2. Investigations of vestibular system involves two categories:
They are:
Clinical methods
• Spontaneous Nystagmus
• Fistula test
• Romberg test
• Gait
• Past-pointing and falling
• Hallpike-manoeuvre (positional test)
• Test of cerebellar dysfunction
Laboratory
methods
1. Caloric Test
2. Electronystagmography
3. Optokinetic Test
4. Rotation Test
5. Posturography
3. SPONTANEOUS NYSTAGMUS
NYSTAGMUS – defined as involuntary, rhythmical, oscillatory movement
of eyes
it is an important sign in evaluation of vestibular system
It can be either horizontal /vertical/rotatory nystagmus
VESTIBULAR NYSTAGMUS
It has 2 components
SLOW FAST
The direction of this
component indicates the
direction of the
nystagmus
4. Intensity of nystagmus is indicated by its degree.
AS PER ALEXANDER’S LAW,
This law may not hold true in case of nystagmus of central region
1st DEGREE
2nd DEGREE
3rd DEGREE
It is weak nystagmus and is
present when patient looks in
the direction of fast component
It is stronger than 1st degree and
is present when patient looks
straight ahead
It is stronger than the 2nd degree
and is present when the patient
looks in the direction of the slow
component
5. PROCEDURE:
Patient is seated in front of the examiner/lie in supine position on
bed
Examiner keeps his finger 30cm away from patient’s eye in central
position
Examiner moves his finger to the right, left, up or down
( but not moving anytime more than 30˚ from the central position
to avoid gaze nystagmus)
INDICATION:
PRESENCE of spontaneous nystagmus is indicative of ORGANIC
LESIONS
Tone of imbalance of vestibulo-ocular reflux
6. VESTIBULAR NYSTAGMUS consists of two types of lesions:
central
Vestibular nuclei,
Brainstem,
cerebellum
Due to lesion in
central neural
pathway
peripheral
Due to lesion of
labyrinth/viii
nerve
Irritative lesions(Sensory
labyrinth)
Nystagmus is on
the side of lesion
Paretic lesions
Nystagmus is on
the opposite side
Includes:
Purulent labyrinthitis
Trauma to labyrinth
Section of viii nerve
7. Peripheral nystagmus – is suppressed by optic fixation
Enhanced by darkness and use of FRENZEL GLASS
Central nystagmus is not supressed by optic fixation
TORSIONAL NYSTAGMUS – Indicates lesion of brainstem/vestibular nuclei
E.g.. SYRINGOMYELIA
VERTICAL DOWNBEAT NYSTAGMUS – Lesion is at cranio-cervical region
Arnold-chiari malformation/degenerative lesion of
cerebellum
VERTICAL UPBEAT NYSTAGMUS – Lesion at the junction of
pons and medulla/pons and midbrain
PENDULAR NYSTAGMUS – congenital/acquired
E.g.. Multiple sclerosis
May also be disconjugate
Via., vertical in one eye
and horizontal in other.
8.
9.
10. PERIPHERAL CENTRAL
LATENCY 2-20 s No latency
DURATION Less than 1 min More than 1 min
DIRECTION OF NYSTAGMUS Direction fixed towards the
under most ear
Direction changing
FATIGUABILITY fatiguable nonfatiguable
ACCOMPANYING SYMPTOMS Severe vertigo none or slight
DIFFERENCES IN NYSTAGMUS OF PERIPHERAL N CENTRAL LESIONS
11. FISTULA TEST
PRINCIPLE:
Induce NYSTAGMUS
Pressure changes in external auditory canal are produced
These changes are transmitted to the labyrinth
Stimulation of the labyrinth
Production of NYSTAGMUS and VERTIGO
12. PROCEDURE:
Apply intermittent pressure on tragus
OR
By using Siegel's speculum
INDICATIONS:
IN NORMAL PERSON: NEGATIVE
because pressure changes in external auditory canal can’t be
transmitted to labyrinth
ABNORMALITY: POSITIVE
Erosion of horizontal semi-circular canal- cholesteatoma
Surgically created window in horizontal canal- fenestration
operation
Abnormal opening in oval window- poststapedectomy fistula
Abnormal opening in round window- rupture of round window
membrane
ALSO INDICATES THAT LABYRINTH IS STILL FUNCTIONAL
14. FALSE NEGATIVE FISTULA TEST :
IN CHOLESTEATOMA: it covers the site of fistula
and it doesn’t allow pressure changes to be
transmitted to the labyrinth
IN LABYRINTH DEAD
FALSE POSITIVE FISTULA TEST :
Means +ve test without presence of fistula
It is seen in two conditions : 1.congenital syphilis
2.Meniere’s disease.
Congenital syphilis: stapes footplate is hypermobile
Meniere’s disease: due to fibrous bands connecting
utricular macula to the stapes
footplate.
15. ROMBERG TEST
PROCEDURE :
Patient is asked to stand with feet together and arms by side with eyes first
open and then closed.
With eyes open : patient can still compensates the balance
With eyes closed : patient cant compensate –Here VESTIBULAR SYSTEM is at
MORE DISADVANTAGE
If patient perform this test without sway then SHARPENED ROMBERG TEST is
performed.
Peripheral:
Patient sways to
side of lesion
Central:
instability
PROCEDURE:
Patient is asked to stand
with one heel in front of
toes and arms folded across
the chest.
Inability to perform this test
Indicates vestibular impairment
18. GAIT
PROCEDURE:
Patient walks along a straight line to a fixed point first with
eyes opened and then closed.
In the case of uncompensated lesion of peripheral vestibular system,
with eyes closed
Patient deviates to affected side
19. PAST-POINTING AND FALLING
PAST-POINTING
FALLING
SLOW COMPONENT OF NYSTAGMUS
E.g. In ACUTE VESTIBULAR FAILURE on RIGHT side
All fall in the same
direction
NYSTAGMUS – on left side
Past pointing
Falling
On right
side
i.e. towards the
side of the slow
component
20. PROCEDURE:
First, the patient is asked to touch his/her index finger to the
examiner’s index finger with the eyes open
Next, the same is repeated with the eyes closed
If abnormality is present then the patient cannot elicit the
procedure with his/her eyes closed.
23. HALLPIKE MANOEUVRE
(POSITIONAL TEST)
USES: 1. when patient complains of vertigo in head position
2. helps to differentiate a peripheral from a central lesion.
METHOD:
Patient sits in the couch
Examiner holds the patient’s head, turns it 45˚ to the right and then places the
patient in a supine position so that his head hangs 30˚ below the horizontal.
Patient’s eyes are observed for nystagmus
The test is repeated with head turned to left and then again in straight head-
hanging position .
Four parameters are observed: 1. Latency
2. duration
3. direction
4. fatiguability
24.
25.
26. In benign paroxysmal positional vertigo
Nystagmus appears after latency : 2-20s
duration : less than 1 min
direction : one i.e. towards the ear that is
under most
On repetition – nystagmus may be elicited but lasts for a shorter period.
On
subsequent
repetition
Nystagmus
disappears
altogether
NYSTAGMUS IS
FATIGUABLE
27.
28. IN CENTRAL LESIONS Tumours of 4th ventricle
Cerebellum
Temporal lobe
Multiple sclerosis
Vertibrobasilar insufficiency
or
Raised intracranial tension
Nystagmus is produced immediately
as soon as the head is in critical
position
No latency
Duration: lasts as long as head is in
that critical position
Direction: changes
Fatiguability: nonfatiguable
29. TEST OF CEREBELLAR DYSFUNCTION
For cerebellar diseases – all cases of giddiness should be tested.
Cerebellar
diseases
MIDLINE DISEASE OF CEREBELLUM
CAUSES:
1. Wide base gait
2. Falling in any direction
3. Inability to make sudden turns
while walking
4. Truncal ataxia
CEREBELLAR HEMISPHERE CAUSES:
1. Asynergia(abn finger-nose
test)
2. Dysmetria(inability to control
range of motion)
3. Adiadochokinesia (inability to
perform rapid alternating
movements)
4. Rebound phenomenon
(inability to control
movement of extremity when
opposing forceful restraint is
suddenly released)
30. Nystagmus observed in cerebellar diseases either in
hemisphere or midline diseases include
GAZE
EVOKED NYSTAGMUS
REBOUND NYSTAGMUS
ABNORMAL OPTOKINETIC NYSTAGMUS
