Last month, we looked the epidemiology, diagnosis and medical management of laryngeal paralysis in dogs. The most effective
means of treating laryngeal paralysis is with surgery. However, the limitations and potential complications of surgery should
be understood and carefully explained to the clients before commencing.
The ideal treatment for this disease would be to reverse the underlying neuropathy or myopathy that affects the cricoarytenoideus
dorsalis (CAD) muscles. At this time, no medical therapy accomplishes this, and surgery to achieve this goal entails grafting
neuromuscular pedicle transfers from nearby functional muscles onto the CAD muscles. While elegant in principle, the technique
for reproducible success with such surgery in dogs remains elusive. Hence, the operations that are currently offered are those
that share the common goal of widening the glottal diameter.
It is important to stress that such surgery is not restoring normal function to the larynx. It is equally important to remember that this complex organ not only has evolved
to open the glottis in response to needs for oxygen delivery and for phonation, but also to close, mostly as a way of protecting
the airway during swallowing of food and liquids, since the pathways for air movement and swallowing evolved with an unfortunate
crossing within the pharynx. The loss of this latter function helps explain the signs of dysphagia often noted before treatment
and has major implications in the postoperative phase. It also means that dogs with megaesophagus are at much higher risk
for aspiration pneumonia after surgery—a factor that might alter the client's decision.
Widening of the glottal opening may be accomplished via partial laryngectomy, laryngoplasty or some combination of these.
Partial laryngectomy usually entails bilateral ventriculocordectomy and unilateral or bilateral partial arytenoidectomy, literally
carving a bigger opening. Such surgery (especially arytenoidectomy) may induce severe bleeding and laryngeal edema and may
cause quite a bit of discomfort for the patient. Dogs may require a temporary tracheotomy if swelling is severe, and hospitalization
times may be prolonged and intensive.
Laryngoplasty techniques are those that strive to widen the glottis without removing tissue. Some are invasive into the laryngeal
lumen (e.g., castellated laryngofissure), while others allow manipulations to remain extraluminal. In the latter category
is the most widely used and recommended technique, the arytenoid lateralization laryngoplasty, commonly referred to as a tie back. With minor modifications based on the surgeon's preference for positioning, incision, suture material and location of the
prosthetic suture or sutures, the shared goal is to place one or two sutures from the muscular process of the arytenoid cartilage
(insertion point for the CAD muscle) to either the caudodorsal aspect of the cricoid cartilage (the natural origin of the
CAD muscle) or the lamina of the thyroid cartilage. As these sutures are tied, they mimic the contraction of the CAD muscle
and, thus, abduct the arytenoid.