Journal of Neuro-Ophthalmology, March 1986, Volume 6, Issue 1

Bilateral internuclear ophthalmoplegia with absence of convergent eye movements. Clinicopathologic correlation.

A case of bilateral internuclear ophthalmoplegia of long duration with autopsy confirmation is reported. The main features of the syndrome included paresis of ocular adduction upon attempted lateral gaze, horizontal nystagmus in the abducting eye, and an absence of converging eye movements. Examination of Weil-stained sections revealed multiple plaques of demyelination. The medial longitudinal fasciculus was demyelinated bilaterally in the upper pons-caudal midbrain. The oculomotor, trochlear, and abducens nuclei appeared relatively well preserved. The internal capsule was severely damaged. Large cyst-like structures were centered in the anterior limb bilaterally and extended caudally to the level of the genu. Plaques of demyelination were present bilaterally in the posterior limb. The left side of the internal capsule was more severely affected than the right. It is thought that convergence in this case may have been eliminated by interruption of fibers from the frontal eye fields and/or other cortical areas in their descent through the internal capsule.

Bilateral Internuclear Ophthalmoplegia with Absence of Convergent Eye Movements Clinicopathologic Correlation* ~1itchell B. Stwminger, B,S., Ernest J. Mincy, M.D., Adele I. Stwminger, tv1.D., and Norman L. Stwminger, Ph.D. ,\ C,lSt' III bil,llt'r,ll IIllt'rnuck',u llphth,'lllluplegl'l ut IUllg ,htr,ltlllil \\'Ith ,1lItll~'~Y Cllllltrlll,ltIUIl i~ replntt'd, TIll' 1ll.l1l1 k,ltures III the ~\Ildrlllllt' Illcluded part'S" ui lll­uLu ,1ddu([lllll Upl'll 'lltl'lllplt'd I,llt'r,ll g,lLt', hllriLllllt,ll 1l\~t,lgIllUS In the ,1bdu([lllg e\'t', ,llld ,111 absellcl' lli Cllll­\ t'rgl~g t'Yt' Illll\l'Illl'llh 'b"llllll1,ltilln lli \\'eil-slained "'C;lll~S revealed Illultlple pl,l'lues III dt'Ill\'elinatilln. The Illedl,ll k)ngltudInal t,l~Clculus \\'a~ dl'm\'elinalt'd bl­!. llt'rall\- In the u~'per p''ll~-caudal midbraIn. The lKulll­llllltl) r. tfllchlear. and ,ll'ducelb nucleI appeared rela­t"' elY \\'ell prese[\ed The Internal capsule was severelv damaged. Large c\'st-likt' stru([ure~ were centered in the a~tenllr li~lb bilatt'rall\- and e'\tt'ndl'd c,lud,lllv tu the le\'t> I lli the gt'nu Pla~lu,'~ ui dt'Ill\'t'llI1atllln \~'erl' present bilaterall\' in the pu~tertllr lilllb. The lett ~Idt' ui the IIlternal capsule \\'a~ mllre ~e\'t'rel\' aiie([ed than the nght. It " thought th'll cun\'t'rgenct' in thIS C,No' Ill,1\' ha\t' been ehmInalt'd b\' Interruplilln III tlbers tWill till' Iwntal e\'e iields and l'r uther curtlcal areas III thl'lr de­scent thrllugh the inlt'rnal capsule. from the Departml'nl ot An,llom", 'lIld 1)"'I'lon lit :"l'lIrll­, urgerv (EJ:Yl). Alban" Ml'dlldl (ollq;t', Alb,IIl\', Nt''' )or~ M. B. Stwmlllger I' a membl'r ot Ihl' tid" ot I'IHh, W,I'hll1glllll Lnl\'erSlIV. School of \ll'dllllll'. St LIlUI', \ll""llrl ... Pre.,~nted at the Aml'f1l"dn A.., ... Ulldllllll til An.ltPllll ... h Ml'eltng, Dl'trolt. MIChigan, M,l\' 1'177 Addre." correspondl'ncl' 'lIld rl'prlilt "'qlll'~h 10 I)r ."" I Stromlllger al Anatom\' Dl'Polrtllll'llt, Alb,lIl\' \kdl"" l ollt-gl', Albanv, NY 12208, USA. This study was supported III pM! bv 1'\111 I gr,lIll NS-12211H 57 The results uf numerous experimental and clin­ical studies shuw that lesiuns lucated in the medial lungitudinal fasciculus (MLF) mav produce distur­bances uf conjugate horizontal eve muvement>, which have been referred to as internuclear ophthalmoplegia, Paton (l), in 1921. appear., to be the first to appreciate that disturbances of the \ILF produce "internuclear pabies," The syndrome uf the MLF has been divided into anterior and posterior tvpes (2,3), Accurding tu Lutz (2), the charactt.'ristic features of anteriur in­ternuclear ophthalmoplegia are: (a) paresis llr pa­ralysis of ocular adduction upun attempted lateral gaze with pre.,en'ation uf adducting e\'e move­ments in ocular cOIl\'ergence; and (b) nvstagmus exclusivelv present l'r most prominent in the ab­d ucting eve, Vertical eve Inll\'el1lents a re unaf­fected, Fullowing Lu tz' s descri ptil)Jl, PllS terillr in­ternuclear ophthalmoplegia is characterized bv a pMesis of ocular abductilln This t\'pe would seem difticult to ditterl'nti,ltl' froIll ,m ,1bducens nen'e p,llsy, Whiit.' there ,Hl' sen'r,ll C,lSl'S llf pl1sterillr intl'rnuclear llphth'llnlllpit.'gi'l repl1rtl'd in the liter­, lture, nllne h,l\'l' dllcul1ll'nted lesillns innl!\'ing the MLF, ,md till' ,lppwpri,ltl'ness llf the term in this wnte,t has been tjuestilllwd (-1-8). Cllgan (3) proposed ,1 different cl,lssificati'ln in which paresis 01 ocul,H ,ldduction togl'ther with nvstagmus in the ,lbducting l'yl' is ch,H,lCtl'ristic of both ,1nterior ,1I1d posterior intl'rnucleM ophthalmoplegias, with con\'ergl'IKe "bulislwd in the former. The present rq~llrt describes a C,lse of bilateral ,lntl'rior internuclear ophth'lll1loplegia in which OCUIM nmvergence clluld Illlt be elicited . CLINICAL OBSERVAnONS ;\ 52-ye•.H-uld right-handed man was hospital­ized fllr evaluation of ,1 recent onset of numbness ;\1 Ii SIR( )MINCU\ IJ AL. ,1Ild tillglillg lIl\oh'illg hi", I'Ight h,llld dlld d con­Clllllil, lllt 10-lb l\l'ight 10"'''', TIll' ,l.;l'lll'rdl phv",icdl ,11ld Ill'U rologil'd I l'\d Illi 11,11 iOIl \\'d'" UIHl'lll,lrk,lbll' l'\l'l'f't Illr till' prl''''l'lln' 01 d "'Illdll "'Ublll,llldibuldr IYlllfl h Illldl' llil till' right ",idl' dlld pdn'",tlll'",id'" of Ihl' I'Ight h,lIld, ;\11 l'\l'i",iolldl billpW 01 till' IVlllph Illllk rl'\'l',lil'd d plH1rl\' dilll'l'l'lltidll'd l'drcillllllld, :\ priIllM\' Illdl.'" nllild not bl' IllUlld, Sub"'l'LJul'nl Ill'urlllllgiLll tl'",tillg ",lllIwl'd pro­grl'",,,, illil llt 11ll' righl-h,llldl'd p.lrl''''llll'",id''' ,1Ild d nl'\\', Illild, right-",idl'd hl'lllipan''''I''' wilh upfwr Illlltllr nl'Unln ",ign"" Cl'rebrll",pinal fluid dna!v",i"" CMlltid ,1rll'n' angillgr,lphv. ,1Ild pnL'ullllll'ncl'phd­Illgr, lph\' were l'ntirely nllrlll,ll. I'.lrentlll'tic,ll"', it ShllUld bl' nlllL'd th,ll thi", ca",l' preddll'''' cllmpull'r­iled ,l\i,ll tllnlllgraph\', The p,ltient'", Increasing fllC,ll nl'uwlllgic,ll dl'licits were altribulL'd tll dif­fuse Il'It Iwmisplll'ric Ilwtasta"'L'S, In till' ab"'L'nce llf .1 d l'm II n '0 t I'a b k m,1 '" '0 k '" ion, the p ,1 til' n I wa '" tre,lll'd with ,1 21-dav Cllur",e of l'llbalt tlll'rap\' (5,000 rad tlltal) tu the !eft hl'misphere, He wa", discharged lln ,1 regimen uf Oilantin and predni­sune, TIll' p,ltient's cllndition cuntinuL'd tu dell'rillrall' during the ne\t 13 mllnths, Svmptum", includL'd increasing weaknL'ss un the right side, blurrL'd \'i­silln, right retw-llrbital headaches, and cuntinul'd weight Illss, He was ,1dmitll'd tll the "lb,ll1\' \'d­erans "dministratiun Huspital. The ]\;eurlllogical e\aminatiun shu\\'ed ,1 pru­found right hemipkgia grealL'",t in the upper L'\­tremitv and a wide-based g,lil. The pupils \\'('rl' equal, rllund, and n',lCti\'L' tu light and ,lccummll­datiun, The patient e\hibill'd a full r,lIlge llt t'\t' mU\'L'mL'nl. Hurizunt,ll nvstagmus was nulL'd In the abducting e\'L' upun lall'ral gaze tll l'itlll'r side, The visual fields wert' int,lcl. Right I,llial asym­metry was ubser\'L'd, with ,1 Illltl'fwd n,lsulabi,ll fold and widened p,llpebral fissure, Otlwr cr,lIli,ll nerves were un,lffected, An elt,ctn1l'nct'ph,1Iu­gram, radiunucielltidL' brain "'C,lIl, cl'l'\'ic,ll m\'('lll­gram, fuur-vessel angillgram, ,lnd repl',lt pneu­mOL'ncephalugr, lm ",huwed nu pa thulugiC,ll ,liter­a t ions, 'I' h e cere b I' II '0 pin ,1 I flu id ,1 n ,1 II' '0 i '0 , gastwinll'stinal snil's, intr,l\'l'nUUs p\'L'lugram, thvroid ",can, and ruutinL' blood and urine study re",ults wert' within norm,ll limits, The p,ltient again I\'d'" disch,Hged frum the huspit,ll un Cl1J1­tinued Dilantin ,1Ild prednisune tlwrapy, Hi", c1inic,ll course was une llf pwgressive de­cline and he W,lS re,ldmitlt'd tll the huspit.11 \l1 month", 1<1lL'r. The nl'urolugica! l'\amin,ltiun rt'­veakd th<1t Ill' \1',1'0 lethargic but llrienlt'd, The pupils were equdl, round, and reactive tu lighl. For the first time, ,1 bilalt'ral paralysis uf ocular ad-duction was observed both upon attempted lateral gaze (Fig, 1) and cunvergence (Fig, 2), Horizontal nystagmus was present bilaterally in the ab­d~ cting eye, Eye movements in the vertical plane elicited bilateral upbeat nystagmus, In the primary po"ition, the right eye was exotropic (Fig. 3). Thert' wa" nu evidence of papilledema upon fun­d u ",co pic exa mination, Corneal reflexes appeared bilalt'r,ll!v diminished. The right facial paresis per­", i",lL'd, Till' patient'", "peech was slurred and had a na",al LJualit\" Hi" \'oice was hoarse and his swal­lowing retarded, An adductor palsy of the left vocal c()l'd wa" documented by direct laryngos­COPY, A righ them iplegia wa s present together with bilalL'ral increased deep tendon reflexes, anklt- clonus, and Babinski signs. The patient could "tand on'" with aid and exhibited a broad­based gait when supported, Ob"tT\'ation", of abnormal e\'e movements were ducumenll'd cinematographicall;, and reconfirmed at frequent Intt'l'\'al", until the patient died of bron­chupneunlllnia 15 months later, as confirmed by autop"\,, PATHOLOGICAL FINDINGS At autups\', meta"tatic undifferentiated small cell carcinuma \\'.1" fllund in four of fi\'e peritra­cheal kmph nude" un the right side of the neck. There \\'.1" nu e\'idt'nct' uf nwtastases to other loci, includmg the brain, The brain, \\elghing 1,120 g, was removed \\'Ithin 2 h afll'r dt'ath and \\'as perfused through cannul.w in"erkd mtll the inkrnal carotid and \t'rtt'br,11 <1rkrit's \\'Ith isutul1lc saline, followed b\' ill', butfered tl1rm,1lm The nwninges and COI1\'O­lutil1J1" uf the cerebr,l! cork\. appeared normal. There \\',1" nl' ub\illU" di"culuration or cerebral at­roph\', .'\ slight tu mllderate degree of atheroscle­rllsis W,l '0 nlltt'd, m,1 inh' invoking the basilar ar­tl'n' and circle uf \\'illis, The br<1in \\'<1S cut intll 0.5- to 1-cm blocks trans­\' t'rSt' tll the longitudinal ,nis of the brainstem, i\l.lCwscopic e\.amination of serial slices revealed th,lt tht' I,lteral \'entricks were enlarged approxi­m, ltt'h' one and one-half times normal and the septum pellucidum was dilated. Multiple cavita­tillns and art'as of softening were present in the subcortical white matter, beginning rostral to the It'\'e! of tilt' head of the caudate nucleus. Large ne­crotic lesions were centered in the anterior limb of the internal capsule on both sides at different levels and extended into both the caudate nucleus and putamen, Destruction extended caudallv to the level of the anterior commissure (Figs. 4 -and H/LAID\/\I. /Nrtl\i lIl'll .\1\ (l/'//rt /,.\1 Mtl/'l.tC/iI 59 FIG.1. Failure of ocular adduction is documented upon attempted lateral gaze to the left (A) and right (B). 5). The lateral segment of the globus pallidus was im'oh'ed here bilateral"'. Bilateral areas of pitting, involving the dorsome­dial nucleus and to a k'ssl'r e:\tl'nt the intr,llaminc1r nuclear grou p, were the mo..,t pn1m i(wnt grl I..,,, pathological changes in the thalamus. In addition, therl' Wl're Sllnll' discrek Meas llf sllfkninh in the lateral nuclt'M group. PMenchymal destructillIl appec1red less se\'ere in the br,linskm. NlImer(1l1S structurt'S clmtained f(1cal dis(L1Il1l',lti(1n ,1I1d sllftening. incilidinh the in­ferillr colliotlus, superillr clnd middle cerebellar FIG. 2. Bilateral paralysis of ocular adduction is documented upon at­tempted convergence Note pencil (0) in foreground. I C/I/I Ncltro-tll'htJwl,,/tlf, Vol. 6, No 1. 1986 ()(I M, H ST/,()MINCL/, ET At FIG. 3. Exotropia in the right eye is documented with the eyes in the pri­mary position, pedunlll''', dt)r",ll penh pt till' p.tr,l Illl'd 1.11 pllntinl' kgnll'n tu 111 , ,1I1d thL' Illl'di,ll Ielllnl"cu", I he Illl'­dull, l .1~1Pl\Hl'd rl'i,lti\'l'I\' un,lltl't'll'd, An'.l" pi di,,­culuratH1I1 ,lbll t,ccunL'd in till' t'l'rl'bl,jlulll, A bluck thruugh till' uppl'r plln";-C,llIdcll mid­br, lin \\',lS sectiulll'd ,1t 20 f-lm un ,1 irl'l'/ing micnl­tuml', Sl'ctiun" "t,linl'd with llll' ;'\;,Hllc1-C\'g,1' (L)) ,lIld buth \'Mi,lIlh ui till' Fink-Hl'inlt'r (l()) tech­niques iailed tu ducunll'nt thl' prl'''l'IKl' ui degen­erating a,llns, The remaining bluck-., ui brain \H're l'mbeddl'd in celluidin and sectioned at 20 f-lm, A minimulll ui e\'erv tenth seLtilln thwuglwut the br,1in \\',1" stained bv the \VeilmL'thlld and \\'ith cre"vl viulet Selected sectiuns were staim,'d with Crl'S\,j \'itl]L't­luxol iast blue ,1Ild hem,llu:",lin-l'usin, FIG. 4. Brain slice shows cyst-like structures centered in the left anterior limb of the internal capsule and in­volving the pulamen laterally and the head of the cau­date nucleus medially, Cumpll'k br/atl'r,ll dL'm\'l·linatilln was docu­mented in thL' mL'dial Illngitudinal iasciculus (\1 LF) in till' u ppt'r pI ,n ,,-ca uda I mid brain at levels abp\,\, thl' ,lbducl'n" ,1nd c,ludal tll the trochlear nucleu" (Fi,~, h), IIll' \ILF \\.1"; intact adjacent to thL' truchlear ,1Ild uculllnwtur nuclei; it contained p,ltchec, oi lh'mn,lination at medullan' le\'els, Ll1\\'lT ml1tpr neurl1n" lli the abducens, trochlear, and Undlll11l1tl1r nuclei appeared largeh- intact (Fig, 7) All ui these nuclei pl1ssibh' exhibited a small reductitln in cell Clll11pkment, but this is dif­iicult tll dllcument. It should be emphasized that the ucuklnwtllr cllmplex \\'as relati\'ely well pre­served thwughllut ih wstr'lcaudallength, TIlt' majl1r pllrtitlll t1i the antt'ril)r limb of the in- FIG. 5. Brain slice at the level of the anterior commis­sure shows cyst-like structure centered in the right anterior limb of the internal capsule involving the pu­tamen laterally and the head of the caudate nucleus medially Similarly located softening is present on the left Side, but at this level it is less severe, IW:\/U,,\1 INIII,i\JUl '11,\ I, (ll'lll1 /,·\I,A]( JI'IJCIA 6/ FIG, 6, Well-stained section documents bilateral demyelination of the medial longitudinal fasciculus In the teg­mentum of the upper pons Note other plaques of demyelination In the teg­mentum and In the basilar region ternal capsule \\'a~ den1\'elinalt'd bllakrelliv (Fig. S), Dem\'elinatiun e,knded intu till' curLlna 1',1­dlata immediatelY adjacent tu the internal C,lp"Ull' bilateral!\', Sume cell ILl"S uccurrt'd bllakralh' in the head of the caudait' nucleu" elnd tu a ll'"ser e,tent in the putamen Although diffuse demvelinatiun was present in the thalamus, perikan'a appeared mainh' intact. The genu and pustl'rior limb uf till' inkrnal CelP­SUllO had val' ia b Ie amLl un hut d t' nl\' l' jill el t illil , which was greate... t un till' It'lt "Idl', A pclrtlell Ill"" of cells occurred in the putelnll'n elnd gillbu" p'll­! idus bilaterallv at thal,lmic ll'\'t'l " , [hl' "ubth,l­lamic nucleus, substantia nigra, and rt'd nucll'u" were essentially unaffeckd. Cun"idl'rabIL' cell dl'­pletion occurred in caudal pclrh ut the pl'ri\'t'ntric­ular gray matter "urruunding thl' third vl'ntricle. The cerebral peduncle" Wl'rl' pclrtiellh' dl'mVl,jin­ated. Other small plaque" Wl'rl' IUCclll'd within till' pontine and medullary tl'gnll'n tu III , including till' area of the medial ll'mni"cu". The bel"il,lr plln" ,llld the inferior culliculu" al"u Wl'rl' ,lttt'ded TIll' ml'­dulla had fewer art',lS uf dl'lllVl'lineltilln than did more cephalic subdivi"iuns (If the br,lin, 11ll' p\')'­amids appeared well myl'linakd ,lt Sllllle Il'vel" but at others were cumpldelv dl'm\Tlinelll'd bilelt­erally, Several plaques uf demVl'linelti(ln Wl'I'l' present in the medullary substancl' ut the (nl'- bt'llulll, but pl'l'lkan'el uf the deep nuclei and curk, \\'ert' undam,lged, Samplt'" uf ct'rebral curk, abu appt"lred nurlllaL DISCUSSION The prest'nt C,be cunforllls tll the definitilm llf anteriLlr inlt'rnuclear uphthalmllplt'pa as pl'll­pused bv Cugan (3) in th,lt therl' \\'as a 1L,SS uf llC­ul, lr Clll1\'t'rgenn' tugt'tlll'r \\'ith till' c!,lssic,11 signs II t bi I,lll' I' ,11 in ll'rn UCll',l r llp h t h.ll n1l1pll'gi.l, i, t', , p,Hl'"i" III u(ul,lr ,lddu(tiun Uplln .ltkmpll'd 1,1lt'ral g,l/t' in bllth dirl'diun" .llld n\'"t,lgrllu" in the ,lb­dUeling l'\'l', :\ ~ll'l'"i"tl'ncl' l11 llclilelr Cl)J1\ergence W,b rl'purll'd in IllUSt prt'\'IUU" dinic.ll studies llf inkrnude,lr uphth'1Inll1plt'gi'1 (11-32). :'\ecwps\' fi nd ing" h,l \'l' ducu n1l'n It'd th,l t im p,lirments of Jelkr,lJ g,l/e St'l'n in inkrnudeclr uphth,11mllplegia drl' ,lttributdble tll le"lllns Il1\uhing the t\ILF ws­tr, ll tll till' ,1bdu(l'lh nut'il,j (13~ Ih, It', 19,21­2,1,2')), Chri"tult t't elL rq,urkd ,1 CelSt' with a uni­1,1 tl'r,ll 1\ Ill, Il'"iun in \\'hich cun\'t'rgence ine,plic­elblv l'lluld nut be l'licikd despill' sparing of the U(UIUnl\ltur l'lllllpil" (ILJ). F\pl'rinll'nt,ll studil'" in nwnkt'ys with discrete MU: Il'siun" pl'llduCl'd sll'reotelelicallv stwnglv "uggl'"t th,lt the lll'lIr,ll p,lthwavs mediating con­Vl'rging l'\'t' IlW\'l'ml'nts dLl nllt involve the MLF, /e'/I// .\ICllrtJ-ophtlIllIIllOI, \\1/.6. No.1, 1986 M. H. SnWMINCLR LT AL. " .. , ." . , ", .. .; .. . , ., . , It: ~. '" .• ~ :I •. ill" . . .. t .~ ., . " , • - _. '; ~~ 'I. I ~ I ."'•. ,I" I • ••• .: III r ~ ~ .'''''''' • .... ~..':, ~ . ....... ... ..,. ( .. ~ .. ~J .. ~I"'" ." . FIG. 7. Photomicrographs of Nissl-stained material demonstrate the relative intactness of the oculomotor complex (A), trochlear (B) and left (C) and right (D) abducens nuclei Note Intactness In A of oculomotor roots and medial longitudinal faSCiculus fibers at this level, shown With luxol fast blue counterstain. since this function was preserwd (33<1b), In the present case, degenerative changes within the oculomotor complex, abducens nuclei, and troch­lear nuclei were at most slight MId thus the s\'n­drome was not a lower motor neuron type of pa­ralysis. That the oculomotor complex was essen­tiallv intact throughout dl'serves emphasis, The etiology of internuclear ophthaln1llplegi,1 is variable. While most patients present with del11\'e­linating disease (13-15,18,20,22,37,38) inkrnu­clear ophthalmoplegia also has been obsen'ed after head traum,l (11,12,17,27-31). vasculM dis­ease (14,16,18, ISl,21 ,2h,32,37,38), svphilis (37). glioma (3Sl,40), and lymphoma with intrathecal chemotherapy and cranial irradiation (41). Ac-cording tl) Smith and Cogan (18), the bilateral form l)f the syndwn1l' usuallY is associated with . . demwlinating disease, whereas unilateral inter-nucleM l)phth,llml)plegia generally is a result of \'asculM ,Kcident. Since the patient reported here l'xhibikd bilateral den1\'elination of the MLF be­tween the abducens and oculomotor nuclei, the pMesis l)f oculM adduction upon attempted lateral gaze and nystagmus in the abducting eye most certainly was due to this lesion, The paresis of ocular adduction seen in the ipsi­lateral eye after unilateral MLF lesions rostral to the abducens nucleus in monkeys was generally attributed to interruption of the vestibulo-ocular retlex arc. Such lesions elicited ascending axonal RILAITI\/I/ INIIl\Nllt'1/,11\ (ll'lllI IIIUv1( )[JIJCIII 63 FIG. 8. Well-stained section shows bilateral demyelin­ation of the anterior limb of the internal capsule also involving the caudate nucleus and putamen. degeneration, \\"hich \\'<lS differentiallv but not ex­clusivel\' distributed tl) the ventral nucleus Llf the oculomotor complex (}h), a subdi\'isiLln that inner­\' ates the medial rectus. It \\"as assumed that the critical fibers took Llrigin frLlm the cLlntralateral vestibular complex, since this is the SLlurce of the majorit\, l)f fibers in the i\lLF in thl:.' upper pLlns and because of the impLlrtance llf the \'estibuIM sYstem in the contwl Llf eve mlWemt'nl. HLl\\"e\'t.'r, it is note\\"orth\' that large lesions pwduced in the vestibular complex dLl nLlt cause dissLlciated eve movements. ),,'ystagmus in the abducting e\T during at­tempted lateral gaze \\"as regarded as an expres­sion of weakness in con twl of the la teral rectus (35,36). It was postulated that this \\"as due to in­terruption of descending fibers in the MLF fwm the interstitial nucleus of e11al to tlw vestibulM complex, thus interfering with a circuit from tlw \'estibular complex to the Llppo..,ik dbducens nu­cleus (36). The basis for Cllnsidering ..,uch circuitry to be of importance was the observation that dis­crete unilateral MLF lesions in monh'ys elicitcd nystagmus in the contralakral abducting eve, tLl­gether with an ipsilateral pML'..,is of oculM adduc­tion (36). However, with the advent of axonal transport techniques, numL'rou.., an,ltomic,ll and physiological studies have demonstr,llt'd the pres­ence of internuclear neurons in both the ,1bducens nucleus and the oculomotor complL'x that emit axons that travel in both directions bdwL'L'n the two via the MLF (42-55). Abducens inkrrwuwns decussate immediately and terminate in the con­tralateral oculomotor com plex, pa rticula rI y the part that innervates the medial rectus. I\HL'ntlwti­cally, it should be noted that Buttner-Ennever and J\kert (54), Llsing rdrograde transport methods, SI1llWl'd thdt the medial rectus in monkeys is in­nl'rv, ltl'd by neuron.., in two separate cell groups of the oculomotor compil'x, in addition to the ventral cell culumn a.., dL'..,cribed eMlier by WMwick (56). Then' i.., evidencl' to "'Uggl'..,t that one of these cell group'" m,lV bL' of importdncL' in mediating ocular cllnvl'rgl'nCl'. Oculomotor interneuron.., are bilat­erdl. Thi.., tlwrL'forL' enable.., reciprocal inhibition dnd l'xcitdtion for conlugalL' horizontal gaze, and inlL'rruption of thL'..,l' tiber.., v."ould ..,eem to account for the adducting p<1rl'..,i.., a.., wl.'II a.., the nys­tagmus. The deficit in ocular convergence is more diffi­cult tLl explain. Since experimental MLF lesions do not affect convergence, damage elsewhere must be responsible, Of the bilateral cases in the litera­ture in which necwpsy studies have been done, this function has been retained. Electrical stimula­tion studies have shown that the frontal, parietal, and occipital eye fields are important for conjugate eve mLlvements (57,58). Vergence movements have been elicited bv stimulation of the frontal eve field and other cortical areas such as 19 and 22 of Bwdmann in the preoccipital region (58,59). Simi­larlv, cortical units in Mea 18 of the macaque ha\'e been found that respond tLl binocular depth (60). Hubel and Wiesel consider that one function of this cortical area is in elaboration Llf slereLlscopic depth mechanisms (60). Thus, the damage to the anterior limb of the in­ternal capsule present in this case ma\' have inter­rupted corticofugal fibers fwm the frLlntal eve fields, Additionallv, exlensi\'e lesions im'ol\'ing Llther pMts of the internal capsule or even the teg­mentum l)f the pons and midbrain ma\' be respon­sible fLlr the impairment in l)cular CL)J1\'t'rgence b\' intcrrupting cLlrticLlfugal fiber path\\"1\'s fwm pos­terillr cortic,ll regiLlns tl) the medial rectus cell columns of the LlculLlmLltl)r cLlmplex. Thesl:.' must relay thwugh internwdi,lte neuwns, since there Me no direct fibers fwm the cLlrlex tl) the oculL)­mLltLlr nuclei. Recent electwplwsiological e\'idence suggests that neurons in pwximitv to the oculo­motLlr cLlmplex identified ,1S "convergence cells" may be a pMt of the relav (bl). In this context, the patient reported bv ChristLlff t't al. had severe uni­laler, ll cerebral swelling and sLlftening; this may have been responsible for the abolition of con­verging eve mOVt'ments (19). The prest'nt case resembles wall-eyed bilateral inlt'rnuclear ophthalmoplegia or "Webino," This tl'rm was introduced by Lubow (see ref. 62) to de­scribe a variant of Cogan's anterior internuclear ophthalmoplegia with exotropia present in the I Cl", NCllro-ol'hthall1lol. Vol. 6, No. 1. 1986 /VI. H. SI/,()MINGU, cr AL. REFERENCES prim,H\' pusitiun, I,uhll\\' bl'lil'\'l'd lhdl till' '>1'11­dl'\ lnlL' \\'.lS l\lUSl'd bv Il',>iul1s ill\'lll\'illg till' MLI' hil,lll'l',llh' ill llll' midbrdill tllgdllL'r with llll' 1lH'­di, ll rl'dus SUbIlU,'Il'i ,II till' ,lddIlIlH.lllr l'llillpll''\, III thi'> ,\l'>l' ,',\ulrllpid 11'.1'> ,1pp,lrl'1l1 ill llH' right lTl', but till' ml'lti.1i I'\'du,> sublludl'i III llll' Ild"l" IlHlt,lr nUl,ll'us Wl'I'\' in I,ll' I. rhl'rl' hd\'l' bl'l'n llnlt· .I ll'\\' rl,,'l'nt publi'>lll'd rl'pllrh ,II till' VVl'!'lllll ,>\'11' drllllll', UIH' ,',lSl' \Yd,'> l'dU,'>l'd bv .1 tulwr,ulll'>I'> gr,lIlUIUIll,l in llll' midbr,lill th.lt pn'SI1I11.lhh' ill \,\Ih'l'd thl' ILf ,1Ild nll'didl rl'du,> subllulll'i III Ill,· IIClIlllillutur Clllllpil''\ h\' m,lS'> dtl'd (h I). I'llur Lltlll'r p,ltiL'nls Wl'rl' di.1gIlUsl'd .1S h.l\·illg lll',lu'>I\'" ''.lscul.lr disl"lSl' ur Illultipil' '>cil'rtl'>i'> (h~) I Ill' dU' thIll's ,1ttriblllt'd till' s,'ndl'llnlL' tll Il''>llln'> dtll"tlll,~ thl' p,lr,lIlll'di,ln pUlltillL' rl'licul.lr tllrm,ltHln .11ld the MLF, but this \\',lS spl'clIl.1tilln unsuppllrlt'd b,' p.lthlllugic,ll findings. "'Vl' ((lnsidl'r it f" lssibll' th,lt lesil)ns in IllIHl' th,ln Llnl' lucu'> Ill,1\' hl' rl',>~lIlIlSihk iLlr eliciti ng thL' \\' l'bi nu S,'Ild ruml' In ,1dditiul1 tu UCUIM dvsfundilln, thl' mllrl' '>l'­" ere degenl'r,ltilln ut till' puslt'riur limb ,II till' In­ternal capsuiL' L11l the Idt "l'r'>us till' right '>idl' I'> cllnsistent with thl' finding L1f right llL'mipMl'sis, R, I Inkrnucll'.H c)phthalnw­., 'I ': l )1,: .. :I/,1/ 1nl'/. 13: b7'1-67:;, [ntl'rnudear ophthalmoplegia: tvpical and l),'"I""IIII<" 84: 583-589, 1970, l-t, C"g.Jn, D, C, Kubik. C. 5" and Smilh, ). L: Unilateral in­Il'rtllldv,] f "phlhalnHlplt'gi,l: r,'port of K c1ini(al ca,e, with 1 p",I-nlPrlc'Jl) 'Judv, lInk Ul'ht/wllll"l. 44: 7K3-796, 1950. I; C",hlgn·n. ,,-,. ,md ilotman-Bang, E,: A ca~t' of internuclear "phlh,i1nlllpl,'gld (BiL'kh"w,kv) with alllop'y, Ada Psy­'// 1,,1 N"I'" 25: -t2lJ--t1J. IY'iU. , .. (.h'· "', "rei, "I Ilw \1.I"ac-hu't'lh Gener.:ll Hospital: Cast' \"r.r \ 111-.:/ 1 ,\".of 249: 77o-7Im, 1953 17 (,1''''. ( VI.i1'''''lt,h, /1" and B"ulad. Ophth.:llmoplegie in- 1"""",1,,.,,1',' hildll'r,i1,' p",Hrdlimati'lut', R"", Ulol1['/lrooph­1,,/,/ 1,,1 2'1: -t1;- -t1cl, I CI;7 IX '-olllllh. I I . "nd ("gdn, I), C, Int,'rnudL'M ophthalmo­"),-,;,., .J n"'"'''' "I ;X ,.1'V' ..11''-'' UI'ht/lI1ll11ol. 61: 61l7-69-t, II ";11 .' I ICI (IHISI,,'I. ,\. , And"r,,,n, r,) .. !\athan'on, M., and Ilt-nclt-r. \1 B I'n'l'lt-m' In anatomIC analvsis oi lesions oi Ih,' IIll'dl,d l"ngllu,lInal l.:l,(](ulus, .·ir,-h, .\'['111'01. 2: 2q~ 1fl~, ll..Jhll 211 (11'1",,,",. I' o.,l"m'''I. f' . ,'nd WOjtuwicz, 5. Biel- ,h"" '''I -I utI -( "~dn ,,'ndn'me: '\/1/ 1 UI"II"all1/[11. 59: ~ I h - -l11 J, Iqh; . . 21 II"rrll1l.;I .. n, I~ B 11 .. llt-nl'"r'1. f, W. and Saver. G. P.. L nd,ltl'r.d J11h'rnu\ k,lr \l~'\hth,dnlll~')kgid, rt.:pl)rt llt a case Inlllldll1~ ~,.dhldll'~" I',:: ',./fr.,; 15: ~y-)~, lYhb. f....llf'kr, ( "nd l, 'C;,1/1, I' L nJl"I"r,,1 "f'hthalm"plegia. '.,,: I I: ," .. ,.. 1 75: -l -l--l ....\'. )4h,.., ~) I,ll'-,.... .llh1 {It·\h ·r. \\ 1.... ld.1lt-,d ... \-ndr\lmL' L1f tht' I11t'dl,t1 I, Ilh,:l!lJdll1,li 1.1"'\'I~ LIlLI'" In /11,111, ,In ..1tlIJ111lal con fir- Jll,llllll) I, 15: ~II-:;-~I); ]L1hh ~-l \ ,Ill ·\Jkn \1 \\ I .d\:r.d "':'.l/t· ,lIh1 ltln\ l'rt..:\.'nle In Inter­nth. ktlr t ,~')I)l h.dlllt 1~')1t:~1..1 .1 Ih ItL' tin l,\. ..lnlln,l·tl\ln .\·l'ltrllltl'lI 16: 1t,~ ~ ~t'). !4t-.,n .. 2; CII~,Hl. D lJ ,1I1d \\ r,1\ .... H Jntl'rnu\.-ll',H "'lphthalrnLl­t'\ lt'.~I,l ,1'" .111 t',Hh "'1~1l \d l-"r.Hn ... tl'ln tUlntlr ..\·l'llItl/t1,(1I 20: h24_1')_1~. 14:-"11 2,., G,'Il' c',l f BJI,'ll'r.l1 In lvrnlicil',H t'f'hlhalml1plegla .. \,<1, \,'"",;, 31: 1",,>- J ;-,; 1";-.. RICh, I R l,rc',~"rJlI', F f.... "n,j Hc:pil'r. R S Bilateral 1I1ll'fI1uck.H "f'hth,dmc'f'il'gl.l ,1ttn tr.ll1m.l, ,-Irch, Ol'h­: It,lllJ/I'! q2: hf'\-h~. IlI:-"~ 2~, S,ll,'. l)" ""~'t,L f.... l)cl"c,(h",) l't .II Lt',ion c)f lhe me­dl, lll ll)n~ltudlndl t,h('llU]U'" t\)llll\\ In.~ he,lJ injun' .\'cUrl)· ,;""" ';:,' 17: l-t 1- l-t" 1";--t ' 2l.1 T\.,hr,1. ~ l, 1...1)\\ ,Hlh..lT1I.ir.l. ~.•lT1J D..lnlble. \1.. Bilat- ...·Lli Ilh'dl,ll rt'\.-tll'" F',ll ... \· l.illl' tl l 1111L1e..lf In\ t..lh·ement in cl,,,vc1 Ilt',hi Illlun ,1 ,',hc' rC'f,,\rt 1",1 I l)/'hlh'71"",! 2-1: 2~-~t.." }...,:--" _111 B.l!,"'r R ~ Inkrnullt'.H \It-.,hth.llnh1t",!et:1 ..1 tl)II,)\\'ing head Ir.llllll.l. I \\':.1,1.<1'\ 51: ~:;2-:;:;:;. lq:-q. .. 1'<,,", [;:, \\ ,)Ihi \lc,,"It'r, f'\C'.<:I'l .llkr Iw"d t1',111111,1 I"~I 12 f...."mmcTc·II, l, L"d"tc'r,ll 1I1Ic'rIluclc'dr C\f'hlh,'lmoplegia: Till' 1.1," "I ,"ll1ht"" 111\ ,'),<,nwnl III nwd"ll re(IU~ mu~de .h.-tl\lt\· !I:;',· .. t L):,,' .. :;:,;,·n:I'I· \':~. ~t'l .21: 3l.j2-~44, 1981 ," BC'l1ch-r \1 I, .1I1d I\C'II1'tc'ln. E .-\ .. Ett,'d~ "f ~timlliation ,111d IC"'c\11 ", till' Ilwd',ll 1,'n~ltlld,nal t,,,(iculu~ in the ])h'])""" ,\"" \,':",'[ /','II,I",II/'I/ 52: ILlb-I13. 19+!, ,-t BC·'hit-r. \1 H.. ,mel S(h,ll1h'r.' S .. (kult)mc)lor pathwavs d\'t])ll'd I", c'kdfl',l! ,til11ul,1ti"n ,lI1d le~i"ns in the bra';n ,kill pt Ilh'I1"c", In TI,,- (\'1/1.'"','1,'1' SI/';(,-I/I. 1\1. B. Bender, F~d Ildrf'c'r'" R,\,\. :,\:,,\\, ) c\r". 14b-t. pp, SI-I-tO, 1~ l,lrpl'ntl'r \1. H.. ,111...1 7\ll-~l..l~ter~, R, E.: Disturbances of c"'"lug,Hc' IWflb'nt,ll c:\',' I11cl\'eml'nt~ in the monke\' II I'h",,\lc1gl(,lll'lt"(h ,1I1~j ,1I1,1I,)m;(al degeneration restil;ing tr,'\111 1t''iC\I1' 111 tilt' medi,ll IL1n~itudinal fas(iculus, Ardl. ,\1'/11'1 1/. 8: 304:--,)b~. l\.)(:l3. Cnp\'nll'r. 1\ I. B, .•lI1d Slwminger, N. L.: The medial lon­S'ludln, ll I,b(i(ul", ,1I1d di~turban(e~ of (Onjugale hori­Il\ nl,11 l',',' n1l'\'t'nwnt~ in monke\·. I, e'"III'. :Vel/wi. 125: -t 1-(11,. jLJh;, . C,>g,ln. D, G.' ,It\pi(,ll. ..\,,11 ,-, _1/. I )Il' illlll'r\'.ltlilll dl'r Illu"'(uli rl'dl Illtl'1'1l1 H,'I fl"/lh, l, ('I,"t/,,,I I,,', 30: Ih-t 1;-1. II r,llon. L lLJ21 2 Llil/ . .-'\ L'l'l't'r dll' [',Ihn"n d,'r ['lld,"c'ndlln~ lind dvrvn .Jj ......l)Llil'rung: .'\,: ...·b.... t nlilh:dllng l'Jlll' .... t.1Jll''' \'llJl tlphth.ll· n111pleghlllllt.'rnudl'.lri ... ~H)ll'rior in \"t.'rbindung 1111t dl .......p· /Iil'run.g dL'f bllgl'ng,ll·ngl'. k/Ul .\ flllJdt ...N "\/I'~'t'llltt'lt.tf 70: 21 :1-23:1. ILJ~3 . 3, (og,ln, D, C,' .'V"/I/"'/"S '/ ,'I III,' 11,'/1/," ,\I/I,d,·,. 2nd vd, ChMIt', C [h"m,l'. "pringllvld. I";" -t, LMmandv. A, \1. L.J pM,'!I',,,' '"f'r,lnlll"',l1rC' du \'! Id,lv "phla!m"pil'siv Intc'rnllc'k,lIn' f',"I,'r"'lIrv! ,',eI, l '/,1, 11111111/(" ({'Ill"') 29: ;21-;311, 1%", ~, Rclthsteln. T, L.. ,lI1d :\!I'''rd. C f . II', 1'<"tcTI,'r II1tl'rnu· (il'M "phlh,llmop"'gi,l, "\1',1" .\','//1',,1 24: 11/1-202, 11/;-1 h, K"mmvrl'il. C,' Inll'rnudc',lr "f,hlh,lllll"f,I,'gu "I ,l['du,·· tlll11: i.... llldtl·d Inl~).llrnlL'nt III phd ..·.]l tllULn nhlt~lr ,ldl\-jt\ 111 "'upr,lflull"',lr Il"·dllll"'. :\llh t)/,hthlllllll/. q3: ;."'1 ;1.+. l"l:--; 7, ("IIMd. 1\1 . fb,·r. A, 1\1 '-oln',dll'r. L1 .. ,lIld 1{"llIlh I Dt It· ... pp.... lt.·f!\'r intt.'rnlll.:lt..',lr \ 'phth,tlll'h 1~11t.·~1,1 l·\I .... t \ l"t," pl1rt un l'11'\'l'J) Ll .... l·.., .lnd till' rl"''lulh tIl 1l1..-uh1hr,lvdn !'t', ''!','//I'"I, (/',,1'1') US: 21/~~12. 11/;-'1 ,., '["pil"". II, IV 1'<"tvl'I,'r II1Ic'rnll,lv,H "phlh,lIIl1"I'lvgl,1 "I I.utl ..\/1/1 ('1,"111"111,,,1, 13: 221 22;. I""" 'I, N,wt." W, I I I.. ""d (;\'g,l\. I' :\,: ~,!I"'r IInl'r"gn"t'''11 "t dq.':'l·nl'r,lltl1g d\tlrh III till' ll'lltr.d Ill'r\'tlll"" .... \· .... tl'Ill-.1 11111l1l­( It,d Ivch"lc, ... 1",// 1,'eI,,",1 2'1: 1/1 "1.11/;-t Jll, !-t"". R, I' . ,l1ld I "',nwr. I I",,, Ilwlh"d, '''I' ,,'1",1,\'1' lin, prt'hll.l(ltlll til dl'gl'l1l'f.lttng ,\\tlll'" tI,,,,,.1 tlll'lf ... ,'n.q'lh: l'ndlng'" 111 till' 1t.'n1LII Ill'r\PU'" ... \ ... tl'1ll I"d/l/ 1,( ... 04; ~hl) In. 1%7 11Il,I"h"\\,",,. 1\ dl ... ",",jtl·Il\\·"·ndl'r. I C/1l2, 12, 1,Il"h,h. I' i\, IIIl"'lllh " 'upr,lnll"I'''lfC' n1l'dl"II'f',Hc"". 1\1/11, ,\1",",/,/>{ "\/lXo'I,I,,',II.,1 73: -t71--t;-h, IlJ24, I~, C,pilkr, W, (;, ()l'hth"lm"l'lt-gi" mlt-rnudc"J1'" "nlc'o,,1': ,l l',I"'l' wilh Ill'\:rnp"'\,. Hnll1/ 47: Jo4; - 1:;;, Iq~-l. HIL/UD\/\L IN I/I\NLlc'll ,\1\ (J/'/11l I/\IA)( )f'LLC//1 65 ~S. ('r,1I1<'. r 1\ ) l'l'. I, I). 1\,II1lh." 1\' ,1I1d Ilt-f,I"I. " " An.11" .... \.... pI dl.H.ldl'rl .... tll l'\'l' llhl\Tllll'llt ,lbllt11'l1l,dllll"-' III inkrnll,k,lI l'f'hlh,dll1l'f'k.>;I,' \" II ('1,11111.11'/1,,; Illl: 211,,· 2111 Iq~., ~4 1:'nl..'\.- ......\.)11 r IIltl'rIHh.ll,,11 tl~'hth.J1rlltl~lk.~~l,1 ,Ind ~',II'.Ih""I'" l't Ihll"ll\ll1t.ll ~.llt· L!d l l,t/ltlid/IIII'/ -11: hq~ ~l)~ !1I,,-, ~l) Trlll)s!. H \ \ l.nl/l1<'1 I \1>1,1 I \ ,lIld Ilvl, ". I, l L'f'I"',,1 11I'1,1~lllt" ,Ind /l11.'IIlLII k,1I "f'hlh,1I1l1"f,I".I;I.I \I IIh br,lIn ... tt.'ln ~ltl)I1l.1 "t/: \('Iill'/ .'1'7: -tl\ -I-'ll IllSl) ~l Lt'f'11ll' I I ,lIhi \'1"l'IlI,I.,1 \1 H,l.lln,1I /111<'1111111".11 l)f'hlh,IIIl"'I)k~", ,111<'1 /llll,llhl",1I ,h\'IlI\'II"'I'I['1 ,lilli, 1.1 nl,lllrr,hil.llllll1 '".' I l );':.'tl:,/,'II,I,< 4:!: ,'-\;1 S;\ IllS] ..C l~r,l\l"'H.'l \ \1 .11hi I tnt\\ Il'~ I ...... \lllll' .l!kH'lll 1\111- [,ll'dh l l1'" 1'1 the IllUll11ll11h11 Itllll~'ll" III till' l,ll .11l t'\~1l'rl­1nt'I1t. ll "'(lId, \\ 1111 (1,lll'1 (I'\, hlllqlH''''' I~/III!/ f\l" HI: :;.+:,\_ ;;\ \\.1-,+ ~.' H,I~\'I " ,1I1d 11I>;h'I\'l/l -. \1 1'111 ""1,,.>;11,11 IdvIlIIII"I­tl1.. 111 llt Intt'r1h'lIt"I. 1 n..., ,lJlli Illll(l.lIlt'lIf(ln..., In tht' ,Ibdll\..l'n..., nll\... lt'lI'" l~'.;:': !'l'" ql: ~q~ ~ljS Iq~; ~~ \I.1'1t'" 1(/ I, I "'Int'~" l ,,-. 111.>;h'lt'/ll. -. ~1 .llld Etl~t'r I, \ h'q'lh)~'h\"'lllIl,l.L.Il·,ll Ind Il',lth In I, d III tl'rlll'lI fl, 111"" III tht' l.)l"tt!('llhltllr 1l1l(k,1I .... th.lt prll]t'I..-t t(l thl' .1bdllll·ll .... flU­( leu .... In tlh' (,It f~I,IPI 1\(· ... qo: '1U-t':::;, Iq-;:::; ~; BUltlwr-Fnnt'l t'r. I .-\ ,Ind Ikllil \. 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'I' \(/1/(1/ 57: -2:; - - -lq p.~:-- ~s Cralblt'l -\ \1 l)r.>;.1I1I/,IIIIlIl III "'-llllllllllll'r 1',llh",lIs /11 the (at ,1nJ rht· .... u .... n1llnh.L'\ In L~,ll/tili/ 1),1 l~ll::l' 1111 }~IIIII/ ... ft'll/ \'-"""1' R BaJ..t'r.•1I1el.-\ Ilt-rlhll/. hi, EI"'IIt'r \'Ilrlh H"lland HI"lllt'dJ<'.lI Prl''' ..'\Il"lvr,1-\l11 jq;,;,. f'f' ;''I-,S;~ -ly Hl,'t::;h .... tt'ln ~_ \1 .-\bdul,l'n .... dlld Pl"tdlI11111tl1f Inh..TnuLll\H neuflln...,' felatltln hI .~a/l· In l-Illlfrll! (II l~I1:t' Ill/ }1/i1 11/';' ft'll/ \·(I<r"",. R BaJ..t'r. and A Bt'rth,,/, Ed, EI"'I'It'r i\:llrlh Holland B",m~d/(al rr~"..-\J1l,lt'rdaJ1l. 1'1;';'. f'f' I ;,-Ih~ ;(1 Steiger. H I and Buttnl'r-Ennt'Il'r. 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D.-\ "Ild Iud" ..-\ E Elt' nll'l~mt'nh l'\'{lh.l'd D\" .... t1ll1ulcltHll1 lit tfllntall'\"l' held.... \ ('lIrfIJlI/ll';'11 1/ 32: h';' - h~~. IlJh'l :::;q 1<lJ11~11'1. R ~ (1111\l'fhl'l1ll'. dl\'l'ry,l'ncl' ~-'upl!]Jr:' rt'a(­tHin .... and ,lCllIJ11J11tld,ltltln lIt tht' l'\·l· .... tfll111 tdr,ldl( ,::,tlnll1]J­tllll1 ut tht' 11l.11<lljUl' bf<lIl1 I l-IIiIlJl \l'/lI'II/ 115: 371-,lYY, l'Ihll hll Hubt'l. D Hand 1\1t,,,,1. T \, c,t,'rv"""f'I' \I"I"n In 111,1',lljUt' I11l1n~\'1 \/JIIII,' 225: ~I-~~. 1'1711 hI \1.1\...... L. E .'\l'ural ltlntnd (1t \l'fy,l'nl..-t' t·\·l' I1lt l\eml'nh ltll1\·l'fgl'nll' Llnd dl\l'r.~l'nll' nl'Uftln .... In I1lldl'f<lIn I .\(:/­"' I,f/lI'I"; 51: III'II-IIIIS;. I'I,,~ /12 lillY!. \\. f dnd D.lftJtt, 1\. B ~lIF'f,lnlll']l',H dl ....llrdt'r.... III Ultd,lf ll)ntfU] .... \· .... !t'n1 .... In 111.1n In IIII' ((lilt/(li (ll Llll' ,\Ll~'t'. IIIt'l/I,. P. Bad'-I'-R,I,l, C ('IlJIm" and I liI·,it'. Ed.... A,a' dl'l11ll' Prt'S', "'t'" YIlrk. 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