2. Acquired N as seen by a strabismus Dr  Superior Oblique Myokymia SOM  Deteriorated congenital N  N after brainstem injury inc oculopalatal myoclonus OPM  Multiple Sclerosis MS  Spino Cerebellar Atrophy [SCA] syndromes

3. S O Myokymia 25y overview  SOM usually diagnosed on history, then confirmed on exam  SOM can go away  SOM can go away for a long time and then come back  Best drug: gabapentin. 2 nd best: Tegretol. Start with pediatric doses and build up  If drugs work, many pts don’t continue to use drugs  Timolol drops sometimes work ?membrane stabilising effect ?systemic effect  Surgery very rarely indicated  LK: sees >10 new cases/y. No surgery >10y

4. Acquired N that I see:Acquired N that I see:  SOM  Deteriorated congenital N  N after brainstem injury inc oculopalatal myoclonus  MS  SCA

5. Well known ‘facts’Well known ‘facts’  Pts with cong N do not have oscillopsia….unless you ask them: >30% get intermittent oscillopsia

6. Latent Manifest Latent N / Fusion Maldevelopment N Syndrome LMLN / FMNS This is the type of N seen in congenital strabismus. …more common in PVL, Trisomy 21, IVH-Hcephalus, Williams Syndrome If eyes straight: no nystagmus [all latent, LN] If strabismus develops, can develop blur or oscillopsia [N becomes manifest, MLN]

7. Strabismus decompensating FMNS  Treatment of manifest latent nystagmus. Treatment of manifest latent nystagmus. Am J Ophthalmol. 1990 Aug Zubcov AA, Reinecke RD, Gottlob I….., Zubcov AA, Reinecke RD,  8 pts with MLN (recordings): look for N reduction after treatment. 8 pts with MLN (recordings): look for N reduction after treatment.  7/8 had strabismus & reduced BCVA 7/8 had strabismus & reduced BCVA  5/7 : strabismus surgery. Orthotropia postop, & MLN converted to LN. 5/7 : strabismus surgery. Orthotropia postop, & MLN converted to LN.  4/5 : improvement in binocular visual acuity. 4/5 : improvement in binocular visual acuity.

8. Treatment of manifest latent nystagmus. Treatment of manifest latent nystagmus. Am J Ophthalmol. 1990 Aug Zubcov AA, Reinecke RD, Gottlob I….., Zubcov AA, Reinecke RD, Treatment of manifest latent nystagmus. Zubcov AA, Reinecke RD,  3/8 : glasses. 3/8 : glasses.  1/3 had accommodative ET; with glasses MLN was converted to LN with improved vision. 1/3 had accommodative ET; with glasses MLN was converted to LN with improved vision.  The possibility of converting MLN to LN and improving acuity by strabismus surgery is a reasonable goal. The possibility of converting MLN to LN and improving acuity by strabismus surgery is a reasonable goal.  In patients with MLN and strabismus, PERFECT surgical or optical alignment of the eyes decreases the N and may also improve binocular visual acuity In patients with MLN and strabismus, PERFECT surgical or optical alignment of the eyes decreases the N and may also improve binocular visual acuity

9. Strabismus decompensating FMNS LK case #1  Progressive XT and oscillopsia  Presumed loss of accommodative amplitude with age caused exophoria to become XT, and LN to become MLN  Oscillopsia and blur is 2ary to loss of fusion and development of MLN  Cured with surgical alignment

10. From Larry AbelFrom Larry Abel ..‘BA appeared to have LMLN and is continually troubled by oscillopsia.  I recorded his eye movements both monocularly and binocularly. Recording quality was not great, as his large XT made it impossible to get both eyes well- recorded at the same time..’

11. Acq oscillopsia Symptomatic MLN  In these recordings, green traces are the left and blue the right eye data. You can see that his nystagmus beats in both of the above recordings towards the viewing eye and does so with a generally decreasing velocity waveform.  The strange waveforms of the non- fixating eye seen in the OS and OU figures are not, I believe, actual. I think they may arise from his gaze going outside the recording system’s limit.

12. Strabismus decompensating FMNS LK case #2  Blur and oscillopsia on reading caused by A –pattern. The blur was due to MLN; on upgaze he had better acuity, stereo and he had pure LN  Surgery for A- pattern allowed fusion in downgaze, and converted MLN to LN, improving downgaze clarity.

13. Deterioration of ‘regular’ CN  Well described if there is an associated neurological problem or sensory deterioration  ANY suggestion of deterioration warrants careful ophthalmic and neurological evaluation & usu MRI  Well described in some cases of ‘stress’ e.g worse @ exam times or when having vision tested for driving test

14. Stress causing deterioration of CN LK case #3 55 yo WF with known familial CN [3 female sibs, one with oscillopsia] and pre-existing astigmatism. Previous BCVA 6/15, N5 OU [2001]. 2002: Is assaulted during her work [inc sexually]. No LOC. 6 weeks later develops reduced BCVA 6/80 OU and ocsillopsia

15. Stress causing deterioration of CN #3 Tests:  ERG normal  MRI 8X15 mm lesion left trigone.  Recordings: typical CN waveforms with poor foveation. Predominantly pendular and pseudoccycloid in central ±20° with jerk beyond that Recordings NOT consistent with 6/15

16. Her primary position waveform is not one particularly likely to give very good acuity…there is only minimal foveation; the waveform is pseudo-cycloid. Since at first glance it looks pendular, I've marked the saccades with arrows. I don't really know when this can be distinguished from pendular with braking saccades, since in both cases there's a bidirectional slow eye movement that's interrupted at one extreme by a fast phase.. This is a 6/60 waveform…not a 6/15 waveform implies a degradation in her waveform & [esp] foveation time Rich Hertle: Yes this stressful situation can alter the CN, especially in a patient with one of the less visually advantageous waveforms, i.e. pendular types.

17. Acquired N that I see:Acquired N that I see:  SOM  Deteriorated congenital N  N after brainstem injury inc oculopalatal myoclonus  MS  SCA

18. McLean & Gottlob Expert Opin Pharmacother 2009 SEMINAL ARTICLE

19. Types of acq nystagmusTypes of acq nystagmus  Oculopalatal myoclonus Starts in Y2 after pontine injury A type of aberrant regeneration. In the complete OPM syndrome, you can have the palate, Eustachian tube, eye/s, diaphragm, face, neck, and shoulder going together, and they are synchronous  See- saw G. M. Halmagyi;et al. Jerk-waveform see-saw nystagmus due to unilateral meso- diencephalic lesion Brain (1994), 117, 789-803  MS Can be very complex.

20. Drugs for acq nystagmusDrugs for acq nystagmus  Gabapentin…up to 3g/d start with pediatric doses  Memantine  Clonazepam 2mgm, 2-3/d is max dose, otherwise sedating  ?quinine for OPM  3,4 diaminopyridine [available in Australia through Special Access Scheme]  ‘Medical Marijuana’ [legally available in Australia through Special Access Scheme; test doses not legal but available more freely]  Alcohol [orally – but usu only in inebriating doses]

21. Surgery in acq nystagmusSurgery in acq nystagmus  Several anecdotal case reports: tenotomy - resuture  No reliable effect can be expected in your 1 st / next case

22. Acquired N that I see:Acquired N that I see:  SOM  Deteriorated congenital N  N after brainstem injury inc oculopalatal myoclonus  MS  SCA

23. Spino Cerebellar Atrophy (SCA) syndromes  Some pts will have DBN with definite null on extreme downgaze  Some will respond to large IR recessions  Duration of effect cannot be predicted – weeks/ months/ years

24. Acquired nystagmusAcquired nystagmus  Difficult group of patients  Need expert assistance from neurologists and neuro- radiologists, and they need yours  N recording can be diagnostic and imply specific reliable therapy