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13: Ear > Chapter 122 Pinna and External Ear > Flashcards

Chapter 122 Pinna and External Ear Flashcards

1
Q

Label the diagram

A
  • The anthelix is a cartilaginous protuberance on the medial auricular surface separating the flat scapha from the beginning of the funnel-shaped external ear canal.
  • Opposite the anthelix is a roughly rectangular dense cartilage plate called the tragus that demarcates the lateral margin of the opening of the ear canal.
  • Caudal to the tragus and delineating the caudal opening of the ear canal is the antitragus.
  • Separating the two is the intertragic incisure.
  • Rostral to the tragus is the helix, forming the cranial border of the ear canal.
  • Separating these two is the pretragic incisure
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2
Q

What are the cartilaged of the ear?

A
  • Auricular
  • Scutiform
  • Annular
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3
Q

Hpe does external ear differ in the cat?

A
  • Osseous acoustic meatus has a more pronounced flare
  • Vertical canal tapers venrally instead of forming cylindrical tube
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4
Q

What type of gland are present in the ear canal?

A

Sebaceous and ceruminous

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5
Q

What is serumen made up od

A

Secretions from sebaceous glands, ceruminous glands and desquamated epithelium

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6
Q

What nerve supplies motor innervation the extrenal ear?

A

Facial n CN VII

(Vagus = sensory to canal)

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7
Q

Where does the facial nerve exit the cranial vault?

And where does it exit the skull?

A

Internal acoustic meatus (along with vestibulocochlear nerve (CN VIII)). (Then runs through facial canal of petrous temporal bone and through middle ear on its way out of the skull

Stylomastoid foramen (caudodorsal to external acoustic meatus)

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8
Q

What vessel supplies the ear canal?

A

Great auricular artery (branch of external carotid)

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9
Q

What vessels surround the tympanic cavity at following aspects:

Rostrodorsal

Ventral

Medial

A
  • Rostrodorsal = retroglenoid vein
  • Ventral = maxillary vein and external carotid
  • Medial = internal carotid
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10
Q

LAbel the diagram

A
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11
Q

List 7 tumours of external ear

A
  • Actinic keratoses
  • SCC
  • Haemangioma/HSA
  • MCT
  • Histiocytoma
  • Basal cell tumours (cats)
  • Sebaceous adenoma
  • Other inc STS, fibrosarc, rhabdomyoma, melanoma
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12
Q

List 3 tumours associated with UVB exposure

A
  • SCC
  • Actinic keratoses
  • Haemangioma/HSA
  • Basal cell tumour
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13
Q

WHat is risk of white cats developing SCC vs other ctas

A

x13

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14
Q

List 4 options for management of pinna scc

A
  • Pinnectomy (partial or total)
  • Cryosurgery
  • Photodynamic therapy (5 aminolevulinic acid)
  • Radiotherapy
  • Laser ablation
  • Chemo
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15
Q

What was outcome in 4 cats undergoing pinnectomy for HSA removal (recurrence)

A

Recurrence in all, at median time of 9.5 months

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16
Q

What is most common feline cutaneous neoplasm?

And second most common?

A

Basal cell tumour

MCT

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17
Q

Comment on feline auricular MCT

And in dogs?

A

Usually benign!

Auricular ones potentially more aggressive than elsewhere as 43% mets

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18
Q

List 5 non-neoplastic conditions affecting pinna

A

Infectious:

  • Demodex
  • Scabies
  • Malassezia
  • Leish
  • Sarcoptic mange

Inflammatory:

  • Atopic dermatitis
  • Food hypersensitivity
  • SLE/DLE
  • Vasculitis
  • Pemphigus
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19
Q

How is aetiology of OE/OM broken down

A
  • Primary cause
    • ​Otodectes, dermatitis/allergy, FB, autoimmune disease
  • Predisposing factors
    • Pendulous ears, narrrow canals, excessive hair in canal, excessive cerumen production
  • Perpetuating factors
    • ​Proliferation/overcolonization of bacteria
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20
Q

What 4 bacteria are most commonly found in OE

A

Staph intermedius/pseudointermedius, Pseudomonas, Step, Proteus

(no anaerobes)

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21
Q

What % of external ear neoplasia is malignant in dogs?

And in cats

A

Dogs 60%. Bilateral rare

Cats 88% (mostly ceruminous gland adenocarcinoma). Often bilateral

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22
Q

In ear canal avulsion, where does tear usually happen?

How is it approached?

What are management options

A

Tear: Between auricular and annular cartilage

Approach: Caudal approach to ear

Tx:

  • Primary repair
  • TECA-LBO
  • Horizontal canal ablation + LBO (i.e. preservation of the more distal, vertical canal - for chronic injury)
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23
Q

What is anatomy of ear canal at birth in puppies and how does it change?

A

At birth canal is occluded by epithelial overgrowth. Opens at 10d old

24
Q

What embryonic issue –> auditory canal atresia?

A

Improper development of ectodermal cells of first branchial and pharyngeal clefts

25
Q

How canear canal atresia be managed/

A

No tx if not symptomatic

TECA-LBO

R+A of sections of canal

26
Q

What is most common cause of para-aural abscess

A

Remnant epithelial lining of tympanic bulla or annular cartilage

27
Q

What % of TECA LBO dogs develop para aural abscess?
What is time frame

A

6-10%

up to 3 years

28
Q

What approaches canbe perfroemd for para-aural absces

A

lateral or ventral (i.e. VBO)

29
Q

In what % of OM cases is tympanic bulla intact?

A

71%

30
Q

What cells are used to diagnosed cholesteatoma?

A

Keratinized squamous epithelial cells and mixed inflammation

31
Q

What rad views shoud be optained to evaulate external and middle ears?

A
  • Lateral
  • DV or VD
  • Latero-20-degree ventral-laterodorsal oblique
  • Rostro-30-degree ventral-caudodorsal open-mouth oblique radiographs
32
Q

How can US be used to assess TM?

A

Instill saline in canal –> hyperechoic line

33
Q

What is the other name for retroglenoid vein

A

Retro-articular

34
Q

What is typical Ct appearance of cholesteatoma/

A
  • Minimal contrast enhancement, although 25% have rim enhancement
  • Osteolysis/osteoproliferation/osteosclerosis
  • Expansion of bulla
  • Sclerosis of ipsilateral TMJ and paracondylar process
35
Q

How does aural haematoma surgery differ in cats?

A

Place sutures haphazardly

36
Q

How does Tobias recommend repair of ear laceration

A

Vertical mattress suture one side to align skin and cartilage with them, then normal skin closure other side

37
Q

NAme a distant use of auricular cartilage

A

Free graft for oronasal fistula repair

38
Q

How does photodynamic therapy work?

A
  • Photodynamic therapy uses a photosensitizing compound (e.g., 5-aminolevulinic acid) that is preferentially absorbed by tumor cells.
  • After administration of the compound, either topically to the tumor or systemically, the patient is anesthetized.
  • Pinna lesions are exposed to a certain wavelength of light, resulting in interaction of the photosensitizing agent with oxygen and subsequent formation of localized, cytotoxic free radicals.

Tissue penetration of light is poor; thus response is best with small superficial tumors.

39
Q

How is cryotherapy for SCC performed?

A
  • The tissue is frozen in situ to −50° to −60°C, with the spray nozzle positioned perpendicular to, and 1 cm away from, the target tissue and the cryogen administered until a 5-mm halo of frozen tissue is achieved.
  • Typically, two freeze-thaw cycles are recommended for maximal tumor cell destruction, but use of three cycles has also been described to treat malignant lesions.
  • Whereas superficial lesions smaller than 1 cm in diameter can be treated by cryotherapy alone, larger lesions on the pinna can be excised and the remaining base frozen at the level of the skin.

Edema and erythema lasting several days are to be expected in all wounds, with healing taking 21 to 30 days. Provides no opportunity for assessment of surgical margins.

40
Q

NAme a sx option for management of OE (with non-setnosed horizontal canal) + OM

What are proposed benefits?

What was rate of facial nerve damage (what % permanent)

A

VBO + lateral wall resection

Benefits:

  • Reduce rate of facial nerve damage
  • Improved bulla exposure
  • Less post-op deafness

Facial nerve damage in 13% (60% permanent) (vs in TECA LBO 40%, 13% permanent)

41
Q

HOw much cartilage is removed during lateral wall resection?

What level is dissection continued to?

A

50% circumference

To junction between horizontal and annular cartilage (to that lower half can be flipped down to create draining board.

42
Q

List 2 benefits of suturing LWR and vertical canal ablation distant from stoma (i.e. at draining boards)

A
  • Shifts hair bearing skin away from stoma.
  • Decreases sutures near stoma

i.e. lower risk of stenosis and lower maintenance long tem

43
Q

What should be taken care of during TECA LBO to avoid pinna necrosis

A

Ensure medial inscision doesnt extend too far up pinna.

44
Q

Why shoudl dorsal curettage of tympanic cavity be avoided?

A

Round window is there (= communication between middle and inner ear)

45
Q

NAme an option for access to tympanic bulla in brachys

A

VBO + TECA.

46
Q

Name two techniques for preserving ear cosmesis after TECA LBO

and an extra in cats

A
  • Sub total ear canal ablation (i.e. most distal auricular cartilage left in situ (dogs)
  • Venker van Haagen closure (dogs and cats)
  • Ventrally based pedicle advancement flap (cats)
47
Q

How did use of drains following TECALBO affect outcome?

A

No difference in immediate or long term complications

But drains –> longer hospitalisation

48
Q

What is an analgesia option follwoing TECA LBO (not the usual)

A

Continuous local infusion of 2% lidocaine

(but 40% wound complication)

49
Q

What are signs of Horners

A
  • Third eyelid protrusion
  • Miosis
  • Eyelid drooping (ptosis)
  • Enophalmos
50
Q

What % of cats get horners after TECA LBO/

What % permanant

A

27-42% Horner’s

14-27% permanent

51
Q

What % of dogs get facial nerve paralysis after TECA LBO?

How does this compare to cats?

A

13-39% paralysis

4-13% permanent

Worse in cats:

12-56% paralysis

28% permanent

52
Q

Where is TECA LBO haemoarrhage usually from?

How is it stopped

A

Retroglenoid vein (retroarticular vein)

Pack bonewax dorsally into foramen

53
Q

What were cure rates of aural haematoma withthe follwoing treatments

Teat tube drainage

Indwelling drain + glucocorticoids

Longitudinal inscision + sutures

A
  • Teat tube drainage 94%
  • Indwelling drain + glucocorticoids 100%
  • Longitudinal inscision + sutures 60%
54
Q

What is a cholesteatoma

A

Cholesteatoma is an epidermoid cyst located within the middle ear. It is composed of keratin debris surrounded by keratinizing stratified squamous epithelium, inflammatory cells, and more keratin debris.

When resulting from chronic otitis media, the condition is termed primary acquired cholesteatoma

55
Q

In dogs with cholesteatoma, what factor was associated with recurrence after surgery

A

Presence of pre-op neuro signs

56
Q

What was MSt after cat SCC pinnectomy

And cryotherapy outcome

A

800d

100% remission with cryotherapy but regrowth within 18 months

57
Q

What was MST in cats undergoign TECALBO for ceruminous gland adenocarcinoma

A

42 - 50 months

i.e. they do great.

But if consider OVERALL external ear neoplasia MST cats do worse then dogs, probably because lost of SCC and anaplastic carcinoma in cats. They were both associated with worse outome. As was neuro signs at time of diagnosis.)

13: Ear (2 decks)

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