Creutzfeldt‐Jakob Disease (CJD): Time from Symptom Onset Until Subnormal Magnetic Resonance Imaging (MRI) of brain

Background Abnormal MRI of brain is one out of three supportive diagnostic criteria for CJD along with abnormal EEG and positive 14‐3‐3 protein when there is rapidly progressive dementia (RPD), myoclonus, visual or cerebellar disturbance, pyramidal or extrapyramidal dysfunction, akinetic mutism. MRI can be normal in CJD even when the symptoms are advanced posing a diagnostic challenge. The goal of this study was to review cases of RPD suspected to be due to CJD and correlate with the diagnostic findings. Methods Cohort of patients with RPD and/or neuropsychiatric presentation suspicious for CJD over the 10 years at our institution was identified using EPIC Slicer Dicer tool to search electronic medical records. Clinical presentation and diagnostic markers including CSF (protein 14‐3‐3, RT‐QuIC, total‐tau), MRI and EEG findings were analyzed to determine the sensitivity of each at early disease state. Results Total of 25 cases suspected of CJD were identified. 4 patients were confirmed to have probable CJD based on positive RT‐QuIC, protein 14‐3‐3 and elevated total‐tau. Initial suspicion for CJD was later not considered high enough to pursue CSF analysis in 4 patients. 1 patient didn’t have CSF study done due to technical error. 16 patients were tested negative for RT‐QuIC. Out of the 16 patients 4 had elevated protein 14‐3‐3, out of which 3 had elevated total‐tau. Out of 25 patients 24 had MRI, 1 couldn’t undergo MRI due to MRI incompatible cardiac pacemaker. Out of 24 patients 4 had findings suggestive of CJD on the initial MRI, 2 of them confirmed to have CJD based on CSF studies. 2 patients had normal initial MRI despite multiple symptoms of CJD. The first patient developed classic findings for CJD on repeat MRI 8 months from symptom onset and the 2nd had such MRI changes 4 months from symptom onset. These 2 patients had diagnosis confirmed by positive RT‐QuIC, 14‐3‐3 protein and elevated total‐tau. Conclusion While abnormal MRI findings support the diagnosis of probable CJD in the correct clinical setting, negative test results don’t exclude diagnosis of CJD. CSF markers and a repeated brain MRI are instrumental for correct CJD diagnosis.