Otitis media Flashcards
Clinical signs
- Variable
- Often non-specific – pain?
- Most often signs of concurrent OE are the most obvious clinical signs
- Deafness
- Pain on eating
- Signs of OI if progression
- Horner’s
- Facial paralysis
- Stiff neck
- Yawning
- Painful around jaw
- Unless have damage to sympathetic nerves or to the other CN signs are non-specific
Horner’s syndrome
- sympathetic nerves to the face affected
- Drooping of the eyelid on the affected side (ptosis)
- The pupil of the affected eye will be constricted (miosis), or smaller than usual
- The affected eye often appears sunken (enophthalmos)
- The third eyelid of the affected eye may appear red and raised or protruded (conjunctival hyperemia)
Facial paralysis
- CN VII
- Adult age Cocker Spaniels, Pembroke Welsh corgis, boxers, and English setters are most likely to experience this condition
Consequences of OM
Conductive deafness
- Loss of drum (NB dogs have normal hearing with a single hole in their TM)
- High pressure fluid/mucous in the middle ear (drum can’t move and transmit sound)
- Chronic OE or OM ± cholesteatoma
Horner’s syndrome / facial paralysis
- Ear and lip droop, asymmetrical lips, dribbling
- Keratoconjunctivitis sicca, neurogenic dry nose
- Anisocoria with ipsilateral miosis, ptosis of the upper eyelid etc.
Vestibular syndrome (otitis interna [OI])
Investigation of OM
- Appearance of the drum on video otoscopy
- Sampling of the middle ear for
– Bacteriology
– Fungal culture
– Cytology via myringotomy or ruptured TM - Palpation of granulation tissue in the middle ear
- BAER (hearing testing)
- Imaging
Tx of OM
If intact drum
- Perform myringotomy and flush until clean
Using cytology and culture data
- Use aqueous antibiotics (usually home prepared) 2-3 times a day following cleaning with saline or an appropriate aqueous cleaner (TRIZEDTA with 0.15 w/w chlorhexidine in dogs)
- Pain relief
- ? Role of systemic antibiotics
In severe cases
- Poor response to therapy
- Intractable OE
- Evidence of marked new bone on CT / radiographs
Consider total ear canal ablation and bulla osteotomy or bulla osteotomy
Seek advice from experienced or referral vets
Primary Secretory Otitis Media (PSOM) in the CKCS
- Presented for deafness or neck pain
- Marked mucoid build-up in the middle ear (can’t drain what’s in the ear)
- Bulging middle ear noted on otoscopy
- Repeated flushing and myringotomy (3-5 times)
- Sputolysin (mucolytic) and oral N-acetyl cysteine (but causes v+) has been used by some
- Steroids are used to reduce mucous production
- Hard to treat
Myringotomy - indications
- Bulging TM with pain or neurological signs (Horner’s, vestibular signs, facial paresis)
- Tympanosclerosis (an “exploratory myringotomy”)
- Radiographic/MRI bulla changes and intact TM
- Evidence of tissue or fluid behind the TM
- Medically unresponsive vestibular disease with an intact TM
- Chronic otitis cases longer than 6 months that have not responded to treatment for otitis externa (requires judgement)
Myringotomy technique
- Clean and dry the external ear canal
- Incision may be made using a 5-French polypropylene catheter (cut end to make sharper) or an open-ended tomcat catheter or a small wire (clitoral) swab
- Passed through either hand held or video otoscope
- Position: caudoventral aspect of the pars tensa to avoid damaging the tympanic germinal epithelium and the structures of the middle ear.
- Sampling:Pass swab(s) for cytology and bacteriology, instilling and then withdrawing a small amount of sterile saline solution
- Flush with saline (± other agents depending on the cytology results)
BAER
= Brainstem auditory evoked response
- Click applied to tested ear (white noise to other)
- Peaks of response respond to transition through differing structures (e.g. peak I = vestibulocochlear nerve)
- Normal dog – threshold <10dB
- Not widely available
Radiography
- Insensitive way of assessing OM: see thickening of wall of the bulla in chronic disease
- Lateral, lateral oblique and open mouth views.
- Changes absent in many cases of OM
- Very marked changes on bone and thickening of bulla may be seen but otherwise very insesitive
MRI
- Far better appreciation of soft tissue structures
- Expensive – may take significant part of the client’s budget
- CT is often as useful and a much cheaper alternative in many cases.
- Consider when wider neurological diagnoses
Why does OM tend to happen in dogs?
- Tx failure and has come through the external canal
Why does OM tend to happen in cats?
- Polyps
