ABSTRACT: Total laryngectomy is the surgical procedure traditionally used to treat patients with advanced-stage cancer of the larynx. The impairments resulting from removal of such a small organ are, indeed, profound. They include loss of voice and speech; altered respiration, necessitating a permanent breathing opening in the neck; and diminished sense of smell and taste. When one considers these factors, successful treatment of laryngeal cancer cannot be measured by survival rate alone. Rapid, effective restoration of voice and speech is one of the primary focuses of rehabilitation and is pivotal to the prevention of the potential psychosocial and economic consequences of total laryngectomy. This article focuses on the methods of voice restoration currently being employed to reestablish the ability to speak. [ONCOLOGY 14(6):915-922, 2000]
Speech is a uniquely human ability that allows us to communicate with others. It is used primarily to send and receive messages and to express emotions. As part of this process, the larynx generates voice, which renders speech audible and gives each person a recognizable “voiceprint” that is nearly as individual as a fingerprint. Speech is such an integral part of our daily life that most of us rarely appreciate its significance until the ability to speak is interrupted.
The global incidence of cancer of the larynx is estimated to be 136,000 new cases annually, with a 7:1 male predominance. Geographically, there is a higher incidence in western Asia (6% of all cancers diagnosed in males are of the larynx), South America, and eastern, southern, and western Europe. In 1999, 10,600 Americans developed cancer of the larynx, with a male to female ratio of 4:1.
Epidemiologic evidence suggests that cigarette smoking is the major risk factor for the development of squamous cell carcinoma in the glottic and supraglottic areas of the larynx, and that this risk increases when combined with the carcinogenic effect of heavy alcohol(Drug information on alcohol) consumption.[2,3] Accordingly, the development of cancer in this important human organ is largely preventable.
Treatment of laryngeal cancer, determined primarily by precise staging of the disease, includes radiation, surgery, or a combination of the two modalities. There is also emerging interest in chemoradiation protocols aimed at organ preservation.
Total laryngectomy, ie, removal of the entire larynx, is the surgical procedure traditionally employed in patients with advanced-stage disease. A significant proportion of the 10,600 people in the United States diagnosed with laryngeal cancer this year will lose their larynx and their voice after undergoing this ablative procedure.
It is important to appreciate that, unfortunately, the impact of total laryngectomy goes far beyond the elimination of voice and speech. Removal of the larynx results in complete separation of the airway from the digestive tract and, consequently, the person breathes and coughs through a permanent opening or tracheostoma in the midline of the neck. This anatomic diversion eliminates the upper airway humidification and filtration normally provided primarily by the nose and also diminishes olfaction and gustation.
It is clear from the foregoing comments that surgical removal of the larynx has a myriad of devastating physical and psychosocial consequences. In fact, despite the smaller chance of survival with radiation therapy compared to total laryngectomy, some patients choose radiation because of the fear of voicelessness and concomitant postsurgical impairments. Clearly then, the rapid reestablishment of acceptable voice and fluent, intelligible speech is the principal focus of rehabilitation following total laryngectomy.
This report provides a brief overview of the methods of voice restoration currently being employed. Highly technical details have been purposely omitted.
A handheld artificial larynx is probably the most widely used method of postlaryngectomy voice restoration throughout the world today (Figure 1). This may be attributable primarily to the fact that the basic skills necessary for functional use of an artificial larynx often can be rapidly learned. Two basic types of artificial larynx devices are commercially available—pneumatic and electronic—and the designations differentiate the two types with regard to their tone-producing mechanism and power source.
The earliest artificial larynx devices were pneumatic. These devices produced a sustained tone when the user exhaled across a reed housed within the instrument. The cup-shaped end of the device is coupled by hand over the permanent tracheostoma in the neck, and a tube on the other end is inserted approximately 1½ inches into the corner of the mouth. The tone that is introduced is articulated by the tongue, lips, and teeth into fluent, intelligible speech.
Although some pneumatic artificial larynx devices produce an exceptionally high-quality artificial voice, they are not popular because they are cumbersome to use, and coupling of the neck and mouth is hygienically unacceptable. Examples of commercially available pneumatic artificial larynx devices are the Van Humen DSPB, (Velp, The Netherlands) and the Tokyo (Omaha, Nebraska). The price of these devices ranges from approximately $75 to $150.
Most artificial larynx devices in use today are electronic. They are designated as either neck-type or intraoral, reflecting the manner in which the sound is introduced into the user’s vocal tract. All are battery powered and handheld, with the exception of one device that is incorporated into a dental plate.
The tone-generating mechanism is either an electromagnetic diaphragm or a small piston that is driven at high velocity against a rigid plastic membrane. The sound that is produced has been described, at best, as electronic or mechanical, and, in less favorable terms, as robotlike.
Unfortunately, development of an advanced technology electrolarynx that can produce a more human-sounding artificial voice, while simultaneously maintaining small device size, low complexity, and acceptable cost, has undoubtedly been discouraged by corporate awareness of market size and return on investment.
Neck-Type Electrolarynx—The neck-type electrolarynx seems to be used more widely than the intraoral type. To speak, the user couples the head of the neck-type device against the surface of the neck at a location determined to have the most favorable tissue density so as to facilitate introduction of the tone through and into the vocal tract (Figure 1). As the sound reaches the mouth, it is articulated into speech.
The basic skills that a person must learn in order to use the neck-type electrolarynx include constant, accurate placement of the device against the neck. Press-button activation of the electronic voice tone must be correctly timed so that the tone starts precisely at the beginning of a sentence and ends at its completion. As with all methods of postlaryngectomy voice restoration, a comprehensive rehabilitation program with a speech-language pathologist is recommended to achieve maximum speech outcome.
Commercially available neck-type electrolarynx devices vary considerably in quality, and prices range from $150 to $800. Examples include the Servox (Seimens Hearing Instruments, Picatawny, New Jersey) and the Nu Vois (Lauder Enterprises Inc, San Antonio, Texas).
Intraoral Electrolarynx—An intraoral type electrolarynx is selected for use in individuals whose neck tissue is either insufficiently healed to permit contact with a neck-type electrolarynx or too dense to transmit the electronic tone. With the intraoral device, a small piece of plastic tubing connected to a handheld, battery-powered tone generator is inserted approximately 1½ inches into the side of the mouth. The tone is introduced directly into the mouth and articulated into speech. In addition to learning the same skills as those required for use of a neck-type electrolarynx, the user of the intraoral larynx must master speaking with a tube present in the mouth.
An interdental variant of an intraoral artificial larynx, with a tone generator built into a dental plate, avoids a mouth tube and the need to be handheld. The tone is activated by a remote switch.
The concept of the intraoral electrolarynx was introduced first in 1957 and again in 1992, but acceptance has been limited by reliability and substantial cost. Commercial examples of an intraoral electronic larynx are the Cooper-Rand (Luminaud Inc, Mentor, Ohio), which costs approximately $375, and the interdental Ultra Voice (Health Concepts, Inc, Malvern, Pennsylvania), with an estimated cost of $2,000.
The first report of what is known today as esophageal voice was presented by Reprand at the Academy of Science in Paris in 1828 in his account of a patient with atresia of the larynx. Despite a completely nonfunctioning larynx, the patient was able to speak by ingesting air into the esophagus and releasing it to produce a pseudovoice “sufficiently, clearly and in a manner to be audible at a certain distance.”
This report preceded by many years Billroth’s pioneering total laryngectomy in 1874. Other reports of alaryngeal patients able to produce voice with their esophagus gradually appeared as more laryngectomies were performed, but this method of substitute voice remained unnamed until 1919, when the laryngologist Seeman coined the term “esophageal speech.”
The basic mechanism for esophageal voice production is in some ways similar to producing a belch but is purposeful and controlled rather than unexpected and abrupt. To produce esophageal voice, the laryngectomized individual learns to either inject or inhale into the upper esophagus that small amount of air always present in the mouth (Figure 2).
In the injection method, the broad surface of the tongue pushes upward and backward against the palate. This compresses a small volume of air into the upper one-third of the esophagus. The air is then immediately expelled by the user primarily by contracting the intrathoracic-abdominal muscles so as to apply a controlled sustained pressure against the lower esophagus. Upward movement of the air column through the constricted uppermost fibers of the esophagus and other adjacent opposed mucosal surfaces induces a vibration, which is perceived as a sustained sound. The esophageal voice is articulated into speech by the tongue, lips, and teeth.
The sound quality of esophageal voice varies but is often described as husky, rough, and low pitched. This is directly attributable to the physical properties of the bulky mucosal surfaces that vibrate and the altered resonance tract in which the voice is processed. By comparison, normal healthy vocal cords provide an intricately adjustable mechanism specifically designed to produce human voice as we know it.
In addition, esophageal speech is characterized by shortened duration and discontinuous phrasing due to the small reservoir of air in the esophagus available to power sustained voice production. The vital lung capacity of a normal, healthy adult is 2,200 to 4,690 cm³, and most of that air is available for continuous conversational speech prior to requiring replenishment. By comparison, the volume of the esophagus is only 40 to 80 cm³, providing only enough air to speak six to seven syllables before requiring replenishment.
The mechanism of rapidly exchanging air in and out of the esophagus to produce esophageal voice can be a difficult-to-learn, easily tiring, unnatural process. The literature suggests that only about 60% of those who attempt to learn esophageal speech are successful. Failure is attributable to a variety of physical and psychological factors. On the other hand, those who do master this method often acquire an effective method of voice and speech that requires no artificial appliances or surgery.
Advantages and Disadvantages of the Artificial Larynx and Esophageal Voice
Artificial larynx devices and esophageal voice provide two good alternatives to postlaryngectomy rehabilitation for countless thousands of people. Both methods have advantages and disadvantages that often influence which one a person will ultimately use. A prominent advantage of the artificial larynx is that its use is often easily and rapidly learned, while major disadvantages include unnatural voice quality and the need to use a hand to speak.
Advantages of esophageal voice include a more natural-sounding voice and no reliance on a mechanical device, but disadvantages are the length of time it takes to learn this method and the disappointing small percentage of those who are able to do so.
Moreover, there are individuals who for some reason cannot or do not successfully learn to use either an artificial larynx or traditional esophageal voice. Another postlaryngectomy voice restoration option was needed for these individuals, and, eventually, such an option emerged with the introduction of tracheoesophageal voice by Singer and Blom in 1979.