LAUSR

BACKGROUND Rapidly progressive dementias (RPDs) are dementias that progress subacutely over a time period of weeks to months. Primary Sjögren's syndrome (pSS) is an autoimmune disease that can affect any organ system and may present with a wide range of clinical features that may mimic a plethora of medical conditions and in rare cases may manifest as RPD. We describe a unique case of pSS, in which rapidly progressive dementia (RPD) was the first disease manifestation and the patient's radiological and electroencephalogram findings were compatible with Creutzfeldt-Jakob disease (CJD). CASE PRESENTATION Here, we report a 58-year-old woman who presented with cognitive impairment rapidly deteriorating over the last 6 months prior to admission. Brain MRI and EEG were indicative of CJD. However, CSF 14-3-3 and tau/phospho tau ratio were within normal limits and therefore alternative diagnoses were considered. Blood tests were significant for positive antinuclear antibodies, anti-ENA and anti-SSA and a lip biopsy was consistent with pSS. The patient was started on intravenous steroids followed by oral prednisone taper, which prevented further deterioration. CONCLUSIONS This rare case expands the spectrum of neurological manifestations in pSS and highlights the importance of considering pSS in the differential diagnosis of RPDs in order to avoid misdiagnosis and provide appropriate treatment in a timely fashion.