What should be considered when voice surgery is contemplated?
Principles
Surgery can cure many voice problems, but it may also result in complications that worsen the voice. Scar tissue occurs in response to trauma, including surgery. If scar tissue replaces the normal anatomic layers, the vocal fold becomes stiff and adynamic (non-vibrating). This results in asymmetric, irregular vibration with air turbulence that we hear as hoarseness, and/or incomplete vocal fold closure allowing air escape which makes the voice sound breathy. Such a vocal fold may look normal on traditional examination, but will be seen as abnormal under stroboscopic light. Conveniently, most benign pathology (nodules, polyps, cysts, etc) is superficial. Consequently, surgical techniques have been developed to permit removal of lesions from the epithelium or superficial layer of the lamina propria without disruption of the intermediate or deeper layers in most cases. All of these delicate microsurgical techniques are now commonly referred to as phonosurgery, although the term was originally introduced by Dr. Hans von Leden in referring to operations designed to alter vocal quality or pitch.
Techniques (Endoscopic)
Most voice surgery is performed through the mouth after placement of a metal tube called an operating laryngoscope, utilizing a microscope, and is called endoscopic (or internal) laryngeal surgery. Surgical treatment of laryngeal abnormalities can be performed using microscopic scissors and other instruments, or lasers. Lesions involving the vibratory margin are still removed most safely using traditional instruments and magnification through an operating microscope. Such lesions include nodules, polyps and cysts that have not responded to voice therapy. Current techniques allow the surgeon to remove virtually nothing but the diseased tissue. Such atraumatic surgery may not even require post-operative voice rest, and rapid healing with good voice quality usually follows. Although lasers are "high tech," they are not always the best choice for laryngeal surgery -- at least not the lasers currently utilized. The potential problem with the carbon dioxide (CO2) laser in standard surgical use is the associated heat which may damage surrounding tissues. At the power densities required for surgical ablation and the laser beam spot diameters generally used, there is a heat halo around the beam. When used on the vocal fold edge, the heat may be sufficient to provoke scarring. This produces an adynamic segment on the vocal fold, and hoarseness. The CO2 laser is, however, extremely useful for selected lesions such as varicosities that lead to vocal fold hemorrhages, vaporization of blood vessels that supply laryngeal polyps, papillomas (lesions caused by the wart virus) and selected cancers.
When surgery is indicated for vocal fold lesions, it should be limited as strictly as possible to the area of abnormality. Virtually no place exists for "vocal cord stripping" in patients with voice problems. Even when there is good reason to suspect malignancy, more precise surgery can and should be performed in most cases.
Precautions
A detailed discussion of laryngeal surgery is beyond the scope of this publication. However, a few points are worthy of special emphasis. Surgery for vocal nodules should be avoided whenever possible and should almost never be performed without an adequate trial of expert voice therapy, including patient compliance with therapeutic suggestions. In most cases, a minimum of 6 to 12 weeks of observation should be allowed while the patient is using therapeutically modified voice techniques under the supervision of a certified speech-language pathologist and possibly a singing teacher. Proper voice use rather than voice rest (silence) is correct therapy. The surgeon should not perform surgery prematurely for vocal nodules under pressure from the patient for a "quick cure" and early return to voice performance. Permanent destruction of voice quality is a very real complication. Even after expert surgery, voice quality may be diminished by submucosal scarring. This situation produces a hoarse voice with vocal folds that appear normal on routine indirect (mirror) examination, although under stroboscopic light the adynamic segment is obvious. No reliable cure exists for this complication.
There are also other potential complications of voice surgery. Although they are uncommon or rare, they may be seen occasionally even if the surgeon and patient do everything right. They include the following (among others): 1) swelling with airway obstruction requiring tracheotomy; 2) chipping or fracture of a tooth by the laryngoscope; 3) bleeding; 4) infection; 5) recurrence of the problem (or a new mass such as a cyst or granuloma) requiring additional therapy (medications, voice therapy and/or surgery); 6) injury to the larynx, such as arytenoid dislocation; and others.
Techniques (External)
New techniques of external laryngeal surgery to modify the laryngeal skeleton have become extremely useful in treating vocal fold paralysis, a common consequence of viral infection, surgery and cancer. Until recently, vocal fold paralysis was most often managed by endoscopic injection of Teflon into the tissues beside the paralyzed vocal fold. This pushed the paralyzed side toward the midline, allowing the normal vocal fold to meet it, thus permitting glottic closure and improving voice. Although Teflon is relatively inert, granulomatous reactions to the foreign body are not uncommon, and stiffness of the vocal fold edge frequently impairs voice quality. Teflon infiltrated into tissues is hard to remove if the results are unsatisfactory. Teflon injection has been largely replaced by fat injection or thyroplasty. Thyroplasty is a technique in which a window is cut in the laryngeal skeleton, and a piece of thyroid cartilage is depressed inward and held in place with a silicone block. This pushes the vocal fold toward the midline fairly reversibly, without injecting a foreign body into the tissues. We have also introduced an injection technique similar to Teflon, which uses the patient's own fat, harvested from the abdomen. This eliminates the disadvantages of Teflon, but it may have other problems such as resorption of the fat in some cases. Fat may also be used to improve vocal fold scar in selected cases.