Vestibular Disease Flashcards
How does vestibular disease lead to head tilt? Is it ipsilateral or contralateral to the lesion?
The vestibular system stimulates extensors and inhibits flexors. The abnormal side will be “pushed” by the normal side - ipsilateral to the side of the lesion
What are some characteristics of vestibular ataxia?
- wide-based stance
- loss of balance
- circling to one side (small and erratic)
What’s the difference between “circling” with vestibular vs forebrain disease?
Vestibular circling = small and erratic, versus forebrain circling = large and smooth
In peripheral pathological nystagmus, which side is lesions?
The “fast phase” is AWAY from the side of the lesion
What are some signs of central vestibular involvement re: nystagmus?
Vertical nystagmus or fast phase TOWARDS to side of the lesion
(a slower resting nystagmus rate can also be = central lesion)
What kind of strabismus is noted with vestibular disease?
ventral deviation of the eye on the side of the lesion when the head is extended (positional strabismus)
What CN can be involved in vestibular disease?
- Facial nerve paralysis: due to proximity, VN VII (facial) can be affected (both in the brainstem and by inner ear)
- Horner’s Syndrome: due to proximity of the sympathetic innervation of the eye traveling close to the inner ear (usually seen in peripheral vestibular disease)
Is a change in mentation expected with vestibular disease?
- Patients may be anxious, not necessarily depressed
- however, in central vestibular disease, it can affect the ARAS (ascending reticular activating system) responsible for normal alertness
What’s paradoxical vestibular syndrome?
When the head tilt is AWAY from the side of the lesion.
- happens when there is cerebellar involvement –> cerebellum = inhibitory, lack of inhibition will “push” the body away
- will also see ipsilateral paresis, hypermetria, GP deficits, or CN deficits
Where could the lesion be in paradoxical vestibular syndrome?
- flocculonodular lobe of the cerebellum
- caudal cerebellar peduncle
- rostral/ medial vestibular nuclei in the medulla
Is vomiting/nausea associated with central or peripheral vestibular disease?
It can happen with both, though vomiting seems to be more common with peripheral vestibular disease
What are some causes of peripheral vestibular disease?
- otitis media/interna
- nasopharyngeal polyps
- idiopathic (Cuterebra migration in cats! tx not recommended or necessary)
- hypothyroid
- others (congenital, cancer), trigeminal NST
How does hypothyroidism lead to peripheral vestibular disease?
- may be due to deficit in energy metabolism –> disturbance in axonal transport
- possible segmental demyelination
What are some causes of central vestibular disease?
- inflammatory
- infectious: canine distemper virus, FIP, Rocky Mtn spotted fever, ehrlichiosis, cryptococcosis, bacterial (from ear infection)
- non-infectious: MEU (meningioencephalitits of unknown cause), GME/ NME/ NLE
- cancer: choroid plexus in the 4th ventricle, trigeminal nerve, meningioma
- vascular: cerebrovascular accident (CVA)/ stroke; sudden onset, non progressive.
- toxicosis (metronidazole in dogs)
- others (thiamine deficiency, anomaly, trauma, degenerative diseases, postanesthetic vestibular syndrome in cats)
What are some concurrent illness that can lead to a stroke?
Dogs:
- hyperadrenocorticism
- chronic renal failure
Cats:
- liver pathology
- nephritis
