Journal of Neuro-Ophthalmology, December 1981, Volume 1, Issue 4

Total alleviation of downbeat nystagmus in basilar impression by transoral removal of the odontoid process.

The presence of primary position downbeat nystagmus indicates disease at the cervicomedullary junction where craniovertebral anomalies are commonly encountered. This paper reports a patient whose only symptom was disabling oscillopsia and downbeat nystagmus secondary to basilar impression and Arnold-Chiari malformation. He experienced total resolution of his symptoms following transoral removal of the odontoid process. In the past it was felt that ocular signs and symptoms did not improve with surgery for craniovertebral anomalies. In light of this report, the ocular symptoms of craniovertebral anomalies may be considered indications in themselves for surgical intervention.

J. Clin. Nruro-ophth,tlmol. I: 265-201, 1981. Total Alleviation of Downbeat Nystagmus in Basilar Impression by Transoral Removal of the Odontoid Process RICHARD C. SENEUCK, M.D. Absluct Th~ P"'Hnc~ of prim.a!)' position downMoIt nytl.lgmul indiutl'S dise.lse .a. th~ c~",icomrd\lll.ary junction wh~r~ (T,niov~rt~br.al .anom.alil'S,n~ commonly ~ncO\lntu~, This poI~r U!potU .. p.ati~nt whose only symptom WolS diSoibling oscillopsi.a .and downbrut nysl.lgm\ls i«ond.a!)' 10 buibr impr6Sion ,nd Arnold·Chiolri nulfGnn.1tion, H~ n~ri~nc~ totll riKOl\ltion of his symptoms following tr.anso~1 I'tlnl)v.al of th~ odonloid proc6S. In th~ put it .....1$ f~1l tJut ocul,n sips.and symptoms did not improw ....ith s""IffY for cfoIniowrtfbr..1..nonulin. In light of this I'tport, Ot~ ocvlu S)'Inptoms of cTointovnt~r..1 .anolll.llil'S m.ly bf consid~r~ indic.atiom in th~InMIVft for su,pul inlfl"V~ntion. Th~ associ..tion of prim.. ry positIon downbeat nystagmus oInd craniovertebr.al tlbnormalities was fIrst clearly defined by Cog.an. U In recent years, downbe.t nystagmus has been the subject of m,my P"P'!rs which h"ve dealt primarily with etiology "nd the approach toward di"gnosis.I.~ Surgical therapy has been directed toward patients with progressive brain-stem signs, but very little has been written about the ther"peutic .approach to pati~nts whose only problem is downbe.at nystaR­mus and dis.bling oscillopsia. A l.tE'r.1 skull x-ray or cervini spine film will frequently reve.l d vari­ny of cuniovenebr.ll .Ibnorm.alities. In the p.list. one h.as been hesil.nt 10 recommend surgery bec.uS(' of the high morbidity .and poor results of posterior decompression. Ukewise, in the PolSt it w.as felt th.t the nyst.agmus .Ind oscil­lopsi. l were unrrsponsive to surglC.l ther.apy.~I~ A reemt report of .melioroltion of oSClllopsiol dnd nyst.gmus .fter .a suboccipit.l cr.niectomy for an Arnold-Chi.ari nulfonn.ation rontr.dlcts this pr~· vious dogm._11 We report .I p.atient with pl.atyb.sia .Ind Amold·Chi.ri nulform"tion whose sole com- Olnk,l A_"lf Profn1Ot of Nt'u~, UnlwfSlty of T~) Hf,lth Self""'t' Ct'ftlt'l. s,." An'CltnO, Tn" DfC~mMr 1981 pl.aint of incdpolcitating oscillopsi. dnd finding of downbedting nystolgmus were tot.ally reli('ved by transor.al remov.l of the odontoid procrss. Cue Report W. P. is. 33-year-old white m.le who presented in D«em~r 19n With .a 2-month hlslory of ascil­lopsla whICh w.s present in pnnury SoIze .and molde worse by looking down. He compl.med of • mild loss of b.l.nce with .a tendency to bump into objects. He W,IS no longer .ble to work.s. medie.tl products Sollrsm.n. Ex.min.llon rt've.led I.rge .m­plitude down~.tmg nyst.gmus m prim.ary gaze which d.mpened in both upgtlze .and downgolZe in the pnm.ry position but incre.ased on gaze down and to either SIde. On lookmg to eIther side he developed. horizontoll component 10 the nyst.g­mus such Ih.t it dppeared .Imost circul.r m n<llure_ The p.ltient hold .I somewh.at short neck <lnd mild difficulty wilh tolndem g.ait. The remolinder of the neurologic eXdmin.tion was totdlly norm.al. The eye movements were recorded on video tdpe. CerviCdl spine and skull lI-rdYS reve.aled assimi­lation of the arch CI to thE' oecipit.11 bone and elevation of the odontoid process ,Ihove Chdmher­Iolin's line. There WoIS an unusual posterior lip to the fordmen mdgnum, oInd dislocation of IhE' d>;is on Ihe oIllas WdS notE'd on tomography. The p.ltiE'nt WolS placed in skeletdl tr.letion dnd there W<lS no reduction of the dislocation with Ir<lction up to 15 pounds. A Conr.y v('ntriculogram dE'mOnslrdted Iholt the d.st.nce between tnt' postenor portion of the odontoid .nd thl' (,Iudal portIon of the fourth vent ride w.s only 5 mm. A CAT sc.n of the ~rdm ~~.aled mod(,foItt' d.loItollion of the t'nllre v('ntnc­ul. lr system A «rebroll .rtenOKr.m d('m\...nsluled infenor displ.cement of the tonSlll.lr ~r,lOcht'S of the posterior inferior cerebell.r .rtery. An tilT mye­logr. m ~etlled tI normal C('TVIC.) sp1noil cord, and there Wol5 generous room betwffn the br.m stem .and the posterior lip of the foramen m.agnum. It w.as believed th.lt the p.atient's symptoms were the result of .Interior comprrssion of the brtlin stem by the odontoid. Nystagmus in Basil.H Impression On MJy 25, 1978, the p.ltient underwent tran­sorJI rcmovJI of the odontoid proccss by Drs. Allen Grcenber~ Jnd Roberto Negron. Thc arch of CI .Interiorly W.lS remov('d J[on~ with the cntire o.>dontoid pmn>ss, including its b.lse imd part of the ant('rior element of C2. Atthe end of the procedure the pJti('nt WJS pl<lced in G.lrdner- Wells ton~s .md continuous trJction. He hdd dn uneventful post­operdtivc course .md on Junc 5, 1978, <l posterior fusion WdS performed with wiring of C2 to the occiput. The patient noted no significdnt chdngc in his symptoms for .lpproximately 1 month but then noted gradual improvem('nt of his oscillopsid to the point wherc it totally disdppedTed. Repe<lt ex­Jmindtion 21/~ yedrs l<ltl'r demonstrated his eyes to be totally quiet in primary gaze, upgaz(' and down­gaze. He had g,:lZe directiondl horizonul nystdgmus which was dsymptomatic, Thl' pdtient is totdlly asymptomatic and working full time. A review of the Jiterillure quickly est.:lb[ishes the significant morbi~ity i1nd mort<lJity ~f t~~, s~Lf~cal .:Ipproach to cramovertebrill anomalles.-· In view of the high complication r.:lte, most piltients h.:lve been oper.:lted on only in the f.ICe of progres­sive brain-stem compression .:Ind neurologic dys­function. Patients with only ocular signs .:Ind symp­toms have not been considered surgic.:I1 candidates. The tr.:lnsor.:ll-transp.:ll<ltine .:Ippro.:lch to the at­lanto-.: Ixial region h.:ls been utilized in the treatment of p[.:Ityb.:lsia, 17,1~ atl.mtO-<lxidl disloc.:ltion,l~ odon­toid ~'ypoplasi.:l>~' fra.cluTes ~~d., infection,~l Iu· mors,- .:Ind rheumdtOid arthnhs.-1 The complica­tion ratl' of this procedure is minimal and the surgic.:ll success rates impressive. Menezes et .:II. divide p.:ltients with cranioverte­bral anom.:llies into five categories for treatment purposes.l~C1assific.:ltion depends on the reducible nature of thl" lesion .:Ind as to whethN the brain­stem compression is dorsill or ventral. Our cas~ manifested a nonreducible .:Interior compression of the brain stem by the odontoid proccss. A posterior decompression would not have relieved the pres­sure on the brain stem, and the tr<lnsoral approdch presented a much s.:lfer .:Ipprodch to the problem. Patients presenting with oscitlopsi.:l dnd down­bl'dting nystdgmus requirc extensive n('urorddio­logic eV<lludtions to define clNrly the JnJtomic.l1 ahnormdlities in the rej1:ion of th(' ccrvicoml"dulldry junction. CAT scan, cN('hral angiogrdphy, m('tri. umide cistemogr.:lphy, and dir my<'logrdphy mdY dll be necess<lry so thJt the dppropriJte surgic.ll .:Ipproach Cdn he pl<lnn('d. Primdry position down­bedting nystdgmus is frequently <l surgicdl lesion, dnd the i1bsencl" of findings on pldin skull x-rdYS should not preclude the perform<lnce of invJsive studi('s. It h.ls now ciNdy been estdblished thdt the VI"''',1! ("omrl.lint~ mJy be rcvNsible Jnd when disabling should be considered an indication in themselves for surgery. References r. Cog.ln, D. G., <lnd Barrows, I. L.: Platybasiil and the Arnold-Chiari malformation. Arch. Ophthillmol. 52: 13-29, 1954. 2. Cogan, D. G.: Downbeat nystagmus. Arch. Oph­thd/ mol. 80: 757-768,1968. 3. Alpert, J. N.: Downbeat nystagmus due to anticon. vUIS<lntIOl(icity. Ann. Neural. 4: 471-473, 1978. 4. Hart, ,. D., i1nd Sanders, M. D.: Downbe.:lt nystag­mus. Trans. Ophthalmol. Soc. U. K. 90: 483-490, 1970. 5. Keane, J. R.: Periodk altemilting nystdgmus with downward beating nystagmus. Arch. Neural. 3: 399­402, 1974. 6. Milhaley, M. S.: Oculilr motility with foramen mag­num syndromes. In Neuro-Ophthalm%gy, J. L. Smith, Ed C V. Mosby, SI. Louis, 1968, vol. 4. PI' 110-116. 7. ShImizu, N.. Weinberger. J., and Yahr, M.: Down­beat nystagmus as a sign of brainstem involvement In i1cute meningoencephalItis. Neurology 25: 267­270. 1974. 8. lee. D. S.. Friendtich. A R. o and Robinson, D. A.: The mech.:lnism of downbeJt nystagmus. Arch. Neu­rol, 30: 327-337, 1974. 9. Mohr, P. D.. Strang. F. A.. Sambrook, N, I. A.. and BoddIe, H. G.: The clinical and surgical features in 40 patients with primilry cerebellar ectopia (adull Chlui m.:llformationl. Q }. Med. 46: 85-96. 1977. 10. Saenz, R 5.. Onofrio. B. 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