This chapter speaks about an 82-year-old woman who was admitted with apparently sudden-onset neurological symptoms. On examination, this patient appeared well and comfortable. The patient's clinical evolution was characterized by a relentlessly progressive course over several weeks. The visual field defect expanded into a right homonymous hemianopia, and optic ataxia also developed on the left. Dysarthria and dysphagia worsened until she was dependent on tube feeding. The human prion diseases are a comparatively rare cause of dementia, with an estimated incidence of 1 case per million people per year, although some uncorroborated reports would place the true incidence much higher. Therapeutic options for all the human prion diseases are currently limited to palliation, as there are no agents capable of reliably causing a sustained improvement in clinical course. A large and diverse selection of drugs have been tried with limited success, including antivirals, antifungals, antibiotics, antimalarials, antidepressants, antioxidants, and analgesics.