Journal of Neuro-Ophthalmology, September 1981, Volume 1, Issue 3

Arachnoidal cap cell hyperplasia of the intracanalicular optic nerve sheath.

Fifty-two intracanalicular optic nerves from 26 consecutive cadavers at the Dade County Medical Examiner's Office were examined for arachnoidal cap cells three cells thick or greater. Twenty specimens (77%) fulfilled these criteria with predominant involvement of the inferior and lateral aspects of the optic nerve sheath. Twenty-four specimens (92%) had psammoma bodies, and 17 specimens (65%) demonstrated corpora amylacea. Psammoma bodies as well as corpora amylacea were found with increasing frequency with age. However, our study did not show that age was an absolute factor toward the development of arachnoidal cap cell hyperplasia. The factors that incite foci of arachnoidal cap cell hyperplasia to greater activity leading in occasional individuals to the development of a meningioma remain to be determined.

}. Clio. Nl.'uru-llphthJlmll/. 1: 173-1~3, 101'1. Arachnoidal Cap Cell Hyperplasia of the Intracanalicular Optic Nerve Sheath GERARDO M. PEREZ, M.D. JOSEPH C. PARKER, JR., M.D. J. LAWTON SMITH, M.D. Abstract Fifty-two intr c n...licular optic nerves from 26 consecutive c d vers ... t the D...de County Medic...1 ['l(...miner's Office were examined for arachnoidal cap cells three cells thick or greater. Twenty specimens (~ol fulfilled these criteria with predominant involvement of the inferior and lateral aspects of the optic nerve sheath. Twenty-four pecimens (92%) had psammoma bodies, ...nd 17 specimens (65%) demonstrated corpora amylace.... Psammoma bodies as well as corpora amyl...ce... were found with increasing frequency with age. However, our study did not show that ...ge was ... n ... bsolute factor toward the development of arachnoidal cap cell hyperplasia. The factors that incite foci of ar...chnoidal cap cell hyperplasia to greater activity leading in occasional individu ... ls to the development of a meningioma remain to be determined. Optic nerve sheath meningiomas, formerly thought to be rare, have been encountered in sur­prising numbers with computed tomography. A predilection site for the development of these tu­mors appears to be at the mtracrdnidl end of the optic cand!. Two anatomic fdctors visudlized at the intracranial approach to these lesions are the fal­ciform fold of dura on the superior and lateral aspect of the nerves and tufts of hyperplastic ar­achnoidal tissue protruding from the optic canals. It hds been proposed that these tumors Mise from arachnoidal tissue. I -" Therefore, a study to deter­mine the frequency of arachnoidal cap cell hyper­plasia of the intracanalicular optic nerve sheath was undertaken. Materials and Methods Sphenoid bones with the intracanalicular por­tions of the optic nerves were obtained en bloc From the DepartmE'nl of Pathology and lh(" D"partm("nt "f Ophthalmology. Bascom Palmer EyE' Inslilut(". Univ('r,ily uf Miami School of MedicinE', MIami, Florida. September 1981 from 26 consecutive cadavers at the Dade County Medical Examiner's Office. These bones were re­moved with a Stryker saw by cutting coronally fr m the lateral tip of the lesser wing f the sphen­oid bone through both orbital apices into the op­posite lateral tip (Figs. I and 2). A diagonal cut was made from the lateral tip of the les er sphenoid wing toward the chia m on each side. including the anterior c1inoids. Another cut was made longitu­dinally through the body of the sphenoid bone and sinus without injuring the optic nerves. A repre­sentative specimen is shown in Figure 3. All the specimens were fixed in ]0% buffered formalin. The bones were Idter placed in a decalcifyin~ so­lution for 5-7 ddys. Four coronal cross sections taken at equal distances along the dnterior-poste­rior axis of the entire specimen were submitted. Axial (horizontal) sections were obtained from three of the specimens. Paraffin blocks were nude. and the tissues were stained with hematoxvlin and eosin. All slides were evaluated without pr'i r clin­ical knowledge. The cause of death and related di5e,lses were ascertained for all cases from autl1pSV .)nd clinic,)1 records. Specimen were obtained frll", 1° 01.11('5 (73%) and seven females (27%). Fifteen (58";,) were black dnd J I (42%) were whit('. Their ,l~e~ r.1n~ed from 17 to 84 years. with the m,)jl'rity fWIll the fifth decade. The causes of de.3th included dfllwn­ing (4), gunshot wounds (7). vehiclll.H ,ll"l"idents (4). natural deolth (c\)O~estive heolrt f.lilure. ,l~thnl.l. sepsis) (10), and e!"ctrocutilJn (I). TWl) l",ld.\V('r~ hold subcutanellus neurl)fibrllm.l~.Of the hVll. the dia~nosis (If Vl)n Rcc"hn~h,llls('n'~ di~e.1se WdS mdde in (lne. General Anatomy of the Intracanalicular Optic Nerve The optic nerve is a white-matter tract of the brain approximately 47 mm in length from the lamina crib rosa to the chiasm. It is divided into four PdrtS: intraocu(dr, intraorbital. intracanalicu- 173 Arachnoidal C<1P Cell Figure 1. Superior aspect of sphenoid bone. Figure 2. CownJI lui Ihrnugh -rll('[1l'iJ b,)n(', (ar, and intracranial. Their lengths arc I mm, 30 mm, 6 mm, and 10 mm, respectively. The intraor­bital and intracanalicular optic nerve is surrounded by dura mater, arachnoid, and pid m.:atPr. Within the optic canal the dura fuses with the periosteum, and the arachnoid is intimately dttachcd to the dura and pia. Only along the inferior optic nerve is the subarachnoid space in rel.ltively free com­munication with th<? (orr<?spondinx intr,1CraniJI <.,p,H'p ..1 The bottom of the bony optic (.In<ll is 174 contiguous with the sphenoid sinus and the pos­terior ethmoidal air cells (Fig. 4). The optic nerve has unique fibrovascular pial extensions penetrating into the neural substance, producing a well-developed septal system dividing the nerve into parallel columns of variable size (Fig. 5). Astrocytes are intimately related to these pial septa and are involved with the support and nutrition of the nerve fibers. Oligodendrocytes elaborate and maintain the myelin sheaths around Joumal of Clinical Neuro-ophthalmology September 1981 s Figure 4. Ax,..1 (horizont.. l) s.... t",n thruu~h inlr,llJnJlicul.lr ,'pt,( n"rv" showinl\ its proximity to sph....noid sinu~ (X2JOI (5 = ,phcn,"d 'InU', M = mUn"J, D = dur,l, A = arachnoid, ON = optic n"rv.... l, 175 Arachnoid.ll Cap Cell Figure S. Cross section of optic nerve showing septa (arrowhead) (reduced from X225). the dxons. Microglia are found in the optic nerve and serve as the reticuloendothelial systE'm. Of particular interest in this study is thE' falci­form fold of the dura which extends for some distancE' posterior to the cranial opening of the optic canal. The posterior free margin of this dural fold is crescentic in shape and is continuous me­dially with thE' dura on the body of the sphenoid and laterally with the anterior clinoid process (Fig. 3). Thus, this fold makes the optic candl longer than the distilnce .ilctually bounded by the bony P.lrt~.~' Thr thicknrs of thr dura is seen in Figure f> Within the r<1I1al the ophth.llmic artery usu.llly 170 lies inferior and lateral to the optic nerve, separated from the latter by a thin sheath of dura in which it is embedded!"> (Fig. 7). Results The arachnoid lies between the dura and pia mater .md consists of an outer layer of cells called arachnoidal cap cells and an inner network of trabeculae connecting these cells to the pia mater. The subarachnoid space lies between the arach­noidal cap cells and the pia mater and contains vessels and cerebrospinal fluid (Fig. 8). In certain Journal of Clinical Neuro-ophthalmology places the arachnoid sends prolongations intr. thl' dura which protrude into a venous sinus or venous lacuna. These outgrowths are known JS ,n.lChnoid villi when small and ardchnoid gr.lnul.ltions when (Mge. The pia mater and <Irachnoid are collectively known as the leptomeninges. Arachnoidal cap cell hyperplasia was defined in our study as a collection of these cells greater than three cells thick, whether Figur~ 7. Ophthalm.c art(''Y anf('rolal('rallv larwwh('ad) to optiC n('rvc' (r('du ('d from XSI. Figure 8. Arachnoidal ap cdl_ (arf{lw~1 and pIa (drwwhNdl, (I) = dura. A = arachnoid, N = n('rv(') (r('du,'('d from X2(0). September 1981 177 Arachnoidal Cap Cell Figure 9. Whorl (arrow) within arachnoidal cap cell hyperplasia (reduced from X2001. fiI\U,., 10. Ar.,.-hnnidal cap cell hyperplasia (reduced from X600) , J78 Journal of Clinical Neuro-ophthalmology in the dura (drachnoid villus), dr.lChnoid, llr sub­.. uachnoid space. Fifty-two intracanalicul.1r llptir nerves from 2b sphenoid bl'Oe were e .lmined fllr arachnoidal cap cell hyperplJsi.l. TWl.'nty of thl.' 20 sphenoid bones (77%) h.ld circumscribl'd dusters of arachnoid cells greater than three cells thid. in one or more cross sections Mound the l'ptir nl.'rves (Figs. Q and 10). Eight l,f the 20 specimens (40%) with arachnoid.ll cap cell hyperpLlsia h.Id involve­ment of the inferior, medi.ll. .lnd l.Iter.11 sides of one or both optic nerves. Five (25%) had hyperplJ­sia ak'Og the lateral and medial sides only and three (15"0) involved the inferior and 1.1 tI.' r.lI .15­pects. The remaining four specimens hJd chJnges as shown in Table 1. In three (15%) arJchnoid villi were seen in the durJ (Fig. 11). In the two cJdavers with subcutaneous neurofibromas, one (3b-year­old black male) showed no arachnoidal cap cell hyperplasia, and the other (51-year-old black male with von Recklinghausen's disease) had arachnoi­dal cap cell hyperplasia surrounding most of the nerve. Psammoma bodies are calcospherites that may be associated with whorls of arachnoid cells (Fig. 12). The mechanism is not understood, but may be related to calcification of the whorls.'i They are found on the arachnoid and the dura and stain dark purple with the hematoxylin and eosin stain. l'('rl'Z, PJrker, Smith Ap.Ht from being seen in the central nervous sys­tl.' m. they are noted in gastrointestinal. ovarian, and thyroid neoplasms.1 In our series, psammoma bod­ies were seen in every specimen that demonstrated TABLE I. Brukdown of Specimens Eumined N" "I ~Urll'· ul"r- )nl..· M..d,- All'" Jnd ",., P..t- rHlr J1 rllir .1 11,'nt.. 1\ X X X 22WM, 2oWM, 47BM. 4QWM. 516M. 54WF. 64WF, MWM 5 X X 526M, oOWM, o96F. 82WF.84WF 3 X X J7WF, 48WM. 55BF X X 42WM X X X X 42WF X X 67WM X 24WM Figure 11. Arachnoid villus (A V) within dura (D/ (reduced (rom xbbOj. ieptember 1981 179 Arachnoidal Cap Cell ... Figure 12. Psammoma body (arrowhe.td). Note arachnoidal hyperplasia around it (reduced from x2101. arachnoidal cap cell hyperplasia. However, in four specimens, psammoma bodies occurred without arachnoidal changes. Therefore, 24 of the 26 spec­imens (92%) had psammoma bodies in one or more optic nerves. They were located on the arachnoid as well as inside the dura. The number on all four sections of a given specimen were counted and then divided by eight (the number of optic nerves in the four cross sections) to obtain the average number of psammoma bodies per optic nerve per specimen. The specimens were then divided into three groups according to age and average number of psammoma bodies calculated for that age group. (See Table 2.) Corpora amylacea are rounded, PAS-positive structures measuring 10-50 p.m in diameter, which are ultrastructurally nonmembrane-bound inclu­sions in the cytoplasm of fibrillary astrocytes7 (Fig. 13). They stain pale blue with hematoxylin and eosin stain and are associated with age. Typically, they are found around blood vessels as well as below the pia and ependyma. They are considered as part of the aging process and of no pathologic significance. In our series, 17 of 26 specimens (65%) demonstrated corpora amylacea. Fifteen were from cadavers 42 years of age and older. They were rl nliful Jt the periphery of the nerves (Fig. 13). TI,,,, d:lr.} Jnd pial o,erl,} were thicker in older I Ill! TABLE 2. Occurrence of PQmmoma Bodies by Age Group Tot.1 No. of Aveugt No. No. of Agt Groups P$.Immom.l of Psammom. Spt"Clmen~ Bodi.. ptr Bodits Optic Ntrvt 6 17-39 12 2.0 12 40-59 28 2.3 6 60-84 30 5.0 individuals (Fig. 14) as demonstrated by Dolman et al.II Discussion Meningiomas account for about 15% of all pri­mary intracranial tumors.6 Traditionally, those in­volving the optic canals have been divided into intraorbital or intracranial groups depending on the location of the tumor bulk.2. 3. 9. to Primary in­traorbital meningiomas are comparatively uncom­mon. Cushing,!l in his series of 313 meningiomas involving the coverings of the central nervous sys­tem, found only one intraorbital tumor. The latter arose from the optic nerve sheath. Craig and Go­gela3 found 17 primary intraorbital meningiomas in 165 meningiomas located in the anterior and Journal of Clinical Neuro-ophthalmology Figure 14. 5t'pl~ in ~ b4·yNr.uld whit.. m~n. C"mpMl' with th",,' "f .1 ~~·V('.I<-lIIJ whlll' m~n (Fi". 51 (r..dun'd from X22S1 September 1981 181 Arachnoid.11 ap Cdl Figure 12. Psammoma body (arrowhead) \.1(' arachnoidal hyp<'rpla>la ar,'und .t I,<,du, <'d ir,'m ~ 101 arachnoidal cap cell hyperplasia. However. in four specimens, psammoma bodies occurred without arachnoidal changes. Therefore. 24 of the 26 spec­imens (92%) had psammoma bodies in one or more optic nerves. They were located on the arachnoid as well as inside the dura. The number on all four sections of a given specimen were counted and then divided by eight (the number of optic nerves in the four cross sections) to obtain the dverage number of psammoma bodies per optic nervt' per specimen. The specimens were then divided into three groups according to dge dnd dVer.lge number of psammomd bodies cdlculatt'd for thJt .lge group. (See Table 2.) Corpora dmylacea are rounded, PAS-positive structures measuring 10-50/lm in diJmeter, which Me ultrastructurdlly nonmembr.lne-bound indu­sions in the cytopldsm of fibrillJry .lslrocytes7 (Fig. 13). They slain pale blue with hemJto ylin Jnd eo in stain and are J sociJted with Jge. TypicJlly, they are found around blood vessels dS well J. below the pid dnd ependymJ. They .He considered d Pdrt of the dging process Jnd of no pJthologic significdnce. In our series, 17 of 2(> specimens ((>5%) demonstrdted corpor.l JmylJceJ. Fifteen were from (,Id.lv",... 42 V('.lr... (If ,1~(, .lI1d "Ider. They were I'I"plif,,1 .11 lhl' l'l'rirhl'ry (If lht· nerve. (Fig. 13), Th" J;Jrd .md pial septa \\','n' thid,er in older IllO TABLE 2. Occurrence of P~mmom. Bodies by Age Group T,'I.1 I,} ..\f A\'t"rJtit{f N," ,. ,'I A~t' l."lUr~ f'Sdmm('m.J or rSdmmc.\m.a ~rt""lml'n'" Blldi.s reT B('ldlf'S Oplo< Nerve C' 17-~Q I~ 2.0 I~ ·10-5° ~1\ 2.3 C' C'0-1\~ ~O 5.0 individuals (Fig. 14) as demonstrated by Dolman et Jl.~ Discussion Meningiomds dccount for dbout 15% of all pri­mJry intrJcranial tumors.o Traditionally, those in­vt1lving the optic canals have been divided into intraorbitdl or intracranial groups depending on the locJtion of the tumor bulk.~· :1. 9. Itl Primary in­trJMbitJl meningiomas are comparatively uncom­mon. Cushing,I' in his series of 313 meningiomas involving the coverings of the central nervous sys­tem, found only one intraorbital tumor. The latter arose from the optic nerve sheath. Craig and Go­gela: 1 found 17 primary intraorbital meningiomas in 165 meningiomds located in the anterior and Journal of Clinical Neuro-ophthalmology Figure 14. 5eptJ In J t>4-yrJr·,.ld whIt,· mJIl (IImp.H., wllh th,,,,' ,., .' 2.>v('.H-,·I,t ",hIll' 11l.1l1 (hI' Sl (r,,<ill"',l rn'11l x2251 September 1961 181 middle crani<ll fossde and th(' orbit. Forr('st, III in hi series of 184 prim,uy orbit.ll tumor, found 17 meningi mdS. Of thes(', four ar05<> from th(' optic nerve she.lth. S('vcr.ll CdS('S of m('ningiomds involving th<> optic ,m,lls h.lve b('('n describ<>d. In 1877, Sch{ltt'~ d£'­s ribed the .lutopsy of d SS-ye.lr-old blind p.ltient with bildterdl optic n('rve "psdmmom.ls" in th<> region of th(' optic foramen. In 1922, Dandy'" found two individudL with optic n('rv(' m<>nin­giomds aff('cting the optic c.1ndls. The first patient wa d 13-yedr-old girl with bilaterdl meningiomas involving the optic nerves from the posterior aspect of the optic canal extending into the apex of each orbit. The second patient was an 8-y('ar-old boy with a cherry-sized meningioma beneath the left optic nerve at the optic foramen. The only intraor­bital tumor in Cushing'sll series had "sque('zed through each optic foramen into th(' vaginal sheath of Schwalbe so that both optic nerves had become surrounded in their intraorbital course by a sub­dural sleeve of tumor." Of the 17 primary intr'lOr­bital meningiomas reported by Craig and Gogela;' three were foraminal, two were bilateral, nine en­veloped the optic nerve or were firmly attached to its optic sheath, and five were from sources within the orbit other than the optic nerve sheath. Salazar et aLI. reported a 36-year-old white woman who at surgery was found to have meningiomas protrud­ing below the left and right anterior cIinoids and involving both intracanalicular optic nerves. Trobe et al. l . s and Hart et al. '6 have reported similar cases. Why these growths have a predilection for thE.' optic foramen and a tendency toward bilaterality is not known. 17 • "' Dandy'3 stated: . There is no reason to believe that intro3cranio3l optic nerve tumors should be different from those of the intraorbital part, except that within the skull the optic nerve is devoid of the dural sh(,03th. All intracranidl tumors of the optic nerve arising from the duro3 must th('refore o3ris(' at the optl f ram('n, where the durd is reflect('d, and second.1fily proj­ect into the cranial cavity. This tendency toward bilaterality IS Important to consider when evaluating d patient suspected llf having a chiasmal lesion. In our series, 77% of the phen0id bone speci­mens demonstrated clu tcrs 0f dr.lchOllid.lI C.lp cells with psammomd bodies .lround the intr.lc.m­alicular optic nerves. Six sp('cimen did not show th('s(' arachnoidal change, but four of these h.ld psammoma bodies. Sinc(' complete s('ri.ll s<>clions were not done, our incid('nc(' f thrsl' changes is underestimated. Circum crib<>d wllertions llF arachnoid cells have been observed in intr.Kr,lni.ll dnd intravrbitJI mC'ninge' ~..l Schmidt' recllgniz('d th,ll 111"nlngi"IIl,I<' m.ly .lri<;(' frl'm "uch clusters tlf ,r.Khnoid,,1 cells Although these ,lr.Khnoid cell clusters are not neoplastic, Cushing'!! found a well­defin(' d relationship between arachnoid villi and meningiomas. The exact transition between arach­noidal hyperplasia and meningioma is a moot point. We believe that with the development of a mass effect, arachnoidal hyperplasia should be consider('d a meningioma which may demonstrate eVNal different histomorphologic variants includ­ing syncytial, transitional, fibrous, angioblastic, and sarcomatous.~"Arachnoid hyperplasia has also been observed as a leptomeningeal response to gliomas in th(' anterior visual pathway.21 This study has shown that arachnoidal cap cell hyp('rpJasia and psammoma bodies are common throughout the intracanalicular optic nerve sheaths. Psammoma bodies were observed in all the specimens with these arachnoidal changes. They and corpora amylacea increased in frequency in older individuals. However, age was not an absolut(' factor, since collections of arachnoid cells were seen in young as well as old specimens. References Schmidt, M.B.: Ueber die Pacchionischen Gr.1nula­tion(' n u. Ihr Verhaltniss zu den Sarcomen u. Psam­momen der Dura mat('r Virchows Arch 170: 429­464, 1902. 2. Spenc('r, W.H.: Primary neopla m of the optic nerv(' and its sheo3ths: Clinical f('atur('s and current oncepts f pathogen('tic mechanisms. Trans. Am. Ophthd/mo/. Soc. 70: 490-528, 19n. 3. Craig, W. McK.. and Gogela, L./ : Intraorbital men­ingiomas. Am. I Ophthlmo/. 32: 1003-1680. 1049. 4. Hogan, M.J., dnd Z,mmermo3n, L.E.: Th(' optic nerve. In OphthalmIC Patho/og\' (2nd ed.). W. B. Saunders. Philddelphia. 1902. pp. 571-550. 5. Hayreh. S5.. and Dass. R.: The ophthalmic art('ry. I Origin and intro3canalicular course. Br. ,. Ophtha/­mol. .u.: 05-08. 1°02. 6. Rubinst('in. L.J.: Tumllrs of th(' C('ntral ervous System. In At/,l5 of Tumor Patho/ogv, 2nd seri('s. A F.I.P.. W,lshington, D.C. 10 n. pp. 109-189. 7. E!'courolle. R.. and Poin('r, J.: Manudl of Basic. 'eu­Hlp. lth,,!t'gy (2nd ('d.), W. B. Saunders. Philad('lphia, 10 78, pp. 0-10. 8. Dl,lman, c.L.. McCormICk A.Q., and Drance. S.M.: Aging of the optic n('I"\'e. Arch. Ophthd/mol. 98: 2053-2058, 1080. 0, Hl'g.ln, M.J.. ,lnd Zimm('rman, L.E.: eoplasms dnd llth('r tumllrs. In Ophthd/mic P,ltho/ogy (2nd ed.). W. B. S.1und('rs. Philadelphio3, 1902. pp. 607-623. 10. Fllrre.t, A.W.: Intraorbital tumor. Arch. Ophtha/­nlll/. 41: 1°8-323, 1040 II. Cushing. H., and Eis('nhardt L.: Meningiomas: Their CI.Jssific,ltion. Regiondl Behaviour, Life Historv and Surgiral End Results. Charles C Thomas, Spring­field. III., 1938. pp. 56-73 and 283-297. 12. Scott, Prof.: On some affections of the optic nerve. Arch. Ophth.J/mol. Oto/. (N.Y.) 6: 262-283, 1877. 13. D.lndy, W.E.: Pr('chiasmal intracranial tumors of the optic nerv('s. Am. f. Ophthd/mol. 5: 169-188, 1922. 14. Salazar, J.L., Bauer, J., Frenkel. M., and Sugar. 0.: Joumal of Clinical Neuro-ophthalmology Bilateral optic cdndl meningiom.l. ~lIrl-:. Nt'un,l, 8: 11-14, IQ77. 15. Trobe. I.D., CI.lser. I.s.. rl,~t. f.D.. l't .11.: Biblpr.ll optic c.lndl menin~i,'m,,~: A (,l~e f('p,'rt. Nl'lIn'''lIr­ger" 3: t-1I-74. 10 711. 10. Hart. W.M.. Burde. R.M .. Klin~el<·. T.e...",J I'nl­mutter, I.e.: Bil.ller.11 ,'pti( nerve ~h,·.lth nwnin­gi,' mJs. Arch. Urhth.lln ..,I. 98: 14<>-151, 1°110. 17. l.lmes. B.r.. .lnd Smith. f.L: Bil.ltl'r.1i "ptl" 1l('1V(' sh('Jth meningi,'m.l~ pre~enting .l~ thl' dll,,~m,11 syn· dr,'me. In ,\it'ur"-t'rhth.I'm,'J.'l-:~·lIrJ.,llt·. J. L. Smith. Ed. M.ls.,'n rul->llshll1g. N('w "Y,'rk 1<>77. pp. 177­183. III. H"lIenhNst, R.W. Ir, H"II(,llh"fst, R.W.. Sr., .lnJ M.l(C.lrty. C5.. \'isu.11 pf,'gn,'~i~ "i ,'pti( IWlVe she.lth mt'nangl"nl.I" pn,Ju(ing ~hunt ve~~els I'n the ,'pti.- dis\..: The H,'yt·Spell(er synJf,'ml'. Tr.lns. Am. Ophth.l/m," 5.'( 75: t41-103. 1077 10. Cushang. H; Th(' meningiom.ls (Jur.ll end,'the­li,' m.ls): Th('lr s,luree .lnd fdvoured se.lts "f l>rigin. Br.lin ~5: ~II~. 10:!:!. ~O. Russell. OS. Jnd Rubinstein. L.I.: P.lth",,'gy "f Tu- September 1981 (\,,,./. )'.lrk'·r. ':>mith nH>lIr" "f The NC'rvou~ SystC'm (4th I'd.). Willidms & Wilkins. Bolltimure, 1977, p. 73. 21. C"I,ling, R.I., dnd Wright. J.E.: Ardchnoid hyperpld­Si, 1 in I'pti nerve glillmJ: Confusion with orbitdl m('ningillm.l. Br. I. Ophth.llmo/. 63: 590-599, 1979, 22. W.llsh, F,B.; Meningiomols, primdry within the orbit dnd uptil' C.lndl. In Neuru.uphthdlmo'oKY, Vol. 8, I· 5. G1JSN Jnd ). L. Smith. Eds. e. V. Mosby Co" St. Luuis, IQ75, pp. 100-190. Acknowledgments Gr.lteful deknowledgment I expressed to Dr. loseph H, OJvi , Odde County Medicdl EXdminer's Office; Mr. MJnuel Solis, Floridd lions Eye Bank; Mr. Chdrles Bdi­ley; olnd Mrs. Betsy Bdrlon for their help dnd cooperd­lion. Write for reprints to: J. liIwton Smith. M.D., Bdscom Pdlmer Eye Institute. P.O. Box 016880, Midmi, Florida 33101. 183