Spasmodic dysphonia

Office-based procedures for the voice have become significantly more common in recent years, partly because of the wide variety of injectable augmentation substances that have entered the market. In addition, the indications for using botulinum toxin A (Botox) in the larynx have expanded during the past decade. Indeed, it is difficult to envision the practice of laryngology without the armamentarium of injectables currently at our disposal.

Although most of these procedures involve a variety of techniques and approaches, we describe those that we use most often and those that are the easiest to learn.

Augmentation injection laryngoplasty

Augmentation injection laryngoplasty is used for the treatment of symptomatic glottal insufficiency. Indications include unilateral vocal fold paralysis and vocal fold bowing secondary to muscular atrophy, paresis, or presbylaryngis. A variety of injectables is available, and each has its advantages and limitations (table 1). The choice of substance can be matched to the patient's clinical situation.

The injection technique we prefer is a transoral approach guided by fiberoptic laryngoscopy. Local anesthesia should be administered according to the protocol described in the preceding article in this supplement ("Topical anesthesia of the airway and esophagus," page 2).

Vocal fold paralysis. For treating vocal fold paralysis, we prefer to inject collagen in most cases. (1-3) Note that most injectables must be transferred to a 1-ml tuberculin syringe that is loaded into an orotracheal injector (Medtronic Xomed; Jacksonville, Fla.) (figure 1, A). A 27-gauge needle is advanced into the oral cavity under direct vision (figure 1, B). As the needle enters the oral cavity, the patient is instructed to say "aaaah"; this action raises the palate and clears the path into the oropharynx. The surgeon's assistant should position the fiberoptic scope just above the palate until the needle is seen in the oropharynx. The injector is then advanced and the needle tip is guided into the hypopharynx (still under endoscopic visualization) as the assistant follows closely behind with the fiberoptic scope. The assistant must be adept at manipulating the scope because consistent visualization of the injector can be problematic in a narrow airway with copious secretions. The fiberoptic scope should be positioned a few millimeters above the vocal fold. A clear and well-illuminated magnified view of the vocal folds is crucial to achieving the necessary precision (figure 1, C).

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In the case of unilateral vocal fold paralysis, the injection should be placed at two sites: at the posterior aspect (lateral to the vocal process) and at the mid-vocal fold. The injection should be deep enough to reach into the substance of the thyroarytenoid muscle at the level of the free edge of the vocal fold. The surgeon should avoid making a superficial placement into Reinke's space because this will result in a stiff vocal fold and poor voice quality. Conversely, if the subglottis or infraglottis begins to bulge during injection, the needle should be withdrawn slightly. The injection should begin at the posterior aspect of the vocal fold, where the most correction is needed (figure 1, D). Once the posterior vocal fold is adequately medialized, a smaller additional amount can be deposited into the mid-vocal fold (figure 1, E). If the injected substance extrudes from the puncture hole, the material can be cleared by instructing the patient to cough or clear the throat. The injection should be carried out in a stepwise fashion, and the surgeon should periodically check to see if there is any improvement in the patient's voice.

With most injectables, the medialized vocal fold should be overinjected (past the midline) by approximately 30%. In general, the vocal fold is medialized until the voice is maximally improved. Then an additional 0.1 to 0.2 ml is injected to achieve overcorrection. This overcorrection is necessary because almost all injectables have a small aqueous component that will be absorbed 3 to 5 days after injection. The total amount necessary for unilateral augmentation is typically less than 1 ml.

Vocal fold bowing. The injection technique used to treat vocal fold bowing secondary to muscular atrophy, paresis, or presbylaryngis differs slightly from the aforementioned technique. Typically, these cases require injection principally into the mid-vocal fold, where the maximal glottal gap occurs (figure 2). In severe cases of muscular atrophy, the posterior vocal fold can be augmented to fill in the atrophy that occurs just anterior to the vocal process. Again, overcorrection is the rule, even in the case of bilateral injections. Airway compromise should not be a concern because the posterior respiratory glottis remains patent.

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A Bruning syringe can be used to inject collagen, but this instrument is better suited for delivering large-particle injectables (e.g., Gelfoam and fat) that require an 18- or 19-gauge needle. In addition, the mechanics of this injection device are not as smooth and precise as are those of other injection devices; with the Bruning device, the surgeon must rely on a clicking action that deposits a predetermined amount of substance (~0.2 ml).

Laryngeal Botox injection

Botox is very useful in the treatment of a variety of voice disorders, and it is a staple in most laryngologists' offices. The number of uses continues to expand; a few of the more common indications are spasmodic dysphonia, recurrent vocal process granuloma, paroxysmal laryngospasm, and paradoxical vocal fold movement disorder. Botox is a chemodenervation agent that weakens the target muscle by preventing acetylcholine release at the motor end plate. The effect on the muscle is temporary, lasting an average of 3 months.

In our practices, most laryngeal Botox injections are performed transcervically under electromyographic guidance to localize the target muscles. This method is the quickest and most precise means of delivering Botox, but the learning curve is steep. Also, it is not intuitive for most otolaryngologists, who prefer direct visualization of the target rather than blind needle trajectory paths. For many otolaryngologists who perform laryngeal Botox injections on an infrequent basis, transoral injection may be the preferred approach.

The equipment setup and local anesthesia technique are similar to those used for the laryngeal procedures described in the previous section. A 100-unit vial of Botox is diluted with 4 ml of preservative-free normal saline, bringing the concentration to 2.5 units per 0.1 ml. An orotracheal injector with a 27-gauge needle is used. The needle should be primed with the solution; this typically requires 0.2 ml.

We use two methods of Botox injection; one is directed at the false vocal folds (figure 3), (4,5) and the other is targeted to the true vocal folds (table 2). The onset of maximum effect typically takes 3 to 7 days. Breathiness or whisper-voice following injection is normal, but it generally resolves in 1 to 2 weeks. A longer breathy phase should prompt the surgeon to lower the dose of subsequent injections.

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Laryngeal biopsy

We continue to advocate microlaryngoscopy under general anesthesia as the gold standard for the removal or biopsy of glottic lesions. In particular, most benign lesions of the vocal folds (e.g., polyps, cysts, and nodules) require precise dissection techniques to preserve the vibratory characteristics of the vocal folds. The required degree of precision cannot be achieved with an office-based procedure. However, in carefully selected patients with laryngeal lesions, office biopsies can be successful. Moreover, patients who are not good surgical candidates because of coexisting medical morbidities and patients whose anatomy precludes rigid laryngoscopy may be ideal candidates for office-based biopsies.

Using the standard setup for a fiberoptically monitored laryngeal procedure, the surgeon uses a curved laryngeal biopsy forceps (Medtronic Xomed) to biopsy or remove suspicious lesions (figure 4, A). Another method involves the use of a transnasal esophagoscope with a 1.8-mm biopsy forceps placed through the side channel (figure 4, B). In the case of medically infirm patients with advanced head and neck cancer who are not surgical candidates, a complete panendoscopy can be performed in the office using a transnasal esophagoscope. (6)

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As previously mentioned, most benign lesions should be removed in the operating room with the patient under general anesthesia. But as better instrumentation (figure 5) for lesion removal and dilation of strictures becomes available, the use of office-based procedures will continue to expand.

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References

(1.) Ford CN, Martin DW, Warner TF. Injectable collagen in laryngeal rehabilitation. Laryngoscope 1984;94:513-18.

(2.) Ford CN, Bless DM. Clinical experience with injectable collagen for vocal fold augmentation. Laryngoscope 1986;96:863-9.

(3.) Remacle M, Marbaix E, Hamoir M, et al. Correction of glottic insufficiency by collagen injection. Ann Otol Rhinol Laryngol 1990;99:438-44.

(4.) Kendall KA, Leonard RJ. Treatment of ventricular dysphonia with botulinum toxin. Laryngoscope 1997;107:948-53.

(5.) Schonweiler R, Wohlfarth K, Dengler R, Ptok M. Supraglottal injection of botulinum toxin type A in adductor type spasmodic dysphonia with both intrinsic and extrinsic hyperfunction. Laryngoscope 1998;108:55-63.

(6.) Postma GN, Bach KK, Belafsky PC, Koufman JA. The role of transnasal esophagoscopy in head and neck oncology. Laryngoscope 2002;112:2242-3.

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