Vestibular_tests_sundar in otolaryngology .pptx

Ent and head neck surgery

1. VESTIBULAR TESTS (ENG, CALORIE TEST,POSTUROGRAPHY ) Dr. Sundar Dhungana MS( ORL-HNS),3 rd year Resident GMSMA of ENT-H & N Studies MMC-TUTH,IOM

2. Road Map Electronystagmography Calorie Test Bithermal Caloric test Computed Dynamic Posturography Miscellaneous Tests a) Rotatory Chair Test b) Dynamic Visual Acuity Test c) Vestibular Evoked Myogenic Potential d) Craniocorpography

3. Most important diagnostic tool is careful history More than 70% of balance disorder is diagnosed by history If clinical neurotological tests are combined -85% High-tech investigation modalities are necessary in about 10-15% only “In 80% of cases if one doesn’t have an idea of diagnosis at the end of history, one is unlikely to have it at the end of the examination and investigations” Kerr et al.,1997 Introduction

4. Objectives of investigations in vertiginous patients : To estabished whether the patients has any definite vertiginous problem and/or balance disorder To establish and objectectively document the degree of functional impairment To localize the lesion topographically To established etiological diagnosis To established management protocol Introduction contd …

5. Cont’d… CNS 1- Cerebral cortex 2- Brainstem 3- Cerebellum 2-Vestibular 3-Proprioceptive 1- Visual Rotation Gravity Ocular Reflex Postural control 5 Introduction contd…

6. Congenital nystagmus & squint rule out Stop taking for 3days : Medications that reduce vertigo. Sedatives and tranquilizers. Drinks containing alcohol. Stimulants, including foods that contain caffeine (coffee, tea, cola, and chocolate) Before test

7. Monitors eye movements using electro- oculography Ass es s labyrinthine dysfunction and degree of dysfunction Electroocolography types Electronystagmography Magnetic potentials (search coils) Video- nystagmography Infrared Electronystagmography

8. Electronystagmography contd … Corneoretinal potential (CRP)- between the cornea and the retina Retina is negatively charged relative to the cornea Electrical potential can be measured -skin surface electrodes

9. Advantages: R esults of test quantified B ithermal caloric test not accurately done without precise stimulus control and response quantification provided by ENG ENG provides documentation of results F/U of patients M edico -legal and workers compensation cases A ssesses each ear separately and can give side of lesion localizing information Electronystagmography contd …

10. Limitations: ENG tests only lateral semicircular canal Traditional ENG testing using electrooculography relatively insensitive to torsional nystagmus Two of more common illnesses BPPV and Meniere’s disease can have normal ENG despite “classic” symptomatology ENG finding may be incidental and must be considered in light of clinical history and physical examination Electronystagmography contd …

11. Videonystagmography computer-based system for eye movement records eye movements with digital video technology using infrared illumination high-technology goggle visualization and recording of eye movements

12. Videonystagmography contd.. Advantages: Easier and quicker than using electrodes Only one calibration is necessary Records rotational nystagmus Limitations: more expensive patients with claustrophobia may not tolerate patients with ptosis pupil-obscuring eyelashes difficult to test.

13. Magnetic search coil technique Involves patient sitting in a low-strength alternating magnetic field soft contact lens in which a wire coil is embedded Motion of the coil of wire in the alternating magnetic field induces a very small current in the wire

14. Magnetic search coil technique contd … Advantages: very precise determination of eye position in three dimensions allows eye position to be recorded very rapidly (500-1,000 times per sec). Limitations: requires a sophisticated laboratory highly experienced personnel

15. based on the differing reflectance properties of the iris compared to the sclera photocells of the eye remain stationary while the edge of the iris moves with the eye light sensed by the photocells differs according to eye position Infrared oculography

16. Infrared oculography contd … Advantages: Direct estimate of the eye position as a function of time can be calculated Limitations: Bulk of the equipment limits visual stimulation- interference with eyelid motion makes vertical recording difficult

17. Electronystagmography Comprises of several tests: Test for sponataneous nystagmus Gaze nystagmus test Saccade( caliberation ) test Pendulum tracking test Optokinetic test Positional and posinoning test Caloric test Rotational test Fistula test

18. Records nystagmus when eyes open or close Test for spontaneous nystagmus

19. Test for spontaneous nystagmus Right vertibular neuronitis

20. Test for spontaneous nystagmus Brain stem tumour

21. Nystagmus –look at apoint 30 degree away from midline G aze evoked nystagmus : Side effects of drugs: Anticonvulsants, alcohol Multiple sclerosis M yasthania gravis C erebellar atrophy Gaze nystagmus

22. Gaze nystagmus contd … Test for gaze nystagmus in normal patient

23. Gaze nystagmus contd … Test for gaze nystagmus in patient suffering from cebellar tumour

24. tells us about the occulomotor system and optic connections of the labrynth Pendular tracking test

25. Patients concentrates on randomly moving target 80 targets ( 40 right, 40 left), amplitude ( 5-25 deg ) Computer calculates Peak velocity Accuracy Latency Saccade(calibration) test

26. Slow velocity saccade : Degenerative/metabolic CNS diseases Internuclear opthalmoplegia Cerebral hemisphere disturbances Drug intox ication Inattentive p atient Abnormal fast velocity saccade : Orbital tumours Myasthenia gravis Saccade(calibration) test contd …

27. Cerebellum plays an important role in determining the accuracy of saccadic movements Inaccurate saccades, or ocular dysmetria are classified as hypermetria (overshooting the target) hypometria (undershooting) Saccade(calibration) test contd …

28. Saccadic latency abnormalities may be seen in patients with Abnormal vision Parkinson's disease Huntington's chorea Alzheimer's disease Focal hemispheric lesions Saccade(calibration) test contd …

29. Allows continuous tracking of moving objects U sed to track targets at slower speeds and operates when eyes move within orbit with head still VOR used when target mov e at faster speeds with head moving Smooth pursuit system: C omputer -controlled visual target moves back and forth (at frequencies from 0. 2 to 0.7 Hz) in horizontal plane Pursuit and Optokinetic test contd …

30. Normal individuals follow target smoothly in both directions at all target frequencies Deficits in smooth pursuit may from Age Medication visual problems attention deficit lesions of brainstem , cerebellum, and occipitoparietal junction Pursuit and Optokinetic test contd …

31. Optokinetic Test images of whole visual field fixed in retina and prevent retinal slip. Pursuit and Optokinetic test contd …

32. Pursuit and Optokinetic test contd … Patient with a unilateral pursuit defect

33. Determine if different head positions induce or modify vestibular nystagmus P ositional nystagmus Patient’s eye movements monitored while at least four head positions 1) sitting 2) supine 3) head right (right ear down) 4) head left (left ear down Eye movement s monitored in each position for about 20 s with visual and without visual fixation Positional Test Positional Test

34. Positional nystagmus i) intermittent ii) persisten t N ystagmus induced by ampullopetal stimulation Persistent positional nystagmus sustained as long as head position maintained Geotropgic, Ageotrophic Direction fixed or changing Eliminated or diminished with visual fixing Positional Test

35. Many patients complain of vertigo or dizziness with head movement N ystagmus differs from positional nystagmus M ost frequently employed test Dix- Hallpike maneuver If nystagmus elicited same maneuver repeated to assess fatigability Positioning Test contd …

36. T orsional nystagmus counterclockwise fast phase ( right ear ) clockwise fast phase ( left ear ) Electronystagmography insensitive to torsional component H orizon tal: fast phase away from u ndermost ear V ertical : upbeating fast phase Positioning Test contd …

37. Positioning Test contd … Electronystagmographic tracing demonstrates horizontal and vertical components of the nystagmus seen in BPPV

38. Distinct features of positioning nystagmus Delayed Onset Always transient A ccompanied by intense vertigo Fatigable Positioning Test contd …

39. Positioning Test contd …

40. Bojrab-Calvert maneuver Positioning Test contd …

41. Bithermal Caloric test Highly sensitive to unilateral lesions of the peripheral vestibular system Integrity of the lateral semicircular canals and their afferent pathways. Caloric Test

42. Bithermal Caloric Test contd …

43. Bithermal Caloric Test contd … Helps us to accurately calculate the percentage of canal paresis Directional preponderance T ests integrity of lateral semicircular canals and their afferent pathways

44. F ive characteristics of calorically induced nystagmus 1) Latency 2) Duration 3) A mplitude 4) F requency 5) V elocity (most important) S low-phase eye velocity equally strong in both directions Compari son of peak slow-phase eye velocity of cool and warm caloric Bithermal Caloric Test contd…

45. Bithermal Caloric Test contd …

46. Bithemal caloric test

47. U nilateral Weakness (UW) : [ (RC+RW ) - ( LC+LW)/ RC+RW+LC+LW]X 100% Directional P reponderance (DP): [(RC+LW)-(LC+RW)/RC+RW+LC+LW]x100% UW > 20 % and DP > 25% usually considered significant Bithermal Caloric Test contd …

48. UW sign of decreased responsiveness of horizontal semicircular canal or the ampullary nerve DP spontaneous nystagmus central sign indicating asymmetric sensitivities Meniere’s Disease B ithermal caloric test highly sensitive to U/L peripheral vestibular dysfunction R elatively insensitive to bilateral dysfunction R ule of thumb : C aloric responses (warm response plus cool response ) of both ears fall below 12 degrees/second per side Bithermal Caloric Test contd…

49. Bithermal Caloric Test contd…

50. Posturography is quantitative balance test A ssesses standing balance function under v ariety of conditions D evice consists of platform capable of moving back and forth Sensory organisation test Motor control test Computerized dynamic posturography

51. COMPUTERIZED DYNAMIC POSTUROGRAPHY Computerized dynamic posturography contd...

52. Support fixed, eyes open, visual fixed 2. Support fixed, eyes closed, visual fixed 3. Support fixed, eyes open, visual sway-referenced 4. Support swayed, eyes open , visual fixed 5. Support swayed, eyes closed, visual fixed 6. Support swayed, eyes open, visual sway-referenced Computerized dynamic posturography contd...

53. Computerized dynamic posturography contd... Posturography test of a patient with total bilateral loss of vestibular function

54. Use of Posturography Planning and monitoring course of postural rehabilitation 2) Documentation of postural responses in suspected a) malingering b) exaggeration of disability for compensation c) conversion disorder Computerized dynamic posturography contd...

55. A nother method of testing for VOR Passive rotational test Patient’s body is rotated without any movement between the head and body Active rotational test patient rotates his or her own head back and forth while the body remains stationary R otational Test

56. most useful passive test vertical axis through head L SCC in the plane of rotation Horizontal eye movements monitored using electro-oculography R otational chair t est

57. The patient is seated in a chair so that the horizontal semicircular canals are in the plane of rotation. Electro-oculography is used to monitor eye movements R otational chair t est contd …

58. P atient oscillated in sinusoidal fashion about vertical axis at various test frequencies (ranging from 0.01 to 01.28 Hz ) P atient undergoes multiple cycles of oscillation at each frequency S timulus level delivered by rotary chair much greater than that delivered in caloric testing (0.002 and 0.004 Hz) C omputer compares h ead velocity and slow-phase eye velocity R otational chair t est contd …

59. Clinical Indications for Rotational Chair Testing when the ENG is normal and oculomotor results are either normal or observed abnormalities when the ENG suggests a well compensated state despite the presence of a clinically significant unilateral caloric weakness when the caloric irrigations are below 12 degrees/s bilaterally or when caloric irrigations cannot be performed When a baseline measure is needed to follow the natural history of the patient's disorder (MD) R otational chair t est contd …

60. Components of Rotary Chair Testing Gain : slow eye velocity / head velocity indicator of overa l l responsiveness Phase: temporal relationship between eye and head velocities m measured in degrees greatest clinical significanc e i ncreased phase lead implies peripheral vestibular system dysfunction decreased phase lead suggest c erebellar lesion R otational chair t est contd …

61. Symmetry: ratio of rightward to leftward slow- phase eye velocity a symmetry result from peripheral vestibular weakness or contralateral excitory lesion R otational chair t est contd …

62. R otational chair t est contd … Normal RCT findings

63. abnormalities seen on RCT can be classified into four categories: vestibular habituation and asymmetry vestibular habituation vestibular deficit vestibular asymmetry R otational chair t est contd …

64. R otational chair t est contd … 1.vestibular habituation and asymmetry

65. R otational chair t est contd … 2.vestibular habituation

66. R otational chair t est contd … 3.vestibular deficit

67. R otational chair t est contd … 4.vestibular asymmetry

68. Vestibular Autorotational Testing Active rotation test Patient actively shakes his/her head from side to side with increasing frequency Angular sensor is fixed to a headband Advantages Portable relatively brief (18 sec) duration of the test ability to test high-frequency (2-6 kHz) oscillations

69. Test of inferior vestibular nerve Records myogenic potential in cervical muscles(SCM) originating from saccule Recorded by surface electrode Active electrode upper half SCM Reference electrode on sternal head Ground electrode fixed on fore head Vetibular Evoked Myogenic Potential

70. Alternate click of 105dB of 0.2 ms width is fed on test ear and white noise of 30dB in another ear for masking EMG is recorded Two trial in done for each ear h Vetibular Evoked Myogenic Potential contd …

71. In healthy subjects Definite VEMP is recorded in 95% of cases Peak latency of positive and negative wave is 13.5 ms and 23ms respectively In patients with dead vestibular labyrinths No VEMP recorded h Vetibular Evoked Myogenic Potential contd …

72. h Vetibular Evoked Myogenic Potential contd … Unilateral weakness for responses to the right VEMP stimulus

73. Test of VOR while reading acuity chart Examiner oscillates patient’s head at 1 Hz; new VA recorded 2 lines suspicious;>3 VOR grossly reduced DYNAMIC VISUAL ACUITY

74. Consist of graphically recording patient’s head and body movement Unterburger’s stepping Romberg’s test Craniocorpography

75. References Glasscock- Shambaugh,Sugery of the Ear,6 th edition Scott-Brown’s otorhinolaryngology head and neck surgery-7 th edition Scott-Brown’s otorhinolaryngology head and neck surgery-6 th edition Cummings otolaryngology head and neck surgery-5 th edition Diseases of Ear,Nose and Thoroat -PL Dhingra5 th edition Ballenger’s Otorhinolaryngology Head and Neck Surgery-16 th edition

76. THANK YOU