Week 2 Intro to Dizziness Flashcards
What is Dizziness?
A descriptive sensory impairment reflecting on the patients perception
- non-specific term that can mean a lot of things
- Patients may describe it as “light headedness, spinning, feeling drunk, feeling like they might faint, being pulled to one side, floating, or giddy”
What causes dizziness?
- Drug interactions
- Orthostatic hypotension
- Cardiac disorders
- Anxiety - (agoraphobia)
- Somatosensory loss in the lower extremities
- VBI (Vertebra Basilar Insufficiency)
- Cerebral Pathology - including stroke
- Migraine
- Multisensory Dizziness
- Cervical spine pathology
- Vestibular system pathology
What is the role of the vestibular system?
Its functions are:
- Sensing and perceiving self motion
- orientation to vertical - the vestibular system is our true reference in relation to gravity
- controlling the centre of mass
- stabilising head
What are the three semicircular canals and what type of acceleration do they detect?
- Anterior Canal
- Posterior Canal
- Horizontal Canal
The semicircular canals sense angular rotation or rotational movement (e.g. nodding head side to side)
What are the 2 Otolith organs and what type of acceleration do they detect?
- Utricle - senses the horizontal plane
- Saccule - senses the vertical plane
The otolith organs give position in relation to gravity or static head tilt. (they sense linear acceleration, e.g. forward, backward, up, and down)
Hair cells in the semicircular canals synapse with neurons of ________________
- Vestibular Nerve (Branch 8)
Vestibulocochlear nerve
In the semicircular canals, a deflection of the stereocilia TOWARD the kinocilium causes _________
- excitation
In the semicircular canals, a deflection of the stereocilia AWAY from the kinocilium causes
- inhibition
What is the sensory organ of the Otolith Organs?
- Macula
What is Otoconia
calcium particles/crystals that sit on top of the Utricle and Saccule
- they are very sensitive to gravity
What is the mechanism by which eyes move in an equal and opposite direction to head motion?
Vestibular Ocular Reflex (VOR)
- this acts to keep what we see stable
- prevents our visual world from bouncing or jumping around whenver you move your head
- - It can be disrupted by a loss of function on one side
What is vertigo?
- an illusion of movement and is usually rotatory in nature
- is often associated with autonomic symptoms (usually accompanied by nausea and sweating)
What is Nystagmus?
- rapid, uncontrolled eye movement
- “characterised by the combination of a slow phase then a quick phase to bring the retina back to the target
- “occurs when the SCCs are stimulated but the head is not in motion
Note: The Direction of nystagmus is defined by the direction of the quick phase.
A type of Physiological Nystgamus were it is induced by looking at a moving visual stimuli…
- Opticokinetic nystagmus
A type of Physiological Nystgamus were it is induced by spinning around and then stopping…
- Postrotatory nystagmus
What is Benign Paroxysmal Positional Vertigo (BPPV)?
- Pathology: when the otoconia from the utricle becomes dislodged
- Common on TBI population and is associated with Vestibular Neuronitis and head trauma
- Diagnosis is by typical history and confirmation of Hallpike-Dix test
What is Unilateral Vestibular Hypofunction/loss?
- One side does not work (nerve pathway disrupted)
- The CNS has to make sense of the new situation and in the interim, the patient experiences dizziness
- In the acute phase, difficulty stabilising gaze:
- Nystagmus
- Oscillopsia - visual world moves with every head movement
- Blurred vision
- Balance and gait impairment
- Fear of falling
- vertigo with head movement
- autonomic symptoms
If both vestibular systems do not work…
- It’s common cause is a recent course of IV antibiotics
- Symptoms: Oscillopsia, ataxic gait, postural disturbance - Patients DO NOT report Vertigo
- We handle their balance by teaching them compensatory systems
According to Hall et al. The success of vestibular rehabilitation depends on….
- accurate identification of the vestibular impairment
- Application of specific exercise appropriate for that disorder
Note: Exercise must be customised
- Early intervention
- A little and often
- Encourage head movement
- may exacerbate symptoms so you should work within tolerable limits
- must have a goal and is progressive
