RESUMO
Sporadic Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative condition and a human prion disease. Rapid progressive dementia, myoclonus, visual disturbances, cerebellar signs, and pyramidal/extrapyramidal symptoms are observed in such patients. However, these are non-specific symptoms and can manifest in a variety of other conditions. The occurrence of sporadic CJD in a patient with multiple sclerosis (MS) is rare. This is the case of a 54-year-old man on natazulimab for MS who developed rapid neurocognitive changes along with visual changes, imbalance issues, and mood changes. Diagnosis of sporadic CJD (sCJD) was confirmed through clinical features, physical examination and electroencephalogram findings, cerebral spinal fluid analysis, and later magnetic resonance imaging findings. sCJD with MS being a rare phenomenon, its recognition requires a high index of suspicion, careful chronological evaluation of the patient's symptoms, and relevant investigations that can aid in reaching the diagnosis.