Voice Feminization Surgery: A Critical Overview
By Anne A. Lawrence, M.D., Ph.D.Updated January 2004
Introduction: This article will briefly summarize current techniques of voice feminization surgery. The information presented here reflects my personal opinions and values, and nothing in this article should be interpreted as medical advice – always consult your personal physician.
Theory: Male and female voice differ primarily in their pitch (frequency) and in their timbre (resonance). The characteristic pitch or fundamental frequency (F0) of the male voice ranges from about 100 to 150 Hz; for the female voice, F0 ranges from 170 to 220 Hz. The lower pitch of the male voice is primarily due to the greater length and mass of the male vocal cords. The distinctive timbre or resonance of the male voice is primarily due to the greater length of the male upper airway (throat, mouth, nose, and sinuses; see Fitch & Giedd, 1999). Both fundamental frequency and resonance provide important acoustic cues to the sex of a speaker, but fundamental frequency is the more important cue (for a review see Oates & Dacakis, 1983). There is currently no practical way to surgically feminize the resonant properties of the airway (more research in this area would be desirable), but there are several operations that can surgically modify the pitch or F0 of the voice.
Fundamental frequency, F0, is inversely proportional to the length of the vocal cords, is inversely proportional to the square root of the density (mass per unit volume) of the cords, and is directly proportional to the square root of the tension of the cords (see Kunachak, Prakunhungsit, & Sujjalak, 2000). Consequently, there are really only three ways to attempt to increase F0 surgically: (a) by decreasing the vibrating length of the vocal cord (highly efficient), (b) by increasing tension of the vocal cord (less efficient, since the relationship is square root rather than linear), or (c) by decreasing the density of the vocal cord (also less efficient, since the relationship is square root).
Crico-Thyroid Approximation (CTA): The most commonly performed operation to raise F0 is crico-thyroid approximation (CTA), which is shown in the illustrations below.
In this technique, the thyroid cartilage (Adam's apple) is pushed against the cricoid cartilage that lies below it. The two cartilages are then sutured together with nylon sutures, usually placed over bolsters (Isshiki, Taira, & Tanabe, 1983; for another variation see Sataloff, Spiegel, Carrol, & Heuer, 1986). Some surgeons use metal clips to hold the cartilages together. The approximation of the thyroid and cricoid cartilages anteriorly increases the tension of the vocal cords by stretching them posteriorly. This raises the pitch at which the cords will vibrate. The operation mimics normal physiology: When we speak at the upper end of our pitch range, we do so by contracting the cricothyroid muscle, which pulls the two cartilages together and increases tension in our vocal cords.
CTA is performed through a small horizontal incision in the neck, which is placed at a natural skin fold; the resulting scar is usually invisible or easily concealed. Either local or general anesthesia can be used. Because F0 varies with the square root of vocal cord tension, CTA is a relatively inefficient way to increase F0.
The few follow-up studies of CTA in the published literature have reported inconsistent outcomes. Neumann, Welzel, and Berghaus (2002) reported results in 67 patients; nearly all achieved an increase in fundamental frequency, with a mean increase of 5 semitones. However, the modal increase was only 2-3 semitones, and only 28% of patients achieved a F0 in the female range (defined by the authors as 174 Hz or greater), although this percentage increased to 38% at 6-month follow-up. Only 2 patients were made worse by the procedure. De Jong (2003) described outcomes in a series of 30 patients, 26 of whom were available for follow-up. Most patients (85%) were satisfied with their results; mean FO increased from 122 Hz to 181 Hz. Wagner, Fugain, Monneron-Girard, Cordier, and Chabolle (2003) reported results in 14 patients who underwent CTA (9 patients), anterior commissure advancement (2 patients), or both (3 patients). Over three quarters achieved subjectively satisfying results, but the median increase in F0 was only 11 Hz. Of the 9 patients who underwent CTA alone, only 4 achieved postoperative F0s of 160 Hz or greater. Brown, Perry, Cheesman, and Pring (2000) described outcomes in 14 patients; their patients had a relatively high mean F0 of 152 Hz before surgery. Mean F0 did not increase significantly after CTA, but modal frequency did, to a mean of 175 Hz. Results were highly variable, with 2 patients showing very large increases in modal F0, and 2 patients showing no increase.
Advantages: No surgery on the vocal cords themselves; theoretically reversible if the patient is dissatisfied.Laser Assisted Thyro-Arytenoid Muscle Resection (Abitbol Technique): Parisian ENT surgeon and laser specialist Dr. Jean Abitbol (1995) described a novel technique of laser-assisted endoscopic thyroarytenoid muscle resection. He has used this technique to attempt to raise the F0 of non-transsexual women with unusually low voices, and of at least a few transsexual women. His technique involves reducing the size of the thyroarytenoid muscle that runs parallel to the vocal cord; this may decrease the density of the cord, and may also be increase tension by creating scarring. However, both these methods should theoretically be relatively inefficient ways of increasing F0. Dr. Stephen Pincus (1997) has observed Abitbol’s technique, and he believes that it can produce only limited elevation of vocal pitch; he also believes that it has the potential to cause hoarseness. I am unaware of any published series of results using this technique in transsexuals or in non-transsexuals.
Disadvantages: Requires neck incision; prolonged healing process; long-term results have sometimes been favorable, but are inconsistent and sometimes unsatisfactory.
Assessment: Cautiously endorsed in selected cases.
Advantages: Performed endoscopically, no neck incision.Laser Assisted Voice Adjustment (LAVA; Orloff Technique): Dr. Lisa Orloff, a professor of otolarygology at the University of California at San Diego, has performed Laser Assisted Voice Adjustment, an endoscopic technique in which a CO2 laser is used to scar and stiffen the area adjacent to the vocal cords, perhaps thereby increasing vocal cord tension. On theoretical grounds, this should also be a relatively inefficient way to increase F0.
Disadvantages: Minimal pitch elevation; potential for hoarseness or breathiness; no published series in transsexual women.
Assessment: Not recommended.
Advantages: Performed endoscopically, no neck incision.Vocal Cord Shortening (Anterior Web Creation): Another technique to increase F0 is to shorten the vibrating length of the cords by suturing them together anteriorly, so that only the free posterior portions of the cords can vibrate. This creates what is called an anterior vocal web. Donald (1982) described an open procedure using an anterior neck incision to accomplish this. In his technique, a portion of the thyroid cartilage was also removed and the anterior one-third of the vocal cords were de-epithelialized, allowing them to fuse together to create an anterior vocal web. The illustration below shows before and after views of the result; it is redrawn from Donald’s article, but without showing the removal of any cartilage. Because vocal cord shortening reduces the vibrating length of the cord, it would be expected to be a relatively reliable and efficient way of increasing F0. Donald reported on only three patients. Two had good pitch elevation (one a complete octave); complications included breathiness of the voice in two patients, and a wound infection in another.
Disadvantages: Minimal pitch elevation; prolonged recovery period; potential for hoarseness.
Assessment: Not recommended.
More recently, Gross (1999) described a similar procedure performed endoscopically, without any cartilage resection. In his series of 10 transsexual patients, the mean postoperative F0 achieved was 201 Hz (range 154 to 240 Hz). The mean increase in F0 was 81 Hz (range 49 to 125 Hz). Duration of follow-up ranged from 35 to 45 months. All but two patients suffered transient decreases in vocal intensity, some very minor; these reportedly improved with speech therapy.
Advantages: Can be performed endoscopically, without neck incision; small published case series demonstrates long-term effectiveness.
Disadvantages: Potential for breathiness or voice weakness.
Assessment: One of the better procedures. Arguably the procedure of choice for patients who insist on undergoing pitch-elevation surgery.
Thyroid Cartilage and Vocal Cord Reduction: Recently a team of Thai surgeons (Kunachak, Prakunhungsit, & Sujjalak, 2000) reported a new, very aggressive, and highly effective (perhaps too effective) surgical technique for pitch elevation. Their procedure involved the open resection of a central strip of the thyroid cartilage, about 8 mm wide, along with resection of the anterior one-third of the vocal cords and reconstruction of the anterior commissure (where the vocal cord meet anteriorly). Their technique is shown in the illustration below.
The authors reported the results of their procedure in six Thai patients, the oldest of whom was 27 years old. F0 increased from a preoperative mean of 147 Hz (range 100 to 172 Hz) to a postoperative mean of 315 Hz (range 264 to 420 Hz). A mean postoperative F0 of 315 is fairly high even by female standards; when such a high F0 is combined with the resonant characteristics of a male airway, the subjective impression might be very unusual, and might perhaps result in unwanted attention to the voice. Interestingly, four patients in the study had preoperative F0s of 160 or higher; such F0s would typically allow them to be judged female without surgery, at least by Western standards (see Spenser, 1988, and Wolfe, Ratusnik, Smith, & Northrop, 1990). Two patients developed granulomas of the anterior commissure, which were easily treated with CO2 laser vaporization. Follow-up times ranged from 5 to 72 months.
Recently Portland ENT surgeon James Thomas web-published his results in a single case using a similar procedure, which he calls "feminization laryngoplasty."
Advantages: Small published case series suggests long-term effectiveness; thyroid cartilage resection offers cosmetic benefits.The Problem of Mismatch Between F0 and Resonance: One potential problem with the pitch-elevation techniques described above is the creation of a mismatch between F0 and the characteristic timbre (resonance) of the patient’s voice. Timbre is the acoustic quality that allows us to distinguish different musical instruments (e.g., a violin and a trumpet) when both are playing the same note. In the human voice, timbre results from the resonant properties of the upper airway (throat, mouth, nose, and sinuses): Airway resonance determine how much the overtones, or harmonics, of the fundamental frequency will be emphasized or diminished. Females generally have a shorter resonator than males, and the timbre of their voices reflects this. In my opinion, the combination of a very high F0 (as is sometimes seen immediately after CTA) and a typically-male vocal timbre sounds very odd. This is one reason that a falsetto voice often sounds "false". Thus I would be concerned that a pitch elevation operation could sometimes be too successful, and might result in an unnatural combination of pitch and resonance – one that is rarely if ever encountered in normal humans of either sex. A highly unnatural voice may be nearly as bad as a masculine voice in impairing one’s ability to pass easily as female. My personal opinion is that optimal pitch elevation in transsexual women would place the postoperative F0 at the low end of the normal female range, which would minimize the potential for a mismatch between F0 and airway resonant properties.
Disadvantages: Highly invasive and irreversible; requires neck incision; high potential for over-correction.
Assessment: One of the better procedures, albeit quite aggressive.
Many if not most transsexual women are capable of achieving an F0 in the lower part of the female range through voice training alone, without voice surgery. The problem is not physiologic incapacity; the problem is finding the motivation to undertake the hard work of learning the necessary vocal skills and of practicing them consistently until they become second nature. Nevertheless, in my opinion, most transsexual women should concentrate primarily on voice training, and consider voice feminization surgery only as a last resort.
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