Video-Assisted Left Partial Arytenoidectomy by Diode Laser

Veterinary Surgery
38:439–444, 2009
Video-Assisted Left Partial Arytenoidectomy by Diode Laser
Photoablation for Treatment of Canine Laryngeal Paralysis
MASSIMO OLIVIERI, DVM, PhD, SIMONA G. VOGHERA, DVM, and THERESA. W. FOSSUM, DVM, PhD, Diplomate ACVS
Objectives—To evaluate the clinical outcome of left partial arytenoidectomy by video-assisted laser
diode photoablation as a surgical treatment for canine laryngeal paralysis (LP).
Study Design—Case series.
Animals—Dogs with bilateral LP (n ¼ 20).
Methods—After endoscopic diagnosis of bilateral LP, left partial arytenoidectomy was performed
by photoablation of arytenoid cartilage tissue using a diode laser (600 mm diameter, 15 W power,
980 nm wave length) to increase the width of the rima glottidis. Outcome was evaluated endoscopically (1 and 6 months) and clinically (1, 6, and 12 months).
Results—No substantial complications occurred during photoablation or in the immediate postoperative period. Postoperative width of the rima glottidis ranged from 6 to 10 mm at its widest
aspect. At 1 month, respiratory function after walking and short running appeared good. Clinical
and endoscopic examination revealed good outcome at 1 and 6 months. At 6 months, there was no
evidence of hypertrophic scar, hypertrophic granulation tissue, or stricture of the laryngeal glottis in
any dog. Two dogs developed aspiration pneumonia after 12 months.
Conclusions—Partial arytenoidectomy using video-assisted diode laser photoablation appears to be
an effective technique for treating LP.
Clinical Relevance—Partial arytenoidectomy by diode laser photoablation should be considered as
an alternative technique for treatment of canine LP.
r Copyright 2009 by The American College of Veterinary Surgeons
traumatic or surgical lesions of the cervical region resulting in secondary nerve damage; by intra- or extrathoracic
masses that cause compression of the recurrent laryngeal
nerves; or by generalized polyneuropathy or hypothyroidism5–7; however, in many dogs the cause is unclear
and LP is considered idiopathic.5–7
The most frequently observed clinical signs are
exercise intolerance, inspiratory stridor, inappropriate
inspiratory effort, loss or alteration in phonation,
coughing (mainly after food and water ingestion), cyanosis, and collapse.1,6 These signs worsen with obesity, exercise, excitement, and high environmental
temperatures.1,6
INTRODUCTION
I
N CANINE laryngeal paralysis (LP), there is bilateral loss of abduction of the arytenoid cartilages and
vocal folds during inspiration1 because of recurrent
laryngeal neuropathy and dysfunction of the intrinsic laryngeal muscles.2 LP may be congenital or acquired;
the former being diagnosed in dogs o1 year of age.3–5
Acquired LP is often seen in adult, older, large-breed
dogs. Labradors, Great Danes, Chesapeake Bay Retrievers, Afghan Hounds, Irish Setters, and Saint Bernards are
most commonly affected, and males are more commonly
affected than females.5–7 Acquired LP may be caused by
From the Clinica Veterinaria Malpensa, Samarate—Varese, Italy and the Michael E. DeBakey Institute for Comparative Cardiovascular Studies, Texas A&M University, College Station, TX.
This work was done at the Clinica Veterinaria Malpensa.
Address reprint requests to Dr. Theresa W. Fossum, DVM, Phd, Dipolmate ACVS Michael E. DeBakey Institute for Comparative
Cardiovascular Studies, Texas A&M University, College Station, TX 77843-4474. E-mail: [email protected].
Submitted December 2007; Accepted February 2009
r Copyright 2009 by The American College of Veterinary Surgeons
0161-3499/09
doi:10.1111/j.1532-950X.2009.00546.x
439
440
VIDEO-ASSISTED DIODE LASER TREATMENT OF CANINE LARYNGEAL PARALYSIS
Unilateral lateralization of the arytenoid cartilage or
partial arytenoidectomy have been recommended for
treatment of LP in dogs. The latter technique is subject to
complications including aspiration pneumonia, submucosal hematoma, and seroma development.1,8,9 We report
a technique for, and outcome after, video-assisted partial
left arytenoidectomy performed by photoablation with a
diode laser in 20 dogs.
MATERIALS AND METHODS
tractors of differing diameters were used to make the measurements (Fig 1C).
Postoperative Care
Cephalexin (25 mg/kg, orally twice daily for 5 days) was
administered to prevent infection, prednisone (0.5 mg/kg
orally every 6 hours for 7 days) to decrease postoperative
edema, and omeprazole (0.7 mg/kg orally once daily for
30 days) to treat the potential gastric ulcers were administered.
All dogs were discharged 48 hours after surgery.
Inclusion Criteria
Outcome
Medical records (2004–2006) of dogs with bilateral LP that
had partial arytenoidectomy with a diode laser were reviewed.
Inclusion criteria were an endoscopic diagnosis of LP and
6 months follow-up clinically and endoscopically. Laryngeal movement, was evaluated using a 5 mm rigid endoscope
positioned caudal to the tip of the epiglottis10 with the dog in
sternal recumbency, premedicated with atropine (0.03 mg/kg
intramuscularly), during light, general anesthesia with propofol (1 mg/kg intravenously [IV] as needed to facilitate the
examination). The same procedure was used to evaluate outcome 1 and 6 months after partial arytenoidectomy. Thoracic
radiographs were taken before surgery and at 15 days, 1–6,
and 12 months after surgery. All dogs had complete hematologic and serum biochemical profile analysis before surgery.
Dogs were reevaluated on day 15, and again at 1, 6, and
12 months, or as needed, and complications (aspiration pneumonia, formation of hypertrophic granulation tissue, or laryngeal strictures) recorded. At 1 month, dogs were
evaluated after 15 minutes walking and 5 minutes running.
Owners were also asked to rate their dog’s activity level as
improved, no change, or worse than before surgery.
Surgical Technique
After endoscopic diagnosis, dogs were immediately taken
to surgery. They were intubated and anesthesia was maintained with isofluorane in oxygen. Cefazolin (25 mg/kg IV)
and dexamethasone (1 mg/kg IV) were administered at anesthetic induction. Partial left arytenoidectomy was performed
using a 600 mm diameter, 15 W power, and 980 nm wavelength
diode laser (easylase 980 nm; Team laser, Padova, Italy). The
energy used during surgery was 4–6 J over 50 seconds in continuous mode. Cartilage vaporization was achieved with a
triangulation technique between the laser and the endoscope.
During the procedure, the endotracheal tube was protected
by using a straight malleable retractor, 4–5 mm wider than the
endotracheal tube, which prevented contact of the tube with
the laser beam. Photoablation of the arytenoid cartilage was
performed under constant endoscopic observation and consisted of photovaporization of a portion of the corniculate
process of the left arytenoid cartilage with char removal by use
of a gauze sponge. The portion of laser-vaporized cartilage
extended from the interarytenoid band to the cuneiform process of the arytenoid cartilage (Fig 1A). The interarytenoid
band was preserved to prevent collapse of the arytenoid cartilage and stricture formation. Caudally, photovaporization
was limited to the laryngotracheal junction (Fig 1B). At the
end of the procedure, the final width of the rima glottidis was
measured at its widest portion from the medial aspect of the
left corniculate process to the corresponding medial aspect of
the right corniculate process (Fig 1E). Straight malleable re-
RESULTS
Left partial arytenoidectomy was performed in
20 dogs. There were 4 large mixed-breed dogs (weighing430 kg), 4 medium mixed-breed dogs (weighing4
19–24 kg), 3 Labrador Retrievers, 2 Maremmano Shepherds, 2 Newfoundlands, and 1 each of Cocker Spaniel,
Saint Bernard, Irish Setter, Springer Spaniel, and Pit Bull
(Table 1). All 20 dogs had pronounced inspiratory
stridor, cough, exercise intolerance, and alteration in
phonation. Three dogs (1 Maremmano Shepherd, 1 Labrador Retriever, 1 Newfoundland) also had cyanosis and
syncopal episodes. Eleven dogs had arytenoid cartilage
‘‘kissing lesions’’ and 9 had ‘‘paradoxical motion’’ of the
arytenoid cartilages.
During laser photovaporization no major complications occurred. Some hemorrhage occurred in all dogs
but was easily controlled with the laser. At the end of
surgery, width of the rima glottidis ranged from 6 to
10 mm; 6 mm for dogs weighing o30 kg; 7–8 mm for
dogs 30–50 kg; and 10 mm for dogs 450 kg. No complications were observed in the immediate postoperative
period. At 1 month, respiratory function after 15 minutes
walking and 5 minutes running appeared good and all
owners noted that dogs had improved exercise tolerance.
There was no evidence of aspiration pneumonia on follow-up radiographs at 15 days or at 1, 6, and 12 months
after surgery in 16 dogs; however, 2 dogs (dogs 9 and
14) developed aspiration pneumonia after 12 months.
One of the 2 Maremmano Shepherds (dog 12) developed
a peripheral neuropathy and was euthanatized after
10 months. One mixed breed dog died from gastric dilatation-volvulus, 9 months after surgery (dog 3) and had
OLIVIERI, VOGHERA, AND FOSSUM
441
Fig 1. (A) Initial photovaporization of the left corniculate process of the arytenoid cartilage; (B) view of the larynx after
photovaporization; (C) final measurement of the glottis with a malleable retractor (R; 10 mm width) in 1 large mixed breed dog;
(dog 2); (D) 1-month follow-up after photovaporization in a Cocker Spaniel (dog 19); (E) 1-month follow-up of dog 10; (F) 1-month
follow-up of dog 4. Note complete healing of the laryngeal mucosa.
no evidence of abnormal respiratory effort after laryngeal
surgery.
Endoscopy at 1 and 6 months revealed complete
healing of the arytenoid cartilage by 1 month (Fig 1D–
F). No hypertrophic scars, hypertrophic or polypoid
granulation tissue, or stricture formation of the glottis
was observed.
DISCUSSION
Partial arytenoidectomy using video-assisted diode laser ablation appears to result in minimal tissue trauma in
human patients.11–15 Observation of laryngeal structures
can sometimes be impaired, especially in the latter part of
the surgery, because the vaporized mucosa and cartilage
tend to become dark, making it difficult to recognize the
limits of the cricoid cartilage; however, these darkened
portions of the vaporized cartilage have been shown to
have a preserved histologic cellular organization in man
and horses.16,17
In humans, laser arytenoidectomy is an intralaryngeal
surgery that results in acceptable air passage through the
glottis while preserving vocal quality.11,13,15,18–23 This
technique is also associated with a reduced incidence of
aspiration pneumonia in humans, because it does not require that temporary tracheotomy be performed after the
procedure.11,13,15,18–23 Formation of hypertrophic granulation tissue resulting in dyspnea has been reported as a
complication in human patients.11–13,22 This tissue can be
easily removed with diode laser.14,21,24 Another reported
complication is stricture formation, but these do not
normally require surgical treatment.13,14,22
Preliminary results of the use of the diode laser for
unilateral partial arytenoidectomy for treatment of LP in
dogs appears to compare favorably with our experience
with intraoral partial arytenoidectomy. Our experience
suggests that it may allow for surgical resolution of obstruction caused by LP with fewer complications than
occur with intraoral partial arytenoidectomy. Further,
our experience suggests that use of video-assisted diode
laser enhances precision of arytenoid cartilage resection
442
VIDEO-ASSISTED DIODE LASER TREATMENT OF CANINE LARYNGEAL PARALYSIS
Table 1. Summary Data for 20 Dogs with Bialteral Laryngeal Paralysis Treated by Unilateral Partial Arytenoidectomy with Photoablation by Diode
Laser
Dog
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Breed
Sex
Age (Years)
Weight (kg)
Final Aditus
Diameter (mm)
Mixed breed
Mixed breed
Mixed breed
Mixed breed
Mixed breed
Mixed breed
Mixed breed
Mixed breed
Labrador
Labrador
Labrador
Maremmano Shepherd
Maremmano Shepherd
Newfoundland
Newfoundland
Irish Setter
Springer Spaniel
Pit Bull
Cocker Spaniel
Saint Bernard
Male
Male
Female
Male Castrate
Female spayed
Female
Female spayed
Male
Male
Male
Male
Female
Male
Female
Male
Male
Male Castrate
Male
Male
Male
11
10
11
12
11
14
12
13
13
13
9
11
11
3
9
14
13
8
10
4
32
74
33
65
24
22
21
19
35
31
41
49
41
43
45
23
25
26
10
67
7
10
7
10
6
6
6
6
7
7
7
8
7
8
8
6
6
6
6
10
because of the magnification afforded by the endoscope.
This, in turn, reduces the total amount of vaporization
performed, which may reduce the risk of aspiration
pneumonia.15,22 The risk of surgical trauma is low and
there appears to be a reduced incidence of marked postoperative edema, in humans as well as in the 20 dogs
we report, which may reduce the need for intubation
or temporary tracheotomy in the early postoperative
period.11–15
The diode laser promotes coagulation from local thermal action created over the cartilaginous tissue during
photovaporization,11,14,15,22,25–27 which dramatically decreases the risk of intramural hematoma formation.11,14,15,22,25–27 Intramural edema and hematoma
formation are potential complications of standard intraoral techniques and generally occur during the early
postoperative period28 as dyspnea, inspiratory stridor,
and occasional cough.29–31 In the worst-case scenario,
edema and hematoma formation, if marked, can be life
threatening.29–31
CO2 lasers are commonly used for laryngeal surgery in
people in conjunction with microlaryngoscopy.27 Reported advantages are improved accuracy, rapid reepithelialization, prevention of scar or granulation tissue
formation, and a low incidence of aspiration pneumonia.11–13,15,19 Hemostasis is generally good with a CO2
laser, unless the arytenoid artery is incised; the latter
vessel requires electrocautery because of its size.11,27
Electrocautery is not needed when a diode laser is used.
Despite the relatively small number of the dogs treated,
the risk of aspiration pneumonia (2/20 dogs) is similar
Concurrent Conditions
Hiatal hernia
Peripheral neuropathy
to other studies and it is an acknowledged common
and potentially fatal complication noted after standard
surgical techniques.7,30,32,33 In 1 report,28 aspiration pneumonia occurred in 15 of 45 (33%) dogs treated with ventriculocordectomy and partial arytenoidectomy during the
early postoperative period, and in 7 of 45 (16%) dogs
it was a long-term complication. Aspiration of food
can occur because the laryngeal aperture at the level of
the corniculate process of the arytenoid cartilage is too
large creating difficulty in closure during deglutition, especially if the LP is associated with a neuromuscular
problem.6,30,34–36
Another serious medium- to long-term complication
that can occur after intraoral arytenoidectomy is glottic
stenosis, which may occur as a direct consequence of the
formation of hypertrophic granulation or scar tissues after resection of oral tissues. Clinically, affected dogs appear to have reduced exercise tolerance and marked
laryngeal inspiratory stridor.28–31,34,37 In our study, glottic stenosis did not occur within 6 months.
Partial arytenoidectomy by diode laser photoablation is a relatively quick technique taking 25–30 minutes11,15 with a maximum of 60 minutes in large dogs.
To be successful, the surgeon must have good knowledge of endoscopic laser technique and video-assisted
procedures. Lasers may also be used to remove the
hypertrophic tissue that occurs after other surgical
procedures.14,21,24
Our results suggest that unilateral partial arytenoidectomy by diode laser photoablation is a safe and promising technique for treatment of LP in dogs.
OLIVIERI, VOGHERA, AND FOSSUM
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