The Larynx: Laryngeal Paralysis, Masses and Trauma Flashcards
How to find the muscular process of the arytenoid?
The wing of the thyroid cartilage; the process being medial to the caudal half of the thyroid.
Laryngeal compromise in dogs usually results in what sound?
Stridor
Larygneal compromise signs?
Stridor
Excessive pant
Why is laryngeal dx difficult to diagnose in cats?
No obvious clinical signs until the disease is quite progressed
Clinical signs of laryngeal dx in cats? (4)
Exercise intolerance,
dyspnoea
abdominal effort
mouth breathing
Laryngeal Paralysis breed?
Large
Laryngeal Paralysis, sex?
Male
Acquired idiopathic laryngeal paralysis is most common in:
A) Age?
B) Breeds? (3)
A) Middle - Older
B) Labrador Retrievers, Afghan Hounds, and Irish Setters
Laryngeal paralysis should be suspected in young (< 1 year old) what breeds with upper respiratory obstruction. (5)
Bouviers,
Siberian Huskies,
Bull Terriers,
Dalmatians, Rottweilers
white GSD
4 possible pathophysiological causes of laryngeal paralysis?
Idiopathic
Trauma
Disease
Iatrogenic (surgery)
When is laryngeal paralysis often asymptomatic?
Unilateral dx
What dx may cause laryneal paralysis?(5)
polyneuropathy,
myopathy,
Chagas’ disease,
hypothyroidism
neoplasia-mediastinal mass
What surgery can cause laryngeal paralysis? (2)
collapsed trachea
thyroidectomy
What about the history make make you suspect laryngeal paralysis? (9)
stridor,
voice change
exercise intolerance. dyspnoea,
cyanosis,
coughing,
gagging,
vomiting,
restlessness and anxiety.
What may exacerbate sings of larygneal paralysis? (4)
Obesity,
exercise,
excitement,
high ambient temperatures
Laryngeal paralysis occurs in approximately how many of dogs with tracheal collapse.
one third
All animals with laryngeal paralysis are at increased risk of what 2ry condition?
aspiration pneumonia
Early sign of laryngeal paralysis in cats?
Change of purr
Which are the longest nerves in the body which may be affected in cases of polyneuropathy? (2)
The sciatic and recurrent laryngeal nerves
Patients with acquired laryngeal paralysis may have other ? signs
neurological
Diagnostic techniques for laryngeal paralysis?
Laryngoscopy
Lateral cervical and thoracic radiographs or CT
Laboratory findings
What anaesthetic is good for laryngoscopy?
alfaxalan, propofol and diazepam plus ketamin
How to know if plane of anaesthetic is light enough for larygnoscopy?
Ideally the plane of anaesthesia should be so light that the animal is pulling back on the tongue or swallowing
In questionable cases what can be given to stimulate laryngeal motion
doxopram (1 mg/kg IV
True or false
Post obstruction pulmonary oedema may occur in dogs and can be recognised as an bronchial pattern (this may coalesce to an alveolar pattern) on thoracic films.
False -interstitial
Why do we need to know the oesophagus is functioning well before larygneal sx?
Corrective surgery in animals with proximal oesophageal dysfunction can cause devastating aspiration
Laryngeal paralysis bloods; what neuropathy needs to be ruled out? What bloods are performed?
Hypothyroid neuropathy
- serum free thyroxine (T4)
- endogenous thyroid stimulating hormone (cTSH) concentrations.
Other than thyroid, what other condition needs to be ruled out with laryngeal paralysis? How is this done?
Acquired myasthenia gravis can be diagnosed by measuring circulating antibodies to acetyl choline receptor
Electromyography using bipolar concentric needle electrodes can detect denervation of the?
Laryngeal muscles
What are the 3 laryngeal muscles?
dorsal cricoarytenoid, ventricular, and thyroarytenoid
How to confirm neurogenic laryngeal muscle atrophy?
Histopathological and histochemistry tests
T or F
Ideally the plane of anaesthesia should be so light that the animal is pulling back on the tongue or swallowing.
True
T or F
Doxopram can be given to decrease laryngeal motion.
False- increases!
T or F
In patients diagnosed with laryngeal paralysis, haematology and biochemistry are usually normal.
True
Which dogs are more successfully managed with medical therapy with laryngeal paralysis?
Small
Cat treatment?
do not usually cope well as with laryngeal paralysis and though medical treatment can be tried most will benefit from surgical treatment in the form of left arytenoid lateralisation
Laryngeal paralysis What measures can be taken if the animal is in moderate to severe respiratory distress?
Sedation
Corticosteroids
Oxygen supplementation
What about laryngeal paralysis would indicate use of furosemide?
Post obstructive pulmonary oedema
What about laryngeal paralysis would indicate use of ABx?
Aspiration pneumonia
If the animal is not responding to medical treatment or has marked clinical signs which are impacting quality of life an what is indicated.
arytenoid lateralisation
what are currently being developed and may be an option in the future, particularly for acute relief of symptoms?
Laryngeal stents
Which sx approach to arytenoid lateralisation is best if right handed?
left sided laryngeal arytenoid lateralisatio
which side is affected first with laryngeal paralysis and why?
The left recurrent laryngeal nerve is longer than the right and thus usually first affected
How to position for laryngeal arytenoid lateralisation?
a wedge under the neck to raise the larynx
Warn os of what risks with a laryngeal arytenoid lateralisation?
post-operative aspiration pneumonia
progression of a polyneuropathy.
Are cats or dogs LESS likely to have polyneuropathy with laryngeal paralysis?
cats
T or F :
The presence of a polyneuropathy in an older dog with severe laryngeal paralysis precludes treatment. Euthanasia should be discussed.
FALSE:
Many dogs are happy pottering around the garden with ataxia.
Surgical Approach to the Larynx:
How to make the incision? What is palpated?
Make a skin incision ventral to the jugular vein, beginning at the caudal angle of the mandible and extending over the dorsal lateral aspect of the larynx to 1 to 2 cm caudal to the larynx. Palpate the laryngeal cartilages prior to cutting.
Surgical Approach to the Larynx:
A) Incise and retract what? (3)
B) What are retracted dorsally? (2)
C) What is retracted ventrally?
A) subcutaneous tissues, platysma and parotidoauricularis muscles.
B) sternocephalicus muscle and jugular vein
C) sternohyoid ventrally.
Surgical Approach to the Larynx:
Identify the thyroid cartilage by palpation and place what and where?
A stay suture (1.5- 2M monofilament) in the wing of the thyroid, halfway along the thyroid wing.
Surgical Approach to the Larynx:
What muscle is incised along wing of thyroid?
thyrohyoideus
Surgical Approach to the Larynx:
Identify the muscular process of the arytenoid process (which will be close to the suture) by?
following the fibres of the dorsal cricoarytenoideus muscle and by palpation
Surgical Approach to the Larynx:
Where is the cricoarytenoid articulation disarticualted?
Using what and how
At muscular process
Metzenbaum scissors, cut the caudal joint capsule and disrupt the articulation with a freer elevator
Surgical Approach to the Larynx:
How are sutures placed? using?
Two polypropylene sutures through the muscular process of arytenoid cartilage and the caudal third of the cricoid cartilage near the dorsal midline to mimic the direction of the cricoarytenoid muscle.
Success rate of
90%
Why do we not bilaterally lateralise unless one side has failed to alleviate clinical signs of obstruction?
High chance of aspirating
Masses that affect the larynx include..? (6)
benign granulomas granulomatous laryngitis
squamous cell carcinoma,
soft tissue sarcomas,
plasmacytoma
lymphoma
What is benign granulomas possibly related to
regurgitation
most common tumout of larynx in cat?
Lymphoma
Granulomatous laryngitis responds to what treatment
steroid
How to treat granuloma?
Resect
