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New Techniques in Vocal Cord Surgery
Spare the Voice
It is hard to believe that the source of
the purest, sweetest singing voice is two small folds of tissue drubbing
together at high speed in the middle of the throat, that even the most delicate
aria is born of pressure and force. The vocal cords move together and apart in a
wave, from bottom to top. Repeat this contact 100 to 1,000 times a second and
you have a voice that can produce exquisitely varied sounds. But too much strain
can leave flaws in this delicate system, and when bumps, cysts, or cancers arise
in the vocal cords, they carry the threat that a patient may lose one of the
most valuable tools for communication.
Armed with a microscope and endoscopic
instruments, Steven Zeitels has been able to remove cancers and tiny
abnormalities on the vocal folds while preserving normal tissue. (Photo by
Graham Ramsay)
Innovations in vocal cord surgery have helped
improve the chances of eliminating some of these problems without losing the
voice. Steven Zeitels, HMS associate professor of otology and laryngology and
director of the Division of Laryngology at the Massachusetts Eye and Ear
Infirmary, has been a leader in developing increasingly precise phonosurgical
techniques. Much of the past decade of these innovations is detailed in two
papers in the December Annals of Otology, Rhinology & Laryngology,
looking at two groups of patients: those with early vocal cord cancer and
singers and orators who develop lesions on the vocal folds.
Better Access
Surgery of the larynx lends itself to
minimally invasive techniques, though the organ is just far enough from the
mouth to have created logistical problems for early physicians trying to view
and manipulate it. Improvements in laryngoscopes and the use of microscopes and
endoscopic instruments have made it easier to access the vocal cords. Over the
past 25 years or so, endoscopic surgery has replaced open surgery in a large
number of laryngeal cancer cases. The surgeon views the vocal cords through a
microscope and removes cancerous tissue with specially elongated instruments and
sometimes with a carbon dioxide laser as well.
| "There's often not a lot of
science to the surgical management of vocal performers"
--Steven Zeitels |
Even with improvements in instrumentation,
surgery generally has been viewed as less desirable than radiation in the
treatment of early vocal cord cancer. Both have high cure rates, but radiation
is thought to result in less damage to vocal cords. Zeitels and his colleagues
have spent the past decade evaluating this issue and boosting the role of
surgery by exploring techniques to perfect more precise resections, remove
smaller amounts of tissue, and reconstruct tissue when needed. "In fact, some
studies have demonstrated that over time, radiation can cause fibrosis and
stiffness of normal vocal fold tissue," Zeitels said. "The goal is to preserve
the normal tissue since this is the primary voice source. So radiation treatment
for early cancer is conceptually flawed because it targets both the normal and
cancerous vocal cords indiscriminately."
Zeitels believes the poor voice outcomes
of surgery are not necessary in many cases. "What we learned about cancer
patients in the early '90s is that their management was frequently not done with
the optimum amount of precision," he said. "Often the approach consisted of
overtreatment." Part of the uncertainty lay in not knowing the depth of the
tumor in the tissue. Cancer excisions confined to the superficial layers of the
folds were much less damaging to the voice than those including the underlying
muscle and vocal ligament, which may compromise the ability of the folds to
close. Zeitels developed the technique of infusion, in which liquid is injected
into the subepithelial tissue; if the tumor rises, it has not yet invaded the
ligament and musculature. He found that many early cancers were shallow and
required less tissue removal.
The latest study gathered vocal outcome
data for a group of 32 patients undergoing phonosurgery for early cancer of the
vocal cords. Infusion showed that nearly half needed only superficial
resections. Of the others, nine required reconstruction, which involved
lipoinjection or a Gore-Tex implant to fill out the folds. All of the patients
are free of cancer without radiation or open surgery, and most achieved
conversationally normal voices after the surgery.
Occupational Hazards
Singers and vocal performers put a stress on
their vocal cords akin to the physical exertion of a marathon runner. With their
vocal folds vibrating at full volume for long periods of time, singers and
orators often develop bumps, polyps, and rough surfaces on the tissues. These
lesions can damage the voice that for many is also a livelihood. Though surgical
removal is possible, there is a chance that any excision will permanently alter
the voice. Zeitels set out to study this patient population more systematically.
"There's often not a lot of science to the surgical management of vocal
performers," Zeitels said. Until this recent study, there was little data to
determine the success of surgical management in vocalists.
Using an approach called stroboscopy, the
surgeon can assess the vibratory function of the vocal cords. A strobe light
creates the illusion of slowing down the rapidly vibrating cords and allows the
observer to watch them move together and apart. Voice outcomes of the surgeries
in both studies were evaluated by Robert Hillman, HMS associate professor of
otology and laryngology and a voice scientist who leads the voice lab at MEEI.
Hillman's group primarily tested two general metrics of the voice: acoustic
measures such as loudness, pitch, and regularity of tone, and aerodynamic
measures--how much air the person must push from the lungs to get the vocal
cords to vibrate.
In the cancer patient group, many of the
measures taken before surgery were abnormal but showed significant improvement
after the procedure and some voice therapy. For the group of 185 singers and
performers, Hillman said, the voice measurements were trickier. The metrics of
normal and abnormal ranges are designed for the general population, not the
exacting standards of a performer. "It's not surprising that the measures we
used to indicate a range of normal limits may not be as sensitive in this
group," he said. "It's like making physical measurements in a group of
athletes." However, the team did find that the few abnormal measures improved
after surgery, and eight of the 24 objective measures showed statistical
improvements across the group. The surgery did not cause any measures to drop
below the normal range, and nearly all the patients thought their voices had
improved. The study helps bring some data to a patient population that often
approaches treatment with trepidation, unsure if the outcome is worth the risk
of worsening the voice.
Zeitels believes that the two studies,
though very different in type of patient, represent a convergence of surgical
approaches. His team found that "when we managed the cancer patient with the
precision that you manage the performer, we could enhance the voice outcome
without sacrificing oncologic efficacy." Similarly, while singers were often
managed with finesse, past approaches to their treatment lacked the systematic
decision-making of surgical oncology.
Singers, like athletes, offer a model for
studying how different behaviors affect the vocal cords: a musical-theater
singer who belts out Broadway numbers is creating a different kind of stress
than an opera singer. "If you can understand how these individuals function, you
can master restoring most other voices," Zeitels said. He has found that singers
can often perform with long-term trauma because their activity has induced more
elastic normal tissue to compensate--their vocal cords even appear larger. The
team has a partnership with Robert Langer, an HMS senior lecturer on surgery at
Children's Hospital and the Kenneth J. Germeshausen professor of chemical and
biomedical engineering at MIT, to develop biomaterials that could be used to
reconstruct this elastic tissue. The trick, Zeitels said, is to find a material
that does not degrade and is pliable, since stiffness is the cause of the
majority of hoarseness. Zeitels believes that maintaining or even supplementing
the healthy tissue may become just as important in vocal surgery as removing the
abnormalities.
--Courtney Humphries
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