Idiopathic Intracranial Hypertension Presenting With Completely Asymmetric Visual Function

Photo and Video Essay Section Editors: Kimberly M. Winges, MD Michael J. Gilhooley, MB, PhD, FRCOphth Idiopathic Intracranial Hypertension Presenting With Completely Asymmetric Visual Function Irina Sverdlichenko, BHSc, Jonathan A. Micieli, MD FIG. 1. Fundus photographs at presentation (A) and final follow-up 8 months later (B). A 41-year-old woman was seen in neuro-ophthalmology consultation for severe left eye vision loss. Her medical history included migraines and obesity (body mass index 32.6 kg/m2), and she did not take regular medications. She was a recent immigrant to Canada, arriving 7 months prior. Her usual migraines occurred 1–2 times per week, but over the past month, this increased in frequency. She denied pulsatile tinnitus, transient visual obscurations, or diplopia. She presented to the emergency room with 3 days of painless vision loss in the left eye. Neuro-ophthalmology consultation revealed the visual acuity of 20/20 in the right eye, no light perception (NLP) in the left eye, and normal automated 24-2 SITA-fast visual field in the right eye with mean deviation of 22.78 dB. There was a left relative afferent pupillary defect. Dilated fundus examination revealed right optic disc edema (Frisen grade 3) and left Faculty of Medicine (IS), University of Toronto, Toronto, Canada; Department of Ophthalmology & Vision Sciences (JAM), University of Toronto, Toronto, Canada; Division of Neurology (JAM), Department of Medicine, University of Toronto, Toronto, Canada; and Kensington Vision and Research Centre (JAM), Toronto, Canada. The authors report no conflicts of interest. Address correspondence to Jonathan A. Micieli, MD, Kensington Vision and Research Centre, 340 College Street, Suite 501, Toronto, ON M5T 3A9, Canada; E-mail: [e-mail] e340 atrophic optic disc edema with peripapillary wrinkles and a few pseudodrusen (Fig. 1A). She underwent MRI and magnetic resonance venography of the brain that showed findings suggestive of chronically raised intracranial pressure including an empty sella and distal transverse sinus stenosis (Fig. 2C and D). MRI of the orbits showed increased T2 signal within the posterior intraorbital, intracanalicular, and prechiasmatic segments of the left optic nerve without associated enhancement (Fig. 2B). The left optic nerve was more tortuous on the left (Fig. 2A). Lumbar puncture on left lateral decubitus position revealed an opening pressure of 34 cm of water and normal cerebrospinal fluid (CSF) contents. She was diagnosed with complete vision loss in the left eye from idiopathic intracranial hypertension (IIH). Surgical treatment options were discussed, primarily optic nerve sheath fenestration given the unilateral nature and absence of systemic symptoms; however, the presence of optic atrophy in the left eye portended a guarded prognosis in that eye, and the patient opted for medical treatment. She was treated with acetazolamide 500 mg by mouth twice a day and escalated to 750 mg by mouth twice a day. Her papilledema resolved 8 months later, and at that time, the visual acuity was 20/20 in the right eye, counting fingers at 1 foot in the left eye, normal optic nerve in the right eye, and optic disc pallor in the left Sverdlichenko and Micieli: J Neuro-Ophthalmol 2023; 43: e340-e342 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay FIG. 2. MRI of the brain and orbits. A. T1 MRI orbits demonstrating asymmetric optic nerve tortuosity (white arrows). B. T2 MRI orbits demonstrating increased T2 signal in the left optic nerve (white arrow). C. MRV showing distal transverse sinus stenosis, and (D) sagittal FLAIR T2 showed an empty sella. MRV, magnetic resonance venography. eye (Fig. 1B). The automated 24-2 SITA-fast mean deviation remained normal in the right eye with mean deviation of 22.34 dB in the right eye. Complete asymmetric visual function (normal visual function in 1 eye and NLP in the other) is very rare in IIH. Moreover, IIH presenting with NLP vision is also rare and would not be expected unless there was severe, chronic, untreated papilledema or acute additional insult such as additional ischemic optic neuropathy. This case provides novel information regarding the visual outcome of medical treatment of NLP vision in IIH, the natural history of asymmetric, delayed IIH presentation, and asymmetric radiological features that can be seen (unilateral increased T2 signal and tortuosity of the optic nerve). We hypothesize that our patient had delayed presentation due to unrecognized chronic vision loss in her left eye and only sought medical attention when vision loss was complete. The presence of optic disc pallor and pseudodrusen support the notion that the left eye process was chronic. The delay in seeking medical care may be due to her recent immigration to Canada, lack of medical system knowledge, and language barrier. It is also possible that she had a superimposed anterior ischemic optic neuropathy, and there was not more significant disc edema due to the atrophy that already occurred. However, recovery of at least some vision suggests this was only chronic papilledema that went unrecognized. Previous literature has reported patients with IIH presenting with NLP. Bersani (1) compared preoperative and postoperative characteristics of pediatric and adult patients with IIH. The authors reported 6 pediatric eyes presenting NLP or light perception (LP), whereas 0 of 46 adult eyes presented this way. One Sverdlichenko and Micieli: J Neuro-Ophthalmol 2023; 43: e340-e342 13-year-old and 1 16-year-old man presented with unilateral NLP vision that improved to hand motion and light perception, respectively, after optic nerve sheath fenestration. Malomo et al (2) reported a 14-year-old Nigerian girl with IIH presenting with bilateral NLP whose vision returned to 6/60 after treatment. However, the authors explained this was a common scenario in their environment, wherein patients present with advanced stage disease. While other studies have reported patients with IIH and NLP, these individuals did not present NLP but progressed to it after poor treatment response (3–5) or long-standing IIH (6). Two patients showed no improvement of NLP vision (3,5); Bhandohal’s patient had significant improvement in visual acuity (4), and Liu’s patient with long-standing IIH demonstrated final visual acuity of 20/20 in both eyes (6). Our patient presented with asymmetric papilledema, hypothesized to be related to asymmetric transmission of CSF pressure to the optic nerve head. Farrokhi et al (7) previously reported a prevalence of 18.6% for very asymmetric papilledema in IIH (2 or more Frisen grades between eyes). Lower prevalences have been reported by the Idiopathic Intracranial Hypertension Treatment Trial at 7% (8) and by Bidot at 3.6% (9). Bidot suspected that asymmetric papilledema was related to differences in the size of the bony optic canals. They later validated this finding by reporting more severe papilledema or optic atrophy and worse visual function on the side of the larger optic canal (10). In contrast, Farrokhi found no difference in the size of the bony optic canal (7). Regardless of the exact mechanism, asymmetric papilledema is likely a result of compartmentalization of the perioptic subarachnoid spaces resulting in a bottleneck of CSF flow between the perioptic subarachnoid spaces and the suprasellar cistern (11). Although rare, IIH can present with complete asymmetric visual function due to chronic unrecognized papilledema likely resulting from asymmetric transmission of CSF pressure to the optic nerve head. STATEMENT OF AUTHORSHIP Conception and design: J. Micieli. Acquisition of data: I. Sverdlichenko. Analysis and interpretation of data: I. Sverdlichenko, J. Micieli. Drafting the manuscript: I. Sverdlichenko. Revising the manuscript for intellectual content: J. Micieli. Final approval of the completed manuscript: I. Sverdlichenko, J. Micieli. REFERENCES 1. Bersani TA, Meeker AR, Sismanis DN, Carruth BP. Pediatric and adult vision restoration after optic nerve sheath decompression for idiopathic intracranial hypertension. 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Compartmentalized cerebrospinal fluid. Int Ophthalmol Clin. 2014;54:95–102. Sverdlichenko and Micieli: J Neuro-Ophthalmol 2023; 43: e340-e342 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.