Journal of Neuro-Ophthalmology, March 1988, Volume 8, Issue 1

Disappearing optociliary shunt vessels and neonatal hydrocephalus.

This is a report of two cases of optociliary shunt vessels in patients with neonatal hydrocephalus. Complete disappearance of the optociliary shunt vessels occurred after surgical procedures to normalize intracranial pressure. The clinicopathological significance, prognosis, and treatment of patients with acquired optociliary shunt vessels is discussed. This is also the first report of the association of optociliary shunt vessels and neonatal hydrocephalus.

' oumal of Clillieal Neuro- ophthalmology 8( 1): 1- 8, 1988. Disappearing Optociliary Shunt Vessels and Neonatal Hydrocephalus Thomas P. Dowhan, M. D., Rafael Muci- Mendoza, M. D., and Phil A. Aitken, M. D. ,[: 1988 Raven Press, Ltd., New York This is a report of two cases of optociliary shunt vessels in patients with neonatal hydrocephalus. Complete dis­appearance of the optociliary shunt vessels occurred after surgical procedures to normalize intracranial pres­sure. The clinicopathological significance, prognosis, and treatment of patients with acquired optociliary shunt vessels is discussed. This is also the first report of the association of optociliary shunt vessels and neonatal hydrocephalus. Key Words: Intracranial pressure- Neonatal hydro­cephalus- Optociliary shunt vessels. From the Division of Ophthalmology, Medical Center Hos­pital of Vermont, University of Vermunt College of Medicine. Burlington, Vermont. U. S. A. Address correspondence and reprint requests to Dr. Phil A. Aitken at Division of Ophthalmology, 1 South Prospect Street, Burlington, VT 05401, U. s A Optociliary shunt vessels were first described in 1893 by Salzmann ( 1) in a patient with an optic nerve sheath meningioma. Optociliary shunt vessels, both congenital and acquired, have been reported rarely since then. Acquired optociliary shunt vessels are associated most commonly with optic nerve sheath meningioma ( 2). They have also been described in association with glauco­matous optic atrophy ( 2), chronic atrophic papill­edema ( 3), central retinal vein occlusion ( 4), optic nerve gliomas ( 5), arachnoid cysts of the optic nerve ( 6), neurofibromatosis ( 7), pseudotumor cerebri ( 8), drusen of the optic disc ( 9), optic nerve coloboma ( 10), and osteoscleroses ( 11). We have recently documented the presence of optociliary shunt vessels in two patients with neo­natal hydrocephalus. Surgical procedures were performed to normalize the increased intracranial pressure. Following a shunt revision, complete disappearance of the optociliary shunt vessels was noted in Case 1. Marked reduction in the caliber of all shunt vessels and complete resolution of most shunt vessels was noted follOWing surgery in Case 2. The association of optociliary shunt vessels with neonatal hydrocephalus has not been previously reported in the literature. However, a point of greater significance in these cases is the resolution of optociliary shunt vessels. Emphasis of this un­common event and clinicopathologic significance is discussed. CASE REPORTS Case 1 The patient is a 1O- year- old, white boy who was a difficult forceps delivery with a history of asso­ciated neonatal subarachnoid hemorrhage. He de- 2 T. P. DOWHAN ET AL. veloped a seizure disorder in the first few weeks of life. Investigations disclosed the presence of a septum pellucidum cyst and hydrocephalus. At age 10 weeks, he underwent a ventriculoperi­toneal ( V- P) shunt procedure and did well until age 7 years ( February 1982). A shunt series was obtained in February 1982 that showed the shunt to be in good position within the ventricles, but distally, the shunt had retracted out of the perito­neal cavity. Further evaluation with a computed tomography ( CT) scan of the head indicated a slit ventricles- type picture. He underwent V- P shunt revision in July 1982 and, subsequently, in No­vember 1982, October 1983, and April 1984 for re­current V- P shunt malfunction. Eye examinations were normal as late as August 1983, with visual acuity of 20/ 20 au. By April 1984, the visual acuity was 20/ 20 au, and Gold­mann perimetry revealed no visual field defects. However, the patient had developed bilateral pap­illedema, with blurring of all margins au, as well as nerve fiber layer hemorrhages 00 ( Fig. lA and B). He presented in November 1985 with new onset of visual disturbances, including blurring, tran­sient obscurations, and difficulty with color vision. Physical exam revealed a generally healthy 10­year- old boy. Head was normocephalic, shunt mechanism was palpable at the right occiput, with shunt tubing palpable in the right neck. The re­mainder of the physical examination was unre­markable. Examination on 11/ 25/ 85, revealed a visual acuity of 20/ 60+ 2 00 and 18/ 200- 1 as, which did not improve with pinhole. Color vision was as­sessed with American Optical pseudoisochromatic color plates. The patient correctly identified 1 of 14 plates au. There was a left relative afferent pupil­lary defect measuring 0.9 log units with neutral density filter balancing. Ocular motility, slit- lamp examination, and intraocular pressure were all within normal limits. Dilated funduscopic exami­nation revealed right disc edema ( Fig. 2A). The left disc was edematous, pale, and elevated, with di­lated optociliary shunt vessels on the inferior disc margin ( Fig. 2B). Macular retinal pigment epithe­lium changes were noted as. He had a CT scan of the head that revealed his ventricles to be within normal limits. No evidence of optic nerve sheath meningioma or other abnor­mality was noted. A shuntgram was performed that revealed no proximal flow. A new catheter was placed and a Holter- Hausner valve was in­serted with good flow of cerebrospinal fluid from FIG. 1. ( Case 1) Fundus photographs taken April 1984. Right eye shows papilledema as well as nerve fiber layer hemorrhages ( A). Left eye shows papill­edema prior to formation of optociliary shunt vessels ( B). the catheter. The opening intracranial pressure was 320 mm water. Follow- up examination 2 months after this pro­cedure showed no improvement in visual acuity. Visual fields were only slightly improved. Of sig­nificance, the shunt vessels on the left disc had completely disappeared ( Fig. 3A and B). The patient's visual acuity deteriorated to 20/ 50- 2 00 and count fingers at 2 ft as by May 5, DISAPPEARING OPTOCILIARY SHUNT VESSELS 3 FIG. 2. ( Case 1) Fundus photographs taken November 1985. Right disc reveals edema and pallor, but no shunt vessels are noted ( A). The left disc reveals edema, pallor, and optociliary shunt vessels at 6 o'clock ( B). 1986. There was marked concentric constriction of the visual field OS. The posterior pole ( OS) con­tinued to show pallor and atrophy, without new optociIiary shunt vessels apparent. The patient's visual function showed gradual improvement. As of January 1987, visual acuity was 20/ 50 00 and 10/ 400 OS. Visual fields im­proved to a more normal configuration. The cen­tral scotoma have diminished, although nerve Flu. 3. ( Case 1) Fundus photographs taken 10 weeks after V- P shunt revision. Right disc shows significant resolution of edema and pallor ( A). Left disc reveals most notably complete disappearance of shunt vessels, as well as significant resolution of edema and pallor ( B). fiber bundle defects ( arcuate type) above remain. The optic nerves continue to show marked pallor. The optociIiary shunt vessels remain completely absent. Case 2 A 17- year- old, black girl was first seen on 3/ 7/ 85 at the Neuro- Ophthalmology Unit, Jose Maria I Clill Nfl/ TO- ophtha/ lllol, Vol. 8, No. 1. 1988 4 T. P. OOWHAN ET AL. Vargas Hospital in Caracas, Venezuela. She pre­sented with a chief complaint of bitemporal head­aches, which she first noted in 1983. The head­aches were precipitated by eyestrain when studying, and occurred approximately twice a month and lasted 3- 4 h. In July 1984, these head­aches increased in frequency and severity. The ep­isodes of headache were associated with brief loss of consciousness and bilateral transient visual loss induced by positional changes. These episodes oc­curred up to 20 times a day. The patient had an unexplained symptom- free period between De­cember 1984 and February 1985. Beginning in March 1985, she experienced progressive bila teral visual loss and recurrence of headaches associated with exertion. Eye examination of February 7, 1985 revealed vi­sual acuity of 20/ 50 00 and 20/ 400 as, which did not improve with pinhole. Color vision was as­sessed using Ishihara pseudoisochromatic plates. The patient could only identify the nasal number on the introductory plate 00; she was unable to identify any plate correctly as. There was no af­ferent pupillary defect. Ocular motility was normal. Visual fields plotted on a Bjerrum's tan­gent screen revealed bilateral relative centrocecal scotomas, as well as a relative bitemporal quan­drantanopia. Funduscopic examination disclosed bilateral atrophic papilledema with minimal disc elevation. Optociliary shunt vessels were noted bi­laterally ( Fig. 4A and B). Plain skull films disclosed disjunction of the coronal suture, expanded sella turcica, and dorsal sella erosion consistent with long- standing intracranial hypertension acquired at an early age ( Fig. 5). CT scan of the brain re­vealed hydrocephalus with a normal fourth ven­tricle, which is consistent with congenital aque­ductal stenosis ( Fig. 6). A markedly enlarged third ventricle was found to be herniated into the sella and was believed to be causing pressure on the optic chaism, as predicted by the clinical findings. On March 20, 1985, a shunt procedure was per­formed to normalize intracranial pressure. Recog­nizing the risk of visual loss occurring as a result of intracranial decompressive surgery, the patient received appropriate medical therapy preopera­tively. Eye examination on March 26, 1985 showed that the patient's visual function had worsened. Visual acuity was 20/ 800 aD, 20/ 30 as and visual fields showed bitemporal hemianopsia in addition to her centrocecal scotomas. On funduscopic ex­amination, marked reduction in caliber of all and complete disappearance of most optociliary shunt vessels was noted ( Fig. 4C and D). Fluorescein an- I Lilli ;< ll""'" '" "::',/,! giography of both optic discs documented filling of the optociliary shunt vessels preoperatively and dramatic resolution of shunt vessels 6 days post­operatively ( Fig. 7A- D). By April 16, 1985, visual acuity was count fingers at 30 cm 00 and 20/ 80 as. The patient's last follow- up examination of September 4, 1986 revealed visual acuity of count fingers at 30 cm 00, 20/ 30 as, and slight improvement of visual fields. DISCUSSION Salzmann ( 1) first coined the term " optociliary vessels" in 1982 to describe abnormal vessels seen on the optic disc in a pathologic specimen from a patient with an optic nerve sheath meningioma. A short time later, Elschnig ( 10) described the micro­scopic features of optociliary shunt vessels in a pa­tient with optic nerve sheath meningioma. He was able to trace these vessels to peripapillary cho­roidal veins that drained into vortex veins. The pathogenesis of optociliary shunt vessels is not clearly understood. Any underlying pathology causing obstruction of retinal drainage directly or through chronic disc edema would be expected to produce optociliary shunt vessels, given a suffi­ciently long period of time. In the case of optic nerve sheath meningiomas, Frisen et al. ( 12) pro­pose a congestive hypothesis. They postulate that patients ( with optic nerve sheath meningiomas) initially have edema of the optic disc due to pas­sive congestion caused by compression of the ret­robulbar portion of the central retinal vein. The shunt vessels that develop within the eye are the result of gradual dilatation of preexisting capil­laries that connect the central retinal vein with peripapillary choroidal veins. Fluorescein angiography is important in evalu­ating the direction and pattern of flow, as well as the competency of these vessels. Proof that these channels shunt retinal venous blood into the cil­iary circulation was provided by Frisen et al. ( 12). They presented fluorescein fundus angiograms of a patient with meningioma of the optic nerve sheath, demonstrating that the blood in the cen­tral retinal vein is in fact shunted into peripapillary choroidal channels. Imes et al. ( 13) were able to document the evo­lution of optociliary shunt vessels associated with optic nerve sheath meningioma. They presented sequential fundus photographs obtained during an 8- year period, demonstrating the development of optociliary vessels. They reported that disc DISAPPEARING OPTOCILIARY SHUNT VESSELS 5 FIG. 4. ( Case 2) Fundus photographs taken March 7, 1985 show atrophic papilledema and optociliary shunt vessels on both the right ( A) and left ( B) optic discs. Photographs taken 6 days postoperatively ( March 26, 1985) show complete disappearance of most, and marked reduction in caliber, of the remaining optociliary shunt vessels on both the right ( C) and left ( 0) optic discs. edema preceded the appearance of shunt vessels by 3 years, and as optic atrophy became profound, the vessels increased in number and in size. This sequence of events had been described earlier by Walsh ( 14) and Spencer ( 15) and is the generally accepted hypothesis. Recently, there have been a small number of cases reported that have raised some questions about the contributing factors in the pathogenesis of acquired optociliary shunt vessels, as well as the validity of the congestive hypothesis in these cases. Rodrigues et al. ( 16) re-ported a case of optic nerve sheath meningioma that included invasion of the sclera and peripapil­lary choroid by an orbital meningioma. In this case, the shunt vessels connected the central ret­inal vein and peripapillary choroid with adjacent nests of meningiomatous infiltration. Cogan ( 17) describes a second pathologic specimen in which the meningioma had extended into the choroid. He points out that the cilioretinal vessels seem to differ from those seen with central retinal vein ob­struction and raises the question of whether or not I Cllll Ncuro' 0l'lItlwlmol. Vol. 8. No. 1. 1988 6 T. P. DOWHAN ET AL. ,. JG. 5. iCdSd 2} Fr'Uurt: l~ l; t: l" f1 angiography a'emonstratlng numerous optociliary shunt vessels on each optic disc preoperatively on right ( A) and left ( 8). Fluorescein angiography performed 6 days postoperatively demonstrates resolution of shunt vessels on both optic discs, right ( C) and left ( 0). these shunt vessels may represent drainage from the tumor itself. Cogan ( 17) suggests a means of answering his own question by pointing out that fluorangiography showing an early fluorescence of shunt vessels would be expected in tumor drainage, as opposed to delayed fluorescence, which would be consistent with an obstructive process. Boschetti et al. ( 2) designed a study to see if a difference in fluorangiographic pattern exits be­tween shunts developing secondary to obstruction of the axial venous system and those developing from circumferential tumor compression. These observations led them to speculate that as the ab­normal vessels fill in the arterial phase, and more commonly in the arteriovenous phase, they may be arteriovenous shunts. However, if they are shunts, they have very low perfusion pressure be­cause the presence of late hyperfluorescence is consistent with a very stagnant flow. If this inter­pretation is correct, it would seem to support the " congestive hypothesis" of Frisen et a1. ( 12). The results of this study do not enable one to deter­mine the pathogenesis of optociliary vessels or to answer definitively the question raised earlier by Dr. Cogan. One may only speculate as to the rela­tionship of obstruction and external compression as possible mechanisms leading to disc edema, vi­sual loss, and optociliary shunt vessels. Acquired optociliary shunt vessels carry a very grim prognosis, which is perhaps in part a reflec­tion of the indolent and insidious processes that DISAPPEARING OPTOCILIARY SHUNT VESSELS 7 FIG. 6. Plain skull films showing disjunction of the co­ronal suture, expanded sella turcica, and dorsal sella erosion, consistent with long- standing intracranial hypertension acquired at an early age. are associated with acquired shunt vessels. In the case of optic nerve sheath meningioma, Hollen­horst et al. ( 17) attribute the poor prognosis for vi­sion to enwrapping of the optic nerve and subse­quent destruction of the pial blood supply to the nerves. Surgical treatment of optic nerve meningiomas has generally been unsatisfactory ( 17- 20). As the optic nerve and the meningeal tumor share a common blood supply, attempts to remove the tumor from optic nerve or chiasm cause destruc­tion of pial blood vessels and subsequent deterio­ration of vision ( 17,18,20). There continues to be FIG. 7. CT scan of the brain showing a widely en­larged third ventricle herniating into the sella. some controversy over what is the most appro­priate management. Surgery, radiation therapy, and conservative observation all have some merit. Regardless of management or etiology, the reso­lution of these grim prognostic indicators has been rarely reported. Six publications describe reduc­tion in caliber of shunt vessels ( 3,8,11,18,21,22). Smith et al. ( 22) describe the regression in one case and complete disappearance in two other cases following radiation therapy for primary optic nerve sheath meningioma. Tyson and Lessell ( 18) reported near total resolution of shunt vessels 1 month after surgical removal of an intracranial me­ningioma. Eggers and Sanders ( 3) and Neville et al. ( 21) reported one case each of total resolution of shunt vessels after surgical removal of menin­gioma. Perlmutter and associates ( 8) noted marked regression after surgical decompression of the optic nerve sheath in patients with chronic atro­phic papilledema. Finally, Miller ( 11) reported near total resolution of optociliary shunt vessels following an occipital craniectomy and lumbar­peritoneal shunt procedure to relieve increased in­tracranial pressure in a patient with osteo­scleroses. These cases, as well as the case reports we have presented, confirm that optic nerve decompres­sion had occurred in the postoperative or post­radiation treatment period. As Eggers ( 3) and Tyson ( 18) point out, and we concur, this implies dependence on elevated pressure for the persis­tence of optociliary shunt vessels. It is generally accepted that the natural course of chronic disc edema that leads to shunt vessels also eventually progresses to atrophy of the optic nerve. This suggests the alternative hypothesis that the persistence of optociliary shunt vessels is related to the degree of atrophy of the optic nerve. In our experience, neither the persistence nor the regression of optociliary shunt vessels is related to atrophy of the optic nerve. Furthermore, chronic atrophic papilledema does not appear to lead to regression of shunt vessels. This finding, i. e. per­sistence of shunt vessels on atrophic optic discs, would further support the conjecture that optocil­iary shunt vessels are dependent on increased pressure in the optic nerve sheath. Unfortunately, there has been no observation or documentation of spontaneous resolution of acquired optociliary shunt vessels. This final hypothesized stage of the natural history of acquired shunt vessels has yet to be confirmed. Finally, these cases illustrate the importance of diagnosing the underlying pathology that led to I Clill Neuro- ophthalmol. Vol. 8. No. 1. 1988 8 T. P. DOWHAN ET AL. the development of optociliary shunt vessels for both prognosis and treatment. In the case of optic nerve sheath meningioma, surgical treatment has very limited application. In cases of chronic disc edema and optociliary shunt vessels that are not the result of optic nerve sheath meningioma, sur­gical treatment may have more general applica­tion. Indeed, surgical procedures that lower intra­cranial pressure and indirectly decompress the optic nerve sheath, or direct surgical decompres­sion of the optic nerve sheath, may be the treat­ment of choice in these infrequently occurring but well- defined situations. Although perhaps the treatment of choice, operative measures to lower intracranial pressure are not without risk. The oc­currence of visual loss following craniotomy per­formed to relieve intracranial hypertension is well documented ( 23). Optic neuropathy is felt to be the cause in some cases. The pattern of visual field loss in a nerve fiber bundle distribution is most typical of damage at the level of the optic disc. The pathogenesis of optic neuropathy in these cases is speculative. As a rule, visual recovery is very poor. Awareness of the ocular manifestations asso­ciated with optociliary shunt vessels may eventu­ally help to establish clear causal relationships and lead to improved management, and ultimately, preservation of sight. Acknowledgment: The authors would like to ac­knowledge the expert photographic assistance of Mr. Rolf Sennhenn and Mr. Enrique Murcia. We are particu­larly grateful to William F. Hoyt, M. D., for assistance in putting these cases together. REFERENCES 1. Salzmann M. Zur Anatomie Der Angebornen Sichel Nach Innenunten. 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