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Tobias ECVS Exam Prep > Ch 122 - Pinna and external ear > Flashcards

Ch 122 - Pinna and external ear Flashcards

1
Q

What is the scutiform cartilage?

A

A cartilaginous structure sitting within the rostroauricular muscles medial to the ear. Was orignially part of the cranial helix spine, becoming detached at the time of birth

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2
Q

What is the annular cartilage?

A

Connects the horizontal canal to the osseous external auditory meatus. Attached to both the auricular cartilage and the temporal bone by fibrous connective tissue

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3
Q

What is cerumen?

A

Secretions of the deeper tubular ceruminous glands, more superficial sebaceous glands mixed with desquamated epithelium

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4
Q

What nerves supply sensory and motor function to the external ear canal?

A
  • Sensory: CN X vagus
  • Motor: CN VII facial
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5
Q

What important vessels surround the bulla?

A
  • Rostral: retroglenoid vein
  • Ventral: External carotid artery and maxillary vein
  • Meidal: internal carotid artery
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6
Q

List DDx for neoplasia of the pinna

A
  • Actinic keratosis (UVB - transform into SCC)
  • SCC
  • Haemangioma and HSA (UVB) - regrowth within 9.5m
  • Basal cell tumours - Siamese, Himalayan, Persians predisposed (UVB). Surgical margin few mms
  • MCT - Siamese overrepresented
  • Histiocytoma - resolve spontaneously
  • Sebaceous Adenoma - Sx or laser excison curative
  • Sebaceous adenocarcinoma - more aggressive
  • STS, FSA, rhabdomyoma, melanoma
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7
Q

List Tx options of pinna SCC

A
  • Partial pinnectomy
  • Complete pinnectomy
  • Complete pinnectomy with vertical canal ablation
  • Cryosurgery
  • Laser ablation
  • Radiation therapy
  • Chemotherapy
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8
Q

How do pinna MCT differ in cats and dogs?

A

Cats:
- Typically benign, well circumscribed lesions
- Excision with narrow skin margin usually curative

Dogs:
- Regional LN mets in 42.8%
- 2cm margins sufficient unless tumour over 5cm
- Chemotherapy recommended for grade 3 or incompletely excised grade 2
- Radiation could be considered

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9
Q

List some inflammatory lesions of the pinna

A

Infectious
- Canine leproid granuloma syndrome (mycobacterium)
- Dermatophytosis
- Malassezia
- Feline cowpox virus
- Leishmania
- Sarcoptic mange
- Demodex

Inflammatory
- Allergic dermatitis
- Food allergy
- Atopic dermatitis
- Pemphigus
- Lupus (DLE/SLE)
- Vasculitis

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10
Q

List primary causes of otitis externa

A
  • FB
  • Parasites
  • Hypersensitivity
  • Keratinisation disorder
  • Autoimmune disease
  • Ear mites, demodex, sarcoptes
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11
Q

List some predisposing factors of otitis externa?

A
  • Pendulous ears
  • Narrow ear canals
  • Excessive hair growth
  • Excessive cerumen
  • Chronic moisture
  • Inappropriate antibacterial use
  • Polyp or tumour
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12
Q

List some perpetuating factors of otitis externa

A
  • Proliferation or overcolonisation of bacteria (Staph intermedius/pseudintermedius most common)
  • Malassezia pachydermatitis
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13
Q

List DDx for neoplasia of the ear canal in dogs and cats

A

Dogs: 60% malignant
- Ceruminous carcinoma
- SCC
- Anaplastic carcinoma
- STS, melanoma, plasmacytoma
- Cocker Sp overrepresented

Cats: 87.5% malignant
- Ceruminous gland adenocarcinoma
- SCC
- Anaplastic carcinoma
- sebaceous adenocarcinoma
- Often have bilateral external canal carcinomas!

Benign:
- Papillomas, ceruminous adenoma, ceruminous cystadenoma, sebaceous adenoma, basal cell carcinoma, histiocytoma
- Often pedunculated

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14
Q

Where does ceruminous gland ACA arise from?

A

Modified apocrine sweat glands.
Locally invasive

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15
Q

What is the most common site of ear canal avulsion?
What are the treatment options?

A

Junction of auricular and annular cartilages

Tx options:
- TECA-LBO
- Horizontal canal ablation and LBO with preservation of vertical canal
- Primary repair through caudal approach

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16
Q

What is congenital external auditory canal atresia?
How can it present?

A

Result of improper development of ectodermal cells of the first branchial and pharyngeal clefts.
- Ear canal is functionally closed at birth and is patent again by 10 days. Failure of this process leads to atresia

Presentations:
- Haired skin covering external auditory meatus
- Blind termination of vertical canal half way down
- Atresia at junction between annular and auricular cartilages

17
Q

In what % of cases is a paraural abscess reported after TECA-LBO?

A

6-11%

18
Q

What is assoc with ulcerations of the external ear canal?

A

Gram negative organism such as pseudomonas

19
Q

What CT changes may be seen with a cholesteatoma?

A
  • Minimal contrast enhancement of tympanic bulla contents
  • Ring enhancement in 25%
  • Severe bone changes: osteolysis, osteoproliferation, osteosclerosis
20
Q

Where does the facial nerve lie in relation to the ear canal?

A

Caudoventral to the terminal horizonal ear canal

21
Q

List Tx options of aural haemotoma

A
  • Repeated drainage
  • Passive/active drains
  • S-shaped incision with mutiple mattress sutures paralled to vessels
  • CO2 laser drainage and ablation
  • Drainage with instillation of dex and concurrent oral dex - successful 92.9%
  • Drainage and methylpred - successful 90-98%
22
Q

What is used to close a pinnectomy?

A

Simple continuous, nonabsorbable sutures

23
Q

List the surgical options for lesions of the external ear canal

A
  • Lateral wall resection
  • Vertical canal ablation
  • TECA-LBO
24
Q

Where should aggressive curettage of the bulla be avoided?

A

Dorsally - round window

25
Q

What may complicate a TECA-LBO in brachycephalic breeds?

A

In many, the bulla sits medial to the mandible

26
Q

How can you maintain ear carraige?
What complication may be associated with this technique?

A
  • Preserve medial pinna cartilage and a portion of the distal (dorsal) vertical ear canal
  • 46% mild to moderate skin infection in preserved canal
27
Q

What techniques can be used for pinna cosmesis in cats?

A
  • Caudal part of pinna folded forward and sutured to rostral aspect
  • Ventrally based, single-pedical advancement flap
28
Q

What is the reported rate of Horners syndrome after TECA-LBO?

A

Results from damage to postganglionic sympathetic fibres running through middle ear

Cats:
- 27-42% post-op
- 14-27% permanent

less common in dogs

29
Q

What is the reported rate of facial nerve paresis/paralysis?

A

Dogs:
- 13-39% post-op
- 4-13% permanent

Cats:
- 12-56% post-op
- 28% permanent

30
Q

What is the reported rate of significant haemorrhage during TECA-LBO?

A

3-14%, most commonly from retroglenoid vein

31
Q

What is the prognosis for surgical treatment of otitis externa?

A
  • Lateral wall resection fails in 42.3-55%
  • TECA-LBO - improvement in 57-92%
  • Cholestestoma - 10/19 recurrence or persistence after TECA-LBO
32
Q

What is a cholesteatoma?
What factor is associated with post-op recurrence?

A
  • Epidermoid cyst located within the middle ear. Composed of keratin debris, surrounded by keratinising stratified squamous epithelium, inflammatory cells and more keratin debris
  • Presence of preop neuro signs correlated with post-op recurrence
33
Q

What factor is associated with recurrence and survival time for pinna MCT in dogs?

A

Histological grade
- Grade 1 and 2 - MST not reached, recurrence 1/20
- Grade 3: MST 10 months, recurrence 7/8

34
Q

What factor is associated with survival with ceruminous carcinoma?

A
  • Involvement of bulla and ear canal associated with shorter survival - MST 5.3m vs 30m if confined to horizontal or vertical ear canal
35
Q

List the poor prognostic indicators of external ear canal neoplasia in cats

A
  • Neuro signs
  • Histo diagnosis of SCC or anaplastic carcinoma (as apposed to ceruminous adenocarcinoma)

Tobias ECVS Exam Prep (110 decks)

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