Abstract
Introduction Acute necrotising encephalopathy (ANE1) is a genetic predisposition related encephalopathy that can occur following influenza type A, parainfluenza or Human Herpes Virus 6 infection. It is commonly seen in children and associated with the autosomal dominant missense mutation in the RAN Binding Protein 2 (RANBP2) gene.1–3
Case A 45-year-old female with known RANBP2 mutation presented with coryzal symptoms, headache and blurred vision and tested positive to influenza A infection. RANBP2 was previously screened in our patient as her daughter developed ANE1 in childhood. Formal visual fields showed bilateral homonymous incongruent quadruple sectoranopia. Magnetic Resonance Imaging (MRI) Brain demonstrated T2 FLAIR bilateral lateral geniculate nucleus hyperintensities with foci of low susceptibility and diffusion restriction and was treated with intravenous methylprednisolone and plasma exchange. Follow-up showed MRI hyperintensities had reduced and the patient’s visual fields improved. Optical coherence tomography (OCT) of the retinal nerve fibre layer (RNFL) and ganglion cell layer demonstrated corresponding thinning in the pattern of field defects consistent with retrograde degeneration.
Discussion We describe novel visual field defects secondary to bilateral thalamic lesions from influenzae A triggered ANE1. The wedge-shaped visual field defects are explained by the vascular topography of the thalamus and the incongruency is related to the anterior location of the visual pathway lesions.
References
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Shukla P, Mandalla A, Elrick MJ, Venkatesan A. Clinical manifestations and pathogenesis of acute necrotizing encephalopathy: The interface between systemic infection and neurologic injury. Frontiers in Neurology. 2022;12.
Jiang J, Wang YE, Palazzo AF, Shen Q. Roles of nucleoporin RANBP2/Nup358 in acute necrotizing encephalopathy type 1 (ANE1) and viral infection. International Journal of Molecular Sciences. 2022;23(7):3548.
