Vestibular System Flashcards
What percentage of dizziness affects people over 70?
30-40%
What are some causes of dizziness
- Drug interactions
- Orthostatic hypotension
- Cardiac disorders
- Somatosensory loss in lower extremeties (MS or diabetes
- VBI
- Cerebral pathology
- Migraine
- Cervical spine pathology
- Vestibular system
Subjective assessment for dizziness, what should you hunt for?
- Cardiac
- Drug interactions
- Orthostatic hypotention
- Anxienty disorder
- Somatosensory loss
- VBI
- Central
What is the role of the vestibular system
Sensing and percieving self motion
Orientation to vertical
Controlling the centre of mass (balance)
Stabilising the head.
Vestibular apparatus anatomy- Where is it located, and what are its features?
Located just behind the cochlear.
It has 3 semicircular canals (Anterior, posterior, horizontal) Crystis ampularis- All controls angular acceleration, side to side,
2 otholith organs (Utricle and Saccule- They control up down/forward back)
Semicircular Canals (SCC’s). What is the name of the part that moves inside? And what nerve does it activate?
Cupula is within the ampulla and activates the vestibular nerve CN 8.
SSC- What causes excitation and inhibition
Deflection of stereocilia towards kinocilium = excite, away = inhibtion
SSC- What perpendicular movements activate what canal?
- Pitch plane
- Roll plane
- Yaw plane
Pitch plane- nodding = verticals
Roll plane, tilting= verticals
Yaw plane, shaking head= horizontal/lateral
Canal excited by head movement occurs in the direction it moved- True/False?
True
How are the SCC’s aligned?
In coplanar pairs, aligned with ocular muscles
- Horizontal pairs, LARP (Left Anterior, Right Posterior), RALP
Otholith Organs- What are the components and whats the sensory organ within?
Utricle and saccule- Utricle is horizontal and saccule vertical (Stairs= saccule). Macula is the sensory organ. Works the same as rest of SSC, except has otoconia on top of hairs
What is vertigo?
Developed from assymetrical vestibular activity
Give a run down of how sensory input is processed
Sensory input is whereby the SSC and otholith organs take vestibular information, which way are we moving, what speed? And then sent to the central processors which are the vestibular nuclei complex (Pons and extends through to medulla). Cerebellum serves as a adapative processor. Monitors and readjusts output. Results in motor output. Eye and postural movements.
Vestibulo-Ocular Reflex (VOR) What is it?
Mechanisms by which eyes move in equal and opposite direction of head movement.
Common symptoms of vestibular deficits
Nausea
Vertigo
Visual impairments
Gait/balance impairments
Nystagmus
What is vertigo?
An illusion of movement
- Usually rotatory in nature
Nystagmus- Different types?
Gaze evoked
Positional- BPPV
Post rotational
Spontaneous
Nystagmus- What is it?
Slow phase followed by a quick phase back to target. Name by the quick phase
BPPV- Benign Paroxysmal Positional Vertigo. What test for it?
Hallpike-Dix Test
Where do displaced Otoconia usually end up?
In the posterior semi-circular canal
Unilaterlal Vestibular Hypofunction- What is it?
One side doesn’t work. Nerve inflamed or disrrupted. Difficulty stabilising gaze.
- Nystagmus, oscillopsia, blurred vision, balance and gait impairment
With Unilateral Vesitvbular Hypofunction, what side does the nystagmus occur?
Eyes move away from the side of the lesion
Vestibular Subject Assessment- What do you look for?
Severeity of symptoms
Frequency
Nature- How do they describe it?
Aggravating/relieving factors
Medical history
Motion sensitivity
General history- Is this normal? Is it worse now, how long did it last? HX of cancer, osteoporosis, arthirtis
Vestibular Assessment- Objective
Balance
Gait- TIme gait test
Neurological signs
Observe aggravating movement- can you reproduce
Oculomotor examination
Specific tests
