[Fatal familial insomnia: case presentation and discussion of typical clinical and imaging findings].

Fatal familial insomnia (FFI) is a hereditary prion disease caused by a mutation in codon 178 of the prion protein gene PRNP on chromosome 20. It is characterized by disturbed night sleep, resulting in daily vigilance perturbations and a variety of other neurological symptoms. We present the case of a 46-year-old woman deteriorating despite immunosuppressive treatment which was initiated suspecting cerebral vasculitis as the cause of her progressive neurological symptoms. The correct diagnosis was established only post mortem. Based on the case presented here, we discuss typical clinical symptoms and imaging findings. In particular, we outline how modern diagnostic methods such as positron emission tomography with [(15)O]H(2)O and [(18)F]FDG and single photon emission computed tomography can add valuable information to results from conventionally performed imaging techniques and genetic testing.