Transient Hemiparesis and Hemianesthesia in an Atypical Case of Adult-onset Clinically Mild Encephalitis/ Encephalopathy with a Reversible Splenial Lesion Associated with Adenovirus Infection

Abstract

We herein report the case of a previously healthy 24-year-old Japanese woman who developed adult-onset clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) presenting with hemiparesis and hemianesthesia secondary to adenovirus infection. The patient's neurological symptoms and the lesion in the splenium resolved within 17 days without therapy. The radiographic features and clinical course observed in this case were consistent with a diagnosis of MERS; however, the only neurological symptoms were hemiparesis and hemianesthesia. This is the first reported case of MERS involving only hemiparesis and hemianesthesia at onset. This case suggests that a diagnosis of MERS should be suspected in patients with hemiparesis and hemianesthesia, especially when these conditions are preceded by infection.

Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion in an Adult Patient with Influenza

“…The clinical symptoms of MERS include reversible consciousness disturbance, seizures, delirium and headaches ( 5 ). MERS is triggered by infections with pathogens such as influenza virus, rotavirus, mumps virus, varicella-zoster virus, Salmonella enteritidis , Escherchia coli O-157, Mycoplasma pneumoniae , or Legionella pneumoniae ( 6 ). In addition to infection, MERS has been caused by hypoglycemia and the administration of antiepileptic drugs ( 6 ).…”

“…MERS is triggered by infections with pathogens such as influenza virus, rotavirus, mumps virus, varicella-zoster virus, Salmonella enteritidis , Escherchia coli O-157, Mycoplasma pneumoniae , or Legionella pneumoniae ( 6 ). In addition to infection, MERS has been caused by hypoglycemia and the administration of antiepileptic drugs ( 6 ). The typical features of the acute phase of MERS on diffusion-weighted MRI include high-intensity signals in the SCC.…”

Reversible lesion in the splenium of the corpus callosum

“…B, body; G, genu; R, rostrum it has become more recognized recently in adults that a reversible lesion in the SCC may no longer be a specific MRI finding in children with mild encephalitis. According to some case reports, MERS could have been triggered by (a) viral infection, including those caused by the influenza virus (Takanashi, Barkovich, Yamaguchi, & Kohno, 2004;Takatsu, Ishimaru, Ito, & Kinami, 2017), rotavirus (Fuchigami et al, 2013), measles virus (Melenotte, Craighero, Girard, Brouqui, & Botelho-Nevers, 2013), adenovirus (Hibino et al, 2014), human parvovirus B19 (Suzuki, Kusaka, & Okada, 2014), and cytomegalovirus (Feraco, Porretti, Marchiò, Bellizzi, & Recla, 2018) and (b) other types of infectious pathogens including Mycoplasma pneumoniae (Yuan et al, 2016), Legionella pneumophila (Tomizawa et al, 2015), Streptococcus pneumoniae (Avcu, Kilinc, Eraslan, Karapinar, & Vardar, 2017), and malaria parasites (Mawatari, Kobayashi, & Yamamoto, 2018).…”

Transient Splenial Lesion of the Corpus Callosum Related to Migraine with Aura in a Pediatric Patient

“…Transient splenial lesions of the corpus callosum are described in association with many diverse clinical conditions including various infections, use or withdrawal of antiepileptic drugs, and hypoglycemia (1)(2)(3)(4)(5)(6). The lesion appears as a well-defined hyperintense ovoid lesion in the center of the splenium of the corpus callosum, best observed in diffusion weighted brain magnetic resonance images.…”