Transcript Vestibular disease - Buffalo Academy of Veterinary Medicine

Neurologic Emergencies:
vestibular events
Todd M. Bishop, DVM, DACVIM (Neurology)
Thursday February 6th, 2014
Goals of this mini-lecture
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Recognize the clinical signs
Correlate with the neurologic exam
Perform point-of-care diagnostic testing
Provide initial therapeutic intervention(s)
Know when to discuss referral
* Making anatomic and differential
diagnoses will NOT be emphasized in this
talk but the details are in the notes.
What the client sees …
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Head tilt
Balance loss; walking as if “drunk”
Jerking eye movements
Eyeball deviation
Nausea, vomiting, drooling
Wide-based stance
Inability to stand
Listing, leaning, falling to one direction
Rolling to one side (“alligator rolling”)
What you should look for …
• Mentation change
• Cranial nerves abnormalities
– Strabismus, nystagmus
• Gait and Posture alteration
– Head tilt, ataxia
• Postural reactions deficits
– Delayed hopping and placing
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The quick and dirty
• When is it in the brain (central vestibular)?
– Mentally inappropriate
– Vertical nystagmus
– Changing direction nystagmus
• Right to left
• Vertical to horizontal
• but NOT horizontal to rotary to the same side!
– Postural reaction deficits
Etiologies*
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PERIPHERAL
Idiopathic
Otitis M/I
Hypothyroidism
Ototoxicity
Trauma
Neoplasia
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CENTRAL
Metabolic
Malformative
Inflammatory
Infectious
Infarction (vascular)
Neoplastic
Degenerative
* Remember this is NOT the emphasis of this lecture!
Diagnostic testing
• Primary Care
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CBC/Chem/UA/CXR/BP
Thyroid panel
Otoscopic exam
Cytology and culture
Myringotomy
Sedated skull
radiographs
• Referral
– MRI > CT scan
– CSF tap
Basic Medical Work-up
• CBC/Chem/T4/UA
• Thoracic radiographs
• A BLOOD PRESSURE
Soapbox ALERT !
• I can not emphasize the importance of the
basic medical work-up enough !
• You may find the cause or a complicating
disease process !!
• This MUST be done before advanced
testing can be considered !!!
• People … it makes financial sense !!!!
• with one exception … same day referral
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Thyroid testing
• A simple total T4 will suffice for cats
• Dogs need a complete thyroid panel
HYPERT4→high BP→stroke→vestibular signs
hypoT4→atherosclerosis→stroke→vestibular signs
hypoT4→abN metabolism in VIII→vestibular signs
Otoscopic exam
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External ear cytology & culture
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Myringotomy (tympanocentesis)
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Sedated skull radiographs
Textbook of Veterinary Diagnostic Radiology- Thrall
Empiric therapies *
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IV fluids
Antibiotics
Dimenhydrinate (Dramamine)
Meclizine (Bonine, Antivert)
Cerenia
Benzodiazepines
Corticosteroids?
* Regardless of etiology!
Intravenous Fluids
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Rehydrate after vomiting
Maintain vascular volume (anorexia)
Combat ongoing losses (drooling)
Promote cerebral profusion (especially
important in ischemic cerebrovascular
disease)
Antibiotic therapy
• Common otic flora
– Strep, Staph, Malassezia
• Base treatment on cytology and culture
• Empiric treatment options:
– Cephalosporin
– Amoxicillin
– Fluoroquinolone
– Fluconazole
Dimenhydrinate
• Antihistaminic (H1), antiemetic and
anticholinergic effects
• Acetylcholine stimulation of the vestibular
and reticular systems may be blocked
• 4-8 mg/kg PO SID-TID
• 12.5 mg PO SID-TID (cat)
• 25–50 mg PO SID-TID (dog)
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Meclizine
• Antihistamine with sedative & antiemetic
effects
• H1 receptor blocker
• 25 mg / dog PO SID x 3-4 days
• 12.5 mg / cat
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Cerenia
• Maropitant (mar-oh-pit-ent) Citrate
• Neurokinin (NK1) Receptor Antagonist
• Inhibits Substance P a neurotransmitter
involved in vomiting
• Acts at the vomiting center to treat motion
sickness
• 8 mg/kg PO q 24h for up to 2 consecutive
days
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Benzodiazepines
• Diazepam or Midazolam :
– 0.5 mg/kg IV bolus
– 0.5 mg/kg/hr IV CRI over 24-72 hrs
• Sedative effect
• Inhibitory neurotransmitter in the vestibular
system
• Metronidazole toxicosis antidote
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Corticosteroids
• Should ideally be employed only after a
definitive diagnosis has been made
• Can be added if all other empiric therapies
are failing and clients not interested in
referral
• If using empirically consider an antiinflammatory dose (ie. Prednisone 0.5
mg/kg BID)
When to refer a case?
• After a patient is stabilized
• Once preliminary testing is done
• When there is no response to general
supportive care described above
• When central disease is suspected