Surgical conditions of the larynx, gutteral pouches and trachea Flashcards
What is the primary function of the larynx?
conduit between pharynx and trachea
protection (swallowing)
What are the cartilages of the larynx?
- cricoid
- thyroid
- epiglottis
- arytenoid (x2)
what is the only part of the arytenoid cartilage can you see when looking down the nose?
corniculate process
Why can you not see the muscular and vocal process of the arytenoid cartilage from going down the nose? what is the significance?
they are extraluminal
they have to be accessed from outside
Why is it important to understand the larynx is made up of different parts?
- can use them as landmarks for surgery access
2. can take pieces off
Why is it important to understand that the epiglottis is bumpy, there are small dorsal vessels?
If you don’t see this then likely it is entrapped
Is the notch of the cricoid artilage constant between horses or variable?
variable
Why is important when performing a tie back that the dorsal suture is as close to midline as possible?
so your tie back causes the fold to go up and out instead of just laterally
what is the important muscles of larynx to know (principle abductors)
- circoarytenoideus dorsalis (CAD)
2. arytenoid transversus
Why is it common to get left laryngeal hemiplasia
the left recurrent laryngeal nerve travels much farther
it is a dying back so get left sided hemiplasia first
extravasation of irritant substances
extravasation of irritant substances (e.g. phenylbutasone)
What is the innervation of the principles abductors?
innervation
- recurrent laryngeal nerve (right loops around the subclavian artery)
- left loops around liagmentum arteriosum
- superior laryngeal nerve (cricothyroideus m (vocal cords))
What does the hypoglossal nerve innervate?
the hyoepiglottis muscle (cranial nervee 12)
What does the hyoepiglottis muscle do?
it prevents the epiglottis from dancing in the wind
How do you palpate cricoarytenoideus dorsalis atrophy
by palpating top of the larynx (it passes over the muscular process)
When you have left laryngeal hemiplasia (not tight) what does the vocal cord and saccule look like? What does the size of the lumen look like?
the vocal cord is not tight–further catches air
the saccule is baggy
the lumen is smaller
What impedes airflow into the trachea with left laryngeal hemiplasia?
- collapsed cartilage–smaller lumen
2. vocal cords catching air
What is the significance of epiglottic entrapment?
inspiratory/expiratory obstruction
entrapped in aryepiglottic membrane
What is the history/exam of epiglottic entrapment?
respiratory noise (inspiratory and expiratory) exercise intolerance nasal discharge and coughing--coughing because feel something on the soft palate--mucosal membrane produces more fluid=nasal discharge. trying to swallow to get the blob back in place
What is the pathogenesis of epiglottic entrapment?
the loose mucosa of the epiglottis gets pulled tight on the underside of the epiglottis, and it is pulled up to the end of the epiglottis like taking off a shirt and you cannot see the cranulated/vessely surface of the epiglottis. it is NOT dorsal displacement because you can see a structure. if you get over the blob of tissue then you can see the epiglottis disappearning into the blob
Why is there inspiratory and expiratory obstruction with epiglottic entrapment
There is a big block on inhalation, also catches air on expiration
How is epiglottic entrapment diagnosed?
endoscopy: serrated border
dorsal vascular pattern
may be INTERMITTENT or PERSISTENT
can see the aryepiglottic fold coming
get hypoplastic epiglottis with epiglottic entrapment?
because they are being squashed down
Why might epiglottic entrapment have ulceration?
it is irritated and rubbing on the underside of soft palate
What is the treatment for epiglottic entrapment?
tissue sparing technique
- laser axial division
- transoral axial diversion (bistoury)
- transnasal axial division (bistoury)
- surgical excision via laryngotomy
What are horses at risk for after epiglottic entrapment treatment?
dorsal displacement of the the soft palate (even though not touching anything else besides epiglottis)! WARN CLIENTS
Why is it important to use a tissue sparing technique for epiglottic entrapment treatment?
because there is a reason there is so much mucosa on the epiglottis! it is needed for keeping the epiglottis loose. if take too much can scar and cause epiglottis to be stuck in mouth (dorsal displacement of soft palate)
What is an issue with transnasal axial division for doing surgery of epiglottic entapment?
as soon as touch epiglottis the horse swallows. want to cut the epiglottis and instead it pops down and you can cut the soft palate or have epiglottic/pharyngeal lacerations
If the epiglottis is very thick and ulcerated what method of surgery to treat epiglottic entrapment is used?
laryngotomy
inside the larynx. put forceps into larynx, retroflex epiglottis and cut off tissue
But everything is upside down!!!
Very important to know anatomy
Careful not to create dorsal displacemnet
What is a subepiglottic cyst?
remnants of thyroglossal duct (embrologic) fills with fluid
What can a subepiglottic cyst be mistaken for?
epiglottic entrapment
How are subepiglottic cysts treated?
inject with formalin
electrocautery
snare
What is prognosis for subepiglottic cysts?
good if get all of it
What are the clinical signs of subepiglottic cysts?
same as epiglottic entrapment. coughing, swallowing, exercise intolerance
What is the significance of laryngeal hemiplasia?
- dysfunction of arytenoid movement (left)
- loss of myelinated nerve fibers (RLN)
- neorgenic atrophy of laryngeal muscles
- abductor and adductor function
- predominantly inspiratory obsutrction
- idiopathic
- PROGRESSIVE
What is a complication of going to deep when cutting an epiglottic entrapment
could cut cartilage! then you are screwed
How does the resp obstruction differ in epiglottic entrapment and laryngeal hemiplasia?
with epiglotic entrapment it is inspiratory and expiratory but larngeal hemiplasia is inspiratory
Why should you write down if you see mild larngeal hemiplasia in a young horse at a sale?
because it is progressive
Why is laryngeal hemiplasia worse at exercise?
the large negative pressure
What is the history of laryngeal hemiplasia?
inspiratory noise
whistle or roar
often jockey assisted diagnosis
How should you examin/diagnose laryngeal hemiplasia?
- check for cricoiarytenoideus atrophy
- check for tie back scar and larynotomy??
scope them!
When scoping, and you are not certain you have laryngeal hemiplasia what should you do?
switch nostrils
Where is the incision for laryngeal hemiplasia treatment?
under linguofacial vein!
What are the grades of laryngeal hemiplasia?
- synchronous full abudction
- asynchronous full abduction
- asynchronous incomplete abduction (a.) at rest, normal at exercise (b.) at rest and at exercise)
- no appreciable abduction
What is important to remember about the grades of laryngeal hemiplasia?
it is progressive!!
What is the treatment for laryngeal hemiplasia?
- laryngoplasty
- -permanent abduction (not too far that create coughing!!
- suture b/w arytenoid and cricoid cartilages
If you are not sure about laryngeal hemiplasia, what should you do?
put a twitch on–laryngeal hemiplasia–if normal they both come up and away (fight or flight moment)
What is an issue with pulling the arytenoid cartilage up and away with laryngeal hemiplasia treatment?
they are supposed to close off the larynx and protect the upper trachea–coughing due to feed material
What are complications of laryngeal hemiplasia treatment?
- prosthesis failure
- infection–have to remove prosthesis, back to zero
- aspiration and coughing
What is the success of laryngoplasty for laryngeal hemiplasia?
50-70% improved performance (even if done very well)–degree of barotrauma to lower airways–inspiration at high pressure against semiclosed glottis
When you tighten your suture and it is placed correctly, what should happen to arytenoid with laryngoplasty?
should rotate up and away NOT just get pulled laterally (as would do when misplaced)
Why do you get relaxation/loosening of the laryngeal tie back?
- soft tissue death
- cutting through cartilage
- if tie up near you instead of near hole
- suture loosening
With laryngeal tie back there is a correlation between tying to far and….
post op coughing
What is often also done alongg with laryngeoplasty (tie back?)
1.sacculectomy/ventriculocordectomy
done via laryngotomy
removes saccule
What is the risk of laryngotomy?
contamination–open incision very close to the tie back location which is not contaminated and must not be contaminated
What animals need a lot of airflow that you may not think need it?
large draft/pulling animals
What is arytenoidectomy? Why is it used?
can be used for laryngeal hemiplasia. some people do it as a primary procedure. most often it is a salvage procedure after the tie back failed or got infected because repeating tie back through fibrous/infected tissue is hard!!! tissue planes don’t open up well/neovascularization
What is a neuromuscular pedicle graft?
reinnervation of cranioarytenoideus dorsalis with 1st cervical nerve
young horses, grade 3, 6-12months recovery
What is the problem with neuromuscular pedicle graft?
- takes a long time for recovery
2. only see arytenoid moving when animal moving–must be moving leg for the nerve to fire
What is arytenoid chondritis?
progressive inflammatory process in arytenoid cartilage. space occupying mass! (abscess usually of corniculate process)
What are the signs of arytenoid chrondritis?
exercise intolerance and repsiratory noise
what is the main ddx of arytenoid chondritis?!!!!!
laryngeal hemiplasia!!!!! (unless have draining tract–into airway)
If there is a draining tract into airway from arytenoid, what is it?
arytenoid chondritis
What is a kissing lesion (talking about arytenoid chondritis)
a lesion due to the banging of the chondritis onto the other side causing granulation tissue?? must know which is the cause. cannot cut both
What is the treatment for arytenoid chondritis?
- antibiotics & rest–reduce airflow past area and thus reduce inflammation’
- antibiotics and surgical debridement (usually not enough alone so don’t do)
- excision of dz arytenoid cartilage
What is the issue of using antibiotics for arytenoid chondritis?
get little antibiotic into the area because it is poorly vascularized
How do you surgically treat arytenoid chondritis?
by removal of part of the arytenoid (NOT ALL!)
In subtotal arytenoidectomy, what portion(s) of the arytenoid are left?
corniculate cartilage
muscular process
In partial arytenoidectomy, what portion(s) of the arytenoid are left?
muscular process
Why would you not do subtotal arytenoidectomy to treat arytenoid chondritis?
because leaving corniculate cartilage that is unsupported so can flop around in the lumen. no point
Describe partial arytenoidectomy
cut off the corniculate process
peel off mucosa lining (hard)
cut out most of the arytenoid (can leave unsutured)
What is the dorsal tracheal ligament?
joins the arytenoid cartilage
Why should you avoid tracheal ligament when doing partial arytenoidectomy?
because if disrupt it, could cause collapse of the other arytenoid
What is very important to be certainn of when doing surgery for partial arytenoidectomy?
are you taking the correct side???
What side should you stand on when doing partial arytenoidectomy?
stand on opposite side
What is aryepiglottic fold collapse?
the aryepiglottic fold flaps into the airway
How do you treat aryepiglottic fold collapse?
sculpt off with a laser
is aryepiglottic fold collapse common?
no
What are the guttural pouches?
air filled diverticuli of auditory tubes
Where do the guttural pouches extend from, to?
extend from roof of pharynx to base of the skull and from the atlanto-occipital joint to pharyngeal recess
What do the guttural pouches communicate with?
nasopharynx–open routinely during swallowing
What borders the guttural pouch medially and ventrally? What about laterally/dorsally
- muscular/muscosa
2. bone laterally, dorsally
What bone divides the guttural pouch?
stylohyoid bone
Describe the structures that come around the guttural pouches
look it up
Why might you radiograph the guttural pouches?not done often
if seems abnormally large?
What are the clinical signs of guttural pouch empyema?
bilateral nasal discharge–opens behind the nostrils!
retropharyngeal swelling
coughing–hurts, dysphagic
dysphagia
What should you do on exam for examining guttural pouch empyema?
scope both pouches (60% have bilateral envolvement)
culture and flush (cuture each side separately!)
How should you flush the guttural pouches?
with a pump
make sure head is down and heavily sedated
don’t want to blast fluid down the trachea!
Could suture in tubes but it is irritating to nostril (sutured in) and with a couple days is irritating to guttural pouch
What happens if purulent material in guttural pouch becomes inspissated?
becomes chondroids
How do you surgically access the guttural pouches?
- viborgs triangle
- modified whitehouse
- hyovertebrotomy
What is the important thing about surgical approaches of guttural pouch?
can cause a major bleed or major neurological injuries!!!
don’t know what you are going to snip through (have an endoscope in the pouch, approach pouch from outside)–check with the endoscope to make sure aren’t hitting something important
will always end up in medial pouch
why is it preferedd to do long term medical management rather than surgical for guttural pouch empyema
so many important structures there!
What animals get guttural pouch tympany?
young female horses
is guttural pouch tympany usually bilateral or unilateral?
unilateral
What is the exam of guttural pouch tympany?
soft, nonpainful swelling parotid region
dyspnea, dysphagia, pneumonia–young animals aspirate milk—pneumonia (severe)–get large
secondary empyema common!!!
why can’t stuff drain out of guttural pouch? 1-way valve–cannot move AIR or FLUID
how is guttural pouch tympany diagnosed?
- exam
2. maybe rads
What is the probltem with stabbing guttural pouch tympany for immedite air release?
the normal anatomy has been distorted (viborgs triangle). ultrasound it first but scoping is preferable
What is a differential for guttural pouch tympany?
branchial arch cyst? ballot them
What are surgical methods to deal with guttural pouch tympany?
- needle decompression (not a permanent fix)
- septal fenestration–vent bad side to good side
- salpingopharyngeal fistula
What is the significance of guttural pouch mycosis?
- severe epistaxis!!!!!!!!!
- mucopurulent/hemorhagic nasal discharge
- coughing
- dysphagia (cr IX, X)
- laryngeal hemiplegia
- horner’s syndrome
- tongue paresis
- head shaking
Why are animals with guttural pouch mycosis coughing?
a. panicking
b. secondary dysphagea (neuropraxia)/pneumonia
What are treatments for guttural pouch mycosis?
- medical–aniconazole?
- internal carotid ligation
- balon catheter + ligation
- coil embolization
What is the danger of medical treatment for guttural pouch mycosis?
you don’t know when it is going to rupture! Also results in you losing time, should go straight to surgery or don’t go at all
What is an issue with internal carotid ligation for guttural pouch mycosis?
you have only blocked the region coming from the heart but the cirle of willis has no valves so reversal of flow can result in bleeding out from that direction
What is ballon catheter and ligation or coil embolization (and what is benefit over ligation of carotid alone)
blow up balloon beyond mycosis to block the region of the carotid so blood does not come from circle of willis and also ligate the carotid lower down.
Why does it get more complicated if guttural pouch mycosis is near maxillary artery?
have to block the major palatine artery (blow up balloon) and block the maxillary artery but it is very hard to find major palatine artery!
When is tracheotomy done?
when there is complete airway obstruction (actually before that)
How is tracheotomy done?
- junction of cranial and middle third of neck
- local anesthetic? (emergency?)
- 10cm incision through skin (midline!!!!!!!)- thin white junction between muscle bellies
- blunt b/w sternothyrohyoideus
- incise annular ligament b/w rings (one cut) HORIZONTAL
- 1/3 to 1/2 circumference only–AVOID VAGUS
- put in tube
Why should you not get into the box with a horse in extreme resp distress?
because the horse could drop on you. wait until the horse is down
