Pathology of the CNS 1

Question 1

Why do the differential diagnoses for dementia include metabolic diseases such as vitamin B12 and folate deficiencies?

Answer 1

These deficiencies can also present as dementia

Question 2

What areas are tested in a neuropsychology test?

Answer 2

Episodic memory
Generative fluency; eg: how many animals can you name in 60 sec?
Recognition memory (false +ves)
Speeded executive function
Recognition memory (true +ves)
Visuospatial episodic memory
Visuospatial learning

Question 3

What changes can be seen in an MRI in dementia?

Answer 3

Decreased frontotemporal size
Expanded ventricle size
General cerebral atrophy

Question 4

Do cognitive deficits and MRI changes always correlate in dementia?

Answer 4

No, you can have significant cognitive problems without MRI changes

Question 5

What does a Pittsburgh B scan show?

Answer 5

Lighting up of amyloid

Not routine scan > confirms diagnosis of Alzheimer’s

Question 6

What is dementia?

Answer 6

Clinical syndrome of global impairment of higher cortical functions
- Memory
- Reason
- Personality, including social skills
In absence of gross clouding of consciousness

Question 7

What proportion of dementia is due to Alzheimer’s disease?

Answer 7

75%

Question 8

What are the main causes of dementia?

Answer 8

Alzheimer's disease
Vascular dementia
Lewy body dementia
Fronto-temporal (Pick's) dementia
Genetic
- Huntington's disease
Infective
- Creutzfeldt-Jakob disease
- HIV
Other
- Alcohol/drug abuse
- Repeated head trauma
- Parkinson's disease

Question 9

What are the risk factors for Alzheimer’s disease?

Answer 9

Age
Genetic predisposition
- 1st degree relative with Alzheimer's
Down's syndrome
Vascular risk factors
Decreased physical/cognitive activity
Depression
Loneliness
Smoking

Question 10

What are the histological abnormalities seen in Alzheimer’s disease?

Answer 10

Amyloid deposition

Loss of neurons and tissue

Question 11

From what normal protein is amyloid in Alzheimer’s disease derived?

Answer 11

Amyloid precursor protein (APP)

Question 12

What parts of the brain are predominantly involved in Alzheimer’s disease?

Answer 12

Frontal and temporal lobes

Question 13

What proportion of strokes are due to an infarct, and what proportion are due to a haemorrhage?

Answer 13

Infarct = 80%
Haemorrhage = 20%

Question 14

What are the causes of an arterial occlusion?

Answer 14

Thrombotic
Embolic
Dissection

Question 15

What are the causes of a venous occlusion?

Answer 15

Thrombotic
Torsion
Strangulation

Question 16

What does an occlusion in a vessel lead to in the tissue it supplies?

Answer 16

Reduction in tissue perfusion

Question 17

What are the investigations for an acute meningitis syndrome?

Answer 17

CT scan - exclude intracranial lesion/hydrocephalus
Lumbar puncture
- CSF microscopy, including Gram and India ink stains
- Culture
- Sensitivity
- Cell count
- Differential of WBCs
- Protein
- Glucose
- Cryptococcal Ag
- Herpes virus multiplex PCR

Question 18

What is an India ink stain usually used for when testing the CSF?

Answer 18

ID of cryptococcal meningitis

Question 19

What are the potential complications of acute bacterial meningitis and what is their pathogenesis?

Answer 19

Death due to raised ICP and herniation
Permanent neurological deficits
Septicaemia

Question 20

What does the revised McDonald criteria for the diagnosis of multiple sclerosis require?

Answer 20

1+ episode of demyelination/objective evidence of >1 lesion on MRI