Vestibular Function
When the head tilts to the left what side has increased action potentials? and in what organ?
Left
the Semicircular canals
What part of the inner ear is responsible for hearing?
the cochlea
What phase is nystagmus described with?
The Fast phase (the hypothetical way the brain thinks the head is turning)
What drug is commonly associated with aquired deafness?
Aminoglycosides (also causes nephrotoxicity)
What is the difference between vestibular disease nausea and motion sickness?
A dog is right next to a firework when it goes off and now doesn't listen to your comands. What happened?
the hair cells became damaged and became unable to fire action potentials to CNVIII
What are the 3 types of ataxia and how do you differentiate between them?
Spinal/Proprioceptive
Vestibular
Cerebellar
What Dogs have a prediliction for deafness? and what is the easiest way to check if an animal is deaf?
Dalmation, Merle colorations and white mutations
Create a loud noise and see how they react
When a dog is leaning to the right is are the action potentials on the left or right side increasing and what corrects the animals posture?
they are increasing on the right and and the anti-gravity muscles on the right side push the dog upright
When frequency increases what to we hear increase?
Pitch
A dog is constantly circling left what side is there a perceived increase in action potentials?
A young heifer is found in the field having trouble walking and with a head tilt. What are your top differentials?
otitis internal
Listeriosis
A dog accelerates down a narrow path in a straight line what organ is responsible for maintaining his balance? and describe the process.
The vestibule
The hair cells embeded in the maculae bend in the opposite direction of acceleration due to the gelatinous otolithic membrane. the hair cells gates open increasing action potentials to CNVIII.
Even though sound travels bilaterally it arrives at the auditory cortex faster on the side it originated from.
How do you know if Vestibular ataxia is from the is Peripheral or the Brainstem?
If other CN (exception CNV) and mentation are effected then it originates from the brainstem also if there is vertical/rotary nystagmus
What syndrome is commonly associated with otitis media and interna
Horners syndrome: Facial nerve paralysis
Describe the vestibulo-ocular reflex (physiological nystagmus) and what CN are involved?
CN VIII (vestibulocochlear), III (oculomotor), IV (trochlear), VI (abducent)
Describe the path of sound through the ear?
The external ear directs sound to the ear canal. the sound waves hit the ear drum causing it to vibrate. The ossicles transmit the sound to the oval window and the oval window causes pressure in the lymph fluid of the cochlea. The spiral organ then vibrates up and down and the hair cells bend against the tectorial membrane
A dog presents to the clinic with a head tilt to the left and circling to the left on exam you find nystagmus to the right with exaggerate postural reactions on the right side. Where is the lesion located?
the right side of the cerebellum
What the most common cause of peripheral vestibular diease with acute onset in an older dog?
Idiopathic vestibular disease