Rapidly progressing dementias

Dementias which progress from normal cognition to severe dementia in less than 2 years (unofficial definition) (Salardini 2019).

• In addition to cognitive decline, they often have behavioral problems, pyramidal or extrapyramidal symptoms, EEG changes, and myoclonus.

Categories (Salardini 2019)

1. Prion disease – misfolded prions are infectious proteins which cause devastating neurodegenerative illness
   1. Creutzfeldt-Jakob disease (CJD)
      1. Most common form of prion disease
      2. Presents with cognitive symptoms, pyramidal / extrapyramidal motor symptoms, ataxia, myoclonus, and psychiatric symptoms
   2. Fatal familial insomnia (FFI)
      1. Presents with insomnia, dysautonomia, cognitive problems
   3. Gerstmann-Straussler-Schinker syndrome (GSS)
      1. Cerebellar and/or extrapyramidal symptoms
      2. Slow progression over 10-20 years
   4. Kuru
   5. Variant CJD
      1. Caused by eating contaminated meat of livestock with bovine spongiform encephalopathy
2. Atypical presentation of other primary dementias
3. Autoimmune diseases including autoimmune encephalitis
4. Secondary encephalopathies (toxic metabolic encephalopathy)

Imaging

DWI images of 2 patients with suspected CJD (Salardini 2019)

• In axial view of patient A there is characteristic increased cortical signal (cortical ribboning) suggesting cortical cytotoxic edema
• In axial view of patient B there is characteristic increased signal in caudate and mesial thalamus (hockey stick)

References

Salardini, A. An Overview of Primary Dementias as Clinicopathological Entities. Semin. Neurol. 39, 153–166 (2019). https://pubmed.ncbi.nlm.nih.gov/30925609/