The vestibular system is responsible for the maintenance of balance in human beings. The basic anatomy consists of bony structures called bony labyrinthine and membranous labyrinthine. The receptors consists of utricle and saccule. The fluid filled within the internal ear called endolymph. The basic physiology of macula, cristae and supporting structures are explained in the presentation.
This presentation deals with the various physical tests used to assess the vestibular system and which can be used as an outcome measures like:
a. Caloric Test
b. Dizziness Handicap Inventory scale
c. Head Impulse Test
d. Head shaking induces nystagmus
e. Dix- Hallpike Test
f. Dynamic Visual Acuity Test
g. Rotational Chair Test
h. Romberg Test
2. ANATOMY
Encased in bony tubules called bony labyrinth.
Chambers within bony labyrinth forming functional
part called membranous labyrinth.
Consists of 2 parts:
1. Cochlea
2. 3 semicircular canals
3. 2 chambers utricle and saccule.
Cochlea supplied by cochlear nerve.
Utricle and saccule are sensitive to orientation of
head to gravity and motion.
Utricle and saccule have 2 types of receptors:
1. Peripheral vestibular receptors
2. Central vestibular receptors
Important factor is endolymph.
3.
4. PHYSIOLOGY
Cristae- receptors for semicircular canals.
Saccule- movement of head in vertical plane.
Semicircular canals- rotational movement in 3
planes.
Movement of endolymph detected by hair cells.
Cristae – kinetic balance receptors.
Maculae- static balance receptors.
Impulses travel with respect to stereocilia and
kinocilium.
Connected to :
1. Eye muscles
2. Spinal cord
3. Autonomic centers
4. Cerebral cortex
5.
6. FUNCTIONS
Sensory processing of head motion.
Coordination of visual and postural
movements.
Maintainence of equillibrium.
Modulation of self , body and self awareness.
Integration of various movements and
balance related parameters.
Adaptation to specific locomotor patterns.
Perception accuracy.
Stabilization of visual field.
Presence of Static and dynamic balance
receptors.
7.
8. PHYSICAL TESTS
Caloric test
Dizziness handicap inventory
Head impulse test
Head shaking induced
nystagmus test
Dix- hallpike test
Dynamic visual acuity test
Rotational chair test
Romberg test
9. Caloric test
Test for vestibulo-occular reflex.
Tests the lateral semicircular canal alone
Uses hot water and cold water simultaneously.
Water irrigated into external auditory canal.
Warm water at 44degrees mimics head turn to
ipsilateral side.
Cold water at 30 degrees or below mimics
head turn to contraleteral side.
Dysfunction- absent reactive eye movement.
10. DIZZINESS HANDICAP
INVENTORY
A questionnaire with 25
questions subgrouped under
functional, emotional and
physical components.
Excellent test retest reliability.
Quantification of patient’s
perception and dysequillibrium.
Self reported measures.
11. HEAD IMPULSE TEST
To examine semicircular canal function.
Cervical range should be known.
Patient should fixate on a target.
Head flexed at 30 degrees.
Small amplitude, moderate velocity and
high acceleration angular impulse is given
in an unpredictable direction.
Corrective sequade to reposition eyes on
target.
12. HEAD SHAKING INDUCED
NYSTAGMUS TEST
Useful in diagnosis of unilateral
peripheral vestibular defect.
Eyes of patient are closed.
Head flexion is 30 degrees.
Horizontal oscillation for 20 cycles
at frequency of 2 reps/second.
Nystagmus to be checked on eye
opening.
Seen in patients with acoustic
neuroma.
13. DIX- HALLPIKE TEST
Commonly used to identify BPPV
benign paroxysmal positional vertigo.
Otoconia get displaced into
semicircular canal.
Starting from long sitting position.
Head rotated 45 degrees to one side.
Supine with head extended beyond
horizontal 30 degrees.
Direction of nystagmus is unique to
involved semicircular canal.
14. DYNAMIC VISUAL ACUITY TEST
Measurement of visual acuity during
horizontal movement of the head.
Static visual acuity determined first.
Identified with smooth persuit eye
movement.
Patient asked to read a lighthouse
EIDRS( Early treatment diabetic
retinopathy study) .
Horizontal rotation of head at a
frequency of 2 Hz.
15. ROTATIONAL CHAIR TEST
Measures dizziness while being
turned slowly in a motorized
chair.
Patients with inner ear disease
becomes less dizzy.
Optokinetic test measures
dizziness by viewing of moving
stripes.
Diagnosis of bilateral vestibular
loss.
16. ROMBERG TEST
Patient stands with feet close
together and arms open by side with
first eyes open and then eyes
closed.
Eyes staring at an object for 3
minutes.
Then eyes closed and sway is seen.
Maximum sway is measured.
Sharpened romberg test includes
standing with one toe forward of the
other and hands folded at the chest
level.