ASSESSMENTS OF VESTIBULAR

SYSTEMUrmila Rawat

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 Test2. Electronystagmogra

phy3. Optokinetic Test4. Rotation Test5. Posturography

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

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

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 LESIONSTone of imbalance of vestibulo-ocular reflux

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 labyrinthitisTrauma to labyrinthSection of viii nerve

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 sclerosisMay also be disconjugate

Via., vertical in one eye and horizontal in

other.

PERIPHERAL CENTRALLATENCY 2-20 s No latencyDURATION Less than 1 min More than 1 minDIRECTION OF NYSTAGMUS

Direction fixed towards the under most ear

Direction changing

FATIGUABILITY fatiguable nonfatiguableACCOMPANYING SYMPTOMS

Severe vertigo none or slight

DIFFERENCES IN NYSTAGMUS OF PERIPHERAL N CENTRAL LESIONS

FISTULA TESTPRINCIPLE: 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

PROCEDURE: Apply intermittent pressure on tragus

OR By using Siegel's speculumINDICATIONS: 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

RUPTURE OF ROUND WINDOW MEMBRANE

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.

ROMBERG TESTPROCEDURE :

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

SHARPENED ROMBERG TEST

GAITPROCEDURE:

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

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 sidePast pointing Falling On right

sidei.e. towards the side of the slow component

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.

PAST-POINTING AND FALLING TEST- WITH EYES OPENED

PAST-POINTING AND FALLING TEST- WITH EYES CLOSED

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

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 mostOn repetition – nystagmus may be elicited but lasts for a shorter period.

On subsequent repetition

Nystagmus disappears altogether

NYSTAGMUS IS

FATIGUABLE

IN CENTRAL LESIONS Tumours of 4th ventricleCerebellumTemporal lobeMultiple sclerosisVertibrobasilar insufficiency orRaised 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

TEST OF CEREBELLAR DYSFUNCTION For cerebellar diseases – all cases of giddiness should be tested.

Cerebellar diseases

MIDLINE DISEASE OF CEREBELLUM CAUSES:1. Wide base gait2. Falling in any direction3. Inability to make sudden

turns while walking4. 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)

Nystagmus observed in cerebellar diseases either in hemisphere or midline diseases include

GAZE EVOKED NYSTAGMUS REBOUND NYSTAGMUS ABNORMAL OPTOKINETIC NYSTAGMUS