Bilateral Outer Retinal Necrosis Following Mumps Infection

A 9-year-old girl with unknown vaccination status was referred for a sudden diminution of vision in both eyes and headache of 4 days duration following an attack of mumps. She had a history of fever and bilateral, painful, parotids swelling 2 weeks previously. On examination, her best-corrected visual acuity (BCVA) was perception of light with inaccurate projection in both eyes. Slit-lamp examination showed an anterior chamber reaction of 1+ and vitritis 1+ (SUN criteria). Pupillary examination was sluggish in both eyes. Fundus examination showed confluent areas of outer retinal necrosis involving the entire retina, hyperemic optic disc, and a few retinal hemorrhages. OCT showed an increased thickness and hyperreflectivity of the outer retinal layers (Figure 1). Intraocular pressures were 10 mmHg on applanation tonometry in both eyes. A provisional diagnosis of bilateral outer retinal necrosis was made. Aqueous tap was negative for herpes simplex (HSV), Varicella zoster (VZV), Cytomegalovirus (CMV), Rubella, Toxoplasmosis, and Mycobacterium tuberculosis by multiplex PCR. As she also had headache, she was referred to a neurologist who did a cerebrospinal fluid (CSF) analysis to rule out meningitis. The CSF analysis was negative for sugar, protein, and lymphocytes. Culture was negative for bacteria and fungi. Multiplex PCR on the CSF was also negative for the encephalitis profile (HSV, VZV, CMV, human herpes virus-6, rubella, mumps, measles, enterovirus, West Nile virus, chikungunya, Dengue, Chandipura virus, JC virus, Japanese encephalitis virus, H. influenzae, Cryptococcus neoformans, S. pneumoniae, N. meningitidis, Mycobacterium tuberculosis, toxoplasmosis). Complete hemogram, VDRL, Treponema pallidum hemagglutination test, ELISA for HIV, toxoplasmosis were negative. Chest X-ray was normal. Serologic tests (ELISA) showed high antibodies (IgG) to the mumps virus (>150 U/ mL; normal: <8 U/mL). Her absolute lymphocyte counts were 1343/μL (normal range: 660–4600/μL). However, there was a transient decrease in absolute CD4 counts at the time of presentation (432/μL; normal range: 650–1500/μL), which can occur post-viral infection. She received intravenous acyclovir 315 mg 8-hourly for 5 days and prednisolone acetate eye drops (6 times/day). In subsequent follow-up visits, the retinitis showed quick, perivascular clearing, and resolution of the retinal edema. In spite of the clearing of the retinal edema, her vision still remained perception of light with inaccurate projection. She was started on oral steroids (20 mg/day) along with oral acyclovir. There was no improvement in vision. She eventually progressed to bilateral retinal pigment epithelium atrophy and optic atrophy in 4 weeks (Figure 2). Fluorescein angiogram showed diffuse choroidal hyperfluorescence caused by the retinal pigment epithelium atrophy and optic atrophy. OCT showed distortion and thinning of the outer retinal layers (Figure 3). There was foveal thinning to 90 μm and 64 μm in the right and left eyes, respectively at 1 month follow-up. Full field electroretinogram showed unrecordable rod and cone responses, suggestive of generalized retinal dysfunction. Repeated CD4 counts showed increased absolute CD4 counts (1983/μL; normal range: 650–1500/μL) at the end of 1 month.