Journal of Neuro-Ophthalmology, March 1982, Volume 2, Issue 1

Anomalous optic discs in a patient with a Dandy-Walker cyst.

A 19-month-old female infant with a Dandy-Walker cyst had anomalous optic discs, each of which appeared to divide to form an accessory optic nerve. The discs probably lie within the spectrum of anomalous discs including optic nerve aplasia and hypoplasia, megallopapillae, morning glory disc, optic disc dysplasia, and optic nerve colobomas. The association of anomalous optic discs with a Dandy-Walker cyst has not been previously recognized. The ocular and brain malformations in this patient likely occurred during the fourth to eighth week of gestation, when the retinal ganglion cell axons were penetrating the optic nerve, and the rhombic lips were enlarging in early cerebellar development. The etiology of these anomalies is not known; however, teratogens, sporadic events, and genetic disorders should be considered.

f. Clin. Neuro-ophthalrnol. 2: 43-47, 1982. Anomalous Optic Discs in a Patient with a Dandy-Walker Cyst JAMES C. ORCUTT, M.D., Ph.D. ANN H. BUNT, Ph.D. Abstract A 19-month-old female infant with a Dandy-Walker cyst had anomalous optic discs, each of which appeared to divide to form an accessory optic nerve. The discs probably lie within the spectrum of anomalous discs including optic nerve aplasia and hypoplasia, megal­lopapillae. morning glory disc, optic disc dysplasia, and optic nerve colobomas. The association of anomalous optic discs with a Dandy-Walker cyst has not been previously recognized. The ocular and brain malfor­mations in this patient likely occurred during the fourth to eighth week of gestation, when the retinal ganglion cell axons were penetrating the optic nerve, and the rhombic lips were enlarging in early cerebellar devel­opment. The etiology of these anomalies is not known; however, teratogens, sporadic events, and genetic dis­orders should be considered. Introduction Congenital defects of the optic disc have been previously described in patients with basal enceph­aloceles. 1 - 3 These optic disc anomalies include disc pallor, optic pits, coloboma of the optic disc, optic disc dysplasia, and megallopapillae. These optic disc anomalies have been included within a spec­trum of abnormal optic nerve development, includ­ing aplastic or hypoplastic discs, megallopapillae, morning glory syndrome disc, optic disc dysplasia, and optic nerve colobomas, which may vary only in degree and form of maldevelopment.:J-6 The patient described in this report had a Dandy­Walker cyst, an abnormality of development of the cerebellum, and bilateral anomalous optic nerve heads, which may be included within the spectrum of optic disc developmental anomalies outlined above. Case Report The patient was a female infant, born at term to a 20-year-old graVida 1, para 1 mother. Delivery From the Department of Ophthalmology, University of Wash­ington, School of Medicine, Seattle, Washington. March 1982 was by cesarian section under general anesthesia. Birth weight was 4423 gr. The pregnancy was complicated by pyelonephritis, for which the mother received ampicillin during the fifth month of pregnancy. This was not accompanied by high fever. The family history was unremarkable. Hy­drocephalus was noted at birth (Occiptofrontal circumference 53 cm, > 95th percentile). A ventri­culoperitoneal shunt was placed in the right lateral ventricle on the first postpartum day. Cranial CT scan at 2 months showed marked ventriculomegaly and cerebral destruction. Linear growth was nor­mal, but there was profound developmental delay. Eye examination at 9 months by R.S. Fantl, M.D. disclosed n" response to light, absent optokinetic nystagmus, and minimal pupillary reaction to light. Cycloplegic retinoscopy was +4.00 in both eyes. The fundus was described by Dr. Fantl as "complete coloboma of the optic nerve with atro­phy of the surrounding retina, as well as the cho­roid ... no arteries entering from the optic nerve cavity into the retina ... veins are present and show evidence of moderately marked attenua­tion ... the retina otherwise has normal color." The remainder of the eye examination was normal. No additional dysmorphic features were seen. TORCH titers* were negative. The child died at 19 months of dge seconddry to pneumonid. The eyes and brdin were obtdined dt autopsy dnd fixed in 10% formdlin. The globes were processed with stdnddrd pdrdffin techniques dnd stained with hematoxylin-eosin, periodic dcid Schiff, Masson trichrome, Luxol fdst blue for mye­lin, Wdldrum silver stdin for reticulum, or Holmes silver stain for neurofildments. Postmortem Examination At autopsy, the skull was noted to be enldrged with malformation of the occipit.ll region. Both the anterior and posterior fontanels were enlarged. A shunt WdS present in the right Idterdl ventricle. A large cyst filled the posterior fossa. The brain disclosed marked cerebral dsymmetry with the • Toxoplasmosis, Rubella, Cytomegalovirus, Herpes, and Syph­ilis. 43 D.1I1dy-W.llker Cyst Figure l. The right cerebral hemisphere is markedly smaller than the left. The cerebellum has been removed. right hemisphere smaller than the left (Fig. 1), apparently due to incomplete cerebrospinal fluid drainage. The gyri were flattened, with the excep­tion of a normal cortical gyral pattern in the right frontal region. In general, the cortex showed nor­mal lamination with atrophic white matter which was more severe on the left side. The striate cortex on the right side showed generalized paucity of neurons and the left visual cortex was absent. The third and fourth ventricles were enlarged. The Sylvian aqueduct was patent (Fig. 2). The cerebel­lum was displaced upwards and laterally, and there was a large midline cyst filling most of the posterior fossa. These findings meet the criteria for a Dandy­Walker cyst 7 . H The remainder of the autopsy was unremarkable, except the lungs showed evidence of pneumonia. The eyes were normal by gross examination. The equatorial diameters were 20 mm .md the corneas were 10 mm in diameter. The globes were opened horizontally. No choroidal coloboma was present. Both optic discs were enlarged. The retinal vessels were attenuated and appeared to exit over the rim of each disc rather than branching from its center. Central white tufts of tissue were present grossly in both discs. Lange's folds of the periph­eral retina were an artifact present in both eyes.~1 Light microscopy of the globes revealed normal .mterior segments in both eyes. There was a marked paucity of ganglion cells, particularly in the left hemiretinae, and the nerve fiber layer was thin in both retinae. Narrow arteries and veins were present in the disc substance but no central retinal artery could be found within either disc. The optic discs in both eyes showed a wide scleral canal (Fig. 3). The retinal pigment epithe­lium terminated near the scleral opening, but reti­nal tissue crossed this edge into the substance of the optic disc. The retina in this area appeared dysplastic. The choroid widened at the scleral edge and a moderate amount of pigment was seen within the disc. An atrophic optic nerve with stainable myelin posterior to the lamina crib rosa exited na­sally in both eyes. Temporally, a second accessory optic nerve was present with glial tissue and gan­glion cell axons passing through the sclera, as revealed with the Holmes neurofilament stain. No myelin or lamina cribrosa was found in either accessory optic nerve. Comment Double-stranded 0rtic nerves have been de­scribed previously.lO-l~The course of these nerves may be restricted to the sclera, or they may extend to the lateral geniculate as uncrossed fibers. Double optic discs have also been described, ranging from two depressions in one disc to two separate discs. 13 Journal of Clinical Neuro-ophthalmology Orcutt, Bunt - ,.J 7312 Figure 2. Roslr.ll view through openl'd p,'stl'rior foss.l cyst. Thl' "pl'n aqul'ducl of Sylvlus C.ln bl' Sl'l'n cl'nlrally. Thl' cl'rl't>l'Ii.lr hl'misphl'rl's arl' displacl'd upward and l.ltl'rally. The ontogeny of the double optic nerve is not without phylogenetic precedent. Many teleosts, as well as some salamanders and deer, have an optic nerve which becomes subdivided into many root­lets just posterior to the globe. 14 Each specimen here clearly showed the exit ofaxons and organized glial tissue from the globe at a second site. Unfor­tunately, the distal segments of the optic nerves were not retained at autopsy, so that the final tennination of the accessory nerves remains un­known. These optic discs may represent the morning glory discs, according to gross and ophthalmo­scopic description. The morning glory disc is de­scribed as an optic nerve head which is funnel­shaped, contains white tissue in the center, and is surrounded by an elevated annulus of chorioretinal pigment disturbance. Retinal vessels appear as multiple narrow branches at the edge of the disc.~· Ir, The morning glory disc has been included in a spectrum of developmental disc anomalies including aplastic or hypoplastic discs, megalopa­pilla, optic disc dysplasia, and optic nerve colo­boma.:!- 6 In addition to the anomalous optic discs, this child also had a Dandy-Walker cyst. Ophthalmic findings reported associated with a Dandy- Walker cyst are related to the hydrocephalus, e.g., cranial March 1982 nerve palsies, papilledema, and nystagmus. Iii Spe­cific developmental defects of the eye associated with Dandy-Walker cysts have not been previ­ously reported to our knowledge. Might the etiologies of the Dandy- Walker cyst and the optic nerve anomalies be associated tem­porally? At least two theories exist for the etiology of the Dandy- Walker cyst. In the first. atresi.1 of the foramina of Lushka .md M.1gendi leads to hydrocephalus H . 17 Cerebrospinal fluid cl)lIects in the fourth ventricle if the for.1mina do not open. This results in enl.ugement of the third .md lateral ventricle through a patent aqueduct l)f Svlvius. These foramina normally open between th~ 18th and 24th week of gestation. IH A second theon' places the defect earlier in cerebelLH develor­ment, M.I!I occurring during enl.ugement of the rhombic lips. This is .m initi.ll ph.1St' of cerebellar development occurring during thl' f,)urth tl) l'ighth week of gest.ltion. H Defective development l)f thl' l)ptiC disc is Ii\...elv to occur early in the development of the eye. The optic stalk or primary optic vesicle might be defec­tive (second to fourth week of gestation), providing an abnormal substructure for ganglion cell axon ingrowth. An abnormality of ganglion cell in­growth (beginning at the seventh week of gestation) could also lead to an anomalous optic disc. The 45 D,lI1dy- W.llkl"r Cyst Figure 3. Optic nerve and disc of left eye. The wide scleral canal can be seen with an atrophic <'ptic nerve existing nasally (". right) and axonal and glial tissue penetrating within the scleral lamellae temporally ('. left). (Holmes silver stain. reduced from X4.) ganglion cell axons have reached the chiasm by 8 weeks of gestation, and normally fill the distal optic nerve at this time.~ll. ~I There appears to be a time during the fourth to eighth week of gestation when a teratogenic, spo­radic, or genetic effect might produce an abnor­mality of ganglion cell ingrowth and influence rhombic lip enlargement. This could lead to the formation of anomalous optic discs and a Dandy­Walker cyst, respectively. However, the existence or identity of a teratogenic agent in the present case remains unknown. References I. van Nouhuys, I.M., and Bruyn, C.W.: N.1Soph.uyn­gl" al transsphenoidal encl"phJlocl"le, crJtl"r-likl" hole in the optic disc Jnd agenl"sis of the l"orpus l"Jllosum. I'sychiatr. Nl"uro/. Nl"urochir. 67: 243-258, 1904. 2. Pollock, LA., Newton, T.H., and Hoyt, W.F.: Trans­sphenoidJI Jnd trJnsethmoidal I'ncl"phJlocl"ll's. RJ­Ji"/,, gy 90: 442-453, 1908. .~ ("ddh,InH1H'r, T., ,lIlJ Smith, I.L.: Optic l1l'rve Jll<lm-alies in basal encephalocele. Arch. Ophthdlmol. 93: 115-118, 1975. 4. V. Szily, A.: Oil' Ontogenese der idiopathischen (erbbildlichen) Spaltbildungen des Auges, des Mik­rophthalmus und der Orbitalcysten. Z. Andt. En­twicklungsgesch. 74: 1-230, 1924. 5. Badtke, G.: Uber die Grossendnomalien der Papilla nervi optici, unter besonderer Berucksichtigung der schwJrzen Megalopapille. Klin. Mondbstl. Augen­heikld. 135: 502-510, 1959. o. Jensen, P.E.. and Kdlina, R.E.: Congenitdl anomalies of the optic disc. Am. f. Ophthdlmol. 82: 27-31, 1970. 7. D.mdy, W.E., and Blackfdn, K.D.: lntemdl hydro­cephalus. Am. f. Dis. Child. 8: 406-482, 1914. 8. lemire, R.J., loeser, J.D., leech, R.W., dnd Alvord, Le: Normdl .Jnd Abnormdl Development of the Hunldn Nervous System. Harper & Row, Hagers­town, Md., 1975, pp. 144-165. Q Kalina, R.E.: A histopdthologic postmortem and c1in­iCdl study of peripheral retinal folds in infant eyes. Am. f. Ophthdlmol. 71: 446-448, 1971. 10. Ganser,S.: Ueber die periphere und centrale Anord­nung der Sehnervenfasem und uber das Corpus bigeminum anterius. Arch. Psychidtrie 13: 341-381, loumal of Clinical Neuro-ophthalmology 1882. 11. Snead, eM.: Congenital division of the optic lH'rve at the base of the skull. Arch. Ophth.Jlnwl. 44: 418­420, 1915. 12. Fuchs, E.: Uber den .m.ltomischen Befund einiger angeborener Anom.llien der Netzh.lUt und des Seh­nerven. Albrecht von Gr.:tefes Arch. Klin. Ophth.l/­mol. 93: 1-48, 1917. 13. Donoso, L.A, Mag.Hgal, L.E., Eiferm,lIl, R.A, and Meyer, D.: Ocul.lf .mom.llies simul,lting double op­tic discs. Cm. 1. Ophth.llmll/. 16: 84-87, 1981. 14. Duke-Elder, S.: System of ophth.llmology. In The Eye in Evolution (Vol. I.). ev. Mosby, St. louis, 1958, p. 310. 15. Kindler, P.: Morning glory syndrome: Unusual con­genital optic disc anomaly. Am r Ophth.l/mo/. 69: 370-384, 1970. 16. Walsh, F.B., and Hoyt, W.F.: Clinical Neuro-opthal­mo/ ogy (Vol. 1.). ev. Mosby, St. Louis, 1969, p. 734. 17. Gibson, J.B.: Congenital hydrocephalus due to atre­sia of the foramen of Magendie. ]. Neuropathol. Exp. Neurol. 14: 244-262, 1955. 18. Hochstetter, F.: Beitrage zur Entwicklungsgeschichte des menschlichen Gehirns (Vol. 2.). Denticke, Vi­enna and Leipzig, 1929. 19. Broda!. A, and Hauglie-Hanssen, E.: Congenital hy­drocephalus with defective development of the cer­ebellar vermis (Dandy-Walker Syndrome). ]. Neu- March 1982 Orcutt, Bunt wI. NeufOsurg. Psychiatr 22: 99-108, 1959. 20. Mann, I.: The Development of the Human Eye. Grune & Stratton, New York, 1964, pp. 136-147. 21. Duke-Elder, S.: System of ophthalmology. In Nor­m•• 1.:tnd Abnormal Development: Part 1, Embryol­ogy. (Vol. 3.). e.V. Mosby, SI. Louis, 1963, p. 109. Acknowledgments The .Juthors thank Drs. A.E. Hendrickson, S. Clarren, D.F. Milam, Jr., M.J. Reeh, R. Pagon, R.E. Bensinger, and R.E. Kalina for their assistance and review of the man­uscript; C. Meligro for histologic processing; J. Foltz and B. Clifton for photographic help; and J. Seng for secre­tari. J1 assistance. Sterling Clarren, MD., and John Di­neen, PhD., performed the neuropathologic examina­tion, and their work is greatly appreciated. The eye examination was performed and cited with permission of R.5. Fantl, MD., Fresno, California. Other clinical information was provided by Cynthia Curry, MD., Fresno, California. This work was supported by the Lions Sight Conser­vation Foundation of Washington and Northern Idaho, and in part by an unrestricted award from Research to Prevent Blindness, Inc. Write for reprints to: J.e. Orcutt, M.D., PhD. De­partment of Ophthalmology RJ-I0, University of Wash­ington, Seattle, Washington 98195. 47