Midbrain Hypometabolism in Fatal Familial Insomnia: A Case Report and a Statistical Parametric Mapping Analysis of a Korean Family

Background and Methods: Fatal familial insomnia (FFI) is a rare genetic disease characterized by intractable insomnia, dysautonomia, and dementia. Herein we describe a patient with FFI. In order to study brain glucose hypometabolism in the patient, we used statistical parametric mapping (SPM) analysis of [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET). Case Report: The patient was a 34-year-old Korean man. He presented with intractable insomnia, rapidly progressive dementia and autonomic disturbances. A comprehensive clinical investigation was conducted, including brain MRI, electroencephalography, polysomnography, neuropsychological tests, FDG-PET and genomic tests. SPM analysis was performed using 7 healthy controls. Direct sequencing of the PRNP gene identified a heterozygous p.Asp179Asn mutation homozygous for methionine at codon 129 and for glutamate at codon 219. The results of the SPM analysis showed marked hypometabolism in the deep cerebral nuclei (including the bilateral thalami, caudate nuclei, and hypothalamus), association cortices (including the frontal, lateral temporal, inferior parietal lobule and posterior cingulate gyri), and midbrain. Conclusions: This is the first Korean report of FFI, in which the family showed male phenotypic predominance. The patient's SPM analysis demonstrated brain hypometabolism in the midbrain and the hypothalamus, as well as the thalami, caudate nuclei, and multiple cortical regions. These results contribute further to the overall understanding of the pathophysiology of FFI.