Optic Nerve Decompression Presumed Burton J.

Postoperative Development

Kushner,

of Medullated Nerve Fibers

MD

child had an inoperable arterial malformation with chronic papilledema first noticed at age 7 months. Bilateral optic nerve decompressions were performed with satisfactory results. What appeared to be medullated nerve fibers developed in the retina of one eye 5\m=1/2\ months after surgery. \s=b\ A

venous

(Arch Ophthalmol 97:1459-1461, 1979)

of medullated

nerve

fibers after

surgery. REPORT OF A CASE

The patient, a girl born July 9, 1974, was the product of a normal pregnancy and delivery. She was referred to University Hospitals at age 7 months after her family physician noted increasing head circumfer¬ ence.

1872 DeWecker described a surgical treatment for papilledema by incising the optic nerve durai sheath.1 The procedure received little atten¬ tion until Hayreh demonstrated in 1964 the effectiveness of this principle in monkeys.- Subsequently reports have appeared of successful treatment of papilledema in humans by cutting a window in the optic nerve sheath. In 1969 Smith and associates3 ap¬ proached the optic nerve medially

In February 1975 (age 7 months), exami¬ nation showed a child performing at the expected developmental level for her age. Head circumference was 49 cm (98th percentile). Large dilated veins could be seen on her forehead. Arteriography dem¬ onstrated a very large arterial venous malformation involving the vein of Galen

(Fig 1). Computerized

axial tomography demonstrated normal-sized ventricles. Ini¬ tial ophthalmic examination demonstrated bilateral papilledema with marked vessel tortuosity but good disc color and no hemorrhages. Neither eye showed sponta¬ neous venous pulsation. The arterial venous malformation was considered inop¬ erable. Because of the normal ventricle size and the absence of symptoms of increased intracranial pressure, a shunting procedure was not advised. I reexamined the patient at intervals of several months with no change in the fundus appearance over the next 11 months. In January 1976 (age 19 months), marked grayish pallor had developed in both optic discs, and the pupils were sluggish. Neuro¬ logic and neurosurgical consultation indi-

Fig 1.—Left, Frontal projection, left vertebral angiogram. Right, Lateral projection of left vertebral angiogram. In both views, hypertrophie posterior cerebral arteries (arrow¬ heads) fill arteriovenous malformation draining into vein of Galen aneurysm (arrow). Straight sinus is anomalous (crossed arrow, right) but drains into superior sagittal sinus

after removing bone laterally by a Krönlein approach. Davidson4 ap¬ proached the optic nerve through a lateral orbitotomy. Galbraith and Sul¬ livan"' described a medial approach to the optic nerve without removing orbital bone, and Billson and Hudson" used a similar technique in children. This article describes the successful treatment of chronic papilledema in a child by cutting a window in the optic nerve durai sheath. Also reported is what appears to be the development Accepted

for publication Nov 1, 1978. From the Pediatric Eye Clinic, University Hospitals, Madison, Wis. Reprint requests to Pediatric Eye Clinic, University Hospitals, 1300 University Ave, Madison, WI 53706 (Dr Kushner).

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Fig 2.—Stereoscopic pairs of optic

nerves.

A, Optic disc, OD, February 1976, showing preoperative papilledema. B, Optic disc, OS, February 1976, showing preoperative papilledema. C, Optic disc, OD, August 1977, demonstrating resolution of papil¬

ledema and whitish lesion that resembles medullated nerve fiber. D, Optic disc, OS, August 1977, showing resolution of papil¬ ledema. (Stereoscopic viewing can be facilitated by placing + 5 sph before each eye and viewing from approximately 25 cm. Placement of sheet of paper at junc¬ tion of two pictures and extending up to viewer's nose will avoid converging. Alter¬

natively, a 20-diopter prism

base out, over one eye, and viewed at 25 cm.)

be placed, photos can be

can

primary disease was still inoperable. Decompression of the right optic nerve was performed on Feb 17 with use of essentially the technique described by Billson and Hudson.6 The optic nerve was approached nasally after detachment of cated that the

the medial rectus muscle. Under direct

visualization, two longitudinal slits, 2 mm apart, were made in the optic nerve sheath with a Wheeler knife. A rectangular window, approximately 2x4 mm, was made by incising the dura between the two

incisions with vitreous scissors. Care was taken to exert minimum pressure on the optic nerve (Fig 2, A and B). Some improvement in the right optic disc was noted six days after surgery. On April 6, optic nerve decompression was performed in the left eye in a similar manner seven weeks after the surgery on the right optic nerve. At surgery, the right optic disc was observed and found to be less edematous than in the preoperative state (Fig 3). Color had improved in the optic disc, and a spontaneous venous pulsation was present. The optic disc was somewhat less elevated. By April 23, appearance of both optic discs had improved. An intermittent left

esotropia was noted, more so at near. Pupils were normal, and no Marcus Gunn pupil was noted. Refraction demonstrated + 3.00 sph +1.25 cyl 30° with the right eye, and + 3.25 sph +1.00 cyl 155° with the left eye. Spectacles were ordered with a + 2.75 addition, and orthophoria was regained. Interestingly, examination of the patient's older brother on the same day showed an accommodative strabismus. On July 26 (age 2), a whitish lesion was noted adjacent to the right optic disc (5% months after surgery). Disc color continued to look satisfactory. Without spectacles, the patient had an esotropia, and the right eye continued to be the fixing eye. With

spectacles, orthophoria was present. On Nov 7 (age 2 years 4 months), the lesion in the right eye had been followed with serial drawings and noted to enlarge until this examination, after which it has not changed. Photographs of both optic discs in August 1977 (age 3 years 1 month) showed considerable improvement over the preop¬ erative appearance (Fig 2, C and D). The

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Fig 3.—Optic disc, OD, April 1977, seven weeks after resembling myelin is not present.

surgery. Whitish lesion

lesion in the right eye has the appearance of medullated nerve fibers. At examination on March 27,1978 (age 3 years 8 months), the appearance of the whitish lesion in the right eye was unchanged (Fig 4). Vision was 20/20 bilat¬ erally with the Sheridan Gardiner isolated letter matching technique. Orthophoria was present with spectacles. Stereopsis was at least 200 s with the Titmus test. Confrontation fields are grossly normal to confrontation; however, the patient's age and cooperation does not allow for quanti¬ tative visual field testing. The child contin¬ ues to prefer to fix with the right eye with spectacles off. Developmentally, she is normal for her age. COMMENT

Medullated nerve fibers were first described by Virchow in 1856.7 They can usually be easily diagnosed clini¬ cally by their characteristic appear¬ ance of patches of white material with irregular feathery edges, often ob¬ scuring vessels and usually not chang¬ ing with time. According to a review by Duke-Elder," medullated nerve fibers have an incidence of between 0.3% to 0.6% of the normal population.

Fig 4.—Optic disc, OD, of whitish lesion from

March 1978, showing no change in appearance in Fig 2, C, eight months earlier.

photograph

Normally, myelinization starts cen¬ trally during gestation and reaches

the lamina cribrosa at full term and stops there." When it does proceed beyond the lamina cribrosa, it is believed to do so shortly after birth.10 Lopez-Enriquez thought that the pres¬ ence of medullated nerve fibers in the optic nerve was due to the abnormal presence of oligodendrocytes in the retina.11 The presence of myelin artifact after enucleation has been described by Cogan and Kuwabara.12 In 1967 they speculated that myelin intrusion into the retina could occur later in life in relation to papilledema. They described one case in which a whitish lesion appeared adjacent to the optic disc after resolution of papilledema. With time this lesion receded. Photo¬ graphs were not presented, and the evanescent course of this lesion sug¬ gests that it may have been an edema residue or artifact.11 The white lesion in the present case was not clinically evident until 5 Ve months after surgery and definitely

was

not

taken

present in the photograph weeks after surgery (Fig

seven

3). This would eliminate the possibili¬ ty that myelin was squeezed into the retina by excessive pressure on the optic nerve during surgery. If medul¬ lated nerve fibers normally develop as late as age 2, and their observation here is a fortuitous coincidence, it

of fibers would have been documented. It is more likely that surgery in some way stimulated the production of myelin. The satisfactory visual result con¬ firms other reports that optic nerve decompression appears to be an acceptable form of treatment for chronic papilledema when the un¬ derlying condition is untreatable. would

seem

that other

acquired medullated

cases

nerve

This investigation was supported in part by research grant 5-T01-EY0039 from the National Eye Institute, National Institutes of Health. Marlene Wahlstrom took the preoperative photographs. Richard Appen, MD, assisted with the patient's surgery. Raymond Chun, MD, and Al Levin, MD, participated in the patient's

References 1. DeWecker L: On incision of the optic nerve cases of neuroretinitis. Int Ophthalmol Cong Rep 4:11, 1872. 2. Hayreh SS: Pathogenesis of oedema of the optic disc (papilloedema): A preliminary report. Br J Ophthalmol 48:522-543, 1964. 3. Smith JL, Hoyt WF, Newton TH: Optic nerve sheath decompression for relief of chronic monocular choked disc. Am J Ophthalmol 68:633\x=req-\ 639, 1969. 4. Davidson GI: A surgical approach to pleurocephalic disc oedema. Trans Ophthalmol Soc UK 89:669-720, 1969. 5. Galbraith JEK, Sullivan HH: Decompres-

in

perioptic meninges for relief of Am J Ophthalmol 76:687-692, 1973. 6. Billson FA, Hudson RL: Surgical treatment of chronic papilloedema in children. Br J Ophthalmol 59:92-95, 1975. 7. Virchow VR: Zur pathologischen Anatomic der Netzhaut und des Schnerven. Virchows Arch Pathol Anat 10:170-193, 1856. 8. Duke-Elder S: The retina, in System of sion of the

papilledema.

Ophthalmology. London, Henry Kimpton 1964,

vol 3, p 647. 9. Duke-Elder S: The neural ectoderm, in System of Ophthalmology. St Louis, CV Mosby Co, 1963, vol 3, p 119.

10. Von Hippel E: Sind die markhaltigen Nervenfasern der Retina eine angeborne Anomalie. Von Graefes Arch Ophthalmol 49:591-598, 1900. 11.

Lopez-Enriquez M: A proposito de la presencia de fibras medladas en la retina. Arch Soc Oftalmol Hisp Am 9:367-389, 1949. 12. Cogan DG, Kuwabara J: Some common artifacts in the retina. J Histochem Cytochem 6:290-293, 1958. 13. Cogan DG, Kuwabara J: Myelin artifacts. Am J Ophthalmol 64:622-626, 1967.

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Optic nerve decompression. Presumed postoperative development of medullated nerve fibers.

Optic Nerve Decompression Presumed Burton J. Postoperative Development Kushner, of Medullated Nerve Fibers MD child had an inoperable arterial ma...
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