Mild Encephalitis/Encephalopathy with Reversible Splenial Lesion: Rare Benign Entity with Less Benign Differentials

Abstract

Mild encephalitis/encephalopathy with reversible splenial lesion is a rare benign clinical-radiological entity, characterized by nonspecific neurological symptoms associated with imagiological findings of corpus callosum lesion in magnetic resonance. Of unknown etiopathogenesis, several triggers have been suggested (infections, metabolic disturbances, drugs, among others). We present the case of a healthy 44-year-old man, admitted at the emergency department with sudden-onset headache, ataxia, facial myoclonus and dysarthria, in a context of flu-like syndrome. After presumptive diagnosis of viral encephalitis, he empirically initiated intravenous acyclovir which was suspended after magnetic resonance imaging disclosed corpus callosum lesions. The patient’s condition favourably evolved without specific therapy, with clinical resolution in less than a week and a normal magnetic resonance at two months. This entity, which requires differential diagnosis between benign conditions and others with worse prognosis, is usually diagnosed by exclusion, does not require targeted therapy and has an almost universally good outcome.