Neuropathology

Question 1

Briefly describe how microorganisms can gain entry to the CNS

Answer 1

Direct spread- skull fracture, middle ear infection
Blood bourne- sepsis compromising BBB, infective endocarditis through blood supply to brain
Iatrogenic

Question 2

Briefly describe meningitis

Answer 2

Inflammation of leptomeninges

Question 3

Briefly describe causes of meningitis

Answer 3

E. Coli, monocytogenes- neonates
H.influenzae type B- 2-5 yrs
N. Meningitides- 5-30 yrs
S. Pneumonia- >30 yrs

Question 4

Briefly describe chronic meningitis and causes

Answer 4

M. Tuberculosis
Granulomatous inflammation
Fibrosis of meninges
Nerve entrapment

Question 5

Briefly describe complications of meningitis

Answer 5

Swelling, raised intracranial pressure and death
Cerebral infarction
Cerebral abscess
Subdural empyema
Epilepsy

Question 6

Briefly describe encephalitis

Answer 6

Inflammation of parenchyma
Virus causes neuronal cell death
Lymphocytic inflammatory reaction
Usually self limiting

Question 7

Briefly describe causes of encephalitis in different areas of the brain

Answer 7

Herpes virus- temporal lobe
Polio- spinal cord motor neurones
Rabies- brain stem

Question 8

What’s a prion?

Answer 8

Protein in the synapse

Question 9

How can prion proteins be mutated?

Answer 9

Sporadic mutation
Familial disposition
Ingested mutated prion

Question 10

Briefly describe what a mutated prion protein does

Answer 10

Interacts with normal prions causing them to undergo a post translational conformational change.
Causes cell death and holes in grey matter.
Called spongiform encephalopathies.

Question 11

Briefly describe what happens in Alzheimer’s disease

Answer 11

Exaggerated ageing process (oxidative damage etc)
Loss of cortical neurones
Neurofibrillary tangles and senile plaques form

Question 12

Briefly describe neurofibrillary tangles

Answer 12

Twisted filaments of tau protein
Tau protein normally stabilises microtubules
Tau protein becomes hyperphosphorylated and more insoluble

Question 13

Briefly describe senile plagues

Answer 13

Axons and dendrites fuse together.

Amyloid deposits build in blood vessels.

Question 14

Briefly describe a genetic predisposition to Alzheimer’s disease

Answer 14

Down’s syndrome
Trisomy 21
Early onset AD
Amyloid precursor protein and other enzymes involved in amyloid breakdown are found on chromosome 21, which leads to incomplete breakdown of APP and amyloid, causing amyloid to be deposited.

Question 15

Briefly describe compensation mechanisms when ICP increases

Answer 15

Reduced blood volume
Reduced CSF volume
Brain atrophy