Rapidly Progressive Dementia in an Elderly Male: Perseverance Becomes the Key to a Rare Diagnosis.

Cognitive impairment in a patient with rapidly progressive dementia (RPD) develops faster than expected for a known dementia syndrome. It poses as a diagnostic challenge for the physician who must identify the diagnosis among a broad spectrum of differentials. Here, we discuss the case of a 60-year-old male who presented with a four-month history of progressive gait disturbance, incoherent talking, dysarthria, hand tremors, and new-onset bladder incontinence. Neurological examination revealed fast saccades, cerebellar dysarthria, hypertonia, and normal power in all four limbs, brisk reflexes, past pointing, intentional tremors, resting myoclonic jerks, and ataxic gait. Initial differentials of progressive paraneoplastic encephalitis, infectious encephalitis, and toxic encephalopathy were considered. However, the results of lumbar puncture and blood investigations-voltage-gated potassium channel (VGKC) antibody and N-methyl-D-aspartate (NMDA) receptor antibody, tumor markers, viral markers being negative and ammonia and lactate levels being normal led us to think of another possibility. With such rapidly progressive dementia, myoclonic jerks, extrapyramidal signs, and cerebellar signs, a diagnosis of Creutzfeldt-Jakob disease (CJD) was taken into consideration. A cerebrospinal fluid (CSF) sample was sent for CSF protein 14-3-3 quantification by enzyme-linked immunosorbent assay (ELISA) and came out positive. During his stay in the hospital, our patient developed multiple complications, and his clinical state progressively worsened. With no signs of improvement and the known fatal nature of the disease, the goals of care were discussed with the family and we all agreed on providing palliative care. The patient passed away on day 15 of hospital admission.