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キーワード:
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要旨:
Focal retrograde amnesia (FRA) is a rare neurocognitive disorder presenting with an isolated loss of retrograde memory. In
the absence of detectable brain lesions, a differentiation of FRA from psychogenic causes is difficult. Here we report a case
study of persisting FRA after an epileptic seizure. A thorough neuropsychological assessment confirmed severe retrograde
memory deficits while anterograde memory abilities were completely normal. Neurological and psychiatric examination
were unremarkable and high-resolution MRI showed no neuroradiologically apparent lesion. However, voxel-based
morphometry (VBM)-comparing the MRI to an education-, age-and sex-matched control group (n = 20) disclosed distinct
gray matter decreases in left temporopolar cortex and a region between right posterior parahippocampal and lingual
cortex. Although the results of VBM-based comparisons between a single case and a healthy control group are generally
susceptible to differences unrelated to the specific symptoms of the case, we believe that our data suggest a causal role of
the cortical areas detected since the retrograde memory deficit is the preeminent neuropsychological difference between
patient and controls. This was paralleled by grey matter differences in central nodes of the retrograde memory network. We
therefore suggest that these subtle alterations represent structural correlates of the focal retrograde amnesia in our patient.
Beyond the implications for the diagnosis and etiology of FRA, our results advocate the use of VBM in conditions that do not
show abnormalities in clinical radiological assessment, but show distinct neuropsychological deficits.
