Journal of Neuro-Ophthalmology, December 1982, Volume 2, Issue 4

Radiologic demonstration of the dorsal medullocervical spur in adult Chiari malformation.

An adolescent female with downbeat nystagmus and long tract signs was evaluated by a number of diagnostic radiologic procedures. Metrizamide CT cisternography was the procedure that established the diagnosis by showing not only the tonsillar herniation, but also the medullocervical deformity characteristic of the Chiari type II malformation. This case report emphasizes the superior diagnostic capability of this technique with respect to conventional radiography in the diagnosis of Arnold-Chiari malformation.

). Clin. Neur,,-,'phth.IIIl111/. 2: 23:>-240. )0t\2, Radiologic Demonstration of the Dorsal Medullocervical Spur in Adult Chiari Malformation ASHWANI KArlLA. M.D. RODGER HBlE. M.D. ROBERT A. RATCHESON, MD. RONALD BURDE. M.n. MOKHTAR H. GAOL), M.D, Abstract An adolescent female with downbeat nystagmus and long tract signs was evaluated by .l number of diag­nostic radiologic procedures. Metriumide CT cistern­ography was the procedure that established the diag­nosis by showing not only the tonsillar herniation. but also the medullocervical deformity characteristic of the Chiari type II malformation. This case report emphasizes the superior diagnostic capability of this technique with respect to conventional radiography in the diagnosis of Arnold-Chiari malformation. The purpose of this reporl is 10 emph<lsize th supt>nQrity of melrizamide CT cisternography over other roentgenographic investigations in demon· strating tonsillar ectopia and the medullo cervical de ormity pathognomic of the hiari type II mal­formation. The presence of an enlarged fourth ventncle In the type II anomaly n routine head CT in the absence of hvdrocephalus is reported, Arnold-Chiari m,llformalion molY fir.t become symptomatic in .1dole cence or adull life ,1Ild should be a diagnostic consideration in .lIlY p.1tient with signs and ymp\llm~ rdcrable I Ihe po.lcrior fossa or upper spin.:!1 cord. The clint al picture may be paroxysma I, recu rrenl. or steadily progressive.' The differential diagnosis includes tumor. inf.H(­tion. inflammalory di case. va cul<lr mJI (lrm.Hien. aneurysm. <lnd demyC'iin.ating processe~"f the p,15­lerior fOSSJ, The IraditionJI radiogr,lphic m()J.1Iiti('~ w,,·J h' diagnose Arnold-Chi.Hi m.dform.1li'1I1 iIH'luc!" plain x-rays of the skull 'lild CC'rviC.11 ~pin(·. Illy"­logr. aphy with oily (Onlr,lst medi.l. pnC'umocn(C'ph­aIogr. aphy, and verlebral angiogr.1phy. The limil.l­tions of these techniques h.lVe been docurnentC?d. From In(' M.,lIin, k",d( I'htilul.. "I ".Ht."I"gv (A". MII( :j, DepartmC'nt... Clf l·urph'.\~v ,1IHJ NI·IHlllp~ll.,1 ~urht'rv IR!.. RAR), 'lnd th(' l.)('pMlmeill (.f nphlh.,I",,,I,,,; (I\f\J, W,,,h,,,,;­ton Univ(lr~ity Schuol of M('dlf" Int', ~1. Ll1111", M1.....4111 1'1 December 1982 Computed tomography (CT) can demonslrate in det.1il the gros p.athologic.al intracrani<ll changes in inf.1nt .md children, !., but its value beyond that .lge group hJ not been established. Rec~ntlv, me­trizil~ ideCT ci terrlOgrJph/,' '; and ventric~logra­phy,' h,lVe been used for Jccur<lte defi nition of the morbid anatomy uf th Chiari Jnd associated mal­formation. Case Report A IS-yeM-old de tral white fem'lle developed slowly progres ive n,ls.ll peech .lppr xim.ately ,;I yeM prior to ,Idmi sion. ne year prior to .ldmis· ion, she begdn experiencing i ual blu rring while viewing the blJckbo,lrd in schoQI. Three mlmth prior to admission. her friends noted thdl h r eves "jumped," and she became aware of horiwl~tilr diplopia. The pJtient related incre.1sing I,lwer e,,· tremity c1umlness for 2 ,)r J yeus. but her p.uents attributed this to the onset of puberty. For almost a yeJr, she hJd mild bifrontal Jnd biL)~cipital head­aches. which often Qccurred upon aw.1J..ening and were usually promptly relieved by ,Lpirtn' The p.ltient ,11 0 h.ld severJI 15-_econd episl)des con-isting of sensation of sudden li~htnes_ in her thrll.ll followed by f.Ki,ll flushing .1I1d IVheezin~. during whkh she w"L1ld bpl:l"l1c "wc.lk" .1nd "hcn slump tll th flol)r will1L1ut Il'ss ,)f n'nsl'iL'llsneSS. These epLodcs fr quenllv ol:l:llrred while C'.ltin~. Physic.ll e .1I11in,lli'1I1 revc,lled .1n .1l1"iL1U~ f m.11E' of .lVer.1gc intellJgC'nce. ".lmill.llilln llf Ihe hE'.ld. lled" spin'. ,1nd ~kil1 W,IS ulH,'m.1rk.1ble. C,'rreeled vi~ll.11 .KlIity 1V.1~ 20/20 in b'llh ('v('s wilh 11<'rl11.11 flilldos,"'pic .1I1d vi~1I.1r Hdd l'".ll11in.1ti,'n, (ll11­firmed by norm.11 kilwtiL" ~1('ril1ll'lrv ,1n .1 bowl perimell r (CoIJm.lIl11). Thl' pupils ~~cre t, mm ill di.l11H'ler .1Ild wert' briskly re.Ktivl.' Il) light. Hl)W­ever. there W.l~ po<\[ (vnvergelK ,1Ild little pupil­I. lry f('.K!ilH1 t" .lCl"(111111Wd.1ti'1I1. Therl.' W,)S .1 con­jug. 1le prim.Hy-posilinn intermittenl (ounlerclock­wi~(' nlt.1lory nysl,lWllll . On right .1nd left later.al g.ne.•1 (0.H5(' conjugal, h,lfizont,ll nyst.lgmus WdS 235 prl'~I'IlI. grl'.ltl'~t ill til(' .lbJuctillg I·Yl·. Thl'rl' W.l~ .11:-11 .Il·l'niu~.,te g.I7.I'·evI,l..eJ duwnbl'.11 lly..t.lglllll~. Atlillw". bil.lll'r.ll intl'rI1l1l k.tr 111'1 h.11 1l11 l plq.\I.1 W.I" pn'''l'nl. Il",n' pn,milll'1l1 1111 right g.l/l·. t )plul..i­I1di, ny.. l.lgmll" w" .. Jillilllil lu l'lillt in .111 din'l­tillll". l'Ill' '-lltt p.d.ll'·I·kv.lll'd puurly PI1 plll l n.lllllll bill dl'v.lll'd hilly wllh till' g.lg 1"1'1[1". Tlwn' W.I'" ,I 11.1 ..,11 qu.llily t,1 Ihl' p,ltil·nt·... "pl'nh. Mild dv..di.l­d" dllll..ine... i.1 W.I'" prl''''l'nl III .111 ,·"dn·lllilll'''. bill Ih'T,' IV.I" IIII "1111'1" I'vldl'llll' pI ,·,1 n'lllllv .It."i.l. 1'111' g.lil W.I" wi,h--b.lwd .1I1l1 ..1.lgg'·I"Jllg..Ind ..Ill' W,I" IIn.lbll· til 1.IIllll'm w.111.. ~Irl'ngth W.l'" 1111.111 1"11'1'1 h'l" mild \'\11·.11-.111' ..... ut Ill(' nl', I-. fie or.... AI­111lIllgh Ihl' mll"'lle ...tretlh rdle,,·... IVI'rI' wlthll1 11lIrm.lllimll....1... 111.111V .1'" "'1'\ bl·.l[.. 111.1111..11' ,Ipnu" l,ltdd lll' I'lidtl·d bil:lll'f,ll1y with "IILkkn .1111..1(' dllr.. ifl," i,lll. Radiologic Findings PI.lin r.ldiogr.lph:- llf thl' .. I..ull Wl'n' I",rm.l!. Thl' b.l~.ll .1ngle 1111·.1 ...un'd 130 o (nllrl11.1 I r.1I1~1· .I'" 1_'1.," - 152°).~ There W.l" n,l ('vidl'n(e ,It .,tl.lnllllllClpll.,1 fusinn ,lr b.1Sil.H il11pres..i,'n. C<:,rvl(.ll :-pine 1".1111­in. ltil1l1 ~howed the ~.lgitt.11 di.lnw!l'r Ilf the b,'ny (ervir.11 r.ln.ll .1t C I .md ('2 tn nll·,l .. url' 22.0 mm .lnd 10.0 111111 rl· .. pe,(tivrly (n,'rm.11 r.lngl· i... fHlm 15.5 111111 tll 23.0 111111 .1t ('I .mJ ['l'twI'en 15.5 111111 .md 22.0 mm .1t (2)." Thl' :-.lgitt.ll dlmen:-II n ,If thl' ..:ervic.11 c.m<11 .1t CI W.IS therefl)re ,It the upper limits llf norm.1/. CT SC.ln of the h('Jd w.I" perform('d bdl1rc .md .1fter th(' Jdministr.l110n llf il>din.ltl'd intr.l\·l'Iwus contr.lst medi.l. There W.IS Ill> evidel)(e Ilf hvdr,>· c ph.llus. The I>nly definitive fltlding 1\'.1S th pres­ence of .1 I.uge fnurth ventri.-!(' (Fig. I). The mid­brain .1I1d pons were vi u.)!Ized Jnd lVer" ,)f IlIlrl11.11 izl' .md c<.ml,)ur lVith,)llt h'C.ll p.lrenrhym.ll ,lb· 1111rm.llitv. The regil)n nf the nwdull.l. hoI\' \'1'1'. 'ould no't be optilll.llly ev.llu.lted due h> Ih pre,,· ence of Ihe uSll.11 .lrt"f.lCtu.11 "tr('.ll...; .11 the level "f the ft)r.llnen m.l~l1um. thllu~h there .lppl'.ned h> be .I pJucity of r('hr,>. pinJI fluid in th.ll n'gilln. A pneu mlll'nCI'ph.lII)gr.lIII 1V.1S perfllnnl'd. Air fJilcd t" ('nt"r the v('ntricul.n "y~I(,1l1. Midline :-.l~· git.ll riC'uridin..-tillll.ll tl>nHlf,r.lphv "f the rr.1I1il>· C('rviC.ll regi,)n (Fif,. 2) shllwl'd .lb~I'nll' I>t .lir in till' "'pJCt· in fnlnt Ilf thl' upper cervir.ll e,>rd .1I1d br.lin­... tcm. Thl'...e finding~ WNl' Ilwrefl>rl' inll'rprl'll'd .l~ ... uggl'... tiVl· llf .Il) inlr.ln1l'dull.H·y tunlllr. VNIl'br.11 .lngillgr.lphv :-h"1\'l'd .IIII\'11\v.1I".1 db­pl. 1l'l'rnl'lll of thl' 1,ln... ill.lr br.lnehl':- lIt bllih r,,~tl" ril'r in(nillr (l'rl'l1l'II.H .lrll'ril''; be!.l1\' Ihl' 11'\'1'1 Ilf the' (llr.lnH'n 1ll.lgnul11. TIll' \,I'rmi.ln br.llldws ,If Ihe r"...tI' r111r infNillr 1·l'rl'bell.H .nll'ril''; I\'l'rt' .. Irel, hl·J .111.1 I.IY .-!I"'I' tIl thl' innl'l' t.lh'" Ilf Ihl' ... I..ull .11 thl' p"..II·ri"r 1ll.1rgin Ilf thl' f,'r.1I11l'1l 1l1.1g· Ilum. Tlll·..I· filldlllg ... rl'pn'",'nll'd ,hllVn\\'.nd di~­pl. l('(·nll·nl ',( 1111' llln ... il ... bl'l,,1\' till' In'I'1 I>t thl' f"r.ll111'11 1ll.lgnlllll..Ind 1.1 Ihl' inkrillr vI'rmi.; .lnd ,,,rl'lwlllllll t"w.Jrd ... thl' 1.'1'.11111'11 In.l~nU1l1. bUI did Fi~ure I. 11l1t de.Hl\' dl~lln~lIl~h .111 Arnl)ld-ChIJri malfor- Ill.ltll>n Ir:1I11 .In .1\·.lSCld.Ir p~",steri(lr f J tumor. Thm "ecll,)n t~.l1 mOl slice thIC)..,ness) metrizJ­mide T cl~terl1q::rJph\' I\'as perf0rmed (Figs. 3.1­31' l f,)I1I)\\,ing mlwductil)n of 7.0 ml of metrizJmide (170 m~1 'mil ,·i.l the lumbar rl"'ute. There was no 1'\"ldence Ilf .llunwr .-\ p~>~leril)rly directed knuckle \,·.l~ id nlifll.1 .1t the dll\\'ll\\'.Hdly dispbced med­til II)CN\,ic.l I junt:til)n )Pp"'. ite C I (Fig. 3.1). The t,>n~il" \\'I'r~' fl.1ttened .lnd displ.Ked d~)l\'nwJrds to .1 1('\,('1 bl'I\\'l'en C I .lnd 2 (Fig. 3b). Jnd the interi,)r "cnnis 'Iended d~)\\'n intI the foramen 1l1.1gnum (FI~. 3r). These findings firmly estab­Ii" lwd the di.lgl1l1sis ~lf .1 Chi.Hi type II m.llforma­lil'n. SI>I11l' mllriz.llllide entered the fourth ventri­( II' .1Ild \'''b ~een tl) byer l)ul in ,] dependent !.>r.ltil)n I)utlilling the pr,1minent postero-superior rl'rl'.;~t?~. A ~rl>t film I)f the lumbJr region following ll1l'triz.lmidl' intwductil)n sh~)\Ved J normally po­~ ltll)l1l'd r,ll1US 1l1edull.His .\t ll-L2. Operative Findings A .;ubl)cripit.ll t:r.miectomy and laminectomy of C I .lnd C2 \V.1S performed. The cerebellar tonsils IVI'1'(' IWrI1i.ltrd through the foramen magnum to 1111' level ~)f C2. but were not significantly com­pres.; ed. The l)bex lay at the level of C1-C2. There \V.l~ free flow of cerospinal fluid from the fourth v('ntricle. with no evidence of a membrane over th(' obex and no dilatation of the central canal. Journal of Clinical euro-ophlhalmology Figur(' 2. PIlt'um')"",l'ph,)I,'gr,)m 1l'1Idllnl' !oJglltJI plJnc, The ptlsl('rJor l"l\lrd\,p, llt thl' (',:t\lpi( llln~lI$ (whllr Jrn1wht".hh) were 11l1~int('rpr('tcd .h l,-lrLlin ..tl"ln l'nl.H~('ml"nl. figur('s 3.. -3c. M,'lril..Jmidl'lT l i'lt'rn"~r,,m. (.1) AI t'~. (It) AI L' I. (<') At the fur.lmC'n m.l~num ....' = 4.:'urd. 111 = nu·dull.l. l = tl\n~il. v = Vl~rllli~. Just lateral to the obex and b.l ed on the medull.l was an eccentrically pl..Ked mass <lbout the size of a small grape. It was unreve.=ding to palpation, and a No. 24 needle was inserted into an avascular December 1982 portion of thi lump to .1 depth of I em. fluid could not be aspirilted. This was thought to represent a medullocervic.ll kink. Biopsy was considered un­justifi. lble in this location. The dura was loosely 237 II .ll'l'r,I'\ II11.llt'd. "'vt'n'd IVlt h ~"It Ii III ,ll1d II", ,','1'\'1­" t1 111l/"', I,''''..111<1 11111"'1\111 \\'.1'" ,I" ...,·d. Dio;cussinn 1'11l' ,1111".d 1'1"1·... '·111.111"11 "I till' hi.lri tv~',· 11 11\.11">1111.111"11 III ."I,dl ... I'" ,-tl<'11 ll\lIll1"'II1~. 11'11\,,'11- 11\111,11 r,ldi,'~r.lphi<' prll"-l'dlireS .He often laborious, dlHil'lIll II' il111'rprrL .11 limes inconclusive, and ,'\'l'n ml~k.ldin~. The clinical findings. in our case, l'"intl'd ll' .1 lesi"ll ill the brain stem, and the ~cri..lu~ di.lgIW<;lic consider,llions were brain stem tllnlllr .lnd Arnnld-Chiari malform.lIion. Cr.lllll..-ervic.ll jUll(tioll anom,11ies reported with IllUrIl,ll"f Clini <11 NE'uro-ophth.,lmology Arnold-Chi.Jri m.llhHm.llillll illdudc pl.ltyb.l~i.l, ,,11.mlo.lxi.ll tu~ilH1, b,l~il.lI· impl"l'ssillll, Klipl1l'I-Fcil syndrl)ll1e, .lIld \Vidl'ni\l~ llf thr c('rvil',ll (,111.11. TIl!' reported illcidl'\l(l' V.Hil,~.I.lI. III S.\l'Z l'I .11" I'l'pllrt abnMI11,lliti('~ 1)11 ~"ull r.1l1ill~r.lphs ill 31%, ,lIId llil cervic,ll ~pi1H' l',.llllin.llillil ill 34% llf Ihl'ir (,lSl'~. 111 lIm (.IS(' pl.lill r.ldkl~r.lphs wl'rl' Ih'rm.ll. Myl'll)gr.lphy with llily (Illltr.lst nll'Ji.l m.1Y lw nMnl.ll in Ihl' pnH1l' pllsitinll, Ill·n·~~ll.llill~ ~upil1l' e\.lmill.ltil'l1 Ilt IIll' hlr.lnll'1l m.I~llllll1.I". II [v('11 Ihl)ugh supille l1lydl)~r.lphy is highly ~(,Ilsilivt' in Ihe dell'ctilln tIt .111 .lbllllrm.llily .11 Ih(' n.1I1ill(('rv­ical junctil)ll. the di.l~nl)si~ of Anlllld-Chi.ui m.ll. ftlfnl.ltilH1 m.lY Ill)t br nlnclu~ive'" (T 5c.ll1nin·~ ,If the hr.ld In thl' .lb~l'IK(, llf hy­drllcerh. llus 111.IY be Illlrln.ll:"·; in .ldults with Ar­nl) ld-Chi.lfi 111.1 Ifl)rm.ll illn, ,IS minl.lr .1Itl'r.ltiCIll of .In.lt,lmy .11 the cr.lllil)cl'rvk.ll jUllction m.1Y be missed due tl) the high incidence l)f .Jrt f.tctuJI slreJ"s in this regil)n. This in1<lg degr.ld,ltion i rr,)b.lbly re!.lted to the surrt)unding bony truc­tures.• lnd the high CT ,lttl'nuJtion differenti'll between bt'ny .)I,d cerebrospin.ll fluid. The p,lUcity ,)f cerebrospinal fluid .Hound the medullJ on the CT imJge sugge ted the possibility of .111 intrinsi tumor. but the bone .Htef,Kts prevented a thorough el'aluation of this finding. Pneumoencephdlogram showed absence of ven­lri ular air. This is usually seen with Arn Id-Chidri malformation, II-I , but dlso occurs with intrJcrani,,1 tumors. The lack of dir in the dnterior subarachnoid space from the dorsum sella down to C2, as well as between the downwardly displaced tonsils and the medulla gave the impression of an intra-axial tumor of the brain tem and upper cervical cord. The lack of air is presumed to be due to the surfa e tension phenomenon of the cerebrospinal fluid trapped by closely approximated surfaces. Posterior fossa angiography revealed downward displacement of th tonsillar branches of the pos­terior- inferior cerebelldr arteries and stretching of the inferior vermian brdnches. In the absence of tumor va cu/ature or other specifi angi grJphic indicators of neoplasm, this finding did n t help distinguish Arnold-Chian malformation from other causes of downward tonsillar herniation. The enhancement of cerebrospindl fluid wilh metrizamide prevented thl' artefdctual streaks. The free mixing of contrast material Jnd c('febro pinJI fluid allowed the structures of the ml'dullocl'rvic,ll junction to be evaluated in minute dl'tJil with no interference by surface tension phenomena. The most valuable conclusion of this I" aminJtion W.15 the unequivocal exclusion of a tumor in thl' brJin stem or upper cervical cord. Whill' the downwJrd tonsillar displacement confirmed thl' diagno is of Amold-Chiari malformation, it Wd thl' demon­stration of the posterior bulge of the downwardly displaced meduJlocervical junction opposite CI-December 1982 ..., K.lpol.l. L1blC', R.ll, h(,~t11I, BurdI', ad ("2 th.11 (llndu<;iVl'ly Ji~pIJcl'd this case in the r.llt'g,'ry l,f ,I Chi.Hi typ(' II m'llformation. This hulgl' h.l~ bt'l'l1 Jl''>crib('d .IS the dor <11 spur or ""nil "lIIlg" ueformity,ll and th(' "hun hback" de­fllrmity.'" It i~ belic'vcd to r('pre ent caudal migra­tilln of the m('dull,l, dorsal to the' upper cervi aJ l'llrd, whi h is held r('/Jtively immobile by it den­t. lll' 1r~.lnll'ntllu~ .llt.llhmc·nh tll thl' torJmen mag­num. 1I TIl(' l.lUJ,dly Ji.,plJled ml'dulla ome t lit, pllstnillr tll thl' UppN crvical cord forming an S-sh.lpc'd bl'nd,'~' such that a tran Vl'rse section IIHllugh th.lt rq~illn would rl'sl'mble the the "figure 8," Iwt dis imil.H from the dppCdfan (' in our ca l' (Fig. 3.1). The idl'nlifi .ltion of the dorsal spur has not been the fo us of attention in recent reports. Re­cently,. two C.l es reportl'd as Chidri I malforma­tions ····· under metrizamide CT c1sternogrdphy. On rl'viewing the illustrations in both these reports. a dorsal deformity of the downwardly di placed medullocervical junction can be appreciated, not significantly different from our ca e. It would thus appear that these tw cases represented Chiari type II malformations according to conventional c1assi­fication'"' I~. of Arnold-Chiari malformation. The large fourth ventricle seen on CT was n ted at surgery to e tend below the foramen mdgnum. The enlargement cannot be explained on the basi of obstruction since there was no dilatation of the Idterdl r third ventricles. We the ref re assume thdt this isolated finding repre ents one of the many dysmorphic fedtures of Arnold-Chiui mJI­formation. The case of this report exhibited no tethering ot the cord on myel graphy or hydrocephalus n CT. These observations seemingly e c1ude the hydro­static pulsion and traction theories of the morph ­genesis of Arnold-Chiari malforlllJti n. References I. D"bl.in. 6.H.: Th(' .ldull -hi.Hi n1.llft'fnl.lli"Il. Bull. L,>' Allg('!('~ Nellr.'!. S",-. 41: 1:'\-17. 1<177 2. Naidich, T.P., Pudll)W ki. R.. .lidich. J.B .. G rmsh. M., and Rodriguez, F. J.: ,Imputed tom"gr.lph .... sIgn of Chiui II malform,'tion. P.lrt I. 51.ull and dural partitions. R.id;o!ogy 134: 05-71 .• <1tlO. 3. N.lidich, T.P.. Pudl,)w 1.1, R.M., .lnd .1Idich. 1.6.. llmputed tllllwgr,lphic slgn~ "( Chi.Hi It m.llf,'r­m. lti'1I1. II. Midbr.lIl1 .1Ild n·n·bl'llum. R.ldl<""~\' 1:,\4: 3~I-J~~, Iq~O. •. 4. N.lidil'h. T.J'.. l'udl'l\·\I~l.i, R...lnd N.lididl, /.6.: I'm­puled tllllWgr.lphic slgn~ 'If til{' Ch,Mi II 1ll.llf, rma­li" Il. III. Vt'ntride~ .lIld ... i~lerns. R.lditl!<'gy 134: ,,'57­Ob:'\, ,<11:\0. 5. I'l'lj('r~lln. R.A., TlHJd, T.. Abel. L.A...1Ild Z,lrub, 0.: Intermittent d'lwnbe.ll nyst.lgmus .lnd ')5cillopSI,' r('v<'r~('d b sub'lcnpit.llrr.lI1ieclomy. eur"}<>gy 30: '2:,\0-1241, '<180. Cl. F.lri.l. M.A., rector, R.H.. .lnd Tind.lll, G.T.: Down­De. lt ny~t,lgmlls .IS the s.llienl m.lI)ifestalion of the 239 An",ld-Chi.Hi m.llform.llion .....ur~. ('ur"I, 13: 333­33l'. 1<1~0. 7. Finn. S.. Ril'ux. n.. Fr('~~in.lllJ. 1'.• F.lrdl1un. R., <lnd Cuy. C.: Chi.lrI In'" I m.,lfl1rm.llll1n wilh hydro­mYl ·li.l; rinJin~~ .,1 ,"ompUlnl7.I·J m('lriz.ll11ide ven­Iril" ullll11yl·lllgr.lphy. ~ur~. Neuro/. 12: 227-229. /<17<1. ~. L.lI~led. L..II.•.lIld Kl·.lb. T. L: 1\ 11.)., "f l<o('nlgen". ..;,..I/,l1i, M ...l,urelllc·nl. Yl·.Hblll1k MI·J'I'.ll /'ubli,h, l'r'. Chil.lf;ll. 1<l7/1. p. 51; 1111, I ILl. " S.ll'Z, R.I.. UI",fri". II.M ...lIld Y.lJl.lgih.lr.l. T.: [ . peril'IlI'(' wilh AnlllIJ-Chi.lri 111.1Iform.ltion, /9.,0 10 1<170. /. N..un'.,u,.~. 45: 4 Jl,-422. IQ7o. 10. Apl,j('by. A.. Fll~l('r. LB.. H"nkinoll. I.. <lnd Hudg· Sllll. 1'.: Thl' Ji.lgllllSI~ .1I1d m.ln,lg('m nl of lhe ChiMi .lJlllm,lli('~ in .1Julllif('. BrJin 9J: 131-139. 190~. II. Rh,!hlI1. A.L... Jr.: Microsurgery llf Arnold·Ch,.HI m.1If"rm.ltillll in .Il.lulb wilh .1I1d withllUI hydromy('. li.l. I. N('un'sur~, 45: 473-483, IQ7<:o, 12. Gardner, W.j .• and Goodall, R.j.: The surgical treat­menl of Arnold-Chiari malformation in adults. An e plolnalion of its mechanis and importance of en­ceph. llography in diagnosis. f. Neuro urg. 7: 199­206. 1950. 13. Tcn~. P., and Papatheodorou. c.: Am Id-Chiari mollformation with normal spine and cranium. Arch. Neuro/. 12: 622-624. 1965. 14. Em('ry. I.L... dnd MdcKenzie. ,: Medullo-cervical dl~l(l dlion deformity (Chiari II deformity) related to Ileurusplndl dysrdphism (meningo-myeJoceJe). Brain 155-lb2. 1973. /5. Pt><lCh. B.: ArnoJd-Chidri mdlformation. Anatomic ft>ature of 20 Cilses. Arch. Neurol. 12: 613-621. 1965, Wril!' for reprinls 10: Mokhtar H. Gddo. M.D,. 510 South KlngshighwdY Blvd,. St. Louis. Mis ouri 63110. lournal of Clinic,,1 Neuro-ophthalmology / "'''