Chiari 1 Malformation presenting as Strabismus of

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

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

Symptoms & Signs of C 1 M n n Symptoms : nonspecific - headache, dizziness, neck pain, extremity weakness, numbness …. Neurologic signs: ataxia, dysarthria, nystagmus, cranial nerve deficit ….

THIS SERIES : 12 CASES 12 cases of acquired strabismus [mostly convergent = esotropia] as the presenting sign of C 1 M. No other credible explanation for the strabismus Isolated acquired esotropia has been previously described as a rare presenting sign of C 1 M in several case reports - this will be the largest series so far.

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

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

4 patients : ET D>N # Age at Presenting signs/ presentation symptoms. Duration. ET ∆ Treatment Follow up [y] 1 7 i/mitt diplopia 1 y N=6 -22* D=14 -26 Glasses 3 4 20 i/mitt diplopia 8 y N=9 D=16 Glasses 0. 1 7 18 diplopia 1 y N=35 D=40 Glasses 0. 2 9 6 i/mitt ET 1 mo N=14 - 30 NSD (age 6 ½) 1 D=25 - 35 • 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

2 patients : ET N>D # Age at Presenting presentation signs & symptoms [yrs] ET ∆ Treatment Follow up [yrs] 6 19 i/mitt near diplopia 11 y N=6 -12* D=1 -4 Glasses 1. 2 10 0. 5 Infrequent ET Increasing to BMR in 10/04. 4 constant ET N=42, Early D=36 orthotropia # 10 : “ Chiari plus”. She has developmental delay, and early closure of fontanelles. MRI : 7 mm C 1 M, stable mild ventriculomegaly.

Other presentations # Age at presentation Presenting symptoms Manifest deviation ∆ Refr’n Other F/up yrs 12 14 Recent onset diplopia ET 40 N=D R+1. 25 L+1. 50 L IO+ L SOMild L/R 1. 2 5 16 Diplopia on R gaze 15 mo ET PP: 0 -14. R gaze 1222 R&L -9 R LR- 1 2 28 Near Diplopia 18 y. Pixilated vision XT 18=N O=D R-1. 50 L-0. 50 Convergence insufficiency 0. 5 • Patient #12: NSD 6 mo s/p dx of CM 1. 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

Other presentations Age presentation 8 Signs and findings Other F/u (yrs) 45 3 Pres. symptoms I/mitt H & V diplopia poor motor fusion Myasthenia and thyroid r/u 1. 3 Upper limb paresthesia 1. 6 Nystagmus 0. 2 9 11 60 H: -2 to +1 V: +/-0. 5 Esophoria / hyperphoria AHP diplopia poor motor fusion Constant H diplopia 10 y Oscillopsia ET 16 D=N RIO +, LSO-. Tilt R • # 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.

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

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

ET as only manifestation of C 1 M Summary of published literature Nunber of cases Age y Squint Sx Neurosurgery Bixenman J Ped Ophthal Strab 1987 1 13 Before C 1 M Dx Recurrence 6 mo later Yes with resolution of ET Pokharel JAAPOS 2004 1 13 PT in borderline C 1 M. Recurrence 6 mo later. Second sx successful s/p neuro-sx. Yes. ET no better Biousse AJO 2000 4 5 to 37 PT in 2. One successful. 2 nd recurrence s/p 2 sx. PT=2 with resolution of ET. F/u 2 -3 y Passo J Clin N-Ophthal 1984 J C lin N-Ophthal 1984 1 24 Recurrence 12 mo after surgery Yes with resolution of ET Weeks & Hamed Ophthalmology 1999 2 Recurrence after surgery Yes with resolution of ET Lewis J N-ophthal 1996 5 17 to 37 No Yes. PT=4 patients with resolution of ET. > 4 y f/u * Defoort-Dhellemmes Amer Jnl Ophthal 2002 1 9 No PT with resolution of ET Imes -Ophthalmology 2001 Imes 1 14 Botox to LMR (successful after 6 mo f/u) PT - ET no better *One patient from Lewis’s series did not get any sx treatment / PT= Primary treatment

Summary of published literature : ET as the ONLY manifestation in C 1 M n n n n 16 patients ages 5 - 37 7/16 : strabismus sx as primary treatment 6/7 : recurrence of strabismus 4/5 : subsequent NSD with resolution of strab 8 patients : NSD as primary treatment 7/8 had resolution all signs/symptoms Conclusion: Strab Sx alone usually ineffective. NSD usually necessary & effective.

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

Summary n n n 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 1 case. Other patients : Most manage well with prism glasses.

Conclusions Isolated acquired strabismus is not a rare presenting sign of C 1 M, and there might be a good number of patients being mis / under- diagnosed. n Appropriate primary management of C 1 M with strabismus alone [whether strabismus surgery or NSD] is unclear. n