Neuropathology of the Inner Ear Flashcards
What are the central (ascending) pathways ?
a complex network of cells in the brain that receive the signal from the ear sensory cells
What are the auditory reflexes (descending pathways)
the motor output of the auditory system. The idea of turning the head via neck muscles towards or away from sounds
What is the BAER and what is it used for.
Brainstem Auditory Evoked Response
used for investigating deafness
results appear on a graph as the 6 major wave forms. no perception of hearing at all appears as a flatline
What are the two types of deafness ?
conductive –> obstruction of the passage of sound or mechanical injury
sensorineural –> an abnormality in the receptor organ or neurons of the cochlear division of CV VIII, may be congenital or acquired
What is the vestibular disease and its function
It is made up of the extensor muscles, extra-ocular eye muscles, 2 receptors (crista ampulla and macula), sensory hair cells
maintains the body in equilibrium by …
- maintaining eye position despite head
- maintaining body position relative to the horizon
- maintaining body posture relative to the horizon
it works to regulate movement, keep objects in visual focus and respond to visual information.
Describe the CS of vestibular syndrome
falling, rolling, tilting of the head, circling, nystagmus, ataxia and vomiting
What is the difference between central and peripheral vestibular disease?
Central –> lesion of the brainstem.
- dull demeanour
- very quiet
- not correcting foot position
- tilting the head
- staggering to the side
Peripheral –> lesion of the neurological components or anatomic components
- walk just fine
- slight head tilt (spontaneously)
- spontaneous nystagmus
- mentally alert
Define paradoxical vestibular disease
a subset. the problem is inside the cerebellum, causing a loss of inhibitory influence - the animal leans the wrong way (away from the lesion instead of towards it)
Define bilateral vestibular disease
caused by metabolic, toxic or anomalous issues, leading to wide searching head movements with low body carriage