Progressive Vision Loss in an Adult With Congenital Optic Nerve Coloboma, Hydrocephalus, and Basal Encephalocele

Clinical Correspondence Section Editors: Robert Avery, DO Karl C. Golnik, MD Caroline Froment, MD, PhD An-Guor Wang, MD Progressive Vision Loss in an Adult With Congenital Optic Nerve Coloboma, Hydrocephalus, and Basal Encephalocele Evan K. Wotipka, BS, Kais M. Karowadia, BS, Pamela A. Davila, MD, Noor A. Laylani, MD, Andrew G. Lee, MD O ptic nerve coloboma (ONC) is a congenital optic nerve malformation that results in a bowl-shaped excavation of the optic disc (1). Retinal detachment is the most common complication producing secondary vision loss. Subretinal fluid from the disc cavitation is the presumed mechanism. ONC can be associated with hydrocephalus or slit-ventricle syndrome (SVS) and either can be associated with shunting and shunt failure (2). In addition, ONC can be associated with basal encephalocele (BE) (1). We describe a 33-year-old woman with a congenital ONC in the left eye and an anomalous disc in the right eye, hydrocephalus, and secondary BE who developed delayed, adult-onset, progressive vision loss despite shunt revision and transsphenoidal surgical repair of the BE and chiasmopexy. Based on our review of the English language ophthalmic literature, we believe that our case is unique. Our patient had a medical history of congenital ONCs in both eyes, hydrocephalus with shunt placement 16 years prior, and secondary hypopituitarism necessitating replacement therapy. MRI showed stable shunted hydrocephalus and a BE (Fig. 1). She was evaluated by an outside ophthalmologist 8 months before our initial visit because of a 1month progression of subjective visual field loss. Neuroophthalmic examination at that time showed a decrease in baseline visual acuity from 20/40 to 20/50 in the left eye. Intraocular pressure was within normal limits both eyes, and visual fields demonstrated generalized depression with a mean deviation of 228 in the left eye; there was no field McGovern Medical School (EW), University of Texas (Houston), Houston, Texas; University of Texas Medical Branch (KK), Galveston, Texas; Department of Ophthalmology (PAD, NAL, AGL), Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas; Departments of Ophthalmology, Neurology, and Neurosurgery (AGL), Weill Cornell Medicine, New York, New York; Department of Ophthalmology (AGL), University of Texas Medical Branch, Galveston, Texas; University of Texas MD Anderson Cancer Center (AGL), Houston, Texas; Texas A and M College of Medicine (AGL), Bryan, Texas; Department of Ophthalmology (AGL), The University of Iowa Hospitals and Clinics, Iowa City, Iowa; and School of Engineering Medicine (AGL), Texas A&M University, Houston, Texas. The authors report no conflicts of interest. Address correspondence to Andrew G. Lee, MD, Blanton Eye Institute, Houston Methodist Hospital, 6560 Fannin Street, Suite 450, Houston, TX 77030; E-mail: [e-mail] e236 comparison. Dilated examination was described as “diffuse optic atrophy” in the left eye. These examination findings were attributed as delayed sequelae from her encephalocele. Two months later, she underwent an encephalocele reduction using endoscopic approach followed 1 week later by a bifrontal craniotomy with correction of her brain herniation defect with a vascularized pericranial graft. The patient also had a shunt revision at the time of craniotomy. Preoperative and postoperative computed tomography showed slit-like ventricles bilaterally. One week before the initial neuroophthalmology visit, she experienced progressive vision loss from baseline of 20/50 to no light perception (NLP) of the right eye over the course of 10 days. The left eye was NLP from prior phthisis bulbi after retinal detachment associated with an ONC in the left eye. A lumbar puncture showed an opening pressure of 23 mm Hg. Shunt series demonstrated stable bilateral parietal approach ventriculoperitoneal shunt tubing, 2 on the left and 1 on the right. The more anterior left shunt was believed to be likely disconnected from the inferior tubing in her neck; the other 2 shunt catheters showed no evidence of kinking or discontinuity. Neuro-ophthalmic examination showed NLP both eyes. The intraocular pressure was 14 mm Hg in the right eye. Slitlamp examination was normal in the right eye. There was phthisis bulbi with band keratopathy, iris atrophy, and an exotropia of 25 prism diopters in the left eye. The optic disc was diffusely atrophic in the right eye with anomalous branching of vessels (Fig. 2). There was no visualization of the posterior segment in the left eye in the phthsical eye. The nuclear medicine shunt-o-gram, performed 1 day after our initial visit, showed a normally functioning right ventriculoperitoneal shunt. The flow of both the left shunts were initially sluggish but normalized after patient ambulation. Our patient developed progressive vision loss in the right eye with ONC, shunted hydrocephalus, and BE but was unrelated to retinal detachment. One other patient with ONC in our literature review had progressive vision loss unrelated to retinal detachment. It demonstrated a 56-year-old woman with ONC and right eye progressive vision loss over a few years due to optic nerve compression of an arachnoid brain cyst (3). Based on our review of the English language Wotipka et al: J Neuro-Ophthalmol 2024; 44: e236-e237 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence FIG. 1. T1 sagittal magnetic resonance images before (left image) and after (right image) bifrontal craniotomy and vascularized graft placement. From left to right, the arrows point to the transsphenoidal encephalocele and then the newly placed vascularized graft, respectively. ophthalmic literature, our case is only the second case of progressive vision loss in ONC without retinal detachment. We propose 2 potential mechanisms for delayed visual loss in our case. First, shunt malfunction was considered, and the shunt was revised. Although progressive ventriculomegaly is a common and diagnostic finding of hydrocephalus, slit-like ventricles can also occur in shunt failure. In the slit-ventricle syndrome, overshunting resulting in negative pressure and collapse of the ventricles or repetitive undershunting leading to a loss of compliance of the ventricles from secondary gliosis can limit the ventricular enlargement despite elevated intracranial pressure (2,4). The opening pressure in our case however was normal, and there was no papilledema noted. Optic atrophy in this setting however might preclude the development of the optic disc edema ophthalmoscopically. Second, visual deterioration to NLP after surgery could be from chiasmopexy failure of the BE, resulting in subsequent worsening ischemic or mechanical chiasmal prolapse. Delayed complications of BEs and surgical treatment however are rare. One prior case of a 56-year-old with transsphenoidal BE and morning glory syndrome described delayed onset of bitemporal hemianopsia (4). The precise mechanism of the visual loss in this case however remains ill-defined. In summary, we present a unique case of progressive vision loss in a patient with congenital ONC, SVS status postshunt and shunt revision, and worsening vision to NLP after transsphenoidal repair of an ONC-associated BE. The most common cause of adult onset visual loss in prior congenital ONC is retinal detachment. Hydrocephalus and shunt failure however should be considered in any Wotipka et al: J Neuro-Ophthalmol 2024; 44: e236-e237 FIG. 2. Image on the left shows anomalous disc with superimposed pallor and nasally displaced vessels with mild cavitary abnormality temporally. Image on the right is the left eye with secondary phthisis bulbi and iris coloboma. shunt-dependent patient with or without ventriculomegaly, and patients with the SVS can have shunt failure. Mechanical prolapse of the optic chiasm may produce worsening vision (e.g., bitemporal hemianopsia), but chiasmopexy has shown only anecdotal success and a few cases of progressive visual loss despite shunt revision, chiasmopexy, or transsphenoidal repair of BE including our case have been reported in the literature. Clinicians should be aware of the differential diagnosis of progressive adult onset visual loss in childhood ONC without retinal detachment. STATEMENT OF AUTHORSHIP Conception and design: E. Wotipka, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee; Acquisition of data: E. Wotipkaa, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee; Analysis and interpretation of data: E. Wotipka, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee. Drafting the manuscript: E. Wotipka, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee; Revising the manuscript for intellectual content: E. Wotipka, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee. Final approval of the completed manuscript: E. Wotipka, K. Karowadia, P. A. Davila, N. A. Laylani, A. G. Lee. REFERENCES 1. Brodsky MC. Congenital optic disk anomalies. Surv Ophthalmol. 1994;39:89–112. 2. Nguyen TN, Polomeno RC, Farmer JP, Montes JL. Ophthalmic complications of slit-ventricle syndrome in children. Ophthalmology. 2002;109:520–524. 3. Rosenberg LF, Burde RM. Progressive visual loss caused by an arachnoidal brain cyst in a patient with an optic nerve coloboma. Am J Ophthalmol. 1988;106:322–325. 4. Koerner JC, Sweeney J, Rheeman C, Kenning TJ. Delayed presentation of morning glory disc anomaly and transsphenoidal encephalocele: a management dilemma. Neuroophthalmology. 2018;43:95–101. e237 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.