Surgery for ear disease

Question 1

external ear =

Answer 1

pinna + vertical and horizontal canals

Question 2

middle ear =

Answer 2

tympanic bulla

Question 3

local blood supply around ear

Answer 3

• caudal auricular br. of external carotid a.
• maxillary artery: rostroventromedial aspect of horizontal canal near tympanic mb
• retroglenoid vein: anterior to horizontal canal at external meatus

Question 4

what nerve innervates the pinna?

Answer 4

auriculopalpebral branch of facial nerve

Question 5

which nerve runs along the dorsal promontory of the tympanic bulla?
CS if it is damaged?

Answer 5

Sympathetic nerve -> horner’s

Question 6

where does the facial nerve exit?

Answer 6

stylomastoid foramen to caudal to external meatus

Question 7

2 types of external ear canal sx

Answer 7

1. vertical ear canal resection

2. total ear canal ablation

Question 8

middle ear surgery

Answer 8

ventral bulla osteotomy

Question 9

indications for external ear canal sx

Answer 9

• otitis externa
• neoplasia
• trauma

Question 10

most common ear neoplasia in dogs?

Answer 10

Ceruminous gland adenoma/adenocarcinoma

–> slow to met, local disease minimally invasive to aggressive

Question 11

DDx for ceruminous gland adenoma in a dog

Answer 11

hyperplastic, ‘inflammatory’ polyps of ceruminous gland

Question 12

most common ear neoplasia in cats

Answer 12

SCC –> locally aggressive –> penetrate ear canal

Question 13

3 factors to consider for sx of ear neoplasia

Answer 13

1. Diagnosis and stage of disease
2. Local extent of disease (potential for infiltration disease beyond ear canal)
3. Location of lesion w/in ear canal

Question 14

Blunt trauma can result in avulsion of the external ear canal at which points?

Answer 14

1. auricular cartilage at annular cartilage junction (weak membranous connection point)
2. Entire ex. ear canal at meatus

Question 15

Preoperative treatment of ears with (???) may reduce inflammation

Answer 15

aggressive systemic therapy - ABs, short course of corticosteroids

Question 16

Indications for vertical ear canal resection

Answer 16

• isolated neoplasia of the proximal vertical canal (no structural changes to horizontal canal - cartilage of the ear becomes good barrier for tumours)
• traumatic avulsion of vertical ear canal

Question 17

VECR post op considerations

Answer 17

• no bandaging!

- E-collar

Question 18

what are some technical complications to VECR?

Answer 18

• facial nerve palsy, hematoma, granulomas, dehiscence, cellulitis/drainage

Question 19

why are VECR more commonly performed in cats than dogs?

Answer 19

Usually the horizontal canal is quite well preserved w/ tumours in cats but dogs tend to get otitis and horizontal canal involvement

Question 20

indications for TECA

Answer 20

• severe end-stage otitis externa
• neoplasia
• trauma

Question 21

what changes might you see on CT for a dog with end stage otitis externa?

Answer 21

• extra bone
• abnormal fluid/soft tissue in ear canal
• uneven level of bony meatus

Question 22

what must you sample before closing a TECA?

Answer 22

culture contents of bulla to know post-op treatments

Question 23

TECA post op care

Answer 23

1. closed-suction drain 24-36hrs w/ bandage over drain
2. Systemic ABs w/ C&S (3-4wks if osteomyelitis present)
3. Monitor/treat facial palsy (KCS)

Question 24

early complications of TECA

Answer 24

• facial palsy, cellulitis/drainay, dehiscence, vestibular injury, fistulation, haematoma, fatal haemorrhage

Question 25

what is the risk of facial palsy with TECA?

Answer 25

relatively high - 22% but 75% resolve

Question 26

how are cat bullas different from dogs?

Answer 26

cats have relatively larger bullae w/ septum diving into dorsomedial and dorsolateral compartments

Question 27

why would you do a myringotomy?

Answer 27

to culture contents of middle ear/clean

Question 28

when is a bulla osteotomy indicated?

Answer 28

- alone - if appropriate medical management has failed (middle ear infection) - to remove otopharyngeal polyps - combined w/ a TECA - confirming disease, addressing concurrent otitis media

Question 29

goal of a bulla osteotomy

Answer 29

obtain bacterial and histologic samples + remove epithelial lining and debris

Question 30

which approach to the bulla can be performed as an isolated procedure?

Answer 30

the ventral bulla osteotomy - better access with this approach esp. cats

Question 31

describe the ventral approach to a bulla osteotomy

Answer 31

between the larynx and angular process of mandibular ramus -> penetration in to the floor of the bulla

Question 32

what structures are at risk during a ventral approach to a bulla osteotomy?

Answer 32

- linguofacial vein | - hypoglossal n

Question 33

complications of ventral bulla osteotomy

Answer 33

- horner's syndrome (cats) - vestibular injury - seroma/wound complications

Question 34

what are lateral ear canal resections used for?

Answer 34

- facilitate cleaning + adminstration of topical agents - aerate the ear - giselle doesn't like them