External Ear Canal Flashcards
(92 cards)
1
Q
Where does the vertical ear canal begin?
A
the external acoustic opening at the level of the tragus, antitragus and anthelix.
2
Q
t the base of the auricular cartilage of the horizontal canal sits the ?
A
annular cartilage,
3
Q
What does the annular cartilage connect?
A
horizontal canal to the external auditory meatus of the temporal bone.
4
Q
What is the ear canal lined with?
A
stratified squamous epithelium
5
Q
What glands are present in the ear canal? (2)
A
Sebaceous glands and ceruminous glands
6
Q
What nerve supplies the external ear canal
A
Facial
7
Q
Facial nexits the skull through the internal acoustic meatus alongside the
? nerve, travels in the facial canal of the petrous temporal bone, through the middle ear and out of the stylomastoid foramen, caudodorsal to the external osseous ear canal.
A
Vestibulocochlear
8
Q
Sensory innervation to the external ear canal is supplied by auricular branches of the ? nerve.
A
Vagus
9
Q
The vascular supply to the external ear canal is from the
A
great auricular artery
10
Q
What is the great auricular artery a branch of?
A
External carotid
11
Q
What vein is immediately rostral to the osseous ear canal?
A
retroglenoid
12
Q
The clinical signs of otitis externa/media are:
A
Head shaking
Ear scratching
Odour
Otorrhoea
Swelling
Pain
Depression
Aural haematoma.
13
Q
Define Primary factors causing otitis
A
hose actually causing external ear dx
14
Q
Define predisposing factors of otitis?
A
Increase the risk for development of dx, but are not actually responsible for it in their own right
15
Q
Define perpetuating factors with otitis?
A
Allow the dx to continue and must be addressed to allow resolution
16
Q
Primary causes of otitis (5)
A
Otodectes Cynotis
Grass seed/FB
Food allergy
Keratinisation disorders- Hypothyroidism, hyperadrenocorticism, sex hormone disorders
Autoimmune disease- pemphigus, discoid lupus erythematosus, vasculitis
17
Q
Predisposing causes of otitis (6)
A
Anatomy
Breed
Excessive wax production
Inappropriate antibiosis
Chronic ear moisture e.g. swim
Ear canal polyp/tumour (obstructs clearance)
18
Q
Perpetuating causes with otitis (3)
A
Bacterial over-colonisation
Secondary yeast infection
Otitis media
19
Q
How do endrocrine dx lead to otitis? (2)
A
leads to ceruminous and seborrhoeic otitis externa
20
Q
Cocker spaniels; what predisposes them to otitis (2)
A
Pendulous ears
Excessive cerumen
21
Q
Shar pei; what predisposes them to otitis
A
Narrow ear canals
22
Q
What treatment of polyps has a common recurrence?
A
traction with follow-up corticosteroid treatment,
23
Q
Surgical options for polyps?
A
ventral bulla osteotomy or total ear canal ablation-lateral bulla osteotomy (TECA-LBO)
24
Q
Neoplasia of the external ear canal in dogs is usually of what cell origin
A
epithelial
25
Neoplasia In cats, almost all are what cell tumours and almost B% are malignant?
A) epithelial
B) 90 %
26
What are the reported neoplasia of dog ear; which is most common (3)
1. carcinomas (ceruminous, squamous cell and anaplastic)
- Soft tissue sarcoma, melanoma
27
Is bilateral neoplastic dx more common in cats or dogs?
Cats
28
Benign tumours of the ear canal in cats and dogs are more commonly pedunculated lesions and include (5)
papilloma,
ceruminous adenoma,
sebaceous adenoma,
basal cell carcinoma
histiocytoma
29
Trauma to the ear can lead to rupture of the junction between?
auricular and annular cartilage
30
Failing to treat rupture of the auricular and annular cartilage junction, allows what to form? What can develop which blocks vertical canal?
Form - pseudotympanic membrane
Leading to - external auditory canal atresia to develop which can potentially block the vertical canal.
31
How do animals with auditory canal atresia present?
swelling, discharge, head tilt and pai
32
Treatment of auditory canal atresia in early stages?
Cartilage apposition
33
Treatment of auditory canal atresia in late stages? (2)
horizontal canal may be debrided and sutured directly to the skin leaving the vertical canal in situ if it is causing no problems.
TECA-LBO may be necessary.
34
Congenital external auditory canal atresia is reported . What are the 3 possibilties?
failure of the external ear canal to open at the skin,
development of a non-patent vertical ear canal
atresia at the level of the annular-auditory cartilage
35
Congenital external auditory canal atresia. Treatment options? (2)
Surgical opening of the horizontal canal and direct suture apposition to the skin may be attempted,
TECA-LBO
36
What is an Infection outside the ear canal termed?
Para-aural Abscess
37
What may a Para-aural Abscess be a result of? (5)
trauma,
neoplasia,
cat bites,
foreign bodies
extensive otitis externa.
38
Most common cause of a paraaural abscess?
incomplete debridement of the secretory epithelial lining of the tympanic bulla during TECA-LBO procedure
39
What clinical signs with a para aural abscess? (4)
- Facial swelling
- Pain
- Head tilt
- Facial neurapraxia
40
Osteomyelitis of the bulla may cause what sign?
may affect the temporo-mandibular joint, causing pain on opening the mouth.
41
Otitis; what investigations? (4)
- Otoscope
- Cytology
-FNA/impressionsmear/biopsy (mass)
- Imaging e.g. CT
42
An intact tympanic membrane is present in 72% cases with confirmed otitis media so What should be performed if this is suspected.
myringotomy
43
Where should ear cytology be taken from?
Deeper parts of horixontal canal
44
Most common bacteria on C+S of otitis?
Staphylococcus (pseud)intermedius
45
Why C+S both ears with otiits.
Results often differ between left and right ears (68% cases in one study had different culture results between the two ears).
46
Why is contrast CT beneficial for ear disease?
Distinguish between mass and abscess – abscesses have a central hypoattenuating region with ring enhancement. Tumours don’t have ring enhancement and only the largest ones have a central area of necrosis.
47
Tumours of the ear:
A) Common effect on bulla?
B) What soft tissue is present?
A) Lysisi
B) Swelling
48
On contrast CT what don’t uptake contrast but may have ring enhancement.
Cholesteatomas
49
Cholesteatomas;
What accompanies on CT? (5)
Severe bony change within the bulla, including: osteolysis, proliferation and osteosclerosis.
Expansion of bulla
Sclerosis of the ipsilateral temporomandibular joint and paracondylar process
50
Medical treatment of external ear disease includes: (4)
Ear cleaners
Local and systemic antibiotics (based on results of culture and sensitivity)
Corticosteroids if significant inflammation is present
Management of primary disorders, e.g., parasite control, removal of foreign bodies, treatment of skin allergies.
51
What surgery may be used as an adjunctive method of treatment?
lateral wall resection
52
What surgery is used for chronic, end-stage external ear disease?
Total ear canal ablation
53
Where to clip fur for TECA-LBO and VCA?
The head should be clipped from dorsal midline to the ipsilateral hemimandible and from the lateral canthus of the eye to the auditory canal and the same distance agai
54
Surgery of ear; what should be used for the more inflamed ear canal and medial pinna skin prep?
dilute povidone-iodine
55
How to tie limbs for ear surgery?
FLs tied caudally
56
Benefits for LWR? (3)
Improved ventilation
Reduced moisture, humidity and temperature
Improved access for topical medications.
57
Indications for LWR? (3)
Congenital canal stenosis
Small tumours of the tragus region or lateral wall of vertical canal
Reversible changes associated with otitis externa that would benefit from improving the local environment.
58
Where are skin incisions made for LWR?
Parallel skin incisions are made along the cranial and caudal borders of the vertical ear canal from the tragus to just ventral to the junction between the vertical and horizontal ear canals.
59
LWR:
Skin is removed and subcutaneous tissue over vertical canal is retracted exposing the cartilage.
What is evident at this point? How should it be managed?
The dorsal aspect of the parotid salivary gland may be evident at this point – this can be retracted ventrally.
60
LWR:
What is used to dissect down the cranial and caudal borders of the ear canal incising the cartilage to the level of the horizontal canal.
Straight Mayo scissor
61
LWR
At what point should the lateral flap of cartilage should be free and easily reflected ventrally.
At the point where the annular and auricular cartilage meet
62
LWR:
How much of the the cartilage is remved, what is the remaining used as?
The dorsal 2/3 of the cartilage is removed, leaving 1/3 to act as a “draining board” ventral to the new external ear canal opening.
63
LWR:
How to Suture?
The epithelium of the remaining vertical canal is sutured to the skin across the cut edge of cartilage using an interrupted suture pattern in monofilament non-absorbable suture material.
64
The failure rate of lateral wall resection as a treatment for otitis externa?
High
65
When is vertical canal ablation indicatied physiologically?
It is indicated if the vertical canal is diseased, but the horizontal canal remains unaffected
66
Possible indications for a Vertical Canal Ablation? (3)
Severe trauma
Neoplasia of the vertical canal
Hyperplastic otitis
67
VCA:
Where is the incsion?
Incise from the tragus to the level of the horizontal canal over the lateral aspect of the vertical canal, in a T-shaped incision.
68
VCA:
How and what is dissected?
issect around the vertical canal using scissors, staying as close to the cartilage as possible to free the vertical canal from all its attachments.
69
VCA:
Reflect the vertical canal laterally and what is ampuatted?
amputate the ventral end at the level of the skin.
70
VCA:
What "draining boards are made to suture to the skin?
Make dorsal and ventral
71
What type of procedure is a TECA?
Salvage
72
Indications for performing TECA include (4)
Ceruminous gland adenocarcinoma
Extensive benign disease – otitis externa and “end-stage ear”
Failed LWR or vertical canal resections
Involvement and extension of disease into the middle ear.
73
TECA
What incisions are made?
Make a T-shaped incision laterally over the vertical canal from the tragus to the level of the horizontal canal.
Dorsally, the incision is extended circumferentially around the external ear opening, allowing removal of all the proliferative tissue.
74
Where does the facial nerve sit with a TECA?
The facial nerve sits just caudoventral at the terminal end of the horizontal ear canal where it enters the bulla
75
T or F:
Retract the facial nerve; but do so with care.
False - don’t try to retract the nerve
76
TECA:
The vertical and horizontal ear canals are dissected free from the surrounding soft tissues. Staying just below the?
perichondrium
77
TECA:
The ear canal is amputated, from:
A) What?
B) Where?
C) Using what? (2)
A) Bulla
B) External auditory meatus
C) Mayo scissors or a blade
78
TECA:
The opening into the tympanic bulla is cleared by dissecting thickened and hyperplastic epithelium from the opening.
Whilst clearing soft tissues from around the opening into the bulla care must be taken to avoid A) What (rostrally) and B) (2) (ventrally).
A) the retroglenoid vein
B) the carotid artery and maxillary vein
79
TECA:
If required, a small osteotomy is made into the bulla to allow (2)
curettage of the internal surface
removal of the bulla epithelial lining.
80
TECA:
Most of the epithelium is located on the bulla floor – care is taken when curetting dorsally to avoid damage to (2)
the round window
ossicles.
81
How to close a TECA?
incision is closed in a T-shape using monofilament absorbable suture material in the muscle and subcutaneous tissues.
82
When is a drain needed for a TECA?
Abscessation
83
Assess what on recovery?
Facial n function (although may have inflammatory neuropraxia)
84
Complications secondary to surgeries of the external ear canal include (6)
nerve damage,
vestibular syndrome,
haemorrhage,
wound dehiscence,
para-aural abscessation
changes in the auditory function
85
What may develop following damage to postganglionic sympathetic fibres running through the middle ear, usually due to excessively vigorous debridement of the middle ear during surgery
Horners
86
Is horners more common in dogs or cats?
Cats
87
A head tilt may develop following TECA-LBO if the what of the inner ear are traumatised during debridement.
ossicles
88
What vein damage can cause life threatening haemorrhage?
retroglenoid vein
89
What is the problem of ligating a retroglenoid vein in surgery?
retracts back into the retroglenoid foramen of the skull making isolation of the vessel impossible
90
How to control retroglenoid vein bleed?
Bone wax - pack foramen
91
Wound dehiscence is common in which ear sx?
LWR
92
What casues para aural abscess after TECA?
The development of para-aural abscesses and chronic fistula formation following TECA-LBO is usually down to poor technique when debriding the bulla, leaving remnant epithelium inside that continues to secrete in the presence of residual debris from the external ear or middle ear.
