Chapter 47 - Guttural Pouch Flashcards
The GP are separated in the midline by
**1.rectus capitis ventralis
2.longus capitis muscles
3.median septum**
Differential diagnosis
1 - mycosis fo GP
2 -rupture of the:
1) rectus capitis ventralis and longus capitis muscles (i.e. the ventral straight muscles of the head)
2) avulsion fracture of the basisphenoid bone where these muscles attach to it
Diferential diagnosis of horse with vestibular syndrome?
vestibular syndrome can be central (basilar skull fracture, equine protozoal myeloencephalotos, trauma to brain) or peripheric. If peripheric
1) petrous temporal bone fracture
2) otitis interna or media
3) Osteoarthropathy of the GP
The vestibulocochlear nerve does not enter GP, enters the internal acoutic meatus caudal to facial nerve VII but can afect in case of THO
Legend the image
FIGURE 10.5-4 (A) Photograph showing a coil coated transversely with synthetic fibers. This type of coil is used for vascular occlusion of the affected
artery in the transarterial coil embolization procedure. (B) Fluoroscopic image showing a coil deployed in the sigmoid flexure of the internal carotid artery with
coil size selected based on the internal diameter of the artery.
What are the structures dorsal to GP?
the petrous part of the temporal bone
+tympanic bulla +
auditory meatus
What are the structures rostral to GP?
basisphenoid bone
What are the structures laterally to GP?
1) digastricus muscle
2) parotid
3) mandibular salivary glands
What are the structures ventrally to GP?
VENTRALY with the retropharyngeal lymph nodes + pharynx + esophagus
What are the structures caudally to GP?
Atlantooccipital joint
The GP is divided in lateral and medial parts by stylohyoid bone say the capacity of each
up to 470 mL MEDIAL1/3 of capacity of medial in LATERAL
Figure 47-9. Left-sided Horner syndrome, showing downward direction of the upper eyelid compared with the normal right side.
Figure 47-8. Guttural pouch mycosis in the typical location on the roof of the medial compartment (right guttural pouch) involving the internal carotid artery and causing epistaxis. A, Stylohyoid bone covered with diphtheritic membrane; B, external carotid artery; C, maxillary artery; D, mucosal fold that contains the glossopharyngeal and hypoglossal nerves; E, internal carotid artery. Extension of the plaque along the stylohyoid bone is not unusual and is rarely if ever clinically significant.
Figure 47-1. Interior of medial compartment of the left guttural pouch, viewed from the lateral aspect in a sagittal section of a horse’s head. The section is cut through the styloid process of the petrous temporal bone on a line that divides the guttural pouch into medial and lateral compartments. IX, Glossopharyngeal nerve; X, vagus nerve; XI, accessory nerve; XII, hypoglossal nerve; A, pharyngeal branch of the glossopharyngeal nerve; B, pharyngeal branch of the vagus nerve; C, cranial laryngeal nerve; D, cranial cervical ganglion. (Redrawn from Freeman DE, Donawick WJ. Occlusion of internal carotid artery in the horse by means of a balloon-tipped catheter: clinical use of a method to prevent epistaxis caused by guttural pouch mycosis
diagnosis
Figure 47-11. Endoscopic view of torn ventral straight muscles of the head in the left guttural pouch. The injury is rostral to the arteries in the caudal part of the guttural pouch. (
Figure 47-12. Radiograph demonstrating avulsion fracture of the basisphenoid bone, soft-tissue obliteration of the guttural pouch cavity, soft tissue impingement on the pharynx, and gas in soft tissues in a horse with ruptured ventral straight muscles of the head.
What are the functions of GP?
1) Pressure equilibration across the tympanic membrane
2) Air warming
3) Resonating chamber for vocalization
4) Flotation device
5) Brain cooling
What are the methods of diagnosis of GP?
External palpation, endoscopy
Palpable externally - empyema (purulent mat) + Tympany (air distension)
2)Endoscopy important in case of blood or pus à that can come from inside but also be aspirated inside
3) Radiography
4) CT good for stylohyoid bone + innear ear + petrous temporal bone or skull foramina
5) US good for soft tissue lesions or tumors or hemorrhage
6) MRI good for soft tissue (parotid melanoma)
What projections in radiographs?
DV and VD projection useful for
stylohyoidbones
temporohyoid joint
Diagnosis of this image
Right lateral radiographic view of skull
Basilar skull fracture between the basisphenoid and basioccipital bone
diagnosis of this MRI
Figure 47-4. Magnetic resonance imaging of parotid melanoma (between arrows) extending rostrally from the left guttural pouch (1). 2, Pterygoideus lateralis muscle; 3, pterygoideus medialis muscle; 4, squamous part of temporal bone; 5, masseter muscle.
Percutaneous centesis through Viborg triangle can be performed what are the normal values of the lavage?
Normal GP lavage has :
<5% neutrohiles
ciliated columnar epitelial cells
**
++ nonciliated cuboidal epitelial cells**
**< 1% monocytes lymphocytes and eosinophils
**
If neutrop > 25% = abnormal –> probably Streptococcus equi subeso. Equi present
The method of sampling by guttural pouch lavage can affect measures of mucosal reactivity!! Ifsample collected by endoscope à much cleaner than lavage transcutaneously
GP tympany is typical in which breed
Arabians and german warmbloods
Describe clinical signs of GP tympany
After 1 month up to 1 year of age
NONPAINFUL, elastic swelling in the parotid regionuIt can swell and give impression that is bilat
Dyspnea + dysphagia + inhalation pneumonia + 2ary empyea
You have to solve quickly as possible
Treatment of GP tympany (no sx option)
Needle decompression
OR indwelling catheter (temporary)
Chronic catherization (2-3 weeks) can be done but can cause:
PERMANENT DEFORMITY + SCARRING of cartilage of the pharyngeal ostium
Empyema
Bronchopneumonia
**Indwelling transnasal Foley catheter (22-24French) for 2 to 4 weeks is effetive (study in 5/8 foals when sx is not anoption)
**
What is the surgical tx for GP tympany
SURGERY – 3 options:
1.Permanent evacuating air through the unaffected GP (fenestration medium spetum)- Viborg triangle or through Whitehouse approach.
2.Through abnormal GP opening (removal of obstructing membrane) via Modified Whitehouse approach
3.Artificially created opening into pharynx (salpingopharyngeal fistula) with Nd:YAG or diode laser transendoscopically
Name the technique
Figure 47-5. Method for creating a fenestration between the abnormal and normal guttural pouches in a foal with unilateral tympany. The affected guttural pouch (on the left side) is approached through an incision in the Viborg triangle, and a Chamber mare catheter in the right guttural pouch is used to elevate and expose the median septum. In the expanded view, a pair of scissors has been placed to start fenestration (broken line). (Redrawn from Milne DW, Fessler JF. Tympanitis of the guttural pouch in a foal.
Fenestration of medium septum is by removal of what size segment?
What can you use to help during the procedure?
Major disadvantage? Advantage?
The median septum can be fenestrated by removal of a 2-cm 2 segment to allow egress of trapped air from the tympanitic pouch through the normal side
*Use Chambers catheter or scope to transilluminate
*Major disadvantage = only effective for unilateral disease - ( majority of cases).
Adv = simple and effective.
When bilateral tympanic involvement is suspected, the fenestration procedure has alterations?
Can be combined with removal of a small segment (1.5 × 2.5 cm) of the medial lamina of the Eustachian tube and associated mucosal fold (plica salpingopharyngea) within the guttural pouch orifice; this forms a larger opening into the pharynx
Describe the opening via GP ostia/removal obstructing membrane
removal of the obstructing membrane via Modified Whitehouse approach.
For bilateral disease, fenestration of the septum can be combined with removal of segment of medial lamina of Eustation tube & associated mucosal fold; (salpingopharyngea)
Superseded by Nd:Yag/diode laser fenestration of the Ostia or septum
What is the technique?
Right ostium fenestration with laser ablation of the protective cartilage flap. This can also be achieve with chronic trochaterization with Foley Catheter
Horse diagnosed with guttural pouch mycosis. Endoscopic examination shows an accumulation of food and saliva in the
nasopharynx, consistent with dysphagia. What is the cause?
This is also seen externally as a bilateral nasal discharge. Injury to CN’s IX and X can result in this clinical finding.
Describe the surgical treatment of opening of GP via pharynx for tympanism
*salpingopharyngeal fistula caudal to guttural pouch opening.
- Nd:YAG or diode laser transendoscopically.
Performed CAUDODORSAL to ostium (ie dorsal pharyngeal recess)
Foley in the fistula for 7-10d
Can be done bilaterally
Risks = delayed thermal necrosis & delayed vessel rupture without warning
*dorsal pharyngeal recess
What is the procedure?
Opening via pharynx: Salpingopharyngeal fistula in the dorsal retropharyngeal recess
What can happen if the fistula is too rostral and ventral to the plica salpingopharyngeal?
The plica can still limit air exit
Describe image
Computed tomographic image (transverse plane [A] and dorsal plane [B]; 2 mm standard window) of a horse head specimen following auditory tube diverticulotomy caudal to the nasopharyngeal ostium. Note communication between the nasopharynx and both left and right auditory tube diverticula (white arrows). The median septum is visible (black arrow).
What is the prognosis for after median septum fenestration?
**favourable ** (61-70%)after median septum fenestration **guarded **in presence of **aspiration pneumonia **and dysphagia
Name the pathologies of nasopharyngeal obstruction
1) Gutural pouch tympany
2) Nasopharyngeal obstruction in adult
3) Gutural pouch empyema
4) Gutural pouch mycosis
5) Rupture of ventral straight muscles
6) Temporohyoid OA
7) Miscellaneous diseases 8neoplasia, parotid melanomatosis, malignant amelanotic, melanomas, fracture of stylohoid, FB, periocular penetration, cystic structures
What is the treatment of GP tympany?
Transendoscopic electrocautery or laser (high powered diode or neodymum:ytrium-aluminu-garnet (Nd:YAG) laser) can be used to create: a fenestration in the septum and to make a fistula into the GP through the pharyngeal recess
Standing or GA
Foley kt through the fistula for 7 to 10 days
What is the cause of nasopharyngeal obstruction in adult horses? cause?
attributed to failed egress of air from one or both guttural pouches during poll flexion possibly caused by an anatomic or functional defect in the salpingopharyngeal fold - congenital
What are the surgical drainage techniques of the GP?
1.Hyovertebrotomy
2.Viborg triangle approach
3.White house
4.Modified whitehouse approach (GA or standing)
5.Modified Garm technique
Different surgerical approach to GP
Figure 47-18. Surgical approaches to the guttural pouch. A, Hyovertebrotomy; B, Viborg triangle; C, modified Whitehouse; D, Whitehouse. 1, Lateral compartment of the guttural pouch, which is partly separated from the medial compartment (2) by the stylohyoid bone (3); 4, vertical ramus of the mandible; 5, wing of the atlas. (Redrawn from Freeman DE. Diagnosis and treatment of diseases of the guttural pouch: Part II.
Hyovertrebrotomy technique description - Most dorsal & caudal of the approaches
‣Enters the pouch where cranial nerves & ICA are more closely grouped,
‣Dorsal so relatively poor for drainage - may need second ventral stab incision
‣TECHNIQUE - 10 cm incision 2cm cranial to & parallel to wing of the atlas through the skin and dense parotid fascia
‣The parotid gland and overlying parotido-auricularis muscle are reflected cranial to expose GP lining beneath areolar tissue
‣Palpate caudal & ventral stylohyoid & puncture GP medial to stylohyoid
‣Hyovertebrotomy can be closed or partially closed
Disadvantages of hyovertrebrotomy
‣Disadvantages: inadvertent parotid salivary gland damage (PO salivary leakage; usually transient), poor ventral drainage
Define the limits of Viborg triangle
Sternocephalicus muscle
Linguofacial vein
Vertical ramus of the mandible
Describe Viborg triangle technique
Boundaries = tendon of sternocephalicus muscle, linguofacial vein and the vertical ramus of the mandible
**
‣Can make a vertical or horizontal incision** in this area, a**voiding parotid duct & branches of CN X **along the floor of the GP
‣Incision usually maintained open with soft rubber catheter to allow continued drainage
‣Ideal approach for foals with tympany as the expanded pouch is positioned SQ
Describe Whitehouse tx
GA dorsal
ventral midline skin incision over the larynx
‣Dissection between sternohyoid & omohyoideus mm & along larynx to GP
‣Open the pouch medial to the stylohyoid avoiding the pharyngeal branch of vagus and cranial laryngeal nn which are close to the incision
Describe Modified whitehouse tx
12cm skin incision along the ventral edge of the linguofacial vein as per LP but extending 4-6cm cranially
‣Expose lateral larynx & continue bluntly until GP is entered
Advantages: avoids incision between sternocephalicus & omohyoideus & dissection occurs through a natural fascial plane
Standing Modified whitehouse
Excellent access and ventral drainage for inspissated material.
‣Avoids contamination of anaesthetic equipment with Strep Equi
‣Sedation and local - 30ml 2% mepivacaine along ventral aspect of the linguofacial vein which is marked with a pen beforehand
‣(Retro)pharyngeal swelling can facilitate sx access, if not distended can insert chambers catheter into the pouch; should be palpable in the medial compartment through the floor of the pouch, to guide dissection
Advantages of Whitehouse and modified Whitehouse approaches?
Dissection through natural fascial plane, no incision between sternohyoideus and omohyoideus muscles
*direct access to the roof of GP
*digital access to lateral compartment
*excellent ventral drainage
*simultaneous access through the septum to both guttural pouches.
Describe the Modified Garm technique
Allows access to the LATERAL compartment & can be done standing (reported in 4 experimental horses TVJ 2008- Munoz et al).
‣6cm skin incision made 4cm more rostral than the originally described Garm technique, between the ramus of the mandible and the mandibular LNs.
‣Blind digital dissection is continued to the rostroventral aspect of the lateral compartment where the mucosa can be penetrated without risk of damaging structures EXCEPT hypoglossal nerve & lingual vessels on route of dissection
What is the disadvantage of modified Garm tx?
Disadvantage: little can be achieved through this approach other than insertion of lavage tube
What are the risks of the surgery modified Garm?
- damage to a vessel wall
- necrosis à delayed rupture without warning
- nerve damage
What is the prognosis modified Garm
**Favorable **after median septum fenestration by any method.
Can be done in 2 steps if is bilateral.
Study foals tx by fenestration only 67% hadgood outcome(no recurrence) and in 71%treatedbyfenestration+ resectionofthemucosalflapcombineduRacing career is possible after? YES!
Gutural pouch empyema what is the cause?
irritant drugs
deep penetration of a periocular FB
fracture of the stylohyoid bone
deep congenital stenosis of pharyngeal orifice
GP tympany
pharyngeal perforation by nasogastric tube
most common affected by the disease? which pathogens?
++ young
S. equi sub equi
2) S. equi subesp zooepidemicus
3) Corynebacterium pseudotuberculosis
is the duration of the infection related to the nº of chondroids?
No
What are the clinical signs of GP emyema
intermitente bilat nasal discharge
swelling of parotid + lymph nodes
pain - extended head carriage
excessive respi noise
fever
difficulty breathing and swallowing
Neuropathy by compression
dysphagia,
RLN,
persistente soft palate displacement
How is the diagnosis performed for GP empyema?
- endoscopic exam purulent discharge in the pharyngeal orifice of the affected side,
- pharyngeal colapse
-Fluid and mass in the x-ray.
-Fluid aspirates or faline washings from GP for culture and sensivity-
For strangles -PCR and culture
What is the conservative tx for GP empyema?
daily irrigation with physiologic saline 7-10d via indwelling Foley
▸DO NOT USE hydrogen peroxide/povidone iodine
▸Acetylcysteine→ not really effective▸+/- topical ABx (Pennicillin 6 gr into gelatin or bovin mammary preps)
▸Systemic AB (TMPs, Penn, Ceftiofur for 21 days)/NSAID▸+/- tracheostomy in those with URT obstruction
‣CHRONIC: Chondroids unlikely to respond to lavage alone; surgical drainage may be preferable
‣ Can attempt removal by maceration or endoscopic grabbing forceps/basket. 44% success with these methods but can be slow/protracted & costly (Judy 1999)
Surgical approach to GP empyema?
1) Via open approaches - approach incisions should be left to heal by second intention (mentioned previously)
2) Laser assisted salpingopharyngostomy or enlargement of the ostium
Prognosis for GP empyema
Satisfactory, neurologic signs are rare
GP mycosis has predisposition?
NO AGE, BREED, SEX or GEOGRAPHIC predispostiion
What is the responsible agent?
Aspergillus fumigatus is the most common to be isolate
Clinical signs of GP mycosis
moderate to severe epistaxis
fungal erosion of the ICA most cases and ECA and MA in 1/3 of cases + any branch of ECA such as caudalauricular artery;
Bilateral issue (but +++ one side)
**dysphagia **–> lesion of pharyngeal branches : vagus (X) (MOTOR function) + glossopharyngeal nerves (IX) –> leads to Aspiration pneumonia in severe or protracted cases
Signs are ptosis, miosis enophtalmos, patchy cervical sweating and congestion of nasalmucosa (CNM)
CNM if permanente = loss of performance due to partial airway obstruction
Anormal respi noise due to: pharyngeal paresis / laryngeal hemiplegia / RLN Horner syndrom
Horner syndrome in GP mycosis why?
Damage to the cranial cervical ganglion and postganglionic sympathetic fibers (usually temporary) causing
Ptosis
Equine sweat glands under alfa adrenergic input from receptor
enophthalmos
Diagnosis GP mycosis
endoscopy + history + clinical signs
Bilateral involvement in which % in GP mycosis?
19% always check both GP
Conservative tx of gutural pouch mycosis
Amphotericin B 0.38 to 1.47 mg/kg diluted in 1L of 5% dextrose has been given intravenously IV for up 40 days to treat phycomycosys
Itraconazole 5mg/kg PO every 24h
Combination of itraconazole and topical enilconazole (60mL of 33.3 mg/mL solution in daily flush)
itraconazole 3mg/kg twice a day in the feed is effective against Aspergillus but may require 4 months of tx
ketoconazole is efficient?
NO very poor efficacy
itraconazole and fluconazole have the same spectrum but who is more effective?
Itraconazole is more effective agains Aspergillus spp
What should the horse receive at reception in emergency?
Horses with blood loss should be treated with polyionic fluids and blood transfusions if necessary, and horses with dysphagia should be fed by nasogastric tube or by esophagostomy and should receive nonsteroidal anti-inflammatory drugs to reduce neuritis
what is the problem with amphotericin B?
nephrotoxicity!!
Figure 47-19. Diagram of major arteries close to and underlying the mucosa of the guttural pouch (numbers) and sites of balloon-catheter occlusion (letters). 1, Common carotid artery; 2, external carotid artery; 3, internal carotid artery; 4, occipital artery; 5, linguofacial trunk; 6, maxillary artery; 7, caudal auricular artery; 8, superficial temporal artery; 9, rostral auricular artery; 10, transverse facial artery; 11, external ophthalmic artery; 12, caudal alar foramen. A, Balloon inserted in the major palatine artery and guided in retrograde fashion to be inflated immediately caudal to the caudal alar foramen; B, balloon of catheter inserted into transverse facial artery (10) at arrow and directed into the external carotid artery, where it is inflated close to the floor of the guttural pouch; C, balloon in internal carotid artery at the sigmoid flexure, dorsal to the roof of the guttural pouch. This catheter is inserted into the internal carotid artery (3) at the arrow. A, B, C, and (arrow) on internal carotid artery are also the sites for obstruction with microcoils delivered through a catheter in the common carotid artery (1) in the upper third of the neck. (Redrawn from Caron JP, Fretz PB, Bailey JV, et al. Balloon-tipped catheter arterial occlusion for prevention of hemorrhage caused by guttural pouch mycosis: 13 cases. J Am Vet Assoc. 1987;191:345; and Smith KM, Barber SM. Guttural pouch hemorrhage associated with lesions of the maxillary artery in horses.
Surgical treatment of GP mycosis
Removal of diphtheritic membrane via modified Whitehouse approach → risk of hemorrage and nerve damage
**
*Artery occlusion: **effect of arterial occlusion n mycotic plaque progression are unknown
- Balloon catheter occlusion
- Detachable balloon catheter occlusion
**
- Transarterial Coil Embolisation (TACE)**
**
- Transarterial embolisation with Nitinol Plug**
GP mycosis - Procedures for arterial occlusion which vessel should be ligated?
Ideally occlusion of just vessel involved
If difficult assessment→ all vessels should be ligated
2/3 of cases involve Internal Carotid Artery (ICA) - External Carotid Artery (ECA) and Maxillary Artery (MA) in the reminder
In case of emergency and no other option you should ligated the ipsilateral ICA that will decrease the flow but NOT PRESSURE. Describe surgical technique
9 cm skin incision 2cm cranial and ventral to the wing of the atla so ICA located deep & caudal to the occipitomandibular part of the digastric muscle, the parotid & mandibular salivary glands, and the guttural pouch
ICA is identified on the cardiac side of the occipital artery and deep to it, & ICA is freed for 2-3 cm
In some horses, both ICA and OA arise as a single trunk and can be ligated simultaneously without risk
ICA BP remains similar to pre-op for 3-4d PO
Ballon (nondetachable ballon) cathether occlusion of ICA
Modified hyovertebrotomy (more ventral) 9 cm skin incision ventral to wing of atlas
ICA ID and ligated proximally and distally close to the origin of the artery
Arteriotomy distal to proximal ligature
6 French venous thrombectomy catheter is inserted for 13 cm (fixed at sigmoid flexure of ICA)
endoscopy can help but is not required
Balloon inflate (saline) and secure in position
back to work once PCV normal
Balloon left in place + kt is secured in the artery by tightening the preplaced ligature around it this portion of the kt is buried in the incision
*NSADs + Abs
Allow at least 7 days for a sufficient thrombus to form before removal
If catheter removed can be identified with US and done under standing sedation.
Really difficult to retract
Fig. 13. (A) Insertion of a balloon catheter into the left ICA so the balloon is inflated
between the first and second flexures of the sigmoid bend in the artery and distal to the
lesion (black with white highlights). Insert shows method of making an arteriotomy with
a number 11 scalpel blade, inserting the blade halfway across the width of the artery
between a ligature tied proximally and a preplaced ligature distally and cutting upward
(arrow) to produce an opening sufficient to accommodate the catheter. (B) Balloon catheter
secured in the artery by tightening the preplaced ligature around it and then tying the long
ends to the folded redundant portion of the catheter. This portion of the catheter is then
buried in the incision.
Name the surgical approaches for GP
Fig. 11. Surgical approaches to the guttural pouch. 1, hyovertebrotomy; 2, Viborg triangle;
3, modified Whitehouse; 4, Whitehouse. Shading is the guttural pouch.
Baloon Catheter occlusion requires angiography?
No and that is why any deviations from normal anatomy are not identified (disadvantage)
Complications of the balloon non detechable catheter occlusion of ICA
Balloon penetrates defect in artery
*Infection→remove catheter and drain
- Meningitis!! →prevented by inflating balloon at least to 8 mm diameter (prevents displacement into infected segment)
*Delayed prolapsed through hole
*Caused by reduce pressure proximal and normal pressure distal prevented by use of rigid catheter
*Failure to prevent haemorrhage → if aberrant branch present
*To prevent expose at least 6 cm of artery and assess if branches present
*Most important is aberrant branch that leads to caudal cerebellar artery → necrosis of brain stem. So if balloon goes more than 13 cm it is probably an aberrant branch.
*Difficult distinction between occipital and ICA→ ICA usually deeper.
Advantages of the ballon non detechable catheter occlusion of ICA
Disadvantage?
Immediate IV occlusion with prevention of retrograde flow from the circle of Willis
*Equipment cheap & readily available, & fluroscopic guidance not required
Disadvantage:
largely unsuitable in the presence of aberrant vascular anatomy
Surgical report Jennings 2019 EVE mentions surgical site infection after occlusion with this tx in 5 cases, how much time after?
10 years
It is possible that the catheter transverse the basisphenoid bone and penetrate the contralateral GP?
Yes described in the report
Hardy et al 2012 reveal a situation of death post removal of catheter due to
fatal meningitis
Ballon Occlusion of ECA and Branches is more challanging than ICA. What is the source of retrograde flow to ECA?
MPA (major palatine art) which is the large continuation of the MA (maxillary artery)
The MPA joins the contralateral MPA behind the upper row of incisior teeth to form a large arterial loop around upper jaw
Attempt occlude the MA by single ballon-tipped kt in the ECA FAILLED why?
kt tip can readily enter the SUPERFICIALTEMPORAL ARTERY rather than the MA
To prevent normograde flow the ECA is ligated after the linguofacial trunk branches and the occlusion of … name the artery
MA (maxillary artery) is performed via an arteriotomy of the MPA through the oral cavity
describe the technique Geton et al 2021 foir ICA occlusion
Local anesthesia was performed with 15 mL
of lidocaine along the incision site, ventral to the atlas
wing (Figure 1). An adhesive drape was used to prevent
potential contamination during the surgery, and staples
were added to improve fixation.
A 10-cm skin incision was performed slightly ventral
(1-2 cm) to the standard hyovertebrotomy. Surgical
approach and occlusion were performed as previously
reported under general anesthesia.4 The parotid fascia
was incised, and the parotid gland was retracted cranially.
Common carotid artery and bifurcation for ICA and
occipital artery were identified deep to these structures.
The ICA was dissected from other tissue, and a hook for cat ovariectomy was used to pull on the artery. At this
stage, the endoscope was switched on to confirm the
choice of the artery. Gentle tension on the artery induced
movement of the ICA in the guttural pouch. The
proximal ligature was performed before arteriotomy of
the ICA; a 6F Fogarty venous thrombectomy catheter
(Edwards Lifescience, Irvine California) was then
inserted, and the balloon was inflated under endoscopic
guidance.
describe the technique Geton et al 2021 foir ECA occlusion
For ECA occlusion, horses were clipped from the
proximal third of the neck to the middle of the head. A
halter without a cheekpiece was used, and the ear was
fixed in a caudal position (Figure 1). The same skin
antiseptic protocol was performed, and local anesthesia
was performed with 10 mL of lidocaine in a circle fashion
around the palpated pulse of the transverse facial
artery (Figure 1). An adhesive drape was placed on the
surgical site and secured with staples. Surgical approach
and occlusion were performed as previously reported
under general anesthesia.1 A 6-cm curved incision was
performed, and the transverse facial artery was found
immediately subcutaneously. The transverse facial
artery was dissected from other tissue. At this stage, the
endoscope light was switched on to confirm the choice
of the artery. Gentle tension on the artery was related
to movement of the ECA in the guttural pouch. The
transverse facial artery was ligated distally; then, the
arteriotomy was performed, a 6F or 4F Fogarty venous
thrombectomy (Edwards Lifescience) catheter was
inserted, and the balloon was inflated with 2 mL of
saline under endoscopic guidance at the level of the
stylohyoid bone.
describe the technique Geton et al 2021 foir MCA occlusion
For MA occlusion, horses were clipped around the
muzzle.
Locoregional anesthesia was performed with
maxillary nerve block (5 mL of lidocaine) and mental
nerve block (5 mL of lidocaine), and local anesthetic was
infiltrated at the incision site at the junction of the smooth mucosal surface with the undulating mucosa of
the palate,** 3 cm caudal to the corner incisor tooth**
(10 mL of lidocaine).
A drape was placed into the mouth
to isolate the surgical site from the tongue, and the lips
were kept open by an assistant (Figure 1).
No mouth gag
was used during the procedure.
Surgical approach and
occlusion were performed as previously reported under
general anesthesia.
A 5-cm incision was performed
along the junction of the smooth mucosal surface with
the undulating mucosa of the hard palate.
Blunt dissection was performed close to the bone surface until the
major palatine artery was exposed. A hook for cat ovariectomy
was used to pull the artery. Distal ligation and
arteriotomy of the major palatine artery were performed,
a** 4F Fogarty **venous thrombectomy catheter was
inserted, and the balloon was inflated under endoscopic
guidance.
Describe image
Venous trombectomy catheter tip
RIGHT smooth is for vein
LEFT is for artery
If the source of bleeding is possible to see on endoscopy of GP and it is maxillary artery (MA), what approach should you use?
The ECA is ligated after the** linguofacial trunk**
or
is occluded with a ballon inserted in** retrograde fashion** through the transverse arterial artery
With what to you ligate ECA after linguofacial trunk?
with venous thrombectomy catheter 6 French Fogarty
Can the ballon occlusion ECA cause blindness?
YEs although ligation of the major **palatineartery at its rostral end could prevent retrograde flow, **a combination of this procedure with ligation of the **ECA and ICA can cause ischemic optic neuropathy** and permanent blindness.
This can be attributed to the “steal phenomenon”
Define the “steal phenomen “
Circle of Willis A - MPA + MA + ECA B - internal carotid artery
The segment A that is occluded “steals” blood from the external opthalmic artery that creats a diversion of blood from from this artery in the direction of the arrow
What are the most aberrant vascular anatomy?
Mainly in association with IC and there are 4 types:
1) origin of ICA and OA from common trunk - most common 5%
2) aberrant branch of the** extra-cranial ICA** connecting with the basilar artery (4%)
c) branch ramifying into surrounding tissues
d) several smaller branches with connections to** ipsilateral OA**
**
Bifurcation or duplication of ICA** also reported
Failure to prevent fatal haemorrahage has been associated with what type of issue?
Aberrant ICA branches and lack of oclusion
Detachable balon cathethers with self sealing latex ballon has been described. What is the standard approach?
Standard approach (hyovertebrotomy) to ICA & 3cm segment close to origin is isolated between ligatures
Balloon delivery system = Tuohy-Borst adapter (rotating Y adapter), attached to 8Fr non-tapered thin walled guiding catheter
2Fr 135cm balloon carrier microcatheter placed through the adapter & guiding catheter
19g arterial access needle is inserted into the ICA between the ligatures, and a 0.9-mm guide wire is placed through the needle into the artery
Needle withdrawn & 8-French introducer advanced over the wire for 4 cm
The balloon delivery system is inserted through the flexible diaphragm of the introducer sheath & advanced 13 cm into the ICA or until resistance is met.
Carrier microcatheter advanced 5-10 mm within the guiding catheter while the guiding catheter is retractedBalloon inflated with 0.5 mL of radiopaque solution, & position confirmed with LM rad
Balloon detached by gentle traction on the microcatheter & all proximal ligatures are secured.
Catheters removed, should be no retrograde flow
Transarterial Coil Embolization (TACE) describe the procedure
8 cm skin incision between proximal & middle 1/3 of the neck just above jugular
Separate brachiocephalicus & omohyoideus bluntly
& elevate carotid sheath (CCA, vagosympathetic trunk, RLN) by finger dissection
Carotid sheath bluntly separated over 5-8 cm w Mosquitos
CCA elevated with Penrose & punctured with angiographic needle
6Fr introducer system inserted & position confirmed with angiography
6Fr single end hole nylon catheter (not PVC) is advanced rostrad into the CCA to the level of the ICA under fluoroscopic guidance
Angiography (injection of 3-5ml 1:2 iohexol and hep saline) essential during advancement to ID the path of each vessel
Cerebral (distal) ICA is embolised first
Typically use 5-8mm coils for distal ICA - select coil 20% larger than arterial diameter is very important
Coil should not be place in necrotic segment of vessel
Embolise cardiac side of ICA midway between the 1st embolisation site and origin of CCA 8-12 mm
Kt is withdrawn and procedure repeat for ECA/MA if necessary
For MA embolised distal to STA and proximal to infraorbital, buccal and inferior alveolar arteries Coils 8-12 mm
ECA performed on the proximal (cardiac) side of the origin of the caudal auricular artery and idstal to origin of linguofacial trunk coils 10-15mm
The CCA puncture site is closed with 5-0 silk in a cruciate pattern and muscle layers and skin
Figure 47-20. Lateral contrast fistulography of a horse with a draining tract in the throatlatch of approximately 1 year’s duration; the draining tract communicated with a balloon-tipped catheter placed 4 years previously.
Figure 47-24. Fluoroscopic image obtained during coil embolization showing location of the distal and proximal coils within the internal carotid artery (white arrows), the contrast material with complete occlusion of the artery (white arrowhead), and the angiography catheter within the internal carotid artery (black arrow).
Transarterial Nitinol Vascular occlusion plug embolization requires the use of what type of plug?
Nitinol vascular plug is a nickel-titanium wire mesh that expands into a dumbell configuration and both ends are marked with radiopaque platinum marker bands
What are the errors with coil positioning that can have disastrous neurological and vascular conseuquences?
Coil too small - can migrate, too large - will elongate rather than assuming coiled position
What are the advantages of TACE comparing to ballon catheter technique?
- superior technique comparing to ballon because it uses fluoroscopic guidance
- less invasive (all arteries accessed through a single incision in CCA)
- no need of removal of implant
- allows precise occlusion and not associated with blindeness for ECA occlusion
What are the disadvantages of TACE comparing to ballon catheter technique?
- Requires fluoroscopy
- radiation-shielding apparel and equipement
- inventory of coils and insertion catheters
TACE can be performed standing or GA, what is the advantages of standing?
- avoid GA and complicaitons specially in hor with hemorrhagic shock or anemia
- decreases total time for the procedure
- reduces the cost of the procedure
The meglumine ioxithalamate can cause adverse reaction, how to prevent?
Warm the material to body temperature and inject slowly
Does nitinol intravascular plug require fluoroscopic guidance?
yes
prognossi for nitinol intravascular plug
‣approx. 50% of those with haemorrhage die. Risk can be abolished/considerablyreduced with arterial occlusion.
‣ Neurologicsigns can persist long beyond disappearance of the mycotic lesion or can bepermanent. RLN is typically permanentbut resolution has been reported
‣Dysphagia may be permanent or improveover 6-18months
‣Hornerssyndrome & CN VII signs improve in 50% of affected horses
‣TACE - 93% success rate - 2/27 hadepistaxis after occlusion (Leville2001)
‣TACE - 31 horses; 84% survival & 71%RTF (Lepage et al. 2005), making this the preferred treatment17% fatal haemorrhagewith CCA ligation alone
Salpingopharyngeal fistula as treatment for guttural pouch mycosis was presented by Watkins in 2018 with NO ADDITIONAL surgical tx. Describe the technique
Mepivacaine local 60 mL with 5 mL of 10% phenylephrine through biopsy channel
‣980 nm Diode laser at 18W used in contact fashion used to cut through the mucosaof the dorsal pharyngeal recess directly into the GP pouch, creating stoma of 1.5 x 1.5cm
‣In cases, applied laser energy directly to fungal plaques in non-contactfashion
‣All had additional medical management: dex & Bute or flunixin in all (1 hadthroat spray instead of systemic dex), 4 had systemic itraconazole, 1 ofthese had topical miconazole, another not on systemic tx had topical voriconazole (ie 5 had some form of antifungal meds)
What is the concolusion of JUKIC at EVJ 2020 for salpingopharyngostomy altered O2 and CO2 levels within the GP but did it change temperature and humidity?
No
Rupture of the ventral straight muscles what are the 2 muscles affected and why?
Longus capitus + rectus capitus ventralis
Trauma falling backward
fx basiphenoid/ basioccipital junction
What are the physical signs of ruptured ventral straight muscles of the head? 1 GP or both are affected?
Epistaxis and BOTH are affected
What is the treatment for rupture of ventral striagh muscles??
Rest for 4-6 weeks to limit head and neck movement
AB for 2ary infection and prognosis is good without neurological signs
If severe neuro signs and subdural involvement euthanasiaRupture of the ventral straight muscles
Bilateral epistaxis after training was observedthe following day and persisted for 1 h before spontaneously resolving. The primary care veterinarian referred themare for further evaluation. What are the differential diagnosis?
Guttural pouch disease, paranasal sinus disease, nasal cavity disease, and lower airway disease—e.g., exercise-inducedpulmonary hemorrhage (EIPH)
Diagnosis
Severe THO of the left side
The temporohyoid joint is a cartilaginous joint that comprises which bones/cartilage?
temporal bone
tympanohyoid cartilage
stylohyoid bone
diagnosis be specific
Endoscopic examination of the RIGHT gutural pouch reveals the presenc of a suspected lesion located on the ROOF of the MEDIAL compartment obscuring the INTERNAL CAROTID ARTERY
THO age of onset and clinical signs (CS)
10.8 yold
‣head shaking, bitting issues, ear rubbing, abnormal headcarriage, facial hyperasthesia, compulsive circling to one side
‣Facial & vestibulocochlear nervesigns evident in many
‣neuro signs incl ataxia, head tilt (pollTOWARDS affected side), spontaneous nystagmus (slow phase TOWARD affected side)
Temporohyoid osteoarthropaty or middle ear - what is the etiology?
middle/inner ear infection of hematogenous origin (?) but also the crib biters are 8x more affected and QH over represented so degenerative cause could be also present
THO diagnosis
‣CS may be abolished w 2% lidocaineplaced in ear canals (Bras 2014)
‣GP ENDOSCOPY most reliable.‣May be bilateral (upto 22%)
‣CT superior to rads; will also detectsubclinical bilateral disease
‣Scintigraphy Brainstem auditory evoked responses BAER;
Medical treatment of THO
Medical - NSAIDs/ABs. Tympanocentesis is technically demanding but may guide AB tx (S. Aureus)
Prognosis is 35% accordingly to Espinosa EVJ 2017 so SX has better outcomes
Name the 2 surgical procedures and which is preferrable for THO
1) Ceratohyoidectomy
2) Partial stylohyoiectomy (PSHO)
CERATO because the other has risk of hypoglossar nerve damage and dysphagia
What are the complications of partial stylohyoidectomy to be replaced by ceratohyoidectomy?
In this surgery a portion of stylohyoid is removed but this can cause
laceration of lingual artery,
hypoglossal neuropathy,
transient dysphagia,
stylohyoid bone regrowth, p
permanent problems with prehension when performed bilaterally
Describe the surgical procedure of ceratohyoidectomy
10 cm incison in the skin medial to the linguofacial vein on the affected side (Fig 47-15) and centered to the basihyoid bone
2 cm from the midline where the incision cresses the basihyoid bone
Fibers of the sternohyoid muscle are separeted bluntly until the basihyoid bone is exposed
Rostral to the basihyoid bone the geniohyoid muscle is separated to expose the ceratohyoid bone and lateral to it the hypoglossal nerve (XII)
The ceratohyoid-basihoid synovial joint is ID and disarticulated with cartilage scissors
which structure do you have to pay attention during this intervention?
Hypoglossal nerve
Lingual branches of the mandibular
Glossopharyngeal nerves
In this surgery the ceratohyoid is freed from
1.Certohyoideus muscle
2.Hyoideus transversus muscle
3.Genioglossus muscles
Diagnosis case report Grant EVE 2019
shear mouth 2ary to THO osteoarthropathy
Prognosis of shear mouth arthropathy
89% improved with ceratohyoidectomy (Maher 2008)
‣87% improved 1yr post PSHO
‣Oliver 2015 - 80% RTF post ceratohyoidectomy, although mild facial nerve paralysis(21.4%) or head tilt (42.8%) persisted (not performance limiting).
Px for resolution ofataxia following ceratohyoidectomy was good
Describe the technique accordingly to Racine et al 2021
▸Skin incision: 10cm long from 2cm caudalto the basihyoid running rostrally, midway between midline & mandible
▸Bluntly separate **sternohyoid &omohyoid mm **to expose basihyoid& its articulation with ceratohyoid.
▸Separate** myelohyoid **from genioglossus rostrally
▸Care re** hypoglossal nn & lingual aa on lateral side of ceratohyoid; dissectionshould remain on its medialaspect
**
▸Transect articulation w basihyoid w Mayos ▸Ceratohyoid mm digitally **separated from caudal ceratohyoid, **then transect articulation with stylohyoid bone &remove
Close front & back of skin incision (USP 1 monofilament nylon);middle open to drain
Surgery by Racine et all 2021
Describe the tx of THO with basihyoid-ceratohyoid disarticulation accordingly to Hall 2019
Standing sx
**3-5 cm incision **after **25 mL of mepi centered along the basihyoid-ceratohyoid joint **medial to the linguofacial vein
Blunt dissection through** sternohyoideus musculature** and underlying basihoid
Rostrally geniohyoideus muscle was separated digitally from the ceratohyoid bone by digital manipulation to expose the **basihoyioi-ceratohyoid joint **that was transected with scissors.
Incision was left open to heal by second intention
No complications in all horses
Surgery by Hall AVAMA 2021 standing
Is the prevalence of temporal bone fractures high in horses with THO, accordingly to Tanner et al 2019?
Yes 41% of the horses with THO had temporal bone fracture
In the surgical tx of Racine et al 2019 the horses with nerve paralysis improved how much time after surgery
9 days to 6 months
Whitty et al 2021 VRU refers that the styloid proccess sheath CT sizes the age, BW and breed changes?
No association between SPS sizes and BW or breed
Significant association of SPS with height and age
Diagnosis
Rupture of the ventral straight muscles
Diagnosis
Rupture of the ventral straight muscles
