ClinNeuro- Vestibular Dz

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  1. What are the functions of the vestibular system? (3)
    maintenance of normal position of the eyes and head, extension of limbs on side of stimulation, flexion of limbs on side contralateral to stimulation
  2. What are the components of the peripheral vestibular system? (5)
    utricle, saccule,semicircular canals in the membranous labyrinth of the inner ear, vestibular nerve (CN VIII)
  3. What are the components of the central vestibular system? (5)
    vestibular nuclei in brainstem, vestibulospinal tracts in spinal cord, medial longitudinal fasciculus, flocculonoduar lobe of cerebelllum/caudal peduncle, reticular formation
  4. With vestibular ataxia, which way does the animal circle/fall/drift?
    toward the lesion
  5. Why do patients with vestibular ataxia fall toward the lesion?
    excessive extensor tone contralateral to the lesion
  6. Clinical signs of vestibular disease. (8) [depends on what TYPE of vestibular disease the patient has]
    head tilt toward lesion, falling/drifting/circling toward the lesion, pathologic nystagmus, positional strabismus, CN deficits, Horner's Syndrome, postural reaction deficits, altered consciousness
  7. Describe pathologic nystagmus in vestibular disease patients and lesion localization.
    fast phase of nystagmus goes AWAY from the lesion (slow phase- eyeball drifting, fast phase- darts back to original position)
  8. What causes pathologic nystagmus?
    loss of vestibular input to extraocular muscles
  9. What positional strabismus is typical of patients with vestibular disease? What side is it on in relation to the lesion?
    ventral or ventrolateral strabismus IPSILATERAL to the lesion
  10. What clinical signs can help you distinguish between central and peripheral vestibular disease? What do they tell you? (5)
    • Nystagmus- vertical pathognomonic for central (central can be horizontal or rotary as well thought)
    • Any deficits in CN V-XII- central only (peripheral may have CN VII-VIII only)
    • Horner's Syndrome- usually only peripheral
    • Postural Reaction Deficits- only central
    • Consciousness- normal with peripheral, may be stuporous with central
  11. What are clinical signs of Horner's Syndrome? (5)
    miosis, ptosis, enophthalmos, third eyelid elevation, hyperemic conjunctiva
  12. What signs of Horner's Syndrome are unique to horses? Cows?
    • Horses- increased sweating of head and neck
    • Cows- decreased sweating of nasal planum
  13. What key clinical features are most helpful in distinguishing central from peripheral vestibular disease? (5)
    mentation, postural reactions, character of nystagmus, presence or absence of other nerve involvement, Horner's Syndrome
  14. What is paradoxical vestibular sydrome?
    head tilt is away from the lesion due to loss of cerebellar input to the vestibular system
  15. What lesions cause paradoxical vestibular syndrome? (2)
    [central lesions] caudal cerebellar peduncle or flocculonodular lobe of cerebellum
  16. How do you identify paradoxical lesions of the vestibular system?
    always localize the lesion based on postural reactions- will be ipsilateral to postural reaction deficits
  17. Paradoxical vestibular syndrome is always indicative of ___________.
    a central lesion
  18. Differentials for peripheral vestibular disease. (6)
    otitis media/interna, idiopathic geriatric vestibular disease, hypothyroidism, toxins, trauma, neoplasia
  19. Differentials for central vestibular disease. (4)
    neoplastic, infectious/inflammatory disease, Metronidazole toxicity, vascular event/stroke
  20. How do you diagnose otitis media/interna? (3)
    otoscopic exam, bull radiographs, myringotomy for cytology/culture (get fluid from middle ear)
  21. How do you treat otitis media/intern? (3)
    6-8 weeks of antibiotics, deep ear flush, bulla osteotomy in refractory cases/cats
  22. In what animals do we usually see idiopathic vestibular disease?
    • dogs > 8 years old
    • cats any age
  23. Describe the onset of idiopathic vestibular disease.
    acute/peripheral onset of unilateral peripheral vestibular signs
  24. How do you diagnose idiopathic vestibular disease?
    presumptive diagnosis after ruling out other causes
  25. Describe treatment of idiopathic vestibular disease. (2)
    supportive, +/- antiemetics/sedatives (if nauseous or thrashing)
  26. Bilateral vestibular disease is more common in _______ than _______.
    cats; dogs
  27. Describe bilateral vestibular disease. (3)
    no head tilt, no nystagmus, lack oculocephalic reflex
  28. Hypothyroidism can cause a __________ neuropathy of _________.
    unilateral; CN VIII
  29. What neoplasias can cause central vestibular signs? (3)
    meningioma, choroid plexus tumors, gliomas
  30. What infectious causes of encephalitis can cause central vestibular signs in young dogs? (3)
    canine distemper virus, Neospora canis
  31. What infectious causes of encephalitis can cause central vestibular signs in cats? (3)
    dry FIP, Toxoplasma, Cryptococcus neoformans
  32. What infectious causes of encephalitis can cause central vestibular signs in dogs of any age? (3)
    RMSF, Cryptococcus neoformans, Prototheca
  33. Describe signs of Metronidazole toxicity. (2)
    acute onset of central vestibular signs, spontaneous recovery after stopping the drug
  34. What causes Metronidazole toxicity?
    high doses/long-term treatment and antagonism of GABA in the brain
  35. How do you treat Metronidazole toxicity? (2)
    stop the drug, Valium speeds recovery
  36. What are 2 types of stroke in vetmed?
    transient ischemic attack (TIA- thrombus), hemorrhagic strokes (rupture of blood vessels and bleeding into surrounding blood vessels--> mass effects from hematoma)
  37. Describe the clinical presentation of vascular events. (4)
    acute onset, non-progressive, geriatric patients, signs improve without specific treatment w/i 24-72hr
  38. What are possible underlying causes of ischemic stroke? (6)
    bacterial endocarditis, cushings, hypothyroidism, cardiac disease, kidney disease, [cats only] cuterebra migration causing feline ischemic encephalopathy
  39. What are possible underlying causes of hemorrhagic stroke? (4)
    rupture of congenital vascular anomalies, brain tumors that bleed, coagulopathies, severe hypertension [rare in dogs!!!]
  40. How do you diagnose ischemic strokes? (4)
    BP monitoring, CBC/Chem, endocrine testing, echocardiogram [trying to ID underlying cause]
  41. How do you diagnose a hemorrhagic stroke? (3)
    BP monitoring, coag profile, thoracic/abdominal rads [try to ID underlying cause]
  42. How do you treat a stroke? (2)
    supportive care, treat underlying cause
  43. What is the prognosis for a stroke?
    • ischemic- good to excellent
    • hemorrhagic- guarded
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ClinNeuro- Vestibular Dz
vetmed clinneuro
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