Chapter 45 - Pharynx Flashcards
1
Q
What are the three main sections of the pharynx?
A
Nasopharynx, oropharynx, and laryngopharynx.
2
Q
What role does the pharynx play during respiration?
A
It is a musculomembranous tubular structe not supported by bone or cartilaginous matrix and facilitates airflow and pressure changes while preventing communication between the nasopharynx and oropharynx.
3
Q
How does the soft palate interact with the larynx during respiration?
A
During respiration,
the caudal free margin of the soft palate intimately contacts the
subepiglottic tissue at the base of the equine larynx
4
Q
What anatomical structures are attached to the nasopharynx?
A
Pterygoid, palatine, and hyoid bones, as well as laryngeal, cricoid, and thyroid cartilages.
5
Q
What intraluminal pressure range must the nasopharynx withstand?
A
24–50 cm H2O.
6
Q
What is the maximum airflow velocity the nasopharynx can accommodate?
A
Up to 90 L/s.
7
Q
Which muscles are primarily responsible for altering the size and configuration of the nasopharynx?
A
Muscles that move the tongue, insert on the hyoid apparatus and larynx, and regulate soft palate position.
8
Q
How is the musculature of the pharynx classified?
A
Into intrinsic and extrinsic muscles.
9
Q
What is the primary function of the intrinsic musculature in the nasopharynx?
A
To stabilize the nasopharynx through muscular contractions.
10
Q
What structure forms the floor of the nasopharynx?
A
The soft palate.
11
Q
What are the components of the soft palate?
A
Oral mucous membrane, palatine glands, palatine aponeurosis, palatinus and palatopharyngeus muscles, and nasopharyngeal mucous membrane.
12
Q
How does the palatine aponeurosis contribute to the anatomy of the nasopharynx?
A
It attaches to the caudal margin of the hard palate and helps maintain structural integrity.
13
Q
Which 4 muscles coordinate the position of the soft palate?
A
Tensor veli palatini, levator veli palatini, palatinus, and palatopharyngeus muscles.
14
Q
What is the innervation of the tensor veli palatini muscle?
A
Mandibular branch of the trigeminal nerve.
15
Q
Which muscle elevates the soft palate during swallowing?
A
Levator veli palatini muscle.
16
Q
Where does the palatinus muscle originate?
A
The caudal aspect of the palatine aponeurosis.
17
Q
What is the function of the palatopharyngeus muscle?
A
To shorten and depress the soft palate towards the tongue.
18
Q
How does the tensor veli palatini muscle affect the nasopharynx during inspiration?
A
It tenses the soft palate and expands the nasopharynx.
19
Q
What is the role of the stylopharyngeus muscle in the pharynx?
A
It acts as a pharyngeal dilator to maintain tension in the nasopharynx.
20
Q
Which nerve innervates the caudal stylopharyngeus muscle?
A
Glossopharyngeal nerve.
21
Q
How is the blood supply to the soft palate provided?
A
By the linguofacial trunk and maxillary artery.
22
Q
What is the venous drainage pattern for the soft palate?
A
It occurs via accompanying veins.
23
Q
Where do lymph vessels from the soft palate drain?
A
Toward the retropharyngeal lymph nodes.
24
Q
What type of receptors provide afferent innervation to the nasopharynx?
A
Pressure, mechanical, and temperature receptors.
25
What anatomical features separate the nasopharynx from the oropharynx?
The soft palate.
26
Which muscle has a pulley-like effect on the soft palate?
Tensor veli palatini muscle.
27
What are the main components of the intrinsic musculature of the nasopharynx?
Muscles of the soft palate and nasopharyngeal muscles.
28
How does the hyoid apparatus influence the nasopharynx?
Muscles affecting the hyoid can alter the size and stability of the nasopharynx.
29
what is the anatomical relationship between the soft palate and the larynx?
The caudal margin of the soft palate forms the floor of the nasopharynx, surrounding the larynx.
30
How is the position of the soft palate dynamically regulated?
Through coordinated contractions of specific muscles during breathing and swallowing.
31
What anatomical structure extends from the base of the epiglottis to the arch of the cricoid cartilage?
Laryngopharynx.
32
What anatomical feature provides structural support to the nasopharynx despite the lack of bone?
Muscular contraction and muscle attachments to adjacent bones.
33
How do the intrinsic muscles affect the configuration of the nasopharynx?
They enable timely contractions that adjust tension and diameter during respiration.
34
What is the effect of the levator veli palatini muscle on the nasopharynx?
It elevates the soft palate, closing off the nasopharynx during swallowing.
35
Why is the role of the oropharynx gaining importance in equine pharyngeal disease?
Increased understanding of its anatomy and functions, particularly related to the hypoglossal nerve.
36
Which muscle fibers continue caudad from the palatine aponeurosis?
The palatopharyngeus muscle fibers.
37
What anatomical relationship exists between the nasopharynx and the auditory tube?
The levator veli palatini arises from the lateral lamina of the auditory tube.
38
How do the intrinsic and extrinsic muscles of the pharynx work together?
They coordinate to adjust the size and position of the nasopharynx and oropharynx during various physiological functions.
39
What is the physiological significance of the nasopharynx's ability to withstand pressure changes?
It allows effective respiration during varying airflow conditions.
40
Figure 45-1. The extrinsic structures relevant to equine nasopharynx
stability, showing the definition of the nasopharynx and relative relationships
of the hyoid apparatus, larynx, and extrinsic muscular attachments. a,
Mandible; b, genioglossus muscle; c, geniohyoideus muscle; d, styloglossus;
e, hyoglossus muscle; f, basihyoid bone; g, hyoepiglotticus muscle.
41
Figure 45-2. The intrinsic structures of the nasopharynx. The nasopharynx forms the passageway that transfers airflow from the caudal aspect of the nasal cavity to the larynx. The floor of the nasopharynx is formed by the soft palate and its relevant structures (a, Palatine aponeurosis; b, oral mucosa; c, glandular layer; d, palatinus muscle) and is normally in a subepiglottic position during respiration. The hamulus (f) of the pterygoid bone, and the tensor veli palatini (e), levator veli palatini (g), and palatopharyngeus (not shown) muscles are underneath the mucosa of the lateral walls of the nasopharynx. The stylopharyngeus (h) with the palatopharyngeus muscles add to the stability of the roof of the nasopharynx.
42
Figure 45-3. The intrinsic structures of the nasopharynx viewed from the ventral aspect of the nasopharynx, showing the muscles of the soft palate, the palatine aponeurosis (d), and the hamulus of the pterygoid bone (arrow). a, Tensor veli palatini muscle; b, levator veli palatini muscle; c, palatinus muscle.
43
Figure 45-4. The intrinsic muscles that form the wall and roof of the nasopharynx. Note that contractions of the stylopharyngeus caudalis support the roof of the nasopharynx.
44
What is the primary structural composition of the pharynx?
The pharynx is a musculomembranous tubular structure unsupported by bone or cartilage.
45
What are the three anatomical divisions of the pharynx?
The nasopharynx, oropharynx, and laryngopharynx.
46
How does the soft palate affect communication between the nasopharynx and oropharynx?
The soft palate prevents communication by contacting the subepiglottic tissue.
47
What is the pressure range (in cm H2O) that the nasopharynx must withstand during respiration?
The nasopharynx withstands pressures from 24 to 50 cm H2O.
48
What airflow velocity can the nasopharynx accommodate?
The nasopharynx can accommodate airflow velocities up to 90 L/s.
49
What role do intrinsic muscles play in the nasopharynx?
Intrinsic muscles stabilize the nasopharynx by contracting to tense and dilate its walls.
50
Which muscle is responsible for tensing the rostral aspect of the soft palate?
The tensor veli palatini muscle.
51
Which nerve innervates the tensor veli palatini muscle?
The mandibular branch of the trigeminal nerve.
52
What is the function of the palatinus muscle?
The palatinus muscle shortens and depresses the soft palate toward the tongue.
53
Which nerve innervates the palatinus and palatopharyngeus muscles?
The pharyngeal branch of the vagus nerve.
54
What is the role of the extrinsic musculature in the nasopharynx?
Extrinsic muscles increase respiratory patency and stability of the nasopharynx.
55
What is the primary action of the hyoglossus muscle?
The hyoglossus muscle retracts and depresses the base of the tongue.
56
Which muscle is primarily involved in the dorsal displacement of the soft palate during exercise?
Dysfunction of extrinsic muscles leads to dorsal displacement of the soft palate.
57
What anatomical structure do the genioglossus and geniohyoideus muscles attach to?
They attach to the basihyoid bone.
58
How does the contraction of the thyrohyoideus muscle affect the larynx?
It enhances stability by moving the larynx rostrad during exercise.
59
Which are the extrinsic muscles?
1. geniohyoideus
2. thyrohyoideus
3. genioglossus
4. hyoglossus
5. hyoepiglotticus
6.styloglossus
7. stenohyoideus
8. sternothyroideus muscles
60
What anatomical disorder is characterized by a web of scarring in the nasopharynx?
Nasopharyngeal cicatrix.
61
Describe the genioglossus
The genioglossus muscle is a fan-shaped extrinsic tongue muscle that originates within the median plane of the tongue and attaches to the oral surface of the mandible, caudal to the symphysis
62
What happens when genioglossus muscle contracts
Contraction of the genioglossus muscle protracts the tongue and pulls the basihyoid bone rostrally.
63
The styloglossus muscle lies on the lateral aspect of the tongue, originates on the lateral aspect of the stylohyoid bone and inserts on the tip of the tongue. Its function is
retraction of the tongue (i.e., retruder)
64
The hyoglossus muscle is located medial to the styloglossus muscle, originates on the
hyoid bones (lingual process, stylohyoid and thyrohyoid bone), and inserts on the median plane of the dorsum of the tongue.
65
Because local anesthesia of the hypoglossal nerve at the midlevel of the ceratohyoid bone interferes with the action of the___________ and ___________ muscles (protruders of the tongue) at the same time as that of styloglossus and hyoglossus (retruders), the exact function of each paired muscle is not yet known
ceratohyoid bone interferes with the action of the geniohyoideus and genioglossus muscles (protruders of the tongue)
66
The sternothyroideus muscle inserts on the caudolateral aspect of the________ cartilage
thyroid cartilage
67
the sternohyoideus muscle inserts on the basihyoid bone and ________ (1 w) process of the hyoid apparatus.
sternohyoideus muscle inserts on the basihyoid bone and lingual process of the hyoid apparatus.
68
______________ (1w) muscle, attaches to the hyoid bone at the base of the epiglottis, and during its contraction, pulls the epiglottis ventrad toward the base of the tongue
hyoepiglotticus muscle, attaches to the hyoid bone at the base of the epiglottis, and during its contraction, pulls the epiglottis ventrad toward the base of the tongue
69
Contraction of sternothyroideus, sternohyoideus results in caudal traction on the________ (1w)apparatus and larynx.
Contraction of these muscles results in caudal traction on the hyoid apparatus and larynx.
70
What is the only muscle that inserts on the epiglottis
hyoepligotticus muscle
71
___________________(1w) muscle, which extends from the lateral lamina of the thyroid cartilage to the caudal aspect of the thyrohyoid bone
thyrohyoideus muscle, which extends from the lateral lamina of the thyroid cartilage to the caudal aspect of the thyrohyoid bone (cut it in tie-forward)
72
disruption of the thyrohyoideus muscle results in....(1w)
DDSP
73
The hypoglossal nerve (XII) innervates which muscles
geniohyoideus m.(main branch)
genioglossus m. (medial branch)
styloglossus m.
hyoglossus m. (lateral branch)
hyoepiglotticus m. (main granch)
74
The first and seconde cervical nerves innervate which muscles?
Sternohyoideus
Sternothyroideus
75
Arterial blood supply to the pharynx is provided by the
1. common carotid
2. external carotid arteries
3. linguofacial trunk
76
The extrynsic muscles the drainage is from
retropharyngeal and cranial cervical lymph nodes
77
Which nerves provide sensosry innervation to the nasopharyngeal mucosa?
Trigeminal n.
vagus n.
glossopharyngeal n.
78
What is the role of the hypoglossal nerve in nasopharyngeal function?
It innervates several muscles involved in tongue and hyoid movement.
79
Nasopharyngeal cicatrix has a predisposition for
females 60%
80
Diagnosis
Figure 45-5. Endoscopic photograph of a nasopharyngeal cicatrix in a horse, characterized by scar formation across the floor of the nasopharynx.
81
Figure 45-6. Endoscopic photograph of a nasopharyngeal cicatrix affecting the larynx and epiglottic cartilage. Note the deformation of right arytenoid cartilage, as well as scar formation across the floor of the nasopharynx. **Treatment options?**
1) **NSAIDs **+ removal from pasture
2) **Transection** of cicatrix using **transendoscopic laser**
3) non-responsive cases **permanent tracheostomy**
82
What percentage of nasopharyngeal cicatrix cases show epiglottic or arytenoid cartilage deformation?
Nearly 95%.
83
In which climate is nasopharyngeal cicatrix more commonly reported?
Hot climates, especially in the eastern and southern United States.
84
Is partial arytenoidectomy advised to correct severe scarring cases?
**NO,** in severe scarring cases **partial arytenoidectomy** leads to an inappropriate diameter of the rima glottis during postop healing and** IT SHOULD NOT BE PERFORMED**
85
What is a common clinical sign of nasopharyngeal cicatrix?
Upper respiratory noise.
86
What types of primary nasopharyngeal masses are mentioned?
Benign lesions (cysts and fungal granulomas), tumors, and ethmoid hematomas.
87
What are common clinical signs of nasopharyngeal masses?
Exercise intolerance, respiratory noise, and nasal drainage.
88
What surgical options exist for nasopharyngeal mass?
1) transendoscopic laser resection transoral under GA
2) transendoscopic laser resection transnasal standing
3) Transoral approach with electrocautery snare under GA
4) Intralesional injection 10% formalin
5) Laryngotomy (preferred for cysts and granulomas)
6) Pharyngotomy
89
What are the values of diode laser for mass resection under endoscopic control? describe the procedure
Sedation deto + butor
Nostril best acess to the mass and topical local anesthesia as well as in nasal passage
vasoconstrictive agent (10 mL 0.15% phenylaphrine) on mass
other nostril place the endoscope
**Diode laser 12-15 W 600 µm**
90
What is a possible treatment for nasopharyngeal masses if mass resection is not feasible?
Intralesional injection of formaldehyde 10 % (10 to 20 mL)with polyethylene catheter fixed to 16G needle and 3 to 5 days of NSAIDs
91
What is a potential treatment for fungal granulomas in the nasopharynx?
in case of coccidiomycosis weekly **intralesional injections of amphotericin B (100 mg of a 100 mg/mL preparation) with 3 mL of 90% solution of DMSO**
**oral fluconazole** (14mg/kg loading dose and 5mg/kg PO SID) and organic ehtylediamine dihydriodide + potassium iodide
92
What preoperative medication is given to horses undergoing endoscopy-assisted resection?
Dexamethasone (0.044 mg/kg IV) and phenylbutazone (4.4 mg/kg).
93
What is the throath flush solution?
250 mL glycerin
250 mL of 90% DMSO
500 mL nitrofurazone
50 mL prednisolone (25mg/mL) administered twice a day using a 12-French red rubber feeding tube and alternating nostrils between treatments
94
Which instruments do you use to remove a mass in the nasopharynx?
Laryngeal forceps or use a snare and with diode lase (12-15 watts) you incise the mass after LA
95
Figure 45-8. Endoscopic view of a pharyngeal mass in a 20-year-old horse. The mass originated from the root of the tongue
96
Describe the surgical approach for laryngotomy
Under GA - DR - **10 to 12 cm ventral** midline incision between the cricoid and thyroid centered in the **cricothyroid space**
Incision of skin, subcut and **sternohyoideus muscle** is bluntly divided
Placement of **self retractor**
Sharp incision of **cricothyroid membrane** and acess to **laryngeal mucosa**
Soft palate caudal free edge is grasped with Allis forceps and with **Stantisky thoracic scissors** the caudal marign of soft palate is removed along mass/cyst
97
Describe pharyngotomy
1. Horse in GA and dorsal recumbency
2. skin incision from rostral aspect of the **thyroid cartilage** cranial towards the **basihyoid** bone
3. **sternohyoideus mm** bluntly separated and incision extended to loose fascia between the thyroid cartilage and the basihyoid
4. **N.B. the hyoepiglotticus mm** is enclosed in elastic fascia (hyoepiglotticus ligament) deep to the loose fascia.
5. the **left and right hyoepiglotticus mm** are **separated on the midline**, and the incision is continued **until the oropharyngeal mucosa** which is incised with curved scissors after picking it with rat's tooth forceps.
6. further exposure is obtained by **splitting the basihyoid longitudinally with an osteotome.**
7. **malleable or Langenbeck retractors** to retract the incision laterad and the root of the tongue forward.
8. Closure:
**oropharyngeal mucosa** with No. 0 poliglecaprone (Monocryl) in a **simple continuous pattern**
few ** simple interrupted sutures** to appose the loose areolar tissue ventral to mucosa
the **basihyoid (if it was split) is reapposed No. 2 steel suture**
**sternohyoideus mm** sutured with No. 0 polieglecaprone in a simple continuous pattern
**skin and subcut**is close only over the split basihyoid bone.
leave it open due to clean-contaminated nature of incision
98
What muscle is separated during the **pharyngotomy** procedure?
**Sternohyoideus muscles + hyoepiglotticus muscle**
99
Complete closure is recommended in the pharyngotomy?
Complete closure is **NOT recommended** because of the clean-contaminated nature of the incision
100
Which muscle is unique for its insertion on the epiglottis?
hyoepiglotticus muscle
101
should you do pharyngotomy as first approach?
**NO, **because high morbidity compared to laryngotomy due to:
1) limited exposure
2) possible damage to **hyoepiglotticus muscle**
102
where is the incision of pharyngotomy?
skin incision from rostral aspect of the **thyroid cartilage** cranial towards the **basihyoid**
103
what is this surgical approach?
Figure 45-10. Pharyngotomy. The sternohyoideus muscles have been bluntly separated, allowing exposure to the underlying fascia. The basihyoid has been split longitudinally with an osteotome (an optional step), and the superficial fascia is being incised with curved Mayo scissors, exposing the underlying hyoepiglotticus muscle
The skin incision is extended from the rostral aspect of the thyroid cartilage forward toward the basihyoid bone. The sternohyoideus muscles are separated bluntly on the ventral midline, and the incision is extended to the loose fascia between the thyroid cartilage and the basihyoid bone (fig 45-10) The hyoepiglotticus muscle is enclosed in elastic fascia (hyoepiglotticus ligament) deep to the loose fascia. The left and right hyoepiglotticus muscles are separated on the midline, and the incision is extended through multiple layers of loose fascia until the oropharyngeal mucosa is reached. Further exposure is obtained by splitting the basihyoid longitudinally with an osteotome. Malleable or Langenbeck retractors are needed to retract each side of the incision laterad and the root of the tongue rostrad.
104
what is this surgical approach?
Figure 45-9. Pharyngotomy. Schematic shows the view of the ventral cervical area of a horse in dorsal recumbency and illustrates the landmarks for a pharyngotomy. The bold line represents the line of incision extending from the basihyoid to the thyroid cartilage.
105
What is the premedication for mass removal?
Preoperatively, horses are administered dexamethasone (0.044 mg/kg) and phenylbutazone (4.4 mg/kg) intravenously. Postoperatively, the steroids are continued for 2 to 3 days and the nonsteroidal antiinflammatory drug (NSAI D) for 3 to 5 days. In addition,
106
How many days postoperatively is phenylbutazone administered?
3 to 5 days.
107
What is the surgical approach for removing a subepiglottic mass?
laryngotomy ( +++ preferred) or pharyngotomy
108
Palatal dysfunction includes which syndromes?
3 syndromes:
1) **DDSP** (70-80% make noise, 20% silent - expiratory)
2) **Palatal instability**
3) **Rostral Palatal instability** (inspiratory)
109
diagnosis
1. **Rostral pharyngeal collapse** (fluttering of the rostral aspect of the soft palate)
-rostral palatal instability (RPI)
-induced experimentally by **bilateral transection of tendon of tensor veli** **palatine mm.-**->** inspiration** **obstruction** but NO DDSP
110
What area of the soft palate is cauterized during thermal palatoplasty?
The ventral surface extending caudad beyond the palatoglossal arch.
111
What is the medical treatment for rostral palatal instability?
1. **systemic dexamethasone** (**30 mg** for 3 d, **20 mg** for 3 d, **10 mg** for 3 d, and **10 mg **every other d) or aerosol fluticasone (3mg BID, or 2200 10 puffs SID)
- throat flush solution 20 ml BID
- Figure 8 nose band or Cornell colar
112
What is the surgical tx for palatal instability?
1) **Laser thermoplasty via nasal approach** (diode laser **20w contact fiber for 3 seconds**)
2) **Thermal palatoplasty** - under GA or standing with mouth gag the tongue is pulled rostrally and head elevated to see SP and metal instrument to protect tongue. Applyiron to cautherize the hard palate beyoun the palatoglossal arch
3) **Tension palatoplasty**
- under GA with mouth gag
- eliptical incision (10-12 cm long by 1 cm wide) using long handled forceps and curved Metznebaum scissors
- mucosa and submuscosa reapposed using Vicrl 0 and monocryl in simple interrupted pattern
113
Figure 45-13. Thermal rostral palatoplasty. (A) Rostral aspect of the soft palate viewed through the oropharynx immediately before surgery. Note parasagittal longitudinal folds on the oropharyngeal mucosa of the rostral aspect of the soft palate. (B) Appearance of the soft palate immediately after cauterizing.
114
Tension Palatoplast the horse is under GA and an elliptical incision is made where?
elliptical incision is made throguh the oral mucosa starting immediately caudal to the caudal edge of the hard palate two thirds of rostal soft palate mucosa and submucosa (9-12 cm by 1-2 cm wide) using long handled forceps and metzenbaum scissors
115
What are the characteristics of the custom-built "irons" used in thermal palatoplasty?
Two 1-cm-diameter steel rods with a T-shaped end.
116
The mucosal and submucosal edges are reapposed using what sutures in the tension palatoplasty?
No. 0 Vicryl or Monocryl in a simple-interrupted pattern. The procedure can be repeated in 4 weeks (a procedure termed maximum tension palatoplasty) to further increase the tension in the soft palate.
117
How long is the incision in the tension palatoplasty?
elliptical section of approximately two thirds of the rostral soft palate mucosa and submucosa is excised (9 to 12 cm long by 1 to 2 cm wide)
118
The degree of postoperative pain is worse in the thermal or tension?
The degree of postoperative pain is reportedly minimal and of short duration after thermal palatoplasty (2–3 days) compared with tension palatoplasty (up to 7 days in some cases).
119
What is the prognosis in case of tension palatoplasty?
**GUARDED Prognosis** is related to the degree of collapse. A guarded prognosis should be given because the current knowledge of this condition is limited
120
Figure 45-14. Tension rostral palatoplasty. Schematic drawing shows the location of the elliptical incision (dotted line) on the ventral and rostral aspect of the soft palate as viewed though the oropharynx. This incision leads to resection of the oropharyngeal mucosa and glandular portion of the soft palate in that specific location. a, Hard palate; b, isthmus faucium; c, sagittal fold; d, caudal border of the soft palate.
121
Staphylectomy or trimming of __________________(5w) is performed by transendoscopic laser assisted tx or sharp excision via ________________(1w)
trimming of the caudal free edge of the soft palate
via laryngotomy
122
What are the neves that can be affecter (efferent mtor pathway) that can creat dorsal lateral collapse?
Glossopharyngeal n. (stylopharyngeus m.) and vagus nerve (palatopharyngeys m)
123
Dillon et al EVJ 2022 described injection of prodcut to treat equine palatal dysfunction what is the name?
Genipin with 76% success
124
What is the postoperative care of rostral palatal instability?
* mash and wet hay for 3 to 7 days before returning to work.
* PBZ and TMPS for 5 to 7 days.
* Walking exercise after 2 days
* Training can resume in 4 weeks.
* Degree of postoperative pain is reportedly minimal and of short duration after thermal palatoplasty (2–3 days) compared with tension palatoplasty (up to 7 days in some cases).
125
what is the muscle believed to be reponsible for rostral pharyngeal collapse?
Tensor veli palatini muscle
126
What is a potential consequence of unsuccessful palatoplasty techniques?
Ineffective long-term reduction of soft palate compliance.
127
Rostral palatal instability is inspiratory or expiratory obstruction?
Inspiratory
128
At what age are dynamic dorsal pharyngeal collapses most commonly observed?
In 2- and 3-year-old racehorses.
129
What is the main clinical sign associated with rostral pharyngeal collapse?
Upper respiratory noise.
130
How is the oropharyngeal muscosa closed in the tension palatoplasty?
The oropharyngeal mucosa is **closed using No. 0 poliglecaprone (Monocryl) in a simple-continuous pattern**.
131
diagnosis
Dorsal/lateral nasopharyngeal colapse
physiologically the roof of nasopharynx does normally displace ventrally at the end of EXPIRATION during exercise but this should not extend beyond the ventral surface of the fully abducted arytendoid cartilages.
132
Collapse of the nasopharynx occurs during (inhalation or expiration)
Collapse of the nasopharynx occurs during inhalation
133
Dysfunction may be associated with
* severe inflammation
* neuritis of the pharyngeal branch of the vagal or glossopharyngeal nerve
* Guttural pouch distention ipsilateral nasopharyngeal roof collapse
* Hyperkalemic periodic paralysis (HYPP) episode
* Botulism, or equine protozoal myelitis, EPM
* Nasal obstruction may more negative inspiratory pressure > activity of the intrinsic nasopharyngeal musculature
134
what is the clinical signs of dorsal/lateral palatal instability?
- 2-3-year-old racehorse where nasopharyngeal collapse occurs during inhalation, reducing its lumen to a diameter less than the cross-sectional diameter of the rima glottidis.
- INSPIRATORY upper respiratory noise and exercise intolerance
135
What systemic treatment is commonly used for nasopharyngeal inflammation? surgical tx?
Dexamethasone.
Surgical treatments included procedures aimed at equilibration of the pressures between the nasopharynx and the guttural pouches such as removal of plica salpingopharyngea or a nasopharyngeal fenestration
136
What muscle dysfunction is linked to collapse of dorsal/lateral nasopharyngeal roof?
Dysfunction of the stylopharyngeus caudalis muscle.
137
In dorsal/lateral nasopharyngeal collapse what is the surgical treatment?
Removal of the plica salpingopharyngea or nasopharyngeal fenestration
138
What diagnostic method can suspect dorsal/lateral nasopharyngeal collapse?
Endoscopic examination during nasal occlusion.
139
What can cause intraluminal collapse of the lateral walls of the nasopharynx?
Dysfunction of the palatopharyngeus muscles.
140
What condition might palatal instability (PI) indicate?
It may be a precursor to DDSP.
141
DDSP with dysphagia indicates:
1. a more advance deficit of the** palatinus/palathopharyngeus muscle** (or their innervation)
2. an **anatomic deficit, such as cleft palate** or an acquired deficit of the caudal free edge of the SP after staphylectomy or loss of epiglottic cartilage secondary septic epiglottic or surgical trauma
3. m**echanical deficit after placement of laryngeal prosthesis** that allows feeds contamination of the nasopharynx from the oropharynx
142
- It is important to identify both the presence and the cause of the DDSP. Not all DDSP require your favourite surgical treatment. which mechanical factors can lead to DDSP
- mechanical factors: abnormal structures/masses/defect around the laryngo-palatal junction, which can mechanically interfere with the seal between the caudal free edge of SP and subepliglottic tissue, or by causing irritation or pain that stimulates DDSP
- epiglottic hypoplasia or deformation
143
144
145
During what phase of exercise does the roof of the nasopharynx normally collapse?
At the end of expiration.
146
Which systemic diseases could contribute to dorsa/lateral nasopharyngeal collapse?
severe inflammation
Hyperkalemic periodic paralysis (HYPP),
GP distension
neuritis pharyngeal branch of vagal or glossopharyngeal nerve
botulism,
equine protozoal myelitis
nasal obstruction
147
diagnosis
3. Dorsal displacement of the Soft Palate (DDSP)
1.3% of population at rest
148
DDSP is from expiratory or inspiratory obstruction?
expiratory
149
Is the resting endoscopy indicated for dx of DDSP?
**resting endoscopy: is poor** and resulted in** A 35% MISDIAGNOSI**S rate of palatal dysfunction as compared to diagnosis obtained from treadmill endoscopy
150
Medical treatment fo DDSP?
- Persevere with this – **good outcomes esp with figure 8** **noseband** and longer time – up to 70% (NL)
- If structural abnormalities are found (epiglottic entrapment, cyst etc) corrected surgically
1) URT INFLAMMATION
- Nasopharyngeal & GP inflammation --> dysfunction of pharyngeal br of vagus n --> ↓palatinus and palatopharyngeal m tone --> PI --> DDSP
- Pharyngitis -->dysfunction of pharyngeal br of vagus n
o Systemic anti-inflammatory medications (dexamethasone or aerosol fluticasone 3mg q12hr)
o Topical solution (DMSO, Dexamethasone, Nitroflurazone)
2) IMMATURE OR UNFIT – should be conditioned & re-evaluated!
3) TACK CHANGES – elevate head position
o Figure-of-8 noseband
o Tongue tie; 30-60% success rate
o Bit that secures the tongue (W bit, a spoon bit, or a “serena song” bit) - restrict caudal movement of the tongue should be used in addition to a tongue-tie
o Throat Support Device = positions larynx and basihyoid more dorsad and rostrad prevent DDSP at exercise in experimental DDSP (Cornell collar)
53%-61% success rate
151
Prognsosis for DDSP medical tx?
53-61%
152
Barton et al 2022 EVJ what was the conclusion about tongue ties do not widen the upper airways in racehorses?
It was not found a positive effect of tongue ties so the study does not support the use of tongue ties to enhance upper airway function
153
What are the surgical treatments for DDSP?
1- Tie-forward combined with partial resection of the sternothyroideus
2- standard myectomy (sternohyoideus and sternothyroideus receted 6-8 cm)
3- Minimal invasive myectomy (sternohyoideus is transected 3 cm)
4- Staphylectomy -not recommended anymore unless cyst present
5- Tension and thermal palatoplasty not advised anymore
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In staphylectomy if you remove more than ____ cm you can distub the seal btw oropharynx and nasopharynx
In staphylectomy if you remove more than 0.75 cm you can distub the seal btw oropharynx and nasopharynx
155
what does it mean to perform a sthapylectomy?
to remove a caudal portion of DDSP
156
describe staphylectomy
* under GA in dorsal recumbency
* laryngotomy (1**0-12cm midline skin incisio**n centered over cricothyroid space)
* bluntly division of **sternohyoideus mm**
*** self-retaining retractor**s (Wetlainer or a Hobday) to expose **cricothyroid space**
* incise the cricothyroid membrane and laryngeal mucosa
* place the retractors in this layer
* the caudal free margin of the soft palate rostral to the incision is identified.
* if the horse was intubated nasotracheally, the soft palate may not be displaced, and the caudal edge of the soft palate may have to be freed from beneath the epiglottis using a pair of sponge forceps.
* if the horse was intubated orally, the palate will be displaced and the endotracheal tube should be retracted at this time.
* **Mucosa of the caudal free margin of SP **is **grasped** with an **Allis tissue forceps** on the midline, and two more forceps used to grasp the left and right mucosa **2-2.5 cm lateral to the midline**
* **Caudal free margin** of the SP (inc mass/cyst) = **resected** using **curved Satinsky thoracic scissors**
* **Crescent-shaped mucosa resected- 3-4 cm long piece of mucosa less 1cm wide on the midline and tapered toward both ends**
157
what is a complication of staphylectomy?
Complications of staphylectomy are rare but can occur if too wide a section of the soft palate is resected =** Dysphagic**
158
What percentage of horses with DDSP are considered "silent displacers"?
35%.
159
What digestive disturbances may accompany DDSP?
Feed, water, and saliva contamination of the upper airways.
160
How does DDSP affect upper airway pressure during exercise?
It creates expiratory obstruction, increasing tracheal expiratory pressure and impedance.
161
What three anatomical deficits can cause dysphagia in horses with DDSP?
Damage to the palatinus/palatopharyngeus muscles, cleft palate, or mechanical deficits from laryngeal prosthesis.
162
What is the goal of tie-forward surgery?
The procedure involves application of prothesis to replace the function of thyrohyoid msuculature and advance the larynx rostraly and dorsally
163
Standard myectomy consistis in what?
- Standard myectomy (a partial **sternohyoideus and sternothyroideus**, with or without omohyoideus resection)
**AIM = Reduce caudad retraction of the larynx**
- Sections of the sternothyroideus and sternohyoideus muscles are removed with the horse standing
164
describe the surgery of standard myectomy
LA midline junction proximal to middle third of neck
-**10-cm ventral midline incision** is made through the skin, continuing through the **cutaneus colli muscles.**
- the **paired sternohyoideus muscles** are identified. Using curved forceps, the **sternohyoideus and sternothyroideus muscles** are undermined. The ste**rnothyroideus** muscle is positioned **caudolateral to the sternohyoideus muscle** at this level of the neck. the muscles are **elevated** through the incision and clamped with a **Rochester- Carmalt forceps** at the proximal and distal extent of the incision.
- the **muscle bellies are sharply transected** between the forceps, removing a **6- to 8-cm-long section of muscle**
- the subcutaneous and skin layers are closed routinely. if a penrose drain is used, it is placed alongside the ventral aspect of the trachea and tunneled through a stab incision distal to the surgical incision. a firm bandage is applied around the neck and may be removed along with the drain 24 hours later.
-box rest with in hand walking exercise for 2 weeks
-thereafter resume training post suture removal
165
what is the complications reported for standard myectomy?
incisional seromas and infections
166
What is the success rate for standard myectomy?
58-71%
167
What is the Llewellyn procedure?
**partial sternothyroidectomy** or minimal invasive sternothyroidectomy
GA, 5-7 cm incision ventral midline centered over cricoid cartilage
Sternohyoideus is blunted separated
Dissection to expose caudolateral border of thyroid cartilage
Sternthyroideus m identified and isolated (watch out with caudal laryngeal artery avoid cricothyroid muscle!!)
transection and removal 3 cm section
closure of sternohyoideus muscle and skin
NSAIDS 3-7 days, training resumed 2-3 d
sucess rate 58-70%
168
what is being performed?
Partial sternothyroidectomy or minal invasive myectomy or Llewellyn procedure
169
describe tie forward
**- GA, dorsal**- ventral **cervical and intermandibular areas **prepared aseptically (10cm rostral to basihyoid bone)
- v**entral skin incision starting 1 cm caudal to cricoid cartilage and extending 2 cm rostral to the caudal aspect of the basihyoid bone.**
- the **sternohyoideus muscle** is separated on the midline and bluntly dissected free of the dorsolateral aspect of the larynx lateral to the thyrohyoideus muscles.
- **Self retaining retractors** placed in the incision
- **Elevation of the ST muscles/tendons** is done by placing a curved **Crile hemostat** immediately caudal to the **cricoid cartilage**
Prior to suture placement as:
- the sutures are first passed through the **thyroid cartilage starting 6 mm dorsal** to **most ventral margin of the lamina of the thyroid cartilage**
- **sutured passed 4 times **(bites 3-4mm apart) staying ventral to the insertion of the** sternothyroid tendon**
-**No. 5 USP polyblend suture (Fiberwire).**
Suture passed through a single hole in the thyroid cartilage.
The needle was **inserted ventromedial to dorsolateral, 1 cm** from the **caudal border of the thyroid cartilage**, at the level of the** sternothyroideus tendon insertion**
- the junction of the **basihyoid and lingual proces** is identified with a **Crile forceps** after limited blunt dissection, and a **wire passer** is inserted dorsal to the **basihyoid bone** immediately **lateral to the lingual process**
* It is important that the suture passer is placed immediately **dorsal to the basihyoid bone **and on its midline to avoid injuring a branch of the **lingual artery/vein that is abaxial.**
- the **wire passer** courses over the** dorsal aspect of the basihyoid** bone and exits on the** midline at the caudal aspect of the basihyoid bone**
-DUDE IS VERY COOL The** i**psilateral **d**orsal suture (lateral) and **c**ontralateral **v**entral suture are passed into the wire passer and retrieved together and tagged with separate hemostats.
-Repeated on the other side
-Dorsal (leader) and ventral (trailer) ends of the sutures of each side can be tied over the ventral aspect of the basihyoid.
-**Bilateral partial sternothyroidectomy **is performed at this time
-the sutures on each side are then tied so the rostral aspect of the thyroid cartilage is located immediately dorsal and **0.1 to 1.5 cm rostral to the caudal border of the basihyoid bone.**
horse’s head was flexed temporarily to facilitate suture tightening at 90º
Closure is obtained by reapposing the s**ternohyoideus muscles **with No. 0 poliglecaprone (monocryl) in a simple-continuous pattern.
the loose fascia overlying the larynx is incorporated into that closure; this is an important step to prevent postoperative seromas.
the subcutaneous tissues and skin are then closed in a routine manner.
170
during the tie-forward you have to be careful with which structures?
-Inadvertent perforation of **cranial thyroid artery **or **caudal laryngeal vein/artery **can result in** bleeding** and consequently identification of ST more difficult and risk of damage to cricothyroid muscles or its innervation from the external branch of the cranial laryngeal nerve
171
DDSP with dysphagia generally indicates 3 situtations, name them
1) a more-advanced **deficit of the palatinus/palatopharyngeus muscles** (or their innervation); (2) an anatomic deficit, such as **cleft palate** or an acquired deficit of the caudal free edge of the soft palate after staphylectomy or loss of epiglottic cartilage secondary to septic epiglottis or surgical trauma; or (3) a **mechanical deficit after placement of laryngeal prosthesis** that allows feed contamination of the nasopharynx from the oropharynx.
172
DDSP with dysphagia should be differentiate from what?
from aspiration of feed material into the trachea from laryngeal disease (or its treatment), which can lead to DDSP , presumably by inducing ventral and caudal laryngeal movement/displacement.
173
In the tie-forward what is important to have as position of the thyroid comparing to basihyoid bone?
rostral aspect of the thyroid cartilage is located immediately dorsal and **0.1 to 1.5 cm rostral to the caudal border of the basihyoid bone.**
174
How is the treatment approach for DDSP influenced by the underlying cause?
Treatment varies significantly based on whether the cause is structural, muscular, or functional.
175
what important that the suture passer is placed immediately dorsal to the basihyoid bone on its midline during tie-forward?
midline to avoid injuring a branch of the lingual artery/vein that is abaxial.
176
Figure 45-19. (A) Palatal granuloma in a 2-year-old Thoroughbred with dorsal displacement of the soft palate. (B) Appearance of the granuloma dorsal to the palate and ventral to the epiglottic cartilage (arrows) with the soft palate replaced. Indication is laryngotomy with staphylectomy
177
Figure 45-21. Bruising of nasopharynx approximately 12 hours following racing in a 7-year-old Standardbred gelding. This supports a **diagnosis of dorsal displacement of the soft palate** during racing.
178
Figure 45-20. Ulcer on the free edge of the soft palate in a 3-year-old Standardbred. This finding **supports a diagnosis of DDSP** and can also be seen if a subepilgottic mass or lesion is present.
179
What early hypotheses were proposed for DDSP?
Paralysis of the palate muscles and elongation of the soft palate.
180
What mechanical factors are associated with DDSP according to anecdotal evidence?
Cysts and other lesions on the soft palate that interfere with its position.
181
What effect do cysts on the soft palate have on DDSP?
They mechanically interfere with the normal subepiglottic position, and their removal can correct DDSP.
182
What are examples of lesions that may cause DDSP?
Subepiglottic or palatal granulomas, masses, and cysts.
183
How is epiglottic hypoplasia related to DDSP?
It may prevent the epiglottis from maintaining the soft palate in a subepiglottic position.
184
What clinical sign is associated with horses that have a flaccid epiglottis?
A decrease in racing performance, particularly in yearlings.
185
What is palatal instability?
Billowing of the soft palate that often precedes DDSP.
186
How does the position of the basihyoid bone relate to DDSP?
A more ventral position of the basihyoid bone is associated with DDSP.
187
What has been observed about horses with permanent DDSP?
They have a more caudal position of the larynx compared to those with intermittent DDSP.
188
What are 3 experimental models that result in DDSP?
1. The blockade of the pharyngeal branch of the vagus nerve model (at rest and exercise).
2. Resection of the thyrohyoideus muscle (at exercise)
3. Blockade of the hypoglassal nerve (at exercise).
189
What muscle is primarily responsible for stabilizing the soft palate at rest?
The palatinus muscle.
190
What are the common clinical signs of intermittent DDSP in racehorses?
Exercise intolerance and gurgling or vibrating noises during exhalation.
191
Intraoperative complications of tie forward
Intraoperative bleeding
Cartilage/bone breakage or laceration
Fracture stylohyoid bone postoperatively -* Passing the suture too close to the caudal border of the thyroid cartilage wing (<0.8 cm) may lead to suture pull out.
* Hyper extension of the head during recovery
192
What is the gold standard for diagnosing intermittent DDSP?
History of poor performance, respiratory noise, and endoscopic examination during exercise.
193
Early postoperative complications of tie forward
seroma
icnsional infection
194
Late postoperative complications of tie forward?
vocal cord collapse due to wider dissection of cricothyroid muscle
195
What are some treatments for upper respiratory tract inflammation associated with DDSP?
Systemic anti-inflammatory medications and topical anti-inflammatory solutions.
196
What is the success rate reported for nonsurgical treatments for DDSP?
A 53% to 61% success rate.
197
What devices are used to prevent DDSP during exercise?
Throat-support devices and figure-of-eight nosebands.
198
*Horse after tie forward sx presenting severe dysphagia and difficult swallowing and evidence of marked swelling within the GP which push the lateral wall of the pharynx medially near the tip of the epiglottic cartilage may be indicative of what?
Fracture stylohyoid bone postoperatively
199
What is the effect of a tongue-tie on DDSP?
It may help prevent caudal retraction of the tongue, potentially stabilizing the soft palate.
200
What role does the thyrohyoideus muscle play in DDSP?
It helps decrease the collapsibility of the nasopharynx during exercise.
201
What is the treatment in case of stylohyoid fracture following tieforward surgery?
* With rest and administration of NSAIDs, and the hematoma usually resolves in ~30 days.
Full healing of the fracture requires ~3 months
* Expected outcome In the majority of cases, clinical signs (dysphagia) resolves but DDSP can persist, especially if the larynx has moved caudally and ventrally.
202
nasopharyngeal and guttural pouch inflammation can lead to dysfunction of the pharyngeal branch of the _______(1w) nerve
nasopharyngeal and guttural pouch inflammation can lead to dysfunction of the pharyngeal branch of the vagus nerve
203
If the vagus nerve (due to GP and ansopharygenal inflammation) is affected what other 2 muscles are affected leading to DDSP?
palatinus and palatopharyngeus muscle tone, leading to PI and/or DDSP .
204
What should include the medical tx of DDSP if upper respiratory tract inflammation is diagnosed?
systemic antiinflammatory medication **(dexamethasone** as described earlier or** aerosol fluticasone 3 mg BID**, or** 220 mcg/puff, 20 puffs every 24 hours**) and **topical antiinflammatory solution containing glycerin, DMSO , dexamethasone**, and **nitrofurazone.**
a** figure-of-eight noseband**
205
Give % success rate when nonsurgical treatments were used alone for DDSP
53% to 61% for DDSP
