Fatal insomnia

Fatal insomnia
Cranial imaging of an FFI patient. In the MRI, there are abnormal signals in the bilateral frontoparietal subcortical area. MRA showed smaller distal branches of cerebral arteries.
Specialty	Neurology, Psychiatry, Sleep medicine, Neuropathology
Symptoms	Progressive insomnia, ataxia, double vision, weight loss, high blood pressure, excessive sweating
Complications	Permanent state of hypnagogia later in the illness
Usual onset	45–50 years old[1]
Types	Fatal familial insomnia, sporadic fatal insomnia[2]
Causes	Genetic mutation, sporadic form (very rare)
Risk factors	Family history
Diagnostic method	Suspected based on symptoms, supported by sleep study, PET scan and genetic testing (if familial form is suspected)[3]
Differential diagnosis	Alzheimer's disease, frontotemporal dementia, other transmissible spongiform encephalopathies[4]
Prevention	None
Treatment	Supportive care[2]
Medication	None
Prognosis	Invariably fatal
Frequency	70 families worldwide are known to carry the gene associated with the disease, 37 sporadic cases diagnosed (as of September 20th, 2022)
Deaths	<1 per year

Fatal insomnia is an extremely rare neurodegenerative prion disease that results in trouble sleeping as its hallmark symptom.^[2] The majority of cases are familial (fatal familial insomnia [FFI]), stemming from a mutation in the PRNP gene, with the remainder of cases occurring sporadically (sporadic fatal insomnia [sFI]). The problems with sleeping typically start out gradually and worsen over time.^[4] Eventually, the patient will succumb to total insomnia (agrypnia excitata), most often leading to other symptoms such as speech problems, coordination problems, and dementia.^[5] It results in death within a few months to a few years, and there is no known disease-modifying treatment.^[2]