Herpes simplex encephalitis: long term magnetic resonance imaging and neuropsychological profile.

Abstract

The first comprehensive in vivo documentation of the long term profile of pathological and spared tissue is described in a group of 10 patients with a diagnosis of herpes simplex encephalitis, who were left with memory difficulties as a major residual sequel of their condition. With a dedicated MRI protocol, which included high resolution images of temporal lobe and limbic system areas, data are provided on structures that have recently gained importance as anatomical substrates for amnesia. The major features of the lesion profile were: (1) unilateral or bilateral hippocampal damage never occurred in isolation, and was often accompanied by damage to the parahippocampus, the amygdala, specific temporal lobe gyri, and the temporal poles; (2) the insula was always abnormal; (3) neocortical temporal lobe damage was usually unilateral or asymmetric. It never occurred in isolation, and was invariably associated with more medial pathological changes; (4) anterior and inferior temporal lobe gyri were damaged more often and more severely than posterior and superior temporal lobe gyri; (5) pronounced abnormality was often present in the substantia innominata (region of the basal forebrain/anterior perforated substance); (6) there was evidence of significant abnormality in the fornix; (7) there was evidence of damage to the mammillary bodies; (8) thalamic nuclei were affected in around 50% of cases, with damage usually unilateral; (9) frontal lobe damage was present in a few patients, and affected medial areas more than dorsolateral areas; (10) there was some involvement of the striatum, although this was usually unilateral and mild; (11)

Viral-like brain inflammation during development causes increased seizure susceptibility in adult rats

“…The proclivity of viral infection sequelae for the temporal lobes may explain the robust memory deficits found in some patients with HSV encephalitis during neuropsychological testing (Gordon et al, 1990;Kapur et al, 1994). However, when we tested adult rats with a history of brain inflammation, they showed only mild deficits in behaviours mediated by mesial temporal lobe structures.…”

“Dazed and diffused”: making sense of diffusion abnormalities in neurologic pathologies

“…Diffusion-weighted abnormalities in herpes encephalitis include bilateral, asymmetrical regions of diffusion-weighted hyperintensity involving the medial temporal lobes and inferior frontal lobes, with relative sparing of the basal ganglia and white matter [18] (Figure 4). Although, typically, there is corresponding T 2 hyperintensity, several studies have suggested that the diffusionweighted signal changes are more sensitive than those on conventional MR sequences [19,20].…”

Herpes simplex virus tipo 1 como factor de riesgo asociado con la enfermedad de Alzheimer

“…El daño infl amatorio y el edema que se produce durante HSE ocurre en el lóbulo frontal y el lóbulo temporal incluyendo el sistema límbico 10,13 . Al respecto, se ha encontrado la presencia de antígenos virales de HSV en cerebros de pacientes fallecidos por HSE concentrados principalmente en los lóbulos temporal inferior y medio, hipocampo, amígdala, corteza olfatoria, ínsula y giro cingulado 14,15 .…”