Vestibular Disease Flashcards
Where is the vestibular apparatus located?
Inner ear (part of temporal bone)
What comprises the vestibular apparatus?
Cochlea, semicircular canals, vestibule
Which CN provides vestibular neurons?
Vestibulocochlear nerve (CN 8)
Where does CN 8 enter the skull?
Internal acoustic meatus
Where does CN 8 terminate?
Lateral wall of 4th ventricle
The efferent pathway of the vestibulospinal tract inhibits what?
Ipsilateral flexor and contralateral extensor muscles
What are clinical signs of peripheral vestibular system disease?
Head tilt, circling, horizontal/rotary nystagmus, facial nerve paralysis or Horner’s syndrome
Which way will a head tilt or circling be with peripheral vestibular disease?
Toward the side of the lesion
With pathologic nystagmus, which direction will fast phase be?
Away from the side of the lesion
Though rare in animals, what is the main clinical sign of bilateral peripheral vestibular system disease?
Wide crouching stance w/wide swaying of the head
Can you determine the side of the lesion with central vestibular system disease?
No
With central vestibular disease, conscious proprioceptive deficits or hemiparesis can be seen on which side of the lesion?
Same side
What are clinical signs of Horner’s syndrome?
Miosis, ptosis, enophthalmos
Does Horner’s syndrome indicate central or peripheral vestibular disease?
Peripheral
Conscious proprioceptive deficits indicate a lesion in which region of the CNS?
Brainstem
Does multiple cranial nerve deficits usually indicate central or peripheral vestibular disease?
Central
The presence of a head tremor indicates _____ disease
Cerebellar
Does altered mentation indicate central or peripheral nervous disease?
Central
What type of lesions typically cause spontaneous nystagmus w/horizontal and rotational components?
Acute peripheral lesions
What type of lesions can cause purely vertical, horizontal, or rotational nystagmus?
Central lesions
What ancillary tests can be done once you localize a lesion to the peripheral nervous system?
Otoscopic exam, typmanic bulla rads, thyroid test, BAER/CT
What ancillary tests can be done once you localize a lesion to the central nervous system?
CT/MRI, CSF analysis
Which disease is often peracute without apparent cause and will start to improve within several days w/o tx?
Idiopathic vestibular syndrome
What clinical sign of idiopathic vestibular syndrome doesn’t usually resolve completely?
Head tilt
How do you dx idiopathic vestibular syndrome?
Dx of exclusion
What is a very common cause of vestibular disease in most species?
Otitis media and interna
What is otitis media/interna commonly treated with?
Enrofloxacin
How long should abx therapy to treat otitis continue?
Up to 8wk
What abx is contraindicated for otitis?
Aminoglycosides
How do you treat otitis media/interna that is refractory to medical therapy?
TECA-BO
What is the most common substance implicated in ototoxicity?
Chlorhexadine
What abx can cause ototoxicity?
Aminoglycosides
Where do nasopharyngeal polyps most commonly appear in cats?
In the typanic cavity
How does hypothyroidism cause vestibular disease?
Polyneuropathy with vestibular signs
How can a tumor cause central vestibular signs?
Cerebella-pontine angle, brainstem compression, brain herniation
Which abx toxicity can cause central vestibular system disease?
Metronidazole >30mg/kg/day
How does Metronidazole toxicity often present?
Acute onset, even in patients with chronic treatment
Often vestibular w/other CNS signs as part of multifocal brain disease
Inflammatory brain disease
Generally sudden onset that may be idiopathic or 2* to hypertension, neoplasia, endocrinopathies, or sepsis
Cerebrovascular disease
Most commonly occurs from overcooked meat diets or all fish diets
Thiamine deficiency
Three ducts at right angles to each other and each filled w/perilymph
Semicircular ducts
What turns perilymph movement into nerve conduction?
Ampulla
What are the macula of the inner ear?
Utriculus and sacculus
What do macula do?
Detect movement in the dorsal and sagittal planes
What do the ampulla do?
Detects angular movement and acceleration
Where in the brainstem does the central vestibular apparatus live?
Cranial aspect of medulla
What are signs of vestibular ataxia?
Circling, leaning, falling, rolling
CP deficits, vertical or changing nystagmus, CN signs other than Horner’s and facial nerve paralysis are associated with which type of vestibular disease?
Central
Ear polyps are relatively common in young _____
Cats
Are inflammatory causes of central vestibular disease more common in cats or dogs?
Dogs (granulomatous meningioencephalitis and necrotizing encephalitis - aka sterile inflammatory dz)
What are the most common causes of infectious central vestibular disease in cats?
FIP, cryptococcus, toxoplasmosis
What is the most common toxic cause of central vestibular disease?
Metronidazole
What is in fish that causes a thiamine deficiency?
Thiaminase
With central vestibular disease, what type of nystagmus will you have?
Vertical
Conscious proprioceptive deficits are assoc. w/which type of vestibular disease?
Central
Head tilt, nystagmus, and circling will be in which direction with respect to the lesion?
Toward the lesion
With paradoxical vestibular disease, which direction will clinicals signs be w/respect to the lesion?
Away from the lesion
If you see peripheral signs in one direction but central signs in the other, where is the lesion?
Lesion is on side of central deficits
When a lesion causes vestibular signs and CP deficits, where is the lesion?
Same side as CP deficits
