Chapter 122 Pinna and External Ear Flashcards
Label the diagram
- 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
What are the cartilaged of the ear?
- Auricular
- Scutiform
- Annular
Hpe does external ear differ in the cat?
- Osseous acoustic meatus has a more pronounced flare
- Vertical canal tapers venrally instead of forming cylindrical tube
What type of gland are present in the ear canal?
Sebaceous and ceruminous
What is serumen made up od
Secretions from sebaceous glands, ceruminous glands and desquamated epithelium
What nerve supplies motor innervation the extrenal ear?
Facial n CN VII
(Vagus = sensory to canal)
Where does the facial nerve exit the cranial vault?
And where does it exit the skull?
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)
What vessel supplies the ear canal?
Great auricular artery (branch of external carotid)
What vessels surround the tympanic cavity at following aspects:
Rostrodorsal
Ventral
Medial
- Rostrodorsal = retroglenoid vein
- Ventral = maxillary vein and external carotid
- Medial = internal carotid
LAbel the diagram
List 7 tumours of external ear
- Actinic keratoses
- SCC
- Haemangioma/HSA
- MCT
- Histiocytoma
- Basal cell tumours (cats)
- Sebaceous adenoma
- Other inc STS, fibrosarc, rhabdomyoma, melanoma
List 3 tumours associated with UVB exposure
- SCC
- Actinic keratoses
- Haemangioma/HSA
- Basal cell tumour
WHat is risk of white cats developing SCC vs other ctas
x13
List 4 options for management of pinna scc
- Pinnectomy (partial or total)
- Cryosurgery
- Photodynamic therapy (5 aminolevulinic acid)
- Radiotherapy
- Laser ablation
- Chemo
What was outcome in 4 cats undergoing pinnectomy for HSA removal (recurrence)
Recurrence in all, at median time of 9.5 months
What is most common feline cutaneous neoplasm?
And second most common?
Basal cell tumour
MCT
Comment on feline auricular MCT
And in dogs?
Usually benign!
Auricular ones potentially more aggressive than elsewhere as 43% mets
List 5 non-neoplastic conditions affecting pinna
Infectious:
- Demodex
- Scabies
- Malassezia
- Leish
- Sarcoptic mange
Inflammatory:
- Atopic dermatitis
- Food hypersensitivity
- SLE/DLE
- Vasculitis
- Pemphigus
How is aetiology of OE/OM broken down
-
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
What 4 bacteria are most commonly found in OE
Staph intermedius/pseudointermedius, Pseudomonas, Step, Proteus
(no anaerobes)
What % of external ear neoplasia is malignant in dogs?
And in cats
Dogs 60%. Bilateral rare
Cats 88% (mostly ceruminous gland adenocarcinoma). Often bilateral
In ear canal avulsion, where does tear usually happen?
How is it approached?
What are management options
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)
What is anatomy of ear canal at birth in puppies and how does it change?
At birth canal is occluded by epithelial overgrowth. Opens at 10d old
What embryonic issue –> auditory canal atresia?
Improper development of ectodermal cells of first branchial and pharyngeal clefts
How canear canal atresia be managed/
No tx if not symptomatic
TECA-LBO
R+A of sections of canal
What is most common cause of para-aural abscess
Remnant epithelial lining of tympanic bulla or annular cartilage
What % of TECA LBO dogs develop para aural abscess?
What is time frame
6-10%
up to 3 years
What approaches canbe perfroemd for para-aural absces
lateral or ventral (i.e. VBO)
In what % of OM cases is tympanic bulla intact?
71%
What cells are used to diagnosed cholesteatoma?
Keratinized squamous epithelial cells and mixed inflammation
What rad views shoud be optained to evaulate external and middle ears?
- Lateral
- DV or VD
- Latero-20-degree ventral-laterodorsal oblique
- Rostro-30-degree ventral-caudodorsal open-mouth oblique radiographs
How can US be used to assess TM?
Instill saline in canal –> hyperechoic line
What is the other name for retroglenoid vein
Retro-articular
What is typical Ct appearance of cholesteatoma/
- Minimal contrast enhancement, although 25% have rim enhancement
- Osteolysis/osteoproliferation/osteosclerosis
- Expansion of bulla
- Sclerosis of ipsilateral TMJ and paracondylar process
How does aural haematoma surgery differ in cats?
Place sutures haphazardly
How does Tobias recommend repair of ear laceration
Vertical mattress suture one side to align skin and cartilage with them, then normal skin closure other side
NAme a distant use of auricular cartilage
Free graft for oronasal fistula repair
How does photodynamic therapy work?
- 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.
How is cryotherapy for SCC performed?
- 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.
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)
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)
HOw much cartilage is removed during lateral wall resection?
What level is dissection continued to?
50% circumference
To junction between horizontal and annular cartilage (to that lower half can be flipped down to create draining board.
List 2 benefits of suturing LWR and vertical canal ablation distant from stoma (i.e. at draining boards)
- Shifts hair bearing skin away from stoma.
- Decreases sutures near stoma
i.e. lower risk of stenosis and lower maintenance long tem
What should be taken care of during TECA LBO to avoid pinna necrosis
Ensure medial inscision doesnt extend too far up pinna.
Why shoudl dorsal curettage of tympanic cavity be avoided?
Round window is there (= communication between middle and inner ear)
NAme an option for access to tympanic bulla in brachys
VBO + TECA.
Name two techniques for preserving ear cosmesis after TECA LBO
and an extra in cats
- 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)
How did use of drains following TECALBO affect outcome?
No difference in immediate or long term complications
But drains –> longer hospitalisation
What is an analgesia option follwoing TECA LBO (not the usual)
Continuous local infusion of 2% lidocaine
(but 40% wound complication)
What are signs of Horners
- Third eyelid protrusion
- Miosis
- Eyelid drooping (ptosis)
- Enophalmos
What % of cats get horners after TECA LBO/
What % permanant
27-42% Horner’s
14-27% permanent
What % of dogs get facial nerve paralysis after TECA LBO?
How does this compare to cats?
13-39% paralysis
4-13% permanent
Worse in cats:
12-56% paralysis
28% permanent
Where is TECA LBO haemoarrhage usually from?
How is it stopped
Retroglenoid vein (retroarticular vein)
Pack bonewax dorsally into foramen
What were cure rates of aural haematoma withthe follwoing treatments
Teat tube drainage
Indwelling drain + glucocorticoids
Longitudinal inscision + sutures
- Teat tube drainage 94%
- Indwelling drain + glucocorticoids 100%
- Longitudinal inscision + sutures 60%
What is a cholesteatoma
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
In dogs with cholesteatoma, what factor was associated with recurrence after surgery
Presence of pre-op neuro signs
What was MSt after cat SCC pinnectomy
And cryotherapy outcome
800d
100% remission with cryotherapy but regrowth within 18 months
What was MST in cats undergoign TECALBO for ceruminous gland adenocarcinoma
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.)
