2. Balance in humans is maintained by the
integration within the central nervous
system (CNS) of information from the
vestibular labyrinths, the eyes and the
proprioceptive systems. Damage to any of
these three systems may lead to
dyscquilibrium.
Assessment of dizziness must include
evaluation of each of these three peripheral
systems and of the ‘central processing unit
it self.
3.
4. ANATOMY OF THE VESTIBULAR
APPARATUS
THE INTERNAL EAR OF THE LABYRINTH
1) Bony labyrinth
A) Vestibule
B) Semicirular Canals Lateral, Posterior &
Superior
C) Cochlea
2) Membranous Labyrinth
10. CENTRALVESTIBULAR CONNECTIONS
Afferents
1. Peripheral vestibular receptors (scc, utricle and
saccule)
2. Cerebellum
3. Reticular formation
4. Spiral Cord
5. Contralateral vestibular nuclei
Efferents
1. Nuclei of CN III IV VI (Vestibulo ocular reflexes)
2. Motor part of spinal cord (vestibulo spinal fibres)
3. Cerebellum (Vestibulo cerebellar fibres)
4. Autonomic nervous system
5. Vestibular nuclei of opposite side.
6. Cerebral Cortex (temporal lobe.)
11. PHYSIOLOGY (VESTIBULAR SYSTEM)
A) Peripheral SCC, utricle & saccule
B)Central made up of nuclei and fibre tracts in CNS to
integrate vestibular impulses with other systems to
maintain body balance.
Semi circular Canals :
Respond to angular acceleration and deceleration
Three canals lie at right angles to each other
One which lies at right angles to the axis rotation is
stimulated the most.
Stimulus to SCC is flow of endolymp which displaces
the cupula.
The quick component is always opposite to the
direction of flow of endolymph.
12.
13. UTRICLE AND SACCULE
Utricle stimulated by linear acceleration and
deceleration or gravitational pull during head
tilts.
Sensory hair cells of macula in different planes
are stimulated during head tilts.
Function of saccule is similar
Cerebellum further coordinates muscle
movements in their rate,range,
force duration and thus helps in
maintenance of balance.
14. ASSESSMENT OF VESTIBULAR FUNCTIONS
1) Clinical History A full general medical
history, cardiovascular & neurological. Specific
aspects of the digginess or imbalance should
be sought.
a) Character of Symptoms (vertigo or digginess)
b) Time, course of dysequilibrium
c) Associated Symptoms hearing loss, tinnitus
palpitation
d) Precipitating factors Head, body and eye
movements
e) Drug history Gentamicin, PCM, Diuretics,
Cisplatinum etc.
2) Clinical Test
3) Laboratory Test
15. CLINICAL TEST
1) Spontaneous nystagmus it is an important sign
Defn Invountary rhythimical, oscillatroy movement
of eyes.
Horizontal, vertical, rotatory
Slow and a fast component
Direction indicated by direction of fast component
Intensity indicated by degree
Degree of nystagmus
1st degree Nystagmus in direction of fast component
2nd degree When patient looks straight ahead.
3rd degree In the direction of slow component.
Vestibular or peripheral, hystagmus due to lestion
of labyrinth or VIIIth nv.
Central nystagmus lesion in central pathways
vestubular nuclei, brainstem, cerebellum.
16. 2) FISTULA TEST
Induction of nystagmus by pressure changes in
the external canal.
Stimulation of labyrinth results in nystagmus
and vertigo.
Performed by intermittent pressure on tragus
or by siegel’s speculum.
Normally test is negative.
Positive test implies labyrinth is functioning
False negative cholesteatoma covers site of
fistula.
False positive congenital syphilis and
Meniere’s disease (Hennebert’s sign)
17. 3) ROMBERG TEST
Stands with feet together, arms by side with eyes first
open and then closed.
Peripheral lesions sways to side of lesion.
Central lesions Shows instability.
Sharpened Rombery test if patient performs above test
without sway. Inability to perform indicates vestibular
impairment.
4) GAIT
Asked to walk along a straight line to a fixed point first
with eyes open and then closed.
Uncomplensated lesion of peripheral vestibular system
with eyes closed, deviates to affected side.
5) Past pointing and falling
Acute vestibular failure right side.
Nystagmus to left, past pointing and falling to right
side.
19. Peripheral Central
1. Latency 2-20 Seconds No Latency
2. Duration Less than 1 min More than 1 min
3. Direction of
nystamus
Fixed to the
undermost ear
Changing
4. Fatiguability Fatiguable Non- fatiguable
5. Accompanying
Symptoms
Servere vertigo Non or slight
20. TEST OF CEREBELLAR DYSFUCTION
Cerebellar Hemisphere
Asysnergia (Abnormal finger nose test)
Dysmetria (unable to control range of motion)
Adiadokokinesia
Rebound phenomenon (unable to control movement of
extremity when opposing force, suddenly released)
Cerebellar midline disease
I. Wide base gait
II. Falling in any direction
III. Inability to make sudden turns
IV. Truncal ataxia
Nystagmus gaze evoked, rebound and opto kinetic.
21. LABORATORY TESTS
Caloric test
Induction of nystagmus by thermal stimulation of
vestibular system
Advantage, each labyrinth tested separately
Ladyrinthine origin of vertigo if qualitatively similar to
the type experienced, during episodes of vertigo
a. Modified kobrak tests
b. Fitzgerald hallpike test (bithermal caloric test)
22.
23. Canal paresis
L30 +L44 X 100
Response from Left ear =L30+L44 + R30+R44
R30 +R44 X 100
Response from Right ear =L30+L44 + R30+R44
Seen in Meniere’s ds, Acoustic neuroma,
Post Labyrinthectomy or Vestibular nv section
24. Directional Preponderance
Takes into consideration the duration of nystagmus to the
right or left irrespective of whether it is elicited from rt or
left labyrinth
If nystagmus is 25-30% or more on oneside than other it is directional pre
ponderance
25. COLD AIR CALORIC TEST
Done if peforated tympanic membrane
Dundas grant tube used
Only a rough qualitative test.
ELECTRONYSTAGMOGRAPHY
Corneo retinal potentials recorded by electrodes
placed around eyes
Detects nystagmus not seen with naked eye
Keeps permanent record of nystagmus.
26.
27. OPTOKINETIC TEST
Normally produes nystamus with slow component in
the direction of moving stripes
Optokintic abnormality seen in brain stem and
cerebral hemisphere lesion.
ROTATION TEST
Barany’s chair, 10 turns in 20 secs.
Normally there is nystagmus for 25-40 secs.
Can be done in congenital abnormality of external ear
canal where caloric best not possible
Disadvantage, both labyrinths are simultaneously
stimulated
28. GALVANIC TEST
Only test to differentiate end organ lesion from that of
vestibular nv.
Normally person sways towards the side of anodal
current
POSTUROGRAPHY
Measures postural stability
Maintenace of posture depends on 3 sensory inputs
visual, vestibular and somatosensory
AUDITORY FUNCTION TEST
Close relationship, both anatomically and
physiologically, between the vestibular and auditory
divisions of VIII the nv.
Precise site of lesions causing vestibular disturbance.