is then used to remove the remainder of the cartilage

Fig. 38.11  A cutting burr is used to outline the window in cases where the cartilage is calcified

Fig. 38.12  A Woodson elevator is then used to gain entry into the paraglottic space, when the cartilage is sufficiently thinned

Fig. 38.13  Release of the inner perichondrium, with a 15 blade superiorly, posteriorly, and inferiorly

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Fig. 38.14  Undermining within the paraglottic space (deep to the inner perichondrium) superiorly, posteriorly, and inferiorly

13.The inferior paraglottic surgical plane should extend below the inferior strut of the thyroid ala. This can be achieved by undermining from below the strut, using the long or a cottle elevator. The TA fascia in the window should be displaced medially to avoid perforation/penetration of the TA muscle fibers (Fig. 38.15).

14.The TA muscle is then displaced within the window while visualizing the effects on vocal fold displacement on the videomonitor. This helps establish the correct plane of medialization. Within the window, the inferior aspect generally is the most desirable for medialization, and corresponds to the free edge of the vocal fold. Displacement within the superior aspect of the window usually medializes the false vocal fold or ventricular mucosa, and results in suboptimal results in most cases.

15.A depth gauge is used to displace the paralyzed TA muscle medially, while the patient counts to “10” (Fig. 38.16). A combination of visual feedback from the videolaryngoscopy monitor and the patient’s vocal quality are used to judge the correct amount of medialization needed. Ideally, the paralytic vocal fold will assume a straight contour in the midline, allowing for complete glottic closure and significant voice improvement. Two principle measurements are obtained. The first is the distance from the anterior

Fig. 38.15  Undermining the paraglottic space from below, to insure release of cricothyroid fibers. This will allow space for the flanges of the implant to rest

window to the point of maximal displacement (i. e., the tip of the depth gauge), which is referred to as the “A” measurement in the corresponding illustration. This is often 10–13 mm in length, as posterior medialization most often is used (in women this measurement is typically closer to mid aspect of the window, 6–8 mm) (Fig. 38.17). The other measurement is the depth of medialization, and is read off the depth gauge instrument. The measurement is taken off the inner table of the cartilage, not the outer table (Fig. 38.18). Typically, 5–7 mm of medialization is needed at the posterior aspect of the window. It is rare that any medialization is needed at the anterior aspect of the window, except in females.

16.Once the appropriate measurements are made, 3 × 0.5-inch Cottonoids soaked in 1:10,000 epinephrine are placed inside the window to aid in hemostasis while the implant is carved.

17.An implant is then carved out of medium-grade Silastic wedge on the back table to meet the specifications provided by the depth gauge measurements.

a)Carving the Silastic implant

The implant may be carved from a medium-grade Silastic block to meet the specifications provided by the depth gauge measurements. A preformed 20-mm wedge block

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Fig. 38.16  Displacement of TA muscle with the depth gauge. Note the displacement is generally at the posterior, inferior border of the window

(“silicone strip” by Medtronic ENT) simplifies this task and shortens surgical time. This section describes its proper preparation for implantation.

The distance from the anterior edge of the window to the point of maximal medialization (typically 11–13 mm in males and 3–8 mm in females) is measured along the block (measurement “A” on the diagram), and a dot is placed with a marking pen (Fig. 38.19).

From the dot, a line is extended into the substance of the block (measurement “B” in the diagram) which corresponds to the depth of medialization (Fig. 38.20). This measurement was obtained using the depth gauge and is typically 5–7 mm in most patients. Lines are then drawn connecting the tip of line B with both the anterior and posterior portions of the block (“C” and “D,” respectively) (Fig. 38.21). This creates a characteristic triangular shape of the implant, with the edge C corresponding to the portion of the implant that displaces the vocalis muscle medially, and segment D corresponding to the posterior extension of the implant that helps to hold it in place.

A 10 blade is used to cut along lines C and D, removing the excess portion of the block (Fig. 38.22). One must be careful to make these cuts at 90° angles to maintain the integrity of the depth of the implant. The implant is placed in a customized implant holder for further shaping.

The plane of medialization (lower, middle, or upper portion of the window) that corresponds to the plane of the true vocal fold is marked with a line along the implant border (Fig. 38.23). In general, this is the inferior or lower border of the window space. The line must be drawn along the medialization “zone” in the middle of the implant, not on the upper or lower “flange” portions

Fig. 38.17  Distance from the anterior window to the point of maximal displacement of the depth gauge. This is generally 10–13 mm in males and 3–8 mm in females. This is referred to as the “A” length during implant carving

Fig. 38.18  Measuring the depth of medialization using the depth gauge. This is typically 5–7 mm. The measurement should be taken of the inner (deep) aspect of the cartilage. This is referred to as the “B” measurement during implant carving

of the implant (Fig. 38.24). Using a 15-blade, the excess Silastic is removed superior and inferior to the plane of medialization, preserving an approximately 3-mm strip of material along the indicated line (Figs. 38.25, 38.26). The extreme upper and lower edges of the implant must be thinned considerably to make the flanges flexible. This