1. Chiari 1 Malformation presenting as “ Strabismus of obscure cause” Chiari 1 Malformation presenting as “ Strabismus of obscure cause” Kowal, L & Yahalom, C Kowal, L & Yahalom, C OMC & CERA RVEEH, Melbourne

2. Chiari 1 malformation (C1M) Tonsillar herniation ≥ 3 - 5 mm below foramen magnum Tonsillar herniation ≥ 3 - 5 mm below foramen magnum Unlike many congenital CNS malformations, C1M patients usually asymptomatic until late childhood or early adulthood Unlike many congenital CNS malformations, C1M patients usually asymptomatic until late childhood or early adulthood

3. Symptoms & Signs of C1M Symptoms : nonspecific - headache, dizziness, neck pain, extremity weakness, numbness …. Symptoms : nonspecific - headache, dizziness, neck pain, extremity weakness, numbness …. Neurologic signs: ataxia, dysarthria, nystagmus, cranial nerve deficit …. Neurologic signs: ataxia, dysarthria, nystagmus, cranial nerve deficit ….

4. THIS SERIES : 12 CASES 12 cases of acquired strabismus [mostly convergent = esotropia] as the presenting sign of C1M. 12 cases of acquired strabismus [mostly convergent = esotropia] as the presenting sign of C1M. No other credible explanation for the strabismus No other credible explanation for the strabismus Isolated acquired esotropia has been previously described as a rare presenting sign of C1M in several case reports - this will be the largest series so far.

5. NON- STRABISMIC FEATURES 10/12 : ‘minor’ neurological symptoms esp. headache 10/12 : ‘minor’ neurological symptoms esp. headache 2/12 : “CHIARI PLUS” - more serious neurological signs/symptoms (#10 & #11) 2/12 : “CHIARI PLUS” - more serious neurological signs/symptoms (#10 & #11)

6. 10 /12 patients with esotropia 4/10 D>N ‘divergence insuff’ 4/10 D>N ‘divergence insuff’ Some may be bilateral 6ths 2/10 N>D ‘convergence Xs’ 2/10 N>D ‘convergence Xs’ 1/10 N=D 1/10 N=D 1/10 6th nerve palsy 1/10 6th nerve palsy 2/10 ET + vertical deviation 2/10 ET + vertical deviation

7. 4 patients : ET D>N Follow up [y] Treatment ET ∆ Presenting signs/ symptoms. Duration. Age at presentation # 3GlassesN=6-22*D=14-26 i/mitt diplopia 1y 71 0.1GlassesN=9D=16 i/mitt diplopia 8y 204 0.2GlassesN=35D=40 diplopia 1y 187 1 NSD (age 6 ½) N=14 - 30 D=25 - 35 i/mitt ET 1mo 69 All : Headache, no other neurological symptoms/signs. All : Refraction -1.50 to +1 DS # 9 : ET N=30, D=35 at age 7 yrs. Strab surgery planned NSD = Neurosurgical decompression * Range of measurements at different examinations

8. 2 patients : ET N>D Follow up [yrs] Treatment ET ∆ Presenting signs & symptoms Age at presentation [yrs]# 1.2GlassesN=6-12*D=1-4 i/mitt near diplopia 11y 196 4 BMR in 10/04. Early orthotropia Increasing to constant ET N=42, D=36 Infrequent ET 0.510 # 10 : “ Chiari plus”. She has developmental delay, and early closure of fontanelles. MRI : 7 mm C1M, stable mild ventriculomegaly.

9. Other presentations F/upyrsOtherRefr’n Manifest deviation ∆ Presenting symptoms Age at presentation # 1.2 L IO+ L SO- Mild L/R R+1.25L+1.50 ET 40 N=D Recent onset diplopia 1412 1 R LR- R&L -9 ET PP: 0-14. R gaze 12- 22 Diplopia on R gaze 15 mo 165 0.5 Convergence insufficiency R-1.50L-0.50XT18=NO=D Near Diplopia 18y. Pixilated vision 282 Patient #12: NSD 6 mo s/p dx of CM1. Little improvement in ET  Bimedial recession 2/04. Ortho 8 mo later The other patients manage with glasses. Patients #12 and #2 presented with headache as well as diplopia

10. Other presentations F/u(yrs)Other Signs and findings Pres. symptoms Age presentation 1.3 Myasthenia and thyroid r/u poor motor fusion H: -2 to +1 V:+/-0.5 Esophoria / hyperphoria I/mitt H & V diplopia 453 1.6 Upper limb paresthesia poor motor fusion RIO +, LSO-. Tilt R AHPdiplopia98 0.2Nystagmus ET 16 D=N Constant H diplopia 10 y Oscillopsia6011 # 11 is the second “Chiari plus”. His symptoms began with diplopia and balance problems. Diplopia persisted s/p 2 neurosurgical procedures. # 3 and #8 manage well with glasses.

11. Our patients who had surgery #10 : Squint sx with good early results (f/u 4w) #10 : Squint sx with good early results (f/u 4w) #9 : NSD. Strab persists. BMR planned. #9 : NSD. Strab persists. BMR planned. #11 : NSD. Strab persists. Prism working. #11 : NSD. Strab persists. Prism working. #12 : NSD. Strab persists. Successful squint sx (f/u 8 mo). #12 : NSD. Strab persists. Successful squint sx (f/u 8 mo). NSD: neurosurgical decompression

12. Age at presentation Most of the patients presented outside normal age range for strabismus

13. ET as only manifestation of C1M Summary of published literature Neurosurgery Squint Sx Age y Nunber of cases Yes with resolution of ET Before C1M Dx Recurrence 6 mo later 131Bixenman J Ped Ophthal Strab 1987 Yes. ET no better PT in borderline C1M. Recurrence 6 mo later. Second sx successful s/p neuro-sx. 131Pokharel JAAPOS 2004 PT=2 with resolution of ET. F/u 2-3 y PT in 2. One successful. 2nd recurrence s/p 2 sx. 5 to 37 4Biousse AJO 2000 Yes with resolution of ET Recurrence 12 mo after surgery 241Passo J Clin N-Ophthal 1984 Yes with resolution of ET Recurrence after surgery 2 Weeks & Hamed Ophthalmology1999 Yes. PT=4 patients with resolution of ET. > 4y f/u * No 17 to 37 5Lewis J N-ophthal 1996 PT with resolution of ET No91Defoort-Dhellemmes Amer Jnl Ophthal 2002 PT - ET no better Botox to LMR (successful after 6 mo f/u) 141 Imes -Ophthalmology 2001 *One patient from Lewis’s series did not get any sx treatment / PT= Primary treatment

14. Summary of published literature : ET as the ONLY manifestation in C1M 16 patients ages 5 - 37 16 patients ages 5 - 37 7/16 : strabismus sx as primary treatment 7/16 : strabismus sx as primary treatment 6/7 : recurrence of strabismus 6/7 : recurrence of strabismus 4/5 : subsequent NSD with resolution of strab 4/5 : subsequent NSD with resolution of strab 8 patients : NSD as primary treatment 8 patients : NSD as primary treatment 7/8 had resolution all signs/symptoms 7/8 had resolution all signs/symptoms Conclusion: Strab Sx alone usually ineffective. NSD usually necessary & effective. Conclusion: Strab Sx alone usually ineffective. NSD usually necessary & effective.

15. Summary We describe 12 cases of ‘acquired strabismus of obscure cause’ probably caused by C1M We describe 12 cases of ‘acquired strabismus of obscure cause’ probably caused by C1M 5/12 aged 10-20 @ presentation 5/12 aged 10-20 @ presentation 10/12 had headache 10/12 had headache Esotropia was the usual squint (10/12) Esotropia was the usual squint (10/12) 4/12 : ‘divergence insufficiency’ ET, D > N 4/12 : ‘divergence insufficiency’ ET, D > N 1/12: [apparent] sixth nerve palsy 1/12: [apparent] sixth nerve palsy 1/12: unexplained head tilt. 1/12: unexplained head tilt. 2/12: i/mitt diplopia with poor motor fusion 2/12: i/mitt diplopia with poor motor fusion

16. Summary Most patients were referred for neurosurgical evaluation. 3/12 had NSD. It is generally felt by neurosurgeons that strabismus alone is an inadequate reason for NSD. Most patients were referred for neurosurgical evaluation. 3/12 had NSD. It is generally felt by neurosurgeons that strabismus alone is an inadequate reason for NSD. Strabismus did not resolve in these 3 cases, with subsequent successful squint surgery in 1case. Strabismus did not resolve in these 3 cases, with subsequent successful squint surgery in 1case. Other patients : Most manage well with prism glasses. Other patients : Most manage well with prism glasses.

17. Conclusions Isolated acquired strabismus is not a rare presenting sign of C1M, and there might be a good number of patients being mis / under- diagnosed. Isolated acquired strabismus is not a rare presenting sign of C1M, and there might be a good number of patients being mis / under- diagnosed. Appropriate primary management of C1M with strabismus alone [whether strabismus surgery or NSD] is unclear. Appropriate primary management of C1M with strabismus alone [whether strabismus surgery or NSD] is unclear.