Identifying neural correlates of memory and language disturbances in herpes simplex encephalitis: a voxel-based morphometry (VBM) study

Abstract

Herpes simplex encephalitis (HSE) is a severe neurological disease that often leads to persistent cognitive deficits in survivors. Memory and naming impairments have been reported most, although direct association between memory and naming performance and disease-related atrophy has not yet been demonstrated in vivo for a larger sample of patients. In the present work, a voxel-based morphometry (VBM) analysis was conducted on 3T magnetic resonance imaging (MRI) of 13 HSE survivors. The gray matter density values were correlated with scores indicating verbal memory decline, as well as errors/omissions in picture naming; both were obtained through neuropsychological assessment. Analysis of individual lesion patterns revealed a considerable inter-individual variability, mainly with atrophy in the basal forebrain, adjacent frontal cortex, medial and lateral temporal cortex, insula and thalamus. The neuropsychological data analysis revealed correlation between verbal memory decline and atrophy especially in the left hippocampal region, whereas naming problems were associated with gray matter loss especially in the lateral temporal lobe, the thalamus and the left insula. These results confirm, for the first time, the assumptions of earlier studies about the considerable variability of individual lesion patterns in HSE in a whole-brain approach in vivo, and thus the anatomical validity of VBM.

Long-Term Memory Dysfunction in Limbic Encephalitis

“…The diagnosis of viral encephalitis must be ascertained by detecting viral DNA in the cerebrospinal fluid via a polymerase chain reaction. The type of LTM impairment in herpes simplex encephalitis affecting either verbal memory (pattern a) and/or memory of names (pattern b) (38), and/or memory of living things (pattern c) (39) depends on structural lesions in the temporal lobe [involving the hippocampus (a) (38) or the lateral temporal lobe (b) (38) or antero-medial temporal cortex (c) (39)].…”

A Feasibility Study of Quantifying Longitudinal Brain Changes in Herpes Simplex Virus (HSV) Encephalitis Using Magnetic Resonance Imaging (MRI) and Stereology

“…Few studies have quantified brain abnormalities in HSV encephalitis and fewer still have correlated these with clinical information. Some studies have performed correlations between different modalities of neuroimaging, for example between FLAIR images and Diffusion Weighted Imaging (DWI), and others have used voxel based morphometry to correlate with neurocognitive problems on research scans not typically acquired in routine clinical practice [ 36 – 37 ].…”

Evidence for a functional specialization of ventral anterior temporal lobe for language

“…This evidence suggests that more complex semantic deficits, such as impaired nonverbal objectaction associations, are the result of more widespread atrophy and cannot be localized to the vATL alone. Similarly, in contrast to SD patients, HSVE patients commonly show categoryspecific semantic deficits and their atrophy is more restricted to the anterior medial rather than posterior lateral portions of the temporal lobe, which also points to a causal relationship between domain-general semantic impairments and temporal lobe atrophy beyond vATL (Noppeney et al, 2007;Frisch et al, 2015).…”