Two Cases of Norovirus Gastroenteritis Associated with Severe Neurologic Complications

Norovirus, along with rotavirus, is a common virus that causes gastroenteritis in children [1]. Complications related to norovirus enteritis are rare, and the prognosis is good. However, various clinical features and poor prognoses have been reported in norovirus-associated encephalopathy [2,3]. Herein, we report two pediatric cases of norovirus infection with severe neurologic complications. A 7-year-old girl (patient A) visited the emergency room (ER) of a local hospital for diplopia, impaired vision, eye movement disorder, and mild neck stiffness that had lasted for 5 days. Days before developing ocular symptoms, she had abdominal pain, was diagnosed with enteritis, and took medications to alleviate the symptoms. Her mental status was alert, and the Glasgow Coma Scale score was 15. In a workup at a local hospital, brain magnetic resonance imaging (MRI) and angiography showed papilledema. She received mannitol for papilledema and intravenous methylprednisolone (1 mg/kg/ day) for 4 days for sixth cranial nerve palsy, followed by dexamethasone (0.5 mg/kg/day) for the next 6 days. During hospitalization, transient ataxia and bilateral periorbital pain were noted. Starting on hospitalization day 9, her symptoms improved, and a dexamethasone dose of 0.25 mg/kg/day was administered for 2 days. Subsequently, a reduced dexamethasone dose (0.125 mg/kg/day) was administered for the next 2 days. She was discharged on hospitalization day 13; the dexamethasone dose was tapered for 4 days and discontinued. However, on day 4 after discharge, her symptoms worsened again. Hence, she was transferred to our hospital. On transfer to our hospital, she had fixed dilated pupils, and her left eye had visual acuity of light perception and exhibited left gaze palsy (Fig. 1). Her right eye had a visual acuity of 0.04. On fundoscopy, stage 4 papilledema was confirmed in both eyes, and a slight decrease in the deep tendon reflex was observed. Whole-spine MRI and an autoantibody panel (anti-aquaporin 4 antibody [AQP4], anti-neurofilament antibody [NF], and anti-myelin oligodendrocyte glycoprotein [MOG]) revealed normal findings. Stool virus polymerase chain reaction (PCR) findings showed positivity for norovirus genogroup II (GII). She received intravenous immunoglobulin (IVIG) at a dose of 0.4 g/kg for 5 days and methylprednisolone (30 mg/kg/day) for 3 days. Her abdominal symptoms and visual acuity in the right eye improved. Further improvement was noted after acetazolamide was administered. A previously healthy 8-month-old girl (patient B) was brought to our ER with an ongoing seizure for 20 minutes. The patient had been treated for