Guttural Pouches Flashcards
Which methods of arterial embolisation are available for tx of GPM (Freeman 2019 EVE CC)
- Simple ligation with detachable or non detachable balloon catheters
- Transendoscopic haemoclip application
- Trans-arterial coil embolisation (TACE)
- Nitinol plugs
TACE and nitinol plugs are best
Probably still justifiable to use nondetachable balloon catheters based on cost and availabiltiy - ie the Fogarty thrombectomy catheter- size 6French for most horses
Embolisation coils, the nitinol plugs and necessary catheter systems are expensive and the wide range of sizes needed to provide a satisfactory inventory could be an argument against their use
Advntages and disadvantages of the nondetachable balloon catheter in the tx of GPM
Adv: + relatively cheap/readily available vs TACE and nitinol plugs which are cost prohibitive in some settings given rareity of dz
+ close proximity of the arteriotomy to the site of infection with nondetachable methods, combined with stiffness of the catheter, allows it to be easily inserted through any thrombus or spasm that could occlude the segment distal to the lesion, vs detachable methods were a remote common carotid cutdown is used and can be difficult to manipulate to the site of desired occlusion
Disadv: - balloon catheter eliminates arteriography by direct insertion into the artery or arteries affected; however, such ‘blind’ insertion could lead to occlusion of the wrong vessel. It also eliminates the opportunity to perform a contrast study on the occluded artery because access to that artery is impeded by the presence of the balloon and catheter shaft. Although the lack of fluoroscopic guidance is a limitation, the actual prevalence of aberrant or unusual branches might be low enoughto make this risk acceptable if no other option is available.
- Potential for SSI (Jennings 2019 EVE)
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Describe the procedure for nondetachable balloon catheter insertion (Fogarty thrombectomy catheter) for tx of GPM for ligation of the ICA
NB venous thrombectomy catheter (6Fr) is preferable to arterial thrombectomy catheter as softer tip less likely to penetrate arterial wall defects at the site of infection, and also has metallic shaft identifiable radiographically
TBC
- Ideally secure the coiled section (approx 13cm) of the catheter with large guage nylon suture that then exits the skin remote from approach incision to guide later cut down for removal. Alternatively can secure redendant length externally but this does make it vulnerable to damage or premature removal
- Catheter should be removed standing 2-3 weeks after its insertion
Describe the procedure for nondetachable balloon catheter insertion (Fogarty thrombectomy catheter) for tx of GPM for ligation of the ECA
NB venous thrombectomy catheter (6Fr) is preferable to arterial thrombectomy catheter as softer tip less likely to penetrate arterial wall defects at the site of infection, and also has metallic shaft identifiable radiographically
TBC
Possible complications of sx tx of GPM by arterial ligation.
Name some specific to the use of balloon catheters
Potential complications of sx tx of GPM incl failure of arterial occlusion leading to fatal haemorrhage, blindness and neurological deficits
Complications specific to the use of balloon tipped catheters incl. failure of the balloon to remain inflated, catheter breakage, incisional infection and wound breakdown
Jennings et al 2019 EVE reported medium/long term (upto 10 years!) SSI infection assoc with catheters left in situ
SSI has been assoc with penetration of the site of arterial infection by the catheter tip
Label the endoscopic anatomy of the GP
A - medial compartment
B - lateral compartment
C - stylohyoid bone
D - temporohyoid articulation
E - ICA
F - ECA
G - Maxillary artery
H - superficial temporal artery (caudal auricular in some texts)
I - Maxillary vein
J - neurovascular fold containing CN IX, X (glossopharyngeal branch and recurrent laryngeal branch), XI, XII
K - CN IX (glossopharyngeal) runs toward stylohyoid
L - stylopharyngeus mm
M - digastricus mm (floor of lateral compartment)
N - median septum including rectus capitis ventralis and longus capitis
O - cranial cervical ganglion
P - CN VII and VIII in roof of lateral compartment
What is this condition and what are the normal radiographic boundaries of the affected structure?
Guttural pouch tympany
The GP doesn’t usually extend beyond the ventral border of the C1-C2 juntion ** check w JD
Describe the TACE prcedure for embolisation of ICA, ECA and MA
- 15cm skin incision at the junction of the proximal & middle 1/3 of the neck, dorsal to jugular
- Bluntly separate the brachiocephalicus and OH mms to isolate the carotid sheath which is elevated and opened & VS trunk separated from CCA and allowed to return to normal position
- CCA elevated w umbilical tape & angiographic needle introduced in distoproximal direction
- 6 Fr introducer placed in the CCA using a guidewire.
- 6 Fr single end-hole nylon angiographic catheter then advanced into the CCA under fluoroscopic guidance, using iohexol, rostrally into the ICA to the level of the basisphenoid.
- ID the sigmoid flexure of the rostral ICA and introduce 2x 5mm, Dacron fibre-covered, stainless steel occluding spring embolisation coils into the cath, inserted into ICA w a 0.038 guide wire
- Complete occlusion was verified using fluoroscopy following injection of contrast agent
- Catheter withdrawn to where ICA enters the GP (ID on fluro) & proximal ICA embolised similarly
- Catheter then retracted into CCA and redirected into maxilary aa, distal to the superficial temporal artery and proximal to the infraorbital, buccal and mandibular alveolar arteries. 2x 8 mm coils introduced into the maxillary artery.
- Catheter then withdrawn into the ECA on the cardiac side of the caudal auricular artery, and 2x 8 mm, 4x 10 mm and 2x 12 mm coils used to occlude this aa in the same way, verified w iohexol
- Cath removed and CCA closed using 4-0 silk suture with an inverted cruciate pattern.
- The brachiocephalicus and omohyoideus muscles are closed w 2-0 polyglactin 910 in simple continuous pattern, and the skin closed w staples
Whats the diagnosis?
List some of the potential clinical signs
List 3 possible treatment options
What is the likely px?
a) THO
b) CSs incl. ear rubbing, bit avoidance, difficulty chewing, head shaking and nonspecific behavioural problems during ridden exercise. Acute clinical manifestations can be associated with the use of full mouth speculae, forceful tongue manipulation during dentistry or during nasogastric intubation
Acute SH or petrous temporal bone fracture following ankylosis of the TH articulation can present with acute vestibular signs and facial paralysis.
c) Tx incl medical (NSAIDs, analgesia, ABs for ossible otitis or 2ary infections) or surgical (PSHO or CHO - the latter less complications). rationale for performing such surgeries are that they eliminate the forces exerted by normal tongue and laryngeal movements on the ankylosed THJ thereby decreasing pain, reducing nerve irritation and reducing morbidity.
d) Px better if tx performed at an early stage in the dz process, prior to neurological deficits becoming apparent. Sx tx more favourable outcome than medical - medical 65% death rate, MST 24 mo, PSHO 25% death rate and CHO 4% death rate
Good rate of return to exercise in CHO group - 65% - vs 50% PSHO and 12.5% medical
Briefly describe the steps in ceratohyoidectomy
What key anatomical landmarks need to be preserved during this procedure?
- Approx 10cm paramedian skin incision centred on the basihyoid bone approx 2cm off midline to the affected side, medial to the linguofacial vein
- Blunt separation of the sternothyroid mm to expose basihyoid rostral to geniohyoid which is then separated to expose the ceratohyoid
- Care to ID and protect the hypoglossal nn lateral to the ceratohyoid bone
- The ceratohyoid-basiohyoid articulation identified and complete arthrotomy through the joint made with scissors to disarticulate the 2 bones
- Grasp the ceratohyoid and detach soft tissues w periosteal elevator (includes ceratohyoideus, genioglossus and transverse hyoideus muscles)
- Once mobilised, articulation w stylohyoid cut w scissors
- Closure of muscle w 3metric PG910, then SQ and skin w staples
