Prion disease

Prion diseases are a group of rare, uniformly fatal neurodegenerative diseases. In humans they occur in three forms: sporadic (85% to 90% of cases), genetic (10% to 15%), and acquired (<1%).

Prions, or proteinaceous infectious particles, are the misshaped proteins responsible for causing transmissible spongiform encephalopathies, or prion diseases.

Present as very rapidly progressive dementias. Symptoms may vary, but include behavioural/psychiatric changes, memory impairment, visual disturbances, myoclonus, ataxia, language and hearing problems, and movement dysfunction.

Misdiagnosis is common, as Creutzfeldt-Jakob disease (CJD) can present similarly to other neurological conditions. Pathology currently is the only definitive way to diagnose prion disease, although biopsy and even autopsy may yield false-negative results.

Pre-mortem diagnostic tools that may be helpful include MRI, EEG, and CSF findings, as well as blood tests to rule out other conditions. Brain MRI, particularly diffusion-weighted imaging, has very high sensitivity and specificity for CJD, as does the real-time quaking-induced conversion (RT-QuIC) test on CSF.

Currently, there is no cure for prion disease, and treatment consists of symptomatic management and palliative care. Survival for most patients with sporadic prion disease is generally one year or less, whereas survival of patients with genetic prion disease varies greatly from a few months to several years, depending on the mutation.

Prion diseases (or transmissible spongiform encephalopathies) are a group of uniformly fatal neurodegenerative diseases characterised by progressive dementia and motor dysfunction. These diseases occur in spontaneous, genetic, and acquired forms. Patients commonly present with behavioural or personality changes, myoclonus, visual disturbances, movement problems, and/or incoordination. Survival from first symptom is typically <1 year in sporadic and acquired cases. Survival of patients with genetic prion disease varies greatly from a few months to several years, depending on the mutation.