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Show 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. M.. and Yangihara. T.: Experience ",ith Amold-Chiari m<llform.ltlon. 1960 to 1970.}. Neurosur8. 45: 416-4Z::, 1976, 11. Williams. B.: A cntical appraisal of posterior fossa surgery for communiC<lting syringomyelia. Br"in 101: 223-250, 1978. IZ. Hoyt. w. F., and Frisen. L.: Supranuclear ocular motor control. Some clinical considerations-1974. In BJslc Mech<lnisms of Ocular Motilitv and Their CllnJC<l1 Implications. G. Lennerstizand ~nd P. BacyY- Rita. Eds. Permilgon Press. New York. 1975. PI'. 379-392. 13. Pedersen, R A.. Troost. B. T., bel. L. A.. and Zorud, D: Intermittent downbeJt nystagmus.:lnd oscillopsia revl.'rsed by subocClpita: craniectomy. Neurology 30: 13::N-134Z. I Q60. 14. Banerji. N. K., and Millar, J. H. D.: Chiari malformation presenting in adult life-Its relationship to syrin!,:omyelia. Brdl-n 97: 157-168. 1974. 15. Cdetano de BdTros, M., Fanils, W., Atilide, L et a!': Bdsllilr imprt>ssion and Arnold-Chian malform.:ltion. I. Nf'urol. Neurosurg. Psycniiltry 31: 596-605, 1968. It>. 5ym"nds, C P., dnd Meadows, S. P.: Compression of the spinal cord in the neighborhood of the foramen m<lgnum with a note on surgiCd.l approach by Juliiln Tdylor. Bril;n 60: 52-84,1937. 17. Delandsheer, J. M., Cuon. J. P., and Jomin, M.: The trJnsbuccopharyngedl approach and malformation of the cervicooccipital foint. Neurochirurgid 23: 276· 281, 1977. (Fr.) Journdl of Clinic.:l] Neuro-Ophthillmology 18. Menezes, A. H.. V.mGildeT. I. C. GT.Jf. C J., .md McDonnell, D. L: Cr.JninvertebT.J1 .tbn"rm,llili.,~..1 comprehensive $urgir.tl .tppw.Jrh. /. N('unl~urJ'. 5J: 444-455, lotiO. 19. Greenberg. A. D.: AII.Jnhl-.Jxi.t1 di~ln""lli"I\~, HT.lIn 91: 655-otl4. 100tl. ZOo Greenberg. A. D., 5..',w'lIe, W. B., ,Iml n,lV"y, L. M.: Transor.J1 d(>comprp$$iun ,~f tIlt' .111.lt1I\",.i.11 di~:I,,,·.I. lion due t(l (ld,lnl,l,d hyp,'pJ,I$l,l. RtT"r1 ,'f hv" C<l$(>$. /. N(>unl$uQo:. 28: Zc>c>_::'.r>0, 10r>1I. Zl. r.tn~, H. S. ) ...md On~, G. B.: Pin·.. t .lt1t('rIlH JppT(lJrh III the upper r",rvi",11 "pin... I 8"nt> /,'lI1t SUI):. lAm,) 44: 151111-1t<l4. 10t>Z. December 1981 Z2. Mull.tn. S.. N.Junton, It. H.. km.JlpdnJh, J.• ('I <II.: The u~.. of dn Jntenor <lppmd..h In vertically pl.tct'd lumors In th(' f\,rJmen mJlo:num .. nd vl,rtt'bral col. umn. I. Nt'urosurX. 24: 530-543, 1960. ::':J. Smith, H, 1', Ch.. I1.., Y, R.. and Alf'x.tndf'r, L Odnn. t"iJ f\'mpr('~sion of tht' bralnstf'm in d patient with rht'um,lluid .Jrlhrilis. / NpurosurJ:, 53: 841-845. 1°30. Writt, for rt>prmts to; Rich.Jrd C Spfelick. M,O., Suile lOOt>. 343 W. Houston 5Ire('l, 5dn Anlunio. Texas 78:1:05. 267 |