Larynx Flashcards
According to DeGroot 2020 in Vet Surg what sedative was associated with maintenance of laryngeal function during sedated airway examination?
Dexmedetomidine did not inhibit laryngeal function (either alone, or in combination with butorphanol or hydromorphone). Propofol led to false positive results.
In a study by Drudi 2022 in Vet Surg, was a greater increase in the rima glottidis area observed following cricoarytenoid lateralization or thyroarytenoid lateralization?
Cricoartytenoid lateralization (200% compared to 150% increase).
A significant reduction in immediate post-operative rima glottidis size was also observed at 15 days post-op in the thyroartytenoid lateralization group.
In a study by Touzet 2022 in VRU, what radiographic ratio was used in the detection of bilateral laryngeal paralysis?
The ratio of maximum ventricular length over length of the third cervical vertebra (MVL/LC3). Bilateral laryngeal paralysis very likely for ratios >0.5, unlikely for ratios <0.3.
In a study by Moser 2022 in JFMS, what was the primary short term complication in cats undergoing partial laryngectomy?
Respiratory distress (temporary tracheostomy required in 2/6 cases).
Lymphoma was the most commonly resected mass.
In a study by Bonanno 2023 in JFMS, what modification of cricoarytenoid lateralization resulted in increased left arytenoid lateralization?
Complete disarticulation of the cricoarytenoid joint. Cadaveric study, so clinical outcomes unknown.
In a study by Mullins 2019 in Vet Surg, what percentage of dogs undergoing epiglottopexy for epiglottic retroversion suffered from failure? In what percentage of cases undergoing either epiglottopexy or epiglottectomy was a major post-operative complication reported? What was the median survival time for all cases?
42% of dogs undergoing either temporary or incisional epiglottopexy suffered from failure.
49% of total cases suffered a major post-operative complication (58.3% temporary epiglottopexy, 54% incisional epiglottopexy, 50% partial epiglottectomy, 17% subtotal epiglottectomy).
MST was not reached at 716 days.
What is depicted in this image of the larynx of a Norwich terrier from a study by Johnson 2021 in JVIM? What is the treatment for this condition?
Norwich terrier upper airway syndrome (thought to be related to a genetic mutation in the gene for the ADAMTS3 metallopeptidase enzyme).
Surgical treatment typically involves ventriculectomy. This study demonstrated good owner assessed outcomes in 81% of dogs, regardless of whether or not surgery was pursued.
In a study by Rishniw 2021 in Vet Surg, did doxepin improve the quality of life in Labradors with laryngeal paralysis? What is the mechanism of action of doxepin?
No improvement in QOL was observed.
Doxepin is a tricyclic antidepressant that primarily inhibits reuptake
of serotonin and norepinephrine.
Name the cartilages of the larynx.
Epiglottic, thyroid, cricoid, sesamoid, interarytenoid, paired arytenoid.
Label the following diagram.
What attaches the epiglottis to the arytenoid cartilages laterally?
The aryepiglottic folds.
Which is the largest laryngeal cartilage?
The thyroid cartilage
What is the attachment of the cricoarytenoideus dorsalis on the arytenoid cartilage called?
The muscular process.
What are the components of the arytenoid cartilages?
Vocal, cuneiform, corniculate, and muscular processes.
What are the extrinsic muscles of the larynx?
Thyropharyngeus and cricopharyngeus. Both innervated by the glossopharyngeal and vagal nerves.
What is the most important intrinsic muscle of the larynx? What is its function?
Cricoarytenoideus dorsalis. Arises from the dorsolateral cricoid and inserts on the muscular process of the arytenoid. Functions to abduct the arytenoid and open the glottis.
What is the innervation to the larynx?
The caudal and cranial laryngeal nerves. The caudal laryngeal nerve (a branch of the recurrent laryngeal) supplies motor innervation to all of the intrinsic muscles of the larynx besides the cricothyroideus muscle).
The cranial laryngeal nerve (originating from the vagus) supplies the cricothyroideus muscle.
What is the blood supply to the larynx?
The cranial and caudal thyroid arteries.
What are the three functions of the larynx?
- Blocking the laryngeal opening during swallowing.
- Controlling airway resistance.
- Voice production
What is the most common laryngeal neoplasia in cats?
Lymphoma
What diagnostics should be performed in the work-up of suspected laryngeal neoplasia?
Laryngeal examination, mass biopsy, thoracic radiographs +/- CT.
Temporary tracheostomy may be required to facilitate work-up.
What are the treatment options for laryngeal neoplasia?
- Radiation or chemotherapy (lymphoma).
- Resection of small benign masses via a transoral or ventral laryngotomy.
- Partial or complete laryngectomy (cordectomy can be performed in tumour confined to the vocal cord).
How can partial laryngectomies be reconstructed?
Sliding of the remaining thyroid cartilage, alternatively if the cricoid is excised the trachea can be advanced cranially and attached to the thyroid.
Large defects can be repaired using free tissue implants (costal cartilage, buccal mucosa) or local muscle flaps (sternohyoideus muscle island flap sparing the cranial thryoid arteries).
How is a total laryngectomy performed?
The skin is incised on midline and the thyropharyngeus, cricopharyngeus, sternothyroideus, and thyrohyoideus muscles are detached from the larynx. The trachea is detached from the cricoid and anastomosed to the skin after passing through the intact sternohyoideus muscles. The larynx is removed.