![]() ![]() Irregular breathing, hypnic jerks, propriospinal myoclonus at the wake-sleep transition, and quasi-purposeful limb gestures are considered to be characteristic features of FFI 6, 7. In some cases, FFI was characterized by the lack of REM-associated muscle atonia and the presence of jerky activity of limb muscles and irregular breathing 8. In FFI, PSG has disclosed a severely reduced total sleep time, reduced rapid eye movement (REM) sleep and abnormal stage shifts. Polysomnography (PSG) recordings document the biophysiological changes that occur during sleep. FFI is mainly characterized by prominent sleep impairment combined with neuropsychiatric disorders, dysautonomia and motor dysfunction 7. Phenotypic variability is a perplexing feature of FFI. Pathologically, FFI is characterized by predominant thalamic degeneration especially in the medio-dorsal and anterio-ventral nuclei 5, 6. The prevalence of FFI is one case per a million population per year, with only about 57 cases in 27 kindreds have been reported worldwide 2.įFI is an autosomal dominant disease that harbors a missense GAC to AAC mutation at codon 178 of the PRNP prion protein gene located on chromosome 20, along with the presence of the methionine polymorphism at position 129 of the mutant allele 3, 4. We propose that structural damages in the thalamus and cortex are mostly responsible for clinical manifestations of FFI.įatal familial insomnia (FFI) is a rare prion disease first described by Lugaresi et al., in 1986 1. In summary, Chinese FFI patients are typically characterized by organic sleep related symptoms, rapidly progressive dementia and sympathetic symptoms. Patient 2's emission tomography scan demonstrated a reduction in glucose uptake in the left thalamus and bilateral inferior parietal lobe. PSG of all these five cases showed reduction in total sleep time, sleep fragmentation, abnormal short non-rapid eye movement - rapid eye movement (REM) cycling, REM sleep reduction or loss, and REM sleep instruction in wakefulness. The most typical clinical manifestations in all 5 patients were sleep disturbances, including insomnia, laryngeal stridor, sleep breath disturbance, and sleep-related involuntary movements. Three of the five patients had more comprehensive family medical records. Two male and three female patients were recruited in this study. The clinical features and the results of the complementary tests, including polysomnography (PSG), brain imaging and genetic analysis, were used. Patients with confirmed clinical and laboratory diagnosis of FFI have been retrospectively reviewed. The selective atrophy of the limbic thalamus that characterizes FFI might be due to the binding of FFI toxic PrP or PrP res to specific receptors on thalamolimbic neurons.This study aimed to examine clinical features, sleep, abnormal sleep-wake transition and non-sleep disturbances as well as lab tests in Chinese fatal familial insomnia (FFI) subjects. Loss of sleep, sympathetic hyperactivity, and flattening of vegetative and hormonal circadian oscillations characterize FFI and result from a homeostatic imbalance caused by the interruption of the thalamocortical limbic circuits, the phylogenetically most advanced structures involved in the control of the sleep–wake cycle and the body’s homeostasis. FFI is thus a prion disease selectively damaging the thalamocortical limbic structures. Both in the thalamus and in the cortex, the limbic structures are those most consistently and severely involved: the anterior ventral and mediodorsal thalamic nuclei, the cingulate gyrus, and the orbitofrontal cortex. Heterozygotes at codon 129, expressing valine in the nonmutated allele, have a longer disease course (often longer than 1 year), ataxia and dysarthria at disease onset, and lesions widespread to cerebral cortex. Homozygotes at codon 129, expressing methionine also in the nonmutated allele, have a shorter disease course (often less than 1 year), prominent sleep and autonomic disturbances at disease onset, and pathology restricted to the thalamus. FFI is linked to a missense mutation at codon 178 of the prion protein gene, PRNP, coupled with the presence of the codon methionine at position 129, the locus of a methionine-valine polymorphism. Fatal familial insomnia (FFI) is an autosomal dominant prion disease clinically characterized by inattention, sleep loss, dysautonomia, and motor signs and pathologically characterized by a preferential thalamic degeneration. ![]()
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