Secondary causes of dementia

Question 1

Huntington’s disease dementia

Answer 1

• autosomna dominant
• CAG expansion
• on Huntingtin gene
• occurs in 4th decade with frontal dementia and movement disorder
• recall affected with problems with retrieval rather than encoding

Question 2

MS

Answer 2

• diagnosis confirmed using CSF examination and evoked potentials
• can cause dementia
• MRI is required

Question 3

Prion diseases

Answer 3

• PrP is normal protein coded for by the PRNP gene on chromosome 20
• prion diseases occur when the protein mutates and is insoluble
• causes spongiform encephalopathies
• 4 forms in humans:
  1. Kuru
  2. CJD
  3. Fatal familial insomnia
  4. Gerstmann Straussler syndrome

Question 4

Sporadic CJD

Answer 4

• 0.1/100,000
• CJD is the most common of the human prion diseases
• PrPsc is the protein
• this form is resistant to proteases and accumaltes
• 5th decade
• rapidly deteriorating dementia, myoclonus, cerebellar and EP signs leading to death within one year
• 85% are spontaneous or sporadic
• 10% from genetic mutation
• 5% from iatorgenic transmission
• CT shows atrophy of cortex and cerebellum

Question 5

MRI in sporadic CJD

Answer 5

• non-specific basal ganglia hyperintensities

- high signal changes in the putamen and caudate head

Question 6

EEG in sporadic CJD

Answer 6

• periodic complexes (periodic bi or triphasic discharges) against a low voltage background
• not seen in variant CJD

Question 7

CSF proteins in sporadic CJD

Answer 7

-14-3-3 protein is elevated

Question 8

Treatment of sporadicc CJD

Answer 8

• symptomatic
• sodium valproate and clonazepam may help reduce the severity of movement disorders
• diagnosis made post-mortem

Question 9

New variant CJD (vCJD)

Answer 9

• rise in vCJD followed and epidemic of bovine spongiform encephalopathy in cattle
• felt to originate from cattle feeds that contained CNS material from infected cows
• incubation period between the ingestion of contaminated meat and development of disease is less than 20 years

Question 10

vCJD

Answer 10

• affects mainly young men in their 20s
• anxiety, depressive symptoms, personality changes and then dementia
• 1-2 years to death

Question 11

Pulvinar sign

Answer 11

• diagnostic of v CJD

- seen on FLAIR sequence of MRI in 70% of confirmed cases of vCJD

Question 12

CSF proteins in vCJD

Answer 12

14-3-3 protein levels are elevated in CSF

Question 13

Tonsillar biopsy

Answer 13

-prion protein immunostaining is positive in lymphoid tissues- tonsils are used

Question 14

EEG

Answer 14

• no distinctive changes

- slow waves noted diffusely