Identifying neural correlates of memory and language disturbances in herpes simplex encephalitis: a voxel-based morphometry (VBM) study
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.
KeywordsHerpes simplex encephalitis Memory Language Voxel-based morphometry (VBM) Regional atrophy
The authors want to thank the MRI staff at the Max-Planck-Institute for Human Cognitive and Brain Sciences and the staff at the Clinic for Cognitive Neurology for their help in data acquisition and Heike Schmidt for her support in preparing the figures. This work was supported by LIFE—Leipzig Research Center for Civilization Diseases at the University of Leipzig (AV and MLS), by the German Federal Ministry of Education and Research (BMBF; MLS: German FTLD Consortium, AH: IFB Adiposity Diseases), by the Parkinson’s Disease Foundation (Grant No. PDF-IRG-1307) (MLS), by MaxNetAging (MLS), and by the German Research Foundation (DFG; SFB 1052A5) (AH).
Conflicts of interest
The authors declare that they have no conflicts of interest.
Human and animal rights
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.
The Ethics committee of the University Clinic Leipzig approved that the clinical data were used for the present study and patients provided written informed consent.
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