Improving Laboratory Diagnosis of Creutzfeldt-Jakob Disease.

Background: Creutzfeldt-Jakob disease (CJD) is a rare human form of prion disease caused by misfolded, transmissible proteinaceous infection particles (prions). As a fatal neurological illness, it mostly presents with rapidly progressive dementia, and most patients die within a year of clinical onset and diagnosis. The lack of an intravital test for CJD limits its timely diagnosis. A brain biopsy/autopsy is considered the gold standard for definitive diagnosis of CJD, however owing to its highly invasive and transmissible nature, it is rarely performed. In this case report, we try to highlight the important role of combining serology, EEG, and CSF investigations, often used for the diagnosis of CJD. Combining these in the laboratory improves the timely diagnosis of this rare and fatal disease. Case summary: We report a clinical case study of a 65-year-old female, who presented to the Neurology OPD at a tertiary care referral centre, with chief complaints of forgetfulness, behavioural changes, and involuntary movements in the right upper limb for the last 7 months. According to the informant (daughter), the patient was asymptomatic 7 months ago after which she started developing these gradual onset symptoms. Later she was bed-bound and dependent on her family members for her daily chores and had even lost control over her bowel and bladder habits. On physical examination, the patient was found to be disoriented and afebrile with normal vitals, however, CNS examination showed a low Mini Mental Examination Score (MMSE). The patient was admitted to the neurology ward for further evaluation and a definitive diagnosis. Differential diagnosis was ruled out using various lab tests, CSF analysis, and neuroimaging. CSF report tested positive for 14-3-3 protein and CSF protein marker by RT-QuIC was outsourced. The confirmatory diagnosis of sporadic CJD was made based on clinical presentation, CSF analysis, and neuroimaging. Conclusion: Definitive diagnosis of CJD was possible with the help of various lab tests which helped rule out differential neurodegenerative diseases.