ROBERT H. OSSOFF, DMD, MD
 It
is a distinct honor and pleasure to have the opportunity to present the
Daniel C. Baker, Jr, Lecture of the American Laryngological Association
this year. The subject that I have chosen to speak about reflects an area
that is both near and dear to my heart: laser surgery in laryngology. As
we all know, laser is an acronym that stands for light amplification by
the stimulated emission of radiation. Albert Einstein,(1) in
his early writings in 1917, wrote "Zur Quanten Theorie der Strahlung," which
described the basic physics of stimulated emission of radiation; however,
it was not until 1954 that Townes and Gordon built a microwave laser called
a Maser.(2) Four years later, Schawlow and Townes (3) published
the theoretical calculations of a laser in Physics Review. Ted Maiman (4) made
the first laser, using a synthetic ruby as the lasing medium. Ophthalmologists
began experiments with this laser in 1961, and by 1964, hundreds of patients
had been treated successfully. The laser designed by Maiman was very small
and could be held in his hand.
The C02 laser came on the scene in our literature in 1966,
when Yahr and Strully (5) published their initial surgical
experiments using a laboratory C02 laser. However, it was through the vision
and creative research of a group of otolaryngologists in Boston led by
Gezo Jako and M. Stuart Strong that the introduction of the C02 laser to
our specialty, and especially to the larynx, came about. This group also
expanded applications to the trachea, to pediatric otolaryngology, to the
oral cavity, and to rhinologic surgery. The group, in addition to Jako
and Strong, included our Guest of Honor, Gerald Healy, as well as Charles
Vaughan, Vice President-President Elect Stanley Shapshay, and two scientists,
Thomas Polanyi and H. C. Bredemeier. In 1967, Jako produced a discrete
lesion using a laboratory C02 laser on a cadaver larynx. Polanyi, Bredemeier,
and Davis (6) (7) in 1969 and 1970 developed
a C02 laser for surgical research. In 1969 and in 1973, Bredemeier (8) (9) developed
an endoscopic delivery system for the C02 laser and then finalized the
development of a micromanipulator that coupled the C02 laser to the operating
microscope. This advance allowed animal experimentation to begin, and Jakol (10) performed
the first in vivo experiment in a canine larynx using the C02 laser in
1969, and published his C02 laser canine experiments in 1972, suggesting
that "laryngeal microsurgery with a carbon dioxide laser was ready
for clinical trial." Also in 1972, Strong and Jako (11) published
the initial clinical report on the use of the C02 laser in otolaryngology.
They treated 15 laryngeal lesions, including nodules, polyps, cysts, keratosis,
carcinoma in situ, and papillomas. They found that the C02 laser was a
practical instrument for the incision or excision of tissue and that the
use of the micromanipulator facilitated laryngeal laser surgery with exquisite
precision. They also warned of the potential danger of an endotracheal
tube fire. Four years later, in 1976, Strong, Jako, Vaughn, and Polanyi (12) reported
on 563 patients and over 1,000 operations using the C02 laser. In that
series of patients, they experienced 2 extraluminal endotracheal tube fires.
The advantages of laser surgery in otolaryngology were so significant that
they declared, "It can be recommended for continued usage." Laryngeal
applications, as Strong and his co-investigators saw it in 1976, included
arytenoidectomy, carcinoma in situ, carcinoma, granulomas, internal laryngoceles,
keratosis, nodules, papillomas, polyps, stenosis, and subglottic hemangioma
in children. The first surgical laser used by this group was affectionately
known as the "telephone booth" because of its large size. The
early delivery systems and the optical engineering technology available
at the time allowed for the delivery of a less-than-fundamental-mode laser
beam with a transverse electromagnetic mode (TEMO1) that had a cold spot
in the center of the laser beam. This generation of laser delivered a spot
size of approximately 2.0 to 2.2 mm in diameter at a 400-mm working distance.
Even with this spot size limitation compared to what we are currently used
to, the exquisite precision afforded by the use of this laser in patients
gave rise to tremendous optimism with respect to what would lie ahead in
terms of laser surgery in laryngology.
The Sharplan Laser Company introduced the first fundamental-mode
C02 laser for surgical use, which allowed for a spot size in laryngeal
work of 0.8 mm at a 400-mm working distance, in comparison to the 2- to
2.2-mm spot size that we had previously worked with. Use of this fundamental-mode
(TEM00) laser delivered a beam profile with a clean hot spot and no cold
spot in the center. At that point in time, approximately 1981, the advantages
of laser surgery were felt to be precision, hemostasis, decreased perioperative
edema, and new and modified surgical techniques. These advantages had to
be compared and contrasted to the disadvantages of laser surgery, which
included 1) the risk of an explosion or burn associated with endotracheal
anesthesia; 2) the risk of remote damage to the patient or operating room
personnel; 3) the risk of thermal damage to surrounding normal tissue;
4) the potential negative effect on wound healing; and 5) the need to ascend
the learning curve associated with this new technology. This learning curve
required that laser courses be given around the country to teach the proper
use of the laser to otolaryngologist-head and neck surgeons who had not
had exposure to laser surgery in their residency training. Dr Strong and
his group in Boston had started these workshops in the 1970s, and I reintroduced
the workshops in Chicago in 1981 as a young faculty member at Northwestern.
The purpose of the workshop was to teach
laser biophysics and tissue interaction, as well as to emphasize safety
precautions and clinical applications. The real feature of these courses,
however, was to allow for supervised hands-on training in the animal research
laboratory. With regard to laser safety, we taught precautions for laser
surgery and had everyone leave well-versed in a laser safety protocol.
We also emphasized the complications of laser surgery and specifically
addressed what could go wrong, how to keep that from occurring, and how
to manage complications if they occurred. An endotracheal tube fire was
demonstrated at each workshop. Furthermore, we held a lengthy discussion
detailing how these fires occurred, how to avoid them, and how to manage
them. (13) I continued the course at Vanderbilt after
my move there in 1986 to assume my current position as Professor and Chairman
of the Department of Otolaryngology. The clinical applications that we
focused on at these workshops included arytenoidectomy, carcinoma in situ,
granulomas, internal laryngoceles, keratosis, nodules, polyps and polypoid
degeneration, recurrent respiratory papillomatosis, selected T1 vocal fold
carcinoma, subglottic hemangioma, subglottic stenosis, and web excision.
The endoscopic arytenoidectomy with laser was one of the operations that
we critically stressed in terms of its performance, allowing every registrant
to participate in performing one on the first day of the workshop and then
to come back and do it again on the second day. We felt it to be a reliable
treatment option for the management of patients with bilateral vocal fold
paralysis at the time of the workshop, and we also found the treatment
and results to be reproducible. (14) (15) We
had videotaped demonstrations of the laboratory animal model procedures
to be done by the registrants, and then we had the registrants perform
clinical procedures on living animal models on day 1, and repeat the clinical
procedures on living animal models on day 2.
In terms of lasers in laryngology in the present, the main
things that have changed have been modifications to the C02 laser and improvements
to its delivery systems, which include the reduced spot size, the computer-controlled
beam delivery, and the variations in the energy pulse duration and repetition
rate. Dr. Shapshay (16) introduced to our specialty the
first reduced-spot-size micromanipulator, which delivered a spot size of
approximately 250 um. It had a virtual aiming system, and one had to manually
superimpose the visible helium neon laser aiming beam on the invisible
infrared C02 laser beam because of the optical characteristics of that
particular delivery system. A second-generation microspot micromanipulator
was introduced to the specialty in 1991.(17) This device
allowed for the coincidental delivery of the visible helium neon beam to
superimpose on the infrared C02 laser beam. This also corrected the previous
parallax problems with micromanipulators through the purposeful design
of the coincidental optical and therapeutic beam paths associated with
this particular device. This new generation of smallspot-size micromanipulators
allowed us to take care of diseases such as recurrent respiratory papillomatosis
with even greater percision than that afforded us by previous generations
of micromanipulators. At this time, our current laryngeal applications
included The free electron laser, and our ability at Vanderbilt to use
this experimental device for several years in the 1990s, led us down the
pathway to where we are at the present time. For example, experiments with
this laser gave us a better appreciation of the importance of selective
photothermolysis or laser tissue interaction selectivity and specificity.
A series of experiments using infrared spectroscopy on living tissue allowed
us to define the absorption characteristics of potential target tissue
and to define the appropriate laser wavelength to irradiate that tissue
with. (18-20) This resulted in a much cleaner tissue
ablation with less thermal injury. The Teflon granuloma model using an
8.5-um wavelength as compared to a 10.6-um wavelength that I demonstrated
during my talk (21) is but one example of this.
Later experiments taught us that the reduction in tissue
injury had more to do with the pulse structure than with the wavelength
itself. This was very enlightening and caused us to perform a series of
experiments using the C02 laser delivered in a pulsed versus continuous
mode. The results of these studies revealed improved laser tissue interaction
in the pulsed versus continuous mode. Learning from our colleagues in dermatology
and facial plastic surgery with laser skin resurfacing techniques, we then
began to apply similar types of pulse structures to the larynx for the
superficial spreading variety of recurrent respiratory papillomatosis and
noted much less laser thermal interaction and a quicker return to voice.
There was no significant change, in terms of regrowth of
the disease, although we did not expect to see that. Laser companies have
continued to modify their latest cutaneous laser surgery delivery systems
for applications in laryngeal laser surgery for diseases such as recurrent
respiratory papillomatosis.
That brings us to the future. Where do I think lasers in
laryngology will be in the future? There are probably 5 areas that will
see some change. These areas include 1) new wavelengths; 2) new pulse structures;
3) improvement in selectivity; 4) improvement in specificity; and 5) reduction
in thermal effects.
Following up on a paper delivered this morning by my colleague,
Dr Garrett, I will say that we learned that the laser tissue interaction
by the pulsed C02 laser in the canine larynx yielded far less thermal injury
than that delivered by the continuous-wave C02 laser. (22) This
is most appealing in terms of minimizing the potential for scar tissue
formation secondary to the use of the laser. I appreciate Dr Garrett's
allowing me to use her slide from her talk this morning to bring that point
home.
In conclusion, it is my belief that the ideal laser for
laryngeal surgery remains a work in progress. We ought not to be complacent
with what we have, but rather,
should work to improve all aspects of the technology that we currently work
with: the wavelengths, the pulse regimens, and the delivery systems. Laser
wavelengths and pulse structures should be matched to the task at hand. We
should try to be proactive with our colleagues in industry to design lasers
for specific tasks, rather than try to find uses for lasers that have been
designed without a task in mind. Finally, improvement in pulse structure
should lead to minimal thermal effects, improved wound healing, and improved
functional
outcome.
Again, I want to thank the Council of the American Laryngological
Association, as well as the Daniel C. Baker, Jr, Lecture Committee, for
allowing me the distinct honor of delivering this year's Daniel C. Baker,
Jr, Lecture to the American Laryngological Association. It is truly a very
significant honor, and one that I will cherish throughout my career.
Thank you.
1. Einstein A. Zur Quanten Theorie der Strahlung.
Physik Z 1917;18.121-8. top
2. Gordon JP, Zeiger HZ, Townes CH. Molecular
microwave oscillator and new hyperfine structure in the microwave spectrum
of NH3. Phys Rev 1954;95:282-4. top
3. Schawlow AL, Townes CH. Infrared and optical
masers. Phys Rev 1958;112:1940-9. top
4. Maiman TH. Stimulated optical radiation
in ruby. Nature 1960; 187:493-4. top
5. Yahr WZ, Strully KJ. Blood vessel anastomosis
and other biomedical applications. J Assoc Adv Med Inst 1966;1:28-31. top
6. Polanyi TG, Bredemeier HC, Davis TW Jr.
CO2 Laser zur experimentellen Chirugie. LASER Angewandte Strahlentechnik
1969;4. top
7. Polanyi TG, Bredemeier HC, Davis TW Jr.
A CO2 laser for surgical research. Med Biol Eng 1970;8:541-8. top
8. Bredemeier HC. Laser accessory for surgical
applications. US Patent 3, 659, 613, issued 1972. top
9. Bredemeier HC. Stereo laser endoscopes.
US Patent 3, 796, 220, issued 1974. top
10. Jako GJ. Laser surgery of the vocal
cords. An experimental study with carbon dioxide lasers on dogs. Laryngoscope
1972;82:2204-16. top
11. Strong MS, Jako GJ. Laser surgery in
the larynx. Early clinical experience with continuous CO2 laser. Ann Otol
Rhinol Laryngol 1972;81:791-8. top
12. Strong MS, Jako GJ, Vaughan CW, Healy
GB, Polanyi T. The use of C02 laser in otolaryngology: a progress report.
Trans Am Acad Ophthalmol Otolaryngol 1976;82:595-602. top
13. Ossoff RH. Laser safety in otolaryngology-head
and neck surgery: anesthetic and educational considerations for laryngeal
surgery. Laryngoscope 1989;99(suppl 48). top
14. Ossoff RH, Sisson GA, Duncavage JA,
Moselle HI, Andrews PE, McMillan WG. Endoscopic laser arytenoidectomy for
the treatment of bilateral vocal cord paralysis. Laryngoscope 1984;94:1293-7. top
15. Ossoff RH, Duncavage JA, Shapshay SM,
Krespi YP, Sisson GA Sr. Endoscopic laser arytenoidectomy revisited. Ann
Otol Rhinol Laryngol 1990;99:764-71. top
16. Shapshay SM, Wallace RA, Kveton JF,
Hybels RL, Bohigian RK, Setzer SE. New microspot micromanipulator for carbon
dioxide laser surgery in otolaryngology. Early clinical results. Arch Otolaryngol
Head Neck Surg 1988;114:1012-5. top
17. Ossoff RH, Werkhaven JA, Raif J, Abraham
M. Advanced microspot microslad for the CO2 laser. Otolaryngol Head Neck
Surg 1991;105:411-4. top
18. Reinisch L, Edwards G, Tribble J, Werkhaven
JA, Ossoff RH. Infrared spectral analysis of laryngeal tissue [Abstract].
Lasers Surg Med 1994(suppl6):65. top
19. Edwards G, Logan R, Copeland M, et al. Tissue ablation
by a free-electron laser tuned to the amide II band. Nature 1994; 371:416-9.
20. Reinisch L, Bryant GL, Ossoff RH. Resonant laser incisions:
molecular targets using the free electron laser [Abstract]. Bull Am Phys
Soc 1996;41:658.
21. Lano CF Jr, Reinisch L, Ossoff RH, et
al. Ablation of Teflon granulomas in the canine larynx with the free-electron
laser. Ann Otol Rhinol Laryngol 1999;108:17-23. top
22. Garrett CG, Reinisch L. New-generation
pulsed carbon dioxide laser: comparative effects on vocal fold wound healing.
Ann Otol Rhinol Laryngol 2002;111:471-6. top
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