Laboratory Tests of Vestibular Function

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Laboratory Tests of Vestibular Function

    • Caloric Test
      • Princple of this test
        • inducenystagmus by thermal stimulation of the vestibular system.
      • If  vertigo induced by the caloric test is qualitatively similar to the type experienced by patient during the episode of vertigo. it proves labyrinthine origin of vertigo.
    • Modified Kobrak test
      • Patient is seated with head tilted 60° backwards
      • It places horizontal canal in vertical position
      • Ear is irrigated with ice water for 60 seconds, first with 5 ml and if there is no response, 10 ml, 20 ml and 40 ml.
      • Normally, nystagmus beating towards the opposite ear, will be seen with 5 ml of ice water.
      • If response is seen with increased quantities of water between 5 and 40 ml, labyrinth is considered hypoactive.
      • No response to 40 ml water indicates dead labyrinth.
    • Fitzgerald-Hallpike test (bithermal caloric test)
      • In this test, patient lies supine with head tilted 30° forward
      • It places horizontal canal is vertical
      • Ears are irrigated for 40 seconds alternately with water at 30°C and at 44°C (i.e. 7° below and above normal body temperature) and eyes observed for appearance of nystagmus till its end point.
      • Time taken from the start of irrigation to the end point of nystagmus is recorded and charted on acalorigram
      • If no nystagmus is elicited from any ear, test is repeated with water at 20°C for 4 minutes before labelling the labyrinth dead.
    • COWS: Cold-Opposite, Warm-Same
      • Cold water induces nystagmus to opposite side
      • Warm water induces nystagmus to the same side
    • 2 types of abnormal responses to the caloric test
      • canal paresis or dead labyrinth
      • directional preponderance, i.e. nystagmus is more in one particular direction than in the other
    • Canal paresis
      • It indicates that response (measured as duration of nystagmus) elicited from a particular canal (labyrinth), right or left, after stimulation with cold and warm water is less than that from the opposite side.
      • It can also be expressed as percentage of the total response from both ears
      • L30 is the response from left side with water at 30°C
      • L44 is response from left ear after stimulation with warm water at 44°C.
      • Canal paresis
        • is indicative of depressed function of the ipsilateral labyrinth, vestibular nerve orvestibular nuclei
        • seen in Meniere’s disease, acoustic neuroma, post-labyrinthectomy or vestibular nerve section.
    • Directional preponderance
      • directional preponderance occurs
        • towards the side of a central lesion
        • away from the side in a peripheral lesion
      • directional preponderance does not help to localise the lesion in central vestibular pathways.
      • Canal paresis on one side with directional preponderance to the opposite side is seen in unilateral Meniere’s disease.(MCQ)
      • Canal paresis with directional preponderance to ipsilateral side is seen in acoustic neuroma.(MCQ)
    • Cold-air caloric test
      • This test is done when there is perforation of tympanic membrane because irrigation with water in such a case with perforation is contraindicated.
      • The test employs Dundas Grant tube which is a coiled copper tube wrapped in cloth. (MCQ)
      • The air in the tube is cooled by pouring ethyl chloride, and then blown into the ear.
      • It is only a rough qualitative test.
    • Electronystagmography
      • The test depends on the presence of corneoretinalpotentials which are recorded by placing electrodes at suitable places round the eyes.
      • detectnystagmus which is not seen with the naked eye
      • permits to keep a permanent record of nystagmus.
    • Optokinetic Test
      • Procedure : Patient is asked to follow a series of vertical stripes on a drum moving first from right to left and then from left to right.
      • Normally it produces nystagmus with
        • slow component in the direction of moving stripes
        • fast component in the opposite direction.
      • Optokinetic abnormalities are seen in brainstem and cerebral hemisphere lesions.
      • this test is useful to diagnose a central lesion.
    • Rotation Test
      • Patient is seated in Barany’s revolving chair with his head tilted 30° forward and then rotated 10 turns in 20 seconds.
      • The chair is stopped abruptly and nystagmus observed.
      • Normally there is nystagmus for 25-40 seconds.
      • Advantage : it can be performed in cases of congenital abnormalities where ear canal has failed to develop and it is not possible to perform the caloric test.
      • Disadvantage of the test is that both the labyrinths are simultaneously stimulated during the rotation process and cannot be tested individually.
    • Galvanic Test
        • It is the only vestibular test which helps in differentiating an end organ lesion from that of vestibular nerve
        • Patient stands with his feet together, eyes closed and arms outstretched and then a current of 1 mA is passed to one ear.
        • Normally, person sways towards the side of anodal current


      Tests of vestibular function (1925) Pt. 1 of 3
      A demonstration helping to explain the vestibular system (to do with sense of balance) of the cochlea and labyrinth of the inner ear. Innervation of ocular muscle. Demonstration of horizontal and perpendicular nystagmus
      Tests of vestibular function (1925) Pt. 2 of 3
      A demonstration helping to explain the vestibular system (to do with sense of balance) of the cochlea and labyrinth of the inner ear. Innervation of ocular muscle. Demonstration of horizontal and perpendicular nystagmus
      Tests of vestibular function (1925) Pt. 3 of 3
      A demonstration helping to explain the vestibular system (to do with sense of balance) of the cochlea and labyrinth of the inner ear. Innervation of ocular muscle. Demonstration of horizontal and perpendicular nystagmus
      Vestibular Testing Performed By Jason Yung
      Vestibular Balance Testing
      This is a very sophisticated device that we use to gain understanding of your brain function in many different areas, by observing the function of your eye muscles during movement. The device was pioneered by NASA to assess the adaptation of astronauts nervous systems in zero-gravity environments. It has now been adapted to give us relevant information about the nervous system back on earth. We use VNG at Back to Back Chiropractic Clinic to help us assess a range of conditions.
      To use the machine, we ask you to put on infrared camera goggles that records eye movement. Then we invite you to view static or moving cursors in front of you on a custom made digital light bar. As you perform different tests information is fed to a computer, which records and graphs the actions of your eyes.
      The vestibular system, balance, and dizziness
      What is the vestibular system? What are the different ways that it contributes to our sense of balance and spatial orientation? What are some of the causes of dizziness?
      The Vestibular System
      Clinical Application of Vestibular Testing by Dr. Brian Blakley
      The ear is a wonderfully complex organ for quantitative analysis but some of the elaborate theory does not apply well to patients’ symptoms and disability. This talk will discuss some aspects of tests of vestibular function used in clinical practice and identify some of its strengths and shortcomings. The quantitative basis and application of Electronystagmography, rotational chair and vestibular-evoked myogenic potentials testing will be discussed.