Acute Bilateral Optic Neuritis Associated With Enteroviral Meningoencephalitis in a Seven-Year-Old Child: A Case Report

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Enteroviral central nervous system infections are common in children, but severe encephalitic presentations associated with optic nerve involvement are rare. We report a previously healthy seven-year-old girl admitted with a generalized seizure, severe impairment of consciousness, and acute complete bilateral visual loss. Cerebrospinal fluid contained fewer than 3 white blood cells/mm3, while multiplex polymerase chain reaction was positive for enterovirus. Brain magnetic resonance imaging supported an encephalitic process, and ophthalmological examination confirmed bilateral optic neuritis. The course was complicated by recurrent seizures, transient right hemiplegia, and severe hyponatremia with a nadir of 116 mmol/L. Urine output exceeded 2 L/24 h (>4.17 mL/kg/h at an initial weight of 20 kg), with marked thirst, hypernatriuresis, hyperosmolar urine, and a 10% weight loss. Because fluid intake was not quantified and overt clinical hypovolemia was absent, cerebral salt wasting remained probable but unconfirmed, and differentiation from the syndrome of inappropriate antidiuresis was limited. Treatment included antiepileptic therapy, intravenous corticosteroids for three days followed by an oral taper, intravenous immunoglobulin at 2 g/kg over two days, tailored hydration, and sodium supplementation. Visual function recovered completely within approximately 12 days, and serum sodium reached 134 mmol/L at discharge. This case emphasizes that an acellular cerebrospinal fluid profile does not exclude enteroviral meningoencephalitis and illustrates a rare temporal association with bilateral optic neuritis.