[A case of probable Creutzfeldt-Jakob disease with a point mutation of prion protein gene codon 180 and atypical MRI findings].

A case of probable Creutzfeldt-Jakob disease (CJD) is reported. A 70-year-old Japanese woman was admitted with a complaint of amnesia. She initially developed Klüver-Bucy syndrome, hypergraphia, and later showed myoclonus and startle response. She developed akinetic mutism within nine months from the onset. Prion protein gene codon 180 point mutation (Met/Ile) was detected and we diagnosed her as CJD. Serial MRI studies revealed abnormal T2 elongation and thickening limited to the cerebral cortices, which started at bilateral temporal lobes and later extended to frontal, parietal, and occipital lobes with relative sparing of hippocampi and central gyri. Serial EEG did not show periodic synchronous discharge (PSD). Three cases of CJD with a point mutation of codon 180 were reported in the past. There are several common features in the past cases and the present case, i.e. 1) negative familial history, 2) late onset, 3) T2 high intensity at cerebral cortices on MRI, and 4) negative PSD. These may be characteristic features of CJD with a point mutation of codon 180.