Case Report Optic nerve aplasia: A case report and ...

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To report a case of unilateral optic nerve aplasia with unusual presentation and to review the literature. Clinical and histopathological features of a 36-week-old ...

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Case Report Optic nerve aplasia: A case report and literature review Jerman Alqahtani Department of Ophthalmology, King Fahd Hospital of the University, Alkhobar 31952, Saudi Arabia

Address for Correspondence: Jerman Alqahtani, King Fahd Hospital of the University, P.O. Box 40115, Alkhobar 31952, Saudi Arabia. E-mail: [email protected]

ABSTRACT To report a case of unilateral optic nerve aplasia with unusual presentation and to review the literature. Clinical and histopathological features of a 36-week-old gestation male infant were described with review of all cases of optic nerve aplasia in the literature. The unusual findings in this case are the systemic congenital anomalies. Twenty-nine out of forty-two cases reported in the literature are true cases of optic nerve aplasia; the others probably represent optic nerve hypoplasia. Out of four cases reported as bilateral, only one case could possibly represent bilateral optic nerve aplasia. Optic nerve aplasia is very rare anomaly. It is overdiagnosed entity in the literature. Bilateral cases are exceedingly rare. Key words: Aplasia, hypoplasia, optic nerve

Introduction Optic nerve aplasia is very rare congenital anomaly. It is typically unilateral occurring in healthy patients without gender or racial predilection. This anomaly is overdiagnosed in the literature. Bilateral cases are exceedingly rare. Various ocular anomalies are associated with it. All of the cases of optic nerve aplasia reported in the literature between 1854 and 1976 which others have reviewed were reevaluated. All of the cases reported in the literature between 1977 and 1998 were reviewed for the first time.

Case Report This 1830 g male infant was born to a 37-year-old G3 P2 white female at 36 weeks gestational age by dates via elective cesarean section. This infant was twin A of a twin pregnancy. Both infants were males. Prenataly, it was noted that twin A had polyhydramnios and twin B had oligohydramnios. An amniocentesis was done at 35 weeks to assess fetal lung maturity. Cesarean section was scheduled due to concern about the oligohydramnios of twin B. Twin A was delivered first and noted to be flaccid. His APGAR scores were 0 and Online full text at http://www.pediatricneurosciences.com 150 / J Pediatr Neurosci / Volume 3 / Jul-Dec / 2008

1 at 1 and 5 min, respectively. He could not be rescucitated and expired shortly after delivery. Twin B appeared normal. A complete autopsy was done for twin A. The infant demonstrated multiple dysmorphic features including: facial asymmetry with a triangular - appearing skull, low - set ears, micrognathia, hypoplastic nails, microphthalmos, and a small left palpebral fissure measuring 0.4 cm compared to the right, which was 1.4 cm [Figure 1]. Other congenital anomalies including: subglottic tracheal atresia, tracheoesophageal fistula, annular pancreas, duodenal atresia, aplasia of the left optic nerve, bilateral choanal stenosis, abnormal auricular helix, hypoplastic nails, membranous ventricular septal defect, patent ductus arteriosus, bilateral undescended testis, congenital block vertebra (LI-L2), asymmetry of vertebrae with single left-sided pedicle (S4-S5), bilobed right lung. Cytogenetics: 46 XY, normal karyotype. Gross pathology The left eye was microphthalmic measuring 13.0 mm × 12.0 mm × 12.0 mm. The optic nerve was absent. The cornea was clear and measured 5.0 mm × 5.0 mm [Figure 2]. A horizontal cut including the pupil and posterior pole was made. The anterior chamber was present with thin iris. The lens was normal. No optic disc or retinal vasculature was present [Figure 3]. The right eye appeared normal measuring 16.0 mm × 15.0 mm × 15.0 mm with 5.0 mm of optic nerve stump attached. The cornea measured 8.0 mm × 8.0 mm.

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One hundred serial sections were made. Histopathology The left eye has a vestigial dural sheath with absence of the optic nerve, optic disc, and retinal vasculature. The retina is attached and maldeveloped with loss of ganglion cells and nerve fiber layer. There are multifocal areas of dysplastic retinal rosettes. There is a persistent tunica vasculosa lentis and iris hypoplasia. The angle was incompletely developed with no pars plicata. There was a pupillary membrane. The lens was normal. The peripheral cornea was underdeveloped [Figure 4]. Deeper cuts at the level of the vestigial dural sheath failed to disclose optic nerve [Figure 5]. The right eye was normal.

they do occur, are extremely rare and tend to be associated with significant central nervous system abnormalities as in hypoplasia[3] case reports in the ophthalmic literature frequently misidentify hypoplasia for aplasia.[4] The pathogenesis of aplasia of the optic nerve is controversial.

Discussion Aplasia of the optic nerve and disc is a rare congenital anomaly that is typically unilateral. The optic nerve, disc, retinal ganglion cells, and retinal blood vessels are lacking. [1-3] It occurs sporadically in an otherwise healthy person without sexual or racial predilection. Bilateral cases, if

Figure 3: Gross examination of the left eye showing absence of optic disc and retinal vasculature

Figure 1: Close up view of the face showing small left palpebral fissure, left microphthalmos, facial assymmetry with micrognathia and low-set ears

Figure 4: Histopathology of the left eye showing microcornea, iris hypoplasia, multifocal retinal rosettes, absence of optic nerve, instead there is a vestigial dural sheath (H&E, ×5.0)

Figure 2: The left eye appear microphthalmic with microcornea more prominent. The right eye is normal

Figure 5: Section through the region where a remnant of dural sheath inserts into the sclera. The optic nerve is absent, instead the retina is continues in that area (H&E, ×25)

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Scheie and Adler[5] suggested that it might be due to failure of development of the mesodermal elements that supply the connective tissue and hyaloid vessels. Weiter et al,[3] believed that the failure of the paraxial mesoderm to develop was probably not the cause of aplasia of the optic nerve because the dural sheath was present in the majority of their cases. Instead, they agree with Mann [6] that failure of the fetal fissure to form causes misdirection of the nerve fibers. This leads to their failure to reach the lateral geniculate body and their necrosis. It should be noted that it is now recognized that the dural sheath is not mesodermal but of neural crest derivation. Yanoff et al,[7] postulated a primary failure of ganglion cells to develop and send out axons, which would result in a lack of induction mesodermal ingrowth, with lack of retinal blood vessel development. The problem with this theory is that the ganglion cells do develop and do send axons, but they are misdirected. Hotchkiss and Green[8] postulated a failure of mesodermal induction: secondary to a third-order neuronal defect in the ganglion cell layer is probably responsible for the development of optic nerve aplasia. Scheie and Adler[5] and Little et al,[4] in their review of the literature on optic nerve aplasia prior to 1976 concluded that there were only six reported cases of true optic nerve aplasia. Their conclusion was based on blindness (NLP), absent disc, absent central, and branch vessels, afferent pupillary defect, and absent ganglion cells and nerve fiber layer. Five of these cases were unilateral occurring in healthy patients. Little et al,[4] concluded that the sixth case reported by Meissner et al,[9] is bilateral optic nerve aplasia. When we reviewed

this case the laterality was unknown in a 3-week-old infant with bilateral cleft lip and palate.[9] Fundus examination was impossible due to bilateral corneal opacities and histology was done only on the right eye. There are 27 cases reported as aplasia of the optic nerve in the literature between 1977 and 1998 [Table 1]. The largest series of optic nerve aplasia was published by Weiter et al,[3] who described 13 cases of unilateral optic nerve aplasia, all of which were without systemic abnormalities. Their criteria for aplasia were similarly defined, as being the absence of an optic nerve, retinal ganglion cells, and retinal blood vessels. Typically they have microphthalmos. Other associated ocular anomalies include: remnants of dural sheath, retinal dysplasia and rosettes, retinal detachment, persistent hyperplastic primary vitreous, hypoplasia of choroid and ciliary body, uveoretinal coloboma, segmental hypoplasia of iris, partial aniridia, microcornea, microphakia, cataract, and hypoplasia of the corneal stroma. Yanoff et al,[7] reported a case of bilateral optic system aplasia associated with extensive brain anomalies and normal appearing eyes. We believe it represent severe hypoplasia due to the following reasons: presence of extensive brain anomalies which is typical of severe hypoplasia, presence of ganglion cells, and presence of what he called rudimentary optic papilla. Storm et al,[11] reported a case of bilateral optic nerve aplasia with severe central nervous system malformations based on clinical examination. We feel this case represent a hypoplasia because there was a normal pupillary reflex in addition to the

Table 1: Literature on optic nerve aplasia Date and author

Number of cases

Laterality

Other. cong. anomalies

1977 Weiter et al.[3]

13

Unilateral

Absent

1978 Yanoff et al.[7]

1

Bilateral

Present

1979 Hotchkiss and Green[8]

3

Unilateral

(1) Absent (2) Present

1980 Ginsberg et al.[10]

1

Unilateral

Present

1984 Storm et al.[11]

I

Bilateral

Present

1992 Margo et al. [12]

1

Unilateral

Absent

1992 Blanco et al. [13]

3

Unilateral

Absent

1993 Howard et al. [14] 1994 Recupero et al.[15] 1996 Lee et al.[16]

1 1 2

Unilateral Unilateral Unilateral

Absent Absent Present

Bilateral

Present

h: Histology; c: Clinical; CNS: Central nervous system

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Diagnosis and clinical features

Aplasia - absent disc, vessels and ganglion cells (h) Hypoplasia - ganglion cell present and severe CNS anomalies (h) Aplasia - absent disc, vessels and ganglion cells (h) Aplasia - absent disc, vessels and ganglion cells (h) Aplasia - absent disc, vessels and ganglion cells (h) Hypoplasia - small disc, severe CNS anomalies (c) Normal pupillary reflex. Aplasia -absent disc, vessels and ganglion cells (h) (1) Aplasia - absent disc, vessels (c) (2) Hypoplasia - small disc, normal ERG (3) Hypoplasia - O.N present on CT, normal ERG Aplasia - absent disc, vessels. (c) Aplasia - absent disc, vessels. (c) Aplasia - absent disc, vessels. Absent O.N on CT. (c) Aplasia - absent disc, vessels. Absent O.N on CT. (c)

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presence of a small disc and a hyaloid vessel. Blanco et al,[13] reported three cases of unilateral optic nerve aplasia. The first case represent a true case of optic nerve aplasia based on the absence of optic disc and the central vessels. The other two cases represent hypoplasia because of the presence of small optic discs, the CT-scan findings of optic nerves, and the normal electroretinograms. In our case, there were severe multiple congenital anomalies associated with unilateral optic nerve aplasia. These included cardiovascular, gastrointestinal, and vertebral anomalies. There were no brain anomalies. The ocular anomalies in our case were maldeveloped peripheral cornea, hypoplasia of the iris, malformation of the chamber angle, absence of pars plicata, and persistence of tunica vasculosa lentis. The ganglion cell layer, nerve fiber layer and retinal vasculature were absent. There were several focal areas of retinal dysplasia with rosette formation throughout the retina. These finding are associated with problems with fetal fissure invagination and are frequently associated with aplasia of the optic nerve. Posteriorly where the vestigial dural sheath joined to the sclera there was no defect in the retinal pigment epithelium where the optic nerve should have entered the globe. A hundred serial sections through the posterior pole failed to disclose any optic disc. The unusual finding in our case is the association with severe systemic congenital anomalies, but what distinguishes this case from cases of severe hypoplasia is the absence of central nervous system anomalies.

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Duke-Elder S. Normal and abnormal development. Congenital deformities. In: System of ophthalmology. vol. 3, pt. 2. London: Henry

2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

14. 15.

16.

Kimpton; 1964. p. 668. Hogan MJ, Zimmerman LE, editors. Ophthalmic pathology: An atlas and textbook. 2nd ed. Philadelphia: W.B. Saunders; 1962. p. 582. Weiter JJ, Mclean IW, Zimmerman LE. Aplasia of the optic nerve and disk. Am J Ophthalmol 1977;83:569-76. Little LE, Whitemore PV, Wells TW. Aplasia of the optic nerve. J Pediatr Ophthalmol 1976;13:84-8. Scheie HG, Adler FH. Aplasia of the optic nerve. Arch Ophthalmol 1941;26:61. Mann I. The development of the human eye. New York: Greene and Stratton, Inc; 1964. p. 29. Yanoff M, Rorke LB, Allman MI. Bilateral optic system aplasia with relatively normal eyes. Arch Ophthalmol 1978;96:97-101. Hotchkiss LH, Green WR. Optic nerve aplasia and hypoplasia. J Pediatr Ophthalmol Strabismus 1979;16:225-40. Meissner W. Ein Colobom der Aderhaut und Netzhaut mit Aplasie des Sehnerven. Graefe Arch Ophth 1911;79:308-2. Ginsberg J, Bove KE, Cuesta MG. Aplasia of the optic nerve with aniridia. Ann Ophthalmol 1980;12:433-9. Storm RL, PeBnito R. Bilateral optic nerve Aplasia associated with hydranencephaly Ann Ophthalmol 1984;16:988-92. Margo CE, Hamed LM, Fang E, Dawson WW. Optic nerve aplasia. Arch Ophthalmol 1992;110:1610-3. Blanco R, Salvador F, Galan A, Gil-Gibernnau JJ. Aplasia of the optic nerve: Report of three cases. J Pediatr Ophthalmol Strabismus 1992;29:228-31. Howard MA, Thompson JT, Howard RO. Aplasia of the optic nerve. Trans Am Ophthalmol Soc 1993;91:267-81. Recupero SM, Lepore GF, Plateroti R, Abdolrahimzadeh S. Optic nerve aplasia associated with macular atypical coloboma. Acta Ophthalmoligica 1994;72:768-70. Lee BL, Bateman JB, Schwartz SD. Posterior segment neovascularization associated with optic nerve aplasia. Am J Ophthalmol 1996;122:131-3.

Source of Support: Nil, Conflict of Interest: None declared.

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