Orbital disease Flashcards
(101 cards)
1
Q
How to differentiate extra- vs intraconal tumors?
A
Intrazonal tumor = eye moves anteriorly
Extraconal tumor = moves laterally away from direction of tumor
2
Q
What cranial nerves run intraconally?
A
CN II-VI
3
Q
Third eyelid protrusion: occurs with exophthalmos or enophthalmos?
A
BOTH– passive protrusion with enophthalmos, forced protrusion with exophthalmos
4
Q
How much of the canine orbit is boney? Where is there not bone?
A
4/5ths
Laterally
5
Q
What is the tissue that crosses the non-boney orbit in a dog?
A
Orbital ligament
6
Q
What breeds have naturally less retropulsion available to them?
A
Brachycephalics
7
Q
If a mass is suspected in the retrobulbar/orbital space, what FOUR additional PE tests should you do beyond retropulsion?
A
- Percussion of paranasal sinuses
- Airflow from nares
- Oral exam
- Opening of the mouth
8
Q
On oral exam, where can you sometimes visualize orbital disease?
A
Behind the last upper molar
9
Q
When might you see chemosis with orbital disease?
A
Any inflammatory disease (abscess, cellulitis)
10
Q
When is elevated IOP secondary to a mass more of a concern?
A
Usually large masses don’t cause incr IOP, but if dog has a naturally SHORT PALPEBRAL FISSUE, it can sometimes trap the globe
11
Q
How can you tell if a mass is attached to the globe or not?
A
Look for indentation of fundus on exam or US– if it doesn’t change with movement of the eye, it is attached
12
Q
Pulsating or intermittent exophthalmos, what two particular differentials should be on DDx?
A
arteriovenous fistula or varix
13
Q
To look at orbital disease, what are the 4 locations you can place the ultrasound?
A
- Cornea
- Transpalpebral
- Caudal to orbital ligament (temporal approach)
- Oral mucosa behind last molar (oral approach)
14
Q
Of the 3 structures seen in the orbit–fat, muscle, optic nerve–which is most HYPERechoic?
A
Fat
15
Q
Cavitary lesion on ultrasound: 3 DDx
A
- Abscess
- Cyst
- Neoplasia
16
Q
What neoplasia has been found to produce cavitary lesions in dogs?
A
orbital myxosarcoma
17
Q
What 3 things on ultrasound are more commonly found with neoplasm over inflammatory lesions?
A
- Bone loss
- Sharp delineation of border of mass
- Indentation of globe
18
Q
When is CT preferable over MRI for orbital disease? (3 things)
A
Trauma, osseous changes, and looking for foreign bodies
19
Q
When is MRI preferable over CT for orbital disease?
A
Soft tissue extension of a disease process, especially anything that may go intracranially
20
Q
Do abscesses and cysts show up better on MRI or CT?
A
MRI
But you can never definitively say what something is based on imaging!!
21
Q
Although bone lysis is usually associated with neoplasm, what other thing must you have on your DDx?
A
fungal granuloma
22
Q
What is the success rate (definitive Dx) of a FNA vs biopsy?
A
50% FNA, 75%+ biopsy
23
Q
What tumor type is less likely to give a definitive diagnosis with a FNA?
A
mesenchymal tumors
24
Q
What is the difference between cystic eye and microphthalmia?
A
Cystic eye: development arrested in optic vesicle stage
Micro: small globe with abnormalities to various other structures
25
How can you diagnose microphthalmia from anopthalmia?
Ultrasound to look for any evidence of eye tissue
26
What are 2 causes of orbital varies and AV fistulas?
Congenital
| Trauma
27
What is one manipulation you can do to help diagnose an orbital varix or AV fistula?
Hold off jugular veins, or lower head... exophthalmos worsens
28
What is one way to differentiate an orbital varix from an AV fistula?
Listen for a systolic murmur ("bruit") over the orbital region
29
6 big DDx categories for exophthalmos?
1. Neoplasia
2. Inflammatory (abscess, cellulitis, granuloma)
3. Trauma (hematoma, orbital fracture, emphysema)
4. Vascular (varix, AV fistula)
5. Cyst
6. Craniomandibular osteopathy
30
What species is most likely to get orbital inflammatory disorders?
Dog
31
What PE (non-ocular) and blood work findings are more common with dogs with inflammatory disease?
1. Fever
| 2. Neutrophilia
32
4 causes of orbital inflammation? (methods to get inflammation there, not causative agents)
1. Foreign body
2. Hematogenous
3. Panophthalmitis or scleritis, if significant
4. Infections of the zygomatic salivary gland
33
What worm can cause inflammatory disease (usually in the southwest US, and south central Europe?)
Onchocerca
34
Orbital cellulitis on imaging (US, CT, MR) usually shows what?
Loss of definition of orbital structures and diffuse, poorly-defined mass
35
Where is an orbital abscess usually drained (incision site)?
Behind the last upper molar tooth
36
When draining an abscess, after the initial stab incision, what do you want to use and why?
Hemostats, inserting into incision then opening and withdrawing, to avoid damaging the vasculature and nerves in the area
37
Although rare, what nerves can be damaged by opening an abscess with hemostats?
Optic and ciliary nerves
38
After opening an abscess, what additional treatments are performed? (4 things, including one very important one for the eye)
1. Hot packing
2. Broad-spectrum ABx (like Clavamox)
3. NSAIDs
4. LUBRICATION OF EYE until exophthalmos has resolved
39
After opening an abscess, how long does it usually take to heal? How long does it take for exophthalmos to resolve?
Heals within a week in most cases
| Exophthalmos resolves within 36-48 hours
40
What causes most mucoceles?
Head trauma (+/- skull fractures)
41
Why is a mucocele not considered a true cystic lesion?
Because when it leaks out, it causes lots of inflammation and fibrosis, causing thick fibrous capsule but no true epithelial lining
42
How do salivary retention cysts form? How is a salivary retention cyst different from a mucocele?
A salivary retention cyst is caused by obstruction of the outflow and subsequent cyst formation from ORAL MUCOSAL DISEASE
1. so they are TRUE CYSTS with epithelium lining them
2. and they usually have MINIMAL tissue reaction around them
43
What does the aspirate look like for a mucocele vs a true cyst?
Mucocele: yellow with variable blood
Cyst: clear to mucoid
44
What is the treatment for a mucocele?
Surgical excision
45
What is the treatment of a salivary retention cyst?
1. Treat oral mucosal disease
| 2. Drain orally like you would an abscess
46
Masticatory myositis primary affects what 2 breeds (HINT: Goldens get it but they are not the primary breed)
German shepherd
| Weimaraner
47
What muscles are affected by MMM?
Masseter
Pterygoid
Temporalis
(TPM)
48
Why are there particular muscles affected by the immune response in MMM?
They contain type 2M myofibers
49
Other than exophthalmos, what other ocular sign is rarely seen?
Optic neuritis and blindness
50
How do you test for MMM?
M antibody test (positive in acute phase)
51
What breed(s) are more commonly affected by extraocular polymyositis?
Golden retriever
52
How does extra ocular polymyositis appear?
Bilateral exophthalmos with upper lid retracted WITHOUT third eyelid displacement, congestion of episcleral vessels
53
How does histopath differ between MMM and extra ocular polymyositis?
MMM: eosinophilic and neutrophilic infiltrate
EPM: CD3+ lymphocytic infiltrate
54
What other ocular signs (other than original exophthalmos) is seen with ocular polymyositis?
Esotropia with restrictive nasoventral strabismus; enophthalmos (due to fibrosis?)
55
How do you treat myositides?
Steroids 3-4 wks and azathioprine 10-14 days
56
What is the prognosis for myositides?
Guarded; and although reoccurrence is rare, it can happen
57
What can be done for the enopthalmos that occurs with myositides? What is problem with this treatment?
Silicone or glass beads implanted into the orbit, but they often migrate
58
Other than immune-mediated causes for myositis, what also needs to be ruled out as a cause?
Infectious: Lyme, Neospora, Toxo, Leishmania
59
What is the most common reason for orbital disease in the dog?
Neoplasia
60
Is orbital neoplasia usually painful?
No (although if osteolysis there certainly can be)
61
How often is orbital neoplasia bilateral?
Very rare
62
What two locations of orbital tumors usually result in blindness early in the course of the disease?
1. Optic nerve
| 2. Meninges
63
What are the most orbital common tumors (and their tissue type)? [7] Which of these are malignant?
Mesenchymal origin (#1)
1. Fibrosarcoma
2. Osteosarcoma
3. Osteochondrosarcoma
```
Epithelial origin (#2)
4. Adenocarcinoma
```
Other
5. Mastocytoma
6. Peripheral nerve sheath tumor
7. Orbital meningioma
ALL are malignant!
64
If orbital lymphoma is suspected, what test should be performed on the FNA?
PARR
65
What particular sign is a poor prognostic indicator (survival time) for orbital neoplasia?
Osteolysis
66
If you can't preserve the globe due to neoplasia, what treatment options are there?
Exenteration, or radical orbitectomy, followed by chemo or radiation OR radiation alone (without surgery)
67
How are nasosinal tumors graded? What is the grade of a tumor that invades the orbit?
Scale of 1-4
| Orbit: grade 3, minimum
68
What is the survival time of a nasosinal tumor that invaded the orbit after irradiation?
315 days
69
Wha are the main side effects of radiation near the eye? (4) How can they be avoided?
Cataracts, KCS, retinal degeneration, blindness
| Avoid by limiting the exposure (such as by linear accelerator?)
70
Painless nictitating and eyelid swelling in dogs-- what tumor needs to be ruled out?
lobular orbital adenoma
71
Lobular orbital adenoma: what is the risk of metastasis? Risk of recurrence post-surgery?
Metastasis: never been reported
Recurrence: high unless exenteration is performed
72
Average survival of orbital neoplasia in general for dogs? Cats? How does treatment affect this?
Dog: 13 months
Cat: 1 month
Most dogs that don't have treatment die or are euthanized at time of diagnosis or within 6 months
73
In severe cases of trauma resulting in scleral rupture, where does this most commonly occur (on the eye)?
Lamina cribrosa
74
What should be applied topically after trauma to the eye? What should not be applied and why>
```
Apply steroids (if epithelium intact)
DONE apply NSAIDs = incr risk of hemorrhage
```
75
When do fractures of the orbit need surgery?
Most small displaced fragments will stabilize on their own, unless they are bothering something; large displaced fractures may need surgical fixation
76
If a patient has strabismus post-trauma, what do you need to check and why?
Do a forced duction test, as an extra ocular muscle may be trapped by a bone fragment, and without treatment may be permanent
77
What systemic problem can be seen with orbital fractures?
oculocardiac reflex
78
What is seen with the oculocardiac reflex? (2 things)
1. Bradycardia
| 2. AV block
79
When is orbital emphysema most commonly seen? How?
After enucleation
| Air is pushed into the socket via the NL duct
80
What breed(s) are most commonly affected by orbital emphysema?
Brachycephalics are predisposed
81
What is the treatment for orbital emphysema?
Usually benign neglect and it resolves on its own; if it doesn't resolve, need to go tie off the NL duct
82
How do you differentiate proptosis from exophthalmos?
Eyelids-- either in front of or behind the equator
83
Which muscle is the first to be avulsed in a proptosed globe?
Medial rectus
84
Why is prognosis worse if two rectus muscles are avulsed with proptosis?
The vascular supply and innervation to the anterior segment are seriously compromised
85
What is the prognosis if there is intraocular hemorrhage?
Guarded, although can replace and see how it does
86
What is a major long term complication that can be seen with proposed eyes?
KCS and neurogenic keratitis due to desensitization (requires life-long treatment)
87
Does pupil size affect prognosis post-proptosis?
NO, although PLR is associated with better prognosis
88
Why is a temporary tarsorraphy always recommended after replacing a proptosis?
There is significant hemorrhage and soft tissue swelling
89
Where should you leave the tarsorrhapy open?
Medial canthus
90
What should be performed immediately after performing the tarsorrhapy ?
Cold pack the eye
91
When and how should the 2-3 sutures be removed from a tarsorrhapy?
Starting at at least 1 week, can take one out from medial side; moving laterally at subsequent visits
92
What is a possible long-term side effect of rupture of the medial rectus?
Exotropia
93
Why is the medial rectus the first to rupture?
It is the shortest
94
In most cases, how long does it take for globe position to become normal?
several months
95
What additional surgery should be discussed in cases of proptosis?
Medial or lateral canthoplasty (to shorten palpebral fissure)
96
How common is orbital fat prolapse in dogs?
Very rare
97
How does orbital fat prolapse appear?
Easily movable, non progressive subconjunctival swelling, without evidence of inflammation, sometimes with exophthalmos and elevated third eyelid
98
How is orbital fat prolapse diagnosed?
FNA
99
If fat prolapse is going to be treated, what should be done and avoided?
Avoid taking too much-- will result in exophthalmos
| Suture conj to episcleral tissue
100
How common is it to have ocular signs with craniomandibular osteopathy? What are they?
RARE-- usually just exophthalmos
101
What is the signalment for craniomandibular osteopathy? And clinical signs?
Scottie or Westie, 3-6 months old, unable to open mouth = hyper salivating, unable to eat; enlarged submandibular lnn, mild fever
