Ch 122 Pinna and external ear Flashcards
What is the scutiform cartilage?
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
What is the annular cartilage?
Connects the horizontal canal to the osseous external auditory meatus. Attached to both the auricular cartilage and the temporal bone by fibrous connective tissue
What is cerumen?
Secretions of the deeper tubular ceruminous glands, more superficial sebaceous glands mixed with desquamated epithelium
Anatomy
- rectangular dense cartilage plate called the tragus that demarcates the lateral margin of the opening of the ear canal
- caudal auricular artery branches off the external carotid artery and at the base of the ear
- vertical ear canal begins at the external acoustic opening at the level of the tragus, antitragus, and anthelix.
- osseous auditory meatus in dogs is an approximately 5- to 10-mm extension of the temporal bone
- ear canal is lined by stratified squamous epithelium
What nerves supply sensory and motor function to the external ear canal?
Sensory: CN X vagus
Motor: CN VII facial
What important vessels surround the bulla?
Rostral: retroglenoid vein
Ventral: External carotid artery and maxillary vein
Medial: internal carotid artery
List DDx for neoplasia of the pinna
- 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
List Tx options of pinna SCC
Partial pinnectomy
Complete pinnectomy
Complete pinnectomy with vertical canal ablation
Cryosurgery
Laser ablation
Radiation therapy
Chemotherapy
How do pinna MCT differ in cats and dogs?
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
- may be more aggressive than cutnaeous MCT (lymph node metastasis suggestive of a more aggressive biologic behavior)
List some inflammatory lesions of the pinna
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
List some predisposing factors of otitis externa?
Pendulous ears
Narrow ear canals
Excessive hair growth
Excessive cerumen
Chronic moisture
Inappropriate antibacterial use
Polyp or tumour
List some perpetuating factors of otitis externa
Proliferation or overcolonisation of bacteria (Staph intermedius/pseudintermedius most common)
Malassezia pachydermatitis
List DDx for neoplasia of the ear canal in dogs and cats
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
Where does ceruminous gland Adenocarcinoma arise from?
Modified apocrine sweat glands.
Locally invasive (50% in dogs and 60% in cats invading the cartilage, however into periaural tissue is rare, however, so compartmental excision through total ear canal ablation offers the best chance for local cure)
What is the most common site of ear canal avulsion?
What are the treatment options?
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
What is congenital external auditory canal atresia?
How can it present?
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
In what % of cases is a paraural abscess reported after TECA-LBO?
6-11%
What is assoc with ulcerations of the external ear canal?
Gram negative organism such as pseudomonas
diagnostics
immpression smears
- Immediate staining with Diff-Quik allows for rapid diagnosis of tumor versus organized granulation tissue (polyp).
- Cholesteatomas diagnosed keratinized squamous epithelial cells and mixed inflammation
advanced imaging
- CT: currently the imaging of choice at the author’s institution to investigate external and middle ear disease.
- mineralization of the external ear cartilages, aural neoplasia, and para-aural abscessation middle ear dz
- Abscesses tend to have a central hypoattenuating region with a fairly well-marginated region of ring enhancement
- Tumors often result in lysis of the contour of the tympanic bulla or the petrosal part of the temporal bone, and soft tissue swelling around the middle ear.
- inherent contrast between gas and cortical bone hinders magnetic resonance imaging
- indication vestibular disease > differentiate between peripheral and central cause
What CT changes may be seen with a cholesteatoma?
Minimal contrast enhancement of tympanic bulla contents
Ring enhancement in 25%
Severe bone changes: osteolysis, osteoproliferation, osteosclerosis
Where does the facial nerve lie in relation to the ear canal?
Caudoventral to the terminal horizonal ear canal
List Tx options of aural haemotoma
- 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 concirrent oral dex - successful 92.9%
- Drainage and methylpred - successful 90-98%
List the surgical options for lesions of the external ear canal
Lateral wall resection
- indicated for congenital canal stenosis, small tumors of the tragus or lateral wall of the dorsal portion of the vertical canal, or otitis externa treatment
Vertical canal ablation
- Indications include irreversible hyperplastic otitis, severe trauma, and neoplasia limited to the vertical canal.
TECA-LBO
- ceruminous gland adenocarcinomas, extensive benign disease, revision, and extension of disease into the middle ear cavity
Where should aggressive curettage of the bulla be avoided?
Dorsally - round window
What may complicate a TECA-LBO in brachycephalic breeds?
In many, the bulla sits medial to the mandible
option for these dogs is to perform a ventral bulla osteotomy
TECALBO sx
- To avoid ischemic necrosis of the pinna, the medial incision should not extend too far up the pinna
- working deep to the perichondrium
- facial nerve is located caudoventral to the canal at the level of the terminal horizontal canal
- “keyhole” osteotomy to allow for curettage of the bulla floor, a common location for epithelium to be retained.
- removal of tympanic membrane and auditory ossicles usually leads to complete and irreversible hearing loss
- facial nerve is established and artificial tears or ophthalmic ointment applied as needed.
How can you maintain ear carraige?
What complication may be associated with this technique?
- Preserve medial pinna cartilage and a portion of the distal (dorsal) vertical ear canal
- 46% mild to moderate skin infection in preserved canal
What techniques can be used for pinna cosmesis in cats?
Caudal part of pinna folded forward and sutured to rostral aspect
Ventrally based, single-pedical advancement flap
Microbial Isolates
- Samples are preferably obtained after lavage
- duration of antimicrobial administration after ear canal ablation in dogs ranges from 7 to 30 days (no strong evidence peri-op abs make a difference)
- Antibiotic treatment is rarely effective for resolving recurrent middle ear infections that develop after TECA
- recurrent otitis media, fistula development, and para-aural abscessation are predominantly linked to incomplete removal of annular cartilage, inadequate debridement and removal of middle ear epithelium, and presence of residual debris
post-op
drains
- study found no difference in the incidence of immediate or long-term complications in dogs with wounds closed primarily and those that had indwelling passive Penrose drain placemen
analgesia
- Use of opioids alone is often insufficient, with many patients developing breakthrough pain
- continuous local infusion of 2% lidocaine
- 40% of the dogs undergoing local infusion of lidocaine or sterile saline had wound complications
list complications
- severe hemorrhage 5.5-15.6% (requiring a blood transfusion)
post-op: overall 21-53%;
* SSI, drainage tracts, abscess 2-50%; abscess can develop 5-10mths later
* Horner’s 3.3%
* facial n injury 13-36%, up to 15% permanent
* vestibular dz 1-8%,
* hypoglossal n injury 3-8%
* pinna necrosis
* poor cosmesis
* deafness
cats:
* Horner’s 27-70%,
* facial n injury: 12-56% (up to 28% permanent)
What is the reported rate of Horners syndrome after TECA-LBO?
Results from damage to postganglionic sympathetic fibres running through middle ear
Cats:
- 27-42% post-op (70%)
- 14-27% permanent
less common in dogs
enophthalmos, elevation of the third eyelid, miosis, and ptosis
What is the reported rate of facial nerve paresis/paralysis?
Dogs:
- 13-39% post-op
- 4-13% permanent
Cats:
- 12-56% post-op
- 28% permanent
What is the reported rate of significant haemorrhage during TECA-LBO?
3-14%, most commonly from retroglenoid vein
What is the prognosis for surgical treatment of otitis externa?
- TECA-LBO - improvement in 57-92%
- Cholestestoma - 10/19 recurrence or persistence after TECA-LBO
What is a cholesteatoma?
What factor is associated with post-op recurrence?
- 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
What factor is associated with recurrence and survival time for pinna MCT in dogs?
Histological grade
- Grade 1 and 2 - MST not reached, recurrence 1/20
- Grade 3: MST 10 months, recurrence 7/8
What factor is associated with survival with ceruminous carcinoma?
Involvement of bulla and ear canal associated with shorter survival - MST 5.3m vs 30m if confined to horizontal or vertical ear canal
List the poor prognostic indicators of external ear canal neoplasia in cats
Neuro signs
Histo diagnosis of SCC or anaplastic carcinoma (as apposed to ceruminous adenocarcinoma)
Evaluation of endoscopic-assisted
feline lateral bulla osteotomy:
a cadaveric study
Dory Enright 2023
A total of 13 feline cadaver heads
osseus structures of the middle ear were readily visualized with a 1.9 mm scope
endoscope does not appear to increase the success rate of entry into the hypotympanum during feline TECALBO
Retrospective evaluation of ceruminous gland tumors confined
to the external ear canal of dogs and cats treated with biopsy
and CO2 laser ablation
Jason B. Pieper 2023
Recurrence was identified in 1/14 (7%) ceruminous
gland adenomas and 1/12 (8%) ceruminous gland adenocarcinomas.
Conclusions and Clinical Importance: Video-otoscopic aided biopsy and CO2 laser
ablation of ceruminous gland tumors in dogs and cats is a viable treatment option
with low recurrence and complication rates with CO2 laser ablation.
Influence of extreme brachycephalic conformation on perioperative complications associated with total ear canal ablation and lateral bulla osteotomy in 242 dogs (2010–2020)
Banks 2023
beever
Cross-sectional retrospective study.
242 dogs TECA-LBOs extreme brachycephalic 81, other breeds 225
a younger age
presented more frequently with facial nerve paresis, vestibular syndrome , and Horner’s syndrome
jaw pain, para-aural abscesses , otitis interna, and brainstem changes were more common
CT
anatomical differences: thickened bulla wall, abnormal location, narrow external bony meatus diameter, proximity of neurovascular structures
intraoperative complication: EBBs (9/81, 11.1%) and OBs (12/225, 5.3%) did not reach statistical significance
subjectively more technically challenging in EBB
facial 29%
iatrogenic haemorrhage 5%
no difference in perioperative complication rates between unilateral, single-session bilateral, and staged bilateral TECA-LBO
Influence of computed tomographic dimensions
of the nasopharynx on middle ear effusion and
inflammation in pugs and French bulldogs with
brachycephalic airway syndrome
Dorothee Krainer 2021
computed tomographic dimensions of the nasopharynx on middle ear effusion
Middle ear effusion (56.7%) French bulldogs and (16.7%) pugs
French bulldogs with BOAS seem predisposed to middle ear effusion
The ventral wall of the bulla is significantly thicker in French bulldogs
Previously reported as incidental finding (prevalence of up to 41%)
Otoscopic evaluation of epithelial remnants in the
tympanic cavity after total ear canal ablation and lateral
bulla osteotomy
Meghan M. Watt 2020
Experimental study. Otoscopic evaluation of epithelial remnants after TECABO
use of 1.9mm rigid endoscope
- epithelial remnants in at least 1/5 areas after all TECA-BO
- most common rostrally (35%), least common medially
- caudal, rostral, dorsal > ventral, medial
Intraoperative endoscopy >improve removal of epithelium after initial TECA-LBO or revision surgeries
allow better visualization and curettage in safe areas away from delicate structures such as the ossicles and internal ear structures.
aggressive dissection of the rostromedial > iatrogenic injury to the round and oval windows , inner ear and internal carotid artery (medial to the bulla wall)
Clinical presentation and outcome
in cats with aural squamous cell
carcinoma: a review of 25 cases
(2010–2021)
McGrath 2022
diagnosed with SCC of the ear canal, middle or inner ear
Twenty-five cats were identified. Eleven
cats were treated with surgery, eight with medical management, two with coarse fractionated radiation therapy
The median survival time of cats treated with surgery was 168 days vs 85 days (P = 0.28) for
those treated palliatively
locally aggressive tumor that carries an overall poor prognosis.
Effect of empirical versus definitive antimicrobial selection on postoperative complications in dogs and cats
undergoing total ear canal ablation with lateral bulla osteotomy: 120 cases (2009–2019)
Folk 2022
Effect of empirical versus definitive antimicrobial selection on postoperative complications
95/111 (85.5%) positive on intraoperative culture during TECA-LBO
- Staphylococcus spp most common
- revision due to infection in 13/120 (10.8%)
- pain on opening the mouth → 7.4x of requiring revision
- 10.3x higher risk of revision with positive culture without antimicrobials
- ~50% facial paralysis, 3.3% permanent
Use of a surgical drain, suture type, and intralesional analgesia was not significantly associated with any of the outcome variables.
duration and choice of systemic antimicrobial no effect, antimicrobials postoperatively could play a role in the successful long-term outcome.
Need prospective RTC to determine the true effects of antimicrobial therapy on compli cation rates and outcomes
Coleman 2016 – no significant difference in ear complication rates in bilateral single-session vs
unilateral TECA-LBO
Hettlich 2005 – evacuation and lavage of the tympanic cavity reduced bacterial isolates by 33%
- bacteria remain after evacuation and lavage
- pre-op and post-lavage culture isolates differed in 84%
- 26% isolates susceptible to cefazolin – poor choice of peri-operative antibiotic
- 53% dogs had at least 1 isolate resistant to empirically selected antibiotic
