Fatal insomnia

Fatal insomnia is a rare, invariably fatal neurodegenerative disease and prion disease characterized by progressive and unrelenting insomnia, autonomic dysfunction, and rapid cognitive decline. The condition is classified into two distinct forms based on its underlying etiology. The vast majority of diagnoses are hereditary cases known as fatal familial insomnia (FFI), which stem directly from a dominant mutation in the PRNP gene. The remaining minority of cases occur sporadically without any underlying genetic mutation, a variant recognized clinically as sporadic fatal insomnia (sFI). The hallmark symptom of fatal insomnia is profound trouble sleeping, which typically begins as a gradual disruption of the sleep cycle but worsens relentlessly over time. Eventually, affected patients enter a permanent state of complete sleep inability clinically termed agrypnia excitata. This profound state of sustained wakefulness and sleep deprivation leads directly to other severe neurological symptoms, including speech problems, impaired motor coordination, and rapidly advancing dementia. The disease is universally fatal, typically resulting in the patient's death within a few months to a few years following the onset of symptoms, and there is currently no known disease-modifying treatment available in modern medicine.