Creutzfeldt-Jakob disease (CJD) is a rare and rapidly progressive neurological disorder. This study aims to describe and summarize the key features of CJD by looking back at medical records of patients who were diagnosed with CJD at our hospital. The researchers will collect information from routine clinical evaluations, including patients' symptoms, blood tests, cerebrospinal fluid analysis, brain imaging (such as MRI and PET), and electroencephalography (EEG). By analyzing these data together, the study hopes to provide a clearer picture of how CJD presents in routine clinical practice. This may help doctors recognize the disease more quickly in the future. No new tests or treatments will be given to patients. All data are collected from existing medical records.

Inclusion Criteria:

• Diagnosis of definite or probable Creutzfeldt-Jakob Disease (CJD) according to the established WHO diagnostic criteria
• Available medical records covering at least one of the following: clinical history, peripheral blood test results, cerebrospinal fluid (CSF) analysis findings, brain MRI reports/images, or EEG reports
• Hospitalized or evaluated at the participating institution during the study period

Exclusion Criteria:

• Alternative diagnosis confirmed that explains all clinical features (e.g., autoimmune encephalitis, rapidly progressive dementia due to other causes)
• Incomplete medical records with no relevant clinical, laboratory, imaging, or EEG data available
• Patient or legal representative declined the use of medical records for research purposes (where applicable according to local regulations)

This study population consists of patients who were diagnosed with Creutzfeldt-Jakob Disease (CJD) at the First Affiliated Hospital of Fujian Medical University between Jan 01, 2022 and Dec 31, 2031. Potential participants were identified through a search of the hospital's electronic medical record system using diagnostic codes for CJD and related prion diseases. All patients who met the inclusion and exclusion criteria and had sufficient medical record data available for abstraction were included in the analysis. No additional recruitment or active enrollment was performed, as this was a retrospective chart review study. The study population is expected to reflect the typical clinical presentation and diagnostic workup of CJD in a real-world hospital setting.