Childhood Nystagmus

First year Post graduate, LADY HARDINGE MEDICAL COLLEGE

1. Congenital Nystagmus Dr Sarah Khan

2. PATHOPHYSIOLOGY Three main mechanisms are involved in maintenance of the image of the target of interest on the fovea Ocular fixation Vestibulo ocular reflex Central nervous system as the neural integrator

3. Ocular fixation helps to keep the drifting image of the object on the fovea and also suppresses any unwanted saccades

4. Vestibulo ocular fixation helps to maintain a good visual acuity by keeping the eye movements compensated for changes in the head posture during various routine activities

5. The neural integrator helps to maintain the eye position in an eccentric position during different gazes against the pull of suspensory ligaments and the EOM that tend to bring the eye back to the central position

6. NULL POSITION : Position of gaze in which the nystagmus is minimally ellicited . To keep the eye in this position, the child may adopt a face turn or a chin elevation or depression depending on the null position. This enables the child to keep the image of the target at the fovea for a longer time to enable a clear visual acuity ( Foveation period)

7. PENDULAR NYSTAGMUS has a sinusoidal pattern without differentiation into a slow or fast component

8. NEUTRAL ZONE : This is observed in Periodic alternating nystgamus in which the fast component changes direction after an interval of time

9. CONJUGATE NYSTAGMUS : Nystagmus in the two eyes is similar in amplitude, frequency and direction DISCONJUGATE NYSTAGMUS : The direction of nystagmus in the two eyes is different DISSOCIATED NYSTAGMUS : The amplitude of the nystagmus is different but the direction remains the same

10. JERK NYSTAGMUS has a slow and a fast component and is named based on the fast component Direction of the nystagmus is the direction of its fast component Plane could be horizontal, vertical or rotator or a combination of these Amplitude is the excursion of the nystagmus which maybe small(<5deg), moderate (5-15deg) and large( >15deg) Frequency Number of beats per second, slow (1-2Hz) , medium (3-4Hz), Fast (>5Hz) Intensity = Amplitude * Frequency

11. Classification of Nystagmus CEMAS : Classification of Eye Movement Abnormalities and Strabismus By the National Eye Institute A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

12. NYSTAGMUS AND OCULAR MOTOR OSCILLATIONS A. PHYSIOLOGICAL FIXATIONAL MOVEMENTS MICROTREMOR SLOW DRIFTS MICROSACCADES A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

13. B. PHYSIOLOGICAL NYSTAGMUS VESTIBULAR OPTOKINETIC ECCENTRIC GAZE NYSTAGMUS A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

14. C. PATHOLOGICAL NYSTAGMUS INFANTILE NYSTAGMUS SYNDROME (INS) FUSION MAL DEVELOPMENT NYSTAGMU SYNDROME (FMNS) SPASMUS NUTANS SYNDROME VESTIBULAR NYSTAGMUS PERIPHERAL VESTIBULAR IMBALANCE CENTRAL VESTIBULAR IMBALANCE CENTRAL VESTIBULAR INSTABILITY (PAN) A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

15. 5. GAZE HOLDING DEFICIENCY NYSTAGMUS ECCENTRIC GAZE NYSTAGMUS ( AND ASSOCIATED REBOUND NYSTAGMUS) GAZE INSTABILITY NYSTAGMUS 6. VISION LOSS NYSTAGMUS PRECHIASMAL CHIASMAL POSTCHIASMAL A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

16. 7. OTHER PENDULAR NYSTAGMUS AND NYSTAGMUS ASSOCIATED WITH DISEASE OF CENTRAL MYELIN MS, PELIAZAEUS MERZBACHER DISEASE, COCKAYNE’S PEROXISOMAL DISORDERS, TOLUENE ABUSE PENDULAR NYSTAGMUS ASSOCIATED WITH TREMOR OF THE PALATE PENDULAR VERGENCE NYSTAGMUS ASSOCIATED WITH WHIPLE’S DISEASE A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

17. 8. OCULAR BOBBING (TYPICAL AND ATYPICAL) 9. LID NYSTAGMUS A CLASSIFICATION OF EYE MOVEMENT ABNORMALITIES AND STRABISMUS (CEMAS) Report of a National Eye Institute Sponsored Workshop , Richard W. Hertle , NEI

18. D. Saccadic intrusions and oscillations Square wave jerks and oscillations Square wave pulses Saccadic pulses Induced convergence retraction Dissociated ocular oscillations Hypermetric saccades Macrosaccadic oscillations Ocular flutter Flutter dysmetria Opsoclonus Psychogenic flutter Superior oblique myokymia

19. E. Generalised disturbance of saccades F. Generalised disturbance of smooth pursuit G. Generalised disturbance of vestibular eye movements H. Generalised disturbance of optokinetic eye movements

20. INFANTILE NYSTAGMUS SYNDROME Appears by 0-6 months of age Progresses from pendular to jerk type Conjugate, uniplanar , horizontal Stabilises at 5-6 years of age Accelerating slow phase Increases on attempt to fixate Decreases with convergence Marked head posture

21. Strong family predisposition Abolished during sleep May have a latent component May show reversal pattern with OKN

22. Fusion maldevelopment nystagmus syndrome FMNS has an infantile onset Conjugate, horizontal and uniplanar May appear or increase in mono ocular fixation Linear decelerating slow phase with fast phase in the direction of the uncovered fixing eye Reverses direction with change in fixation Intensity decreases with age

23. Spasmus nutans syndrome Constellation of ocular oscillation , head bobbing and torticollis Appears at 4-18 months of age and disappears by 3 years of age Nystagmus increases with convergence MRI/CT are normal

24. Periodic alternating Nystagmus This is a central vestibular instability nystagmus . It exhibits a neutral point with a jerk nystagmus in one direction for 60-90 seconds which then changes to the other direction for another 60-90 second

25. It, therefore needs to be observed for atleast 3 minutes. It is not affected by visual fixation It can be acquired or it maybe a part of the infantile nystagmus syndrome exhibiting an accelerating slow phase in the ocular motor recordings

26. video

27. Evaluation A good clinical history Ante natal history Birth history Age of onset, associated decreased vision Acute onset, diplopia , oscillopsia point towards acquired causes

28. Family history Maternal drug intake ante natally Or perinatal infections

29. Examination Visual acuity Uniocular and binocular Near and distance With and without head posture

30. A complete ocular examination of the anterior and posterior segments

31. Measurement of any face turn Goniometer or a protractor Helps to decide the amount of surgical correction required

32. Video recording of the ocular movements And if available ocular movement tracing

33. Neuro imaging is required in cases of All acquired nystagmus Periodic alternating nystagmus Seesaw nytagmus Spasms nutans syndrome INS with poor vision and disc pallor

34. Electrooculography

35. Infrared oculography

36. Binocular infrared oculography BIRO Video oculography which traces ocular movements using infra red techniques

37. Electromagnetic search coil method Scleral contact lenses are worn

38. Scleral search coils

39. ICS ChartR VNG

40. Drug treatments Anticholinergics , anti histaminics Acetazoleamide effective in familial periodic ataxia with nystagmus Baclofen decreases symptoms in PAN ( increases the inhibitory effect of GABA on the vestibular nuclei) Botulinum toxin injections

41. Optical treatment In congenital nystagmus , convergence and eccentric gaze decreases nystagmus To induce convergence , 7D base out prism can be placed in each spectacle lens In young patients -1.00 D can be added to the spectacle correction

42. If null zone is in a horizontal eccentric gaze, prism apices pointing towards the null zone may help Contact lenses correct refractive errors more effectively , and the tactile sensory feedback might decrease the intensity of nystagmus

43. Surgery To shift the null position from eccentric position to primary position Increase foveation To reduce a an abnormal head position

44. NYSTAGMUS +++ INTENSITY OF NYSTAGMUS REDUCED IN LEVOVERSION NYSTAGMUS + HENCE PATIENT HAS A FACE TURN TO THE RIGHT

45. It may be good to wait till 4-5 yrs to allow for maturation of binocular visual system

46. To correct the head posture Anderson’s surgery : Weakening the yoke muscles responsible for the slow phase of nystagmus

47. Kestenbaum’s procedure : 5mm resection recession of all four horizontal recti to move the null position to the primary position

48. Goto’s surgery : Resection of the recti that move the eye away from the null position

49. Modified Park’s Kestenbaum procedure : Recession of one MR 5mm, and LR 7mm And resection of other MR 6mm and LR 8mm

50. Augmented modified Kestenbaum’s : If the head turn is up to 30 degree, The values of recessions and resections can be increased by 40%

51. Spielmann’s Procedure : in head turn more than 20 degree, Kestenbaum’s procedure with posterior fixation sutures on the recessed muscle

52. Pratt Johnson’s surgrery : Equal recession and resection of all horizontal recti

53. Chin elevation : Recession of inferior rectus which can be combined with resection of superior rectus And vice versa for chin depression

54. Head tilt : Vertical shift of horizontal recti or horizontal shift of vertical recti

55. If there is no null position, or null position is in the primary position Aim of surgery in nystagmus is to dampen the intensity of nystagmus

56. Surgically induced exotropia Large recession of all horizontal recti

57. THANK YOU