We describe a 63-year-old man diagnosed with sporadic Creutzfeldt-Jakob disease (sCJD), specifically sporadic fatal insomnia, confirmed through real-time quaking-induced conversion (RT-QuIC) analysis of cerebrospinal fluid and polysomnography. He presented with rapid cognitive decline, behavioural changes, sleep disturbances and dysautonomic symptoms. Initial MR imaging, electroencephalogram and cerebrospinal fluid analyses were inconclusive, highlighting the difficulty in diagnosing this rare subtype of CJD. Clinical evaluation is fundamental in defining the diagnosis of sCJD. When clinical suspicion is strong, the diagnostic work-up should be continued. In this case, the combination of comprehensive clinical evaluations and advanced diagnostic tools, including RT-QuIC and polysomnography, proved essential in making a definitive diagnosis.

It is increasingly evident that the association of glycans with the prion protein (PrP), a major post-translational modification, significantly impacts the pathogenesis of prion diseases. A recent bioassay study has provided evidence that the presence of PrP glycans decreases spongiform degeneration and disease-related PrP (PrPD) deposition in a murine model. We challenged (PRNPN181Q/197Q) transgenic (Tg) mice expressing glycan-free human PrP (TgGlyc-), with isolates from sporadic Creutzfeldt-Jakob disease subtype MM2 (sCJDMM2), sporadic fatal insomnia and familial fatal insomnia, three human prion diseases that are distinct but share histotypic and PrPD features. TgGlyc- mice accurately replicated the basic histotypic features associated with the three diseases but the transmission was characterized by high attack rates, shortened incubation periods and a greatly increased severity of the histopathology, including the presence of up to 40 times higher quantities of PrPD that formed prominent deposits. Although the engineered protease-resistant PrPD shared at least some features of the secondary structure and the presence of the anchorless PrPD variant with the wild-type PrPD, it exhibited different density gradient profiles of the PrPD aggregates and a higher stability index. The severity of the histopathological features including PrP deposition appeared to be related to the incubation period duration. These findings are clearly consistent with the protective role of the PrP glycans but also emphasize the complexity of the conformational changes that impact PrPD following glycan knockout. Future studies will determine whether these features apply broadly to other human prion diseases or are PrPD-type dependent.

Prion disease is an uncommon entity characterized by exceptionally rapid neurodegenerative deterioration. There are three categories of prion disease: (1) sporadic: sporadic Creutzfeldt-Jakob disease (sCJD), sporadic fatal insomnia, and protease-sensitive prionopathy; (2) genetic: genetic Creutzfeldt-Jakob disease, familial fatal insomnia, and Gerstmann-Sträussler-Scheinker syndrome; and (3) acquired: Kuru, iatrogenic Creutzfeldt-Jakob disease, and variant Creutzfeldt-Jakob disease. Although it is an incurable disease, a specific pathophysiological mechanism exists involving neuronal loss, glial cell proliferation, absence of inflammatory response, development of vacuoles leading to a spongiform appearance, and the presence of prions. This case report describes the approach to a patient with progressive cognitive deterioration, later developing motor ataxia and difficulty in language expression. The patient was hospitalized for the diagnostic approach of autoimmune or paraneoplastic encephalitis at Hospital Ángeles del Pedregal, Mexico City, Mexico, with poor response to medical treatment and clinical worsening. Finally, a diagnosis of Creutzfeldt-Jakob disease was concluded through cerebrospinal fluid analysis. This demonstrates the diagnostic challenge this entity presents.

This study was undertaken to elucidate the clinical profile of sporadic fatal insomnia (sFI), assess the similarities and differences between sFI and fatal familial insomnia (FFI), and evaluate the influence of ethnicity on the phenotype of sFI patients. The data of sFI and FFI patients were retrieved from our case series and through literature review. The clinical and diagnostic features of sFI and FFI were compared, as were the phenotypes of Asian and Caucasian sFI patients. We identified 44 sFI and 157 FFI cases. The prevalence of sleep-related, neuropsychiatric, and autonomic symptoms among the sFI patients were 65.9%, 100.0%, and 43.2%, respectively. Compared to FFI, sFI exhibited longer disease duration and a higher proportion of neuropsychiatric symptoms, whereas FFI was characterized by a higher incidence of sleep-related and autonomic symptoms in the early stages of the disease or throughout its course. In addition, a higher proportion of the sFI patients showed hyperintensity on magnetic resonance imaging (MRI) and periodic sharp wave complexes on electroencephalography compared to the FFI patients, especially those presenting with pathological changes associated with MM2-cortical type sporadic Creutzfeldt-Jakob disease. The Asian sFI patients had a higher proportion of males and positivity for cerebrospinal fluid 14-3-3 protein, and fewer sleep-related symptoms compared to Caucasian sFI patients. The age at onset and duration of sFI differed between ethnic groups, but the difference failed to reach statistical significance. Despite its similarities to FFI, sFI is characterized by longer disease duration, higher proportion of neuropsychiatric symptoms, and hyperintensity on MRI, along with differences in the clinical characteristics based on ethnicity.