Meningoencephalitis in an adult with human herpesvirus‐6 infection

Review part 2: Human herpesvirus‐6 in central nervous system diseases

“…In pediatric patients, there have been many reports of exanthem subitum associated with neurological complications such as meningoencephalitis [Irving et al, 1990; Ishiguro et al, 1990; Asano et al, 1992; Inagaki et al, 1992; Sato et al, 1992; Yoshikawa et al, 1992; Sloots et al, 1993; Suga et al, 1993; Tan et al, 1993; Itokazu et al, 1994; Jones et al, 1994; Oki et al, 1995; Yanagihara et al, 1995; Fujiwara et al, 1996]. More recently, several reports of HHV‐6 associated encephalitis of non‐immunocompromised children [Kamei et al, 1997; Kimura and Nezu, 1998; Crawford et al, 2007, 2009; Nagasawa et al, 2007; Yoshinari et al, 2007] and adults [Birnbaum et al, 2005; Isaacson et al, 2005] in the absence of classical roseola have been described.…”

“…The clinical features and laboratory diagnosis of HHV‐6 encephalitis has led to a diverse neuroradiographic subset of disease characteristics in both immunocompetent and immunocompromised patients as shown in Table I. Initial case reports on pediatric patients with CNS complications of exanthem subitum revealed computerized tomography (CT) findings of cerebral edema and hypodensities in the cortex, thalami, cerebellum, and brainstem [Irving et al, 1990; Ishiguro et al, 1990; Asano et al, 1992; Inagaki et al, 1992; Sato et al, 1992; Yoshikawa et al, 1992; Sloots et al, 1993; Suga et al, 1993; Tan et al, 1993; Itokazu et al, 1994; Jones et al, 1994; Oki et al, 1995; Yanagihara et al, 1995; Fujiwara et al, 1996]. Larger case series in pediatric immunocompetent patients diagnosed with HHV‐6 encephalitis using MRI, revealed signal abnormalities [Kamei et al, 1997; Kimura and Nezu, 1998; Crawford et al, 2007, 2009; Nagasawa et al, 2007; Yoshinari et al, 2007] of the frontal/temporal‐parietal‐occipital lobes, cerebellum, brainstem, and deep gray nuclei (Table I).…”

Human herpesvirus 6 in the pathogenesis of multiple sclerosis

“…It has been suggested that HHV-6 variant A would have a greater neurotropism compared to variant B since HHV-6A is found relatively more frequently in CSF (14%) than in peripheral blood mononuclear cells (PBMC) (1%) in children with primary HHV-6 infection (49). HHV-6 can cause meningitis and encephalitis in children and adults, as described in several case reports (50)(51)(52)(53)(54)(55)(56)(57). In one retrospective study, HHV-6 DNA was found in CSF from 9 (7%) of 138 patients with clinical or laboratory evidence of encephalitis (58).…”