neuropathology

Question 1

What are the 3 ways infections can get into the CNS?

Answer 1

Direct spread- eg middle ear infection, basilar skull fracture

Blood borne- sepsis, infective endocarditis

Iatrogenic- V-P shunt, surgery, lumbar puncture.

Question 2

What is meningitis?

Answer 2

Inflammation of leptomeninges- which is pia and arachnoid. With or without septicaemia.

Is a form of acute inflammation. Histology will show lots of neutrophils.

Question 3

What organisms most commonly cause meningitis in neonates?

Answer 3

E coli, Listeria monocytogenes

Question 4

Which organisms commonly cause meningitis in 2-5 year olds?

Answer 4

H. Influenzae type B

Question 5

Which organisms commonly cause meningitis in 5-30 year olds?

Answer 5

N meningitides

Question 6

Which organisms commonly cause meningitis in 30 y +?

Answer 6

S pneumoniae

Question 7

Which organism is chronic meningitis commonly caused by?

What are the key features of this disease?

Answer 7

M. Tuberculosis
Granulomatous inflammation
Fibrosis of meninges
Nerve entrapment

Question 8

What complications can arise from meningitis?

Answer 8

Local- death due to raised ICP
Cerebral infarction—> neurological deficit
Cerebral abcess
Subdural empyema
Epilepsy

Systemic- rashes, shock

Question 9

What is encephalitis?

What is it caused by?

What are the characteristics of the disease?

Answer 9

Inflammation of the parenchyma of the brain.

Classically caused by viruses.
Eg temporal lobe- herpes virus
Spinal cord motor lesions- polio
Brain stem- rabies

Disease is characterised by neuronal cell death forming inclusion bodies, yielding lymphocytic inflammatory reaction.

Question 10

What causes prion disease?

Answer 10

Mutated prion proteins which are a normal constituent of the synapse.

These mutated proteins interact with normal prion proteins and cause them to become mutated.

This causes aggregations in cells which causes neuronal death causing a spongiform ecephalopathy.

Question 11

What are examples of ingested prion diseases?

Answer 11

Scrapie in sheep
BSE in cows
Kuru in tribes of new guinea
Variant creutzfeld jacob disease

Question 12

What is dementia?

Answer 12

An acquired global impairment of intellect, reason and personality without impairment of consciousness.

Question 13

What type of dementia is most common?

When does it present?

Answer 13

Alzheimers disease

50-70 yrs old.

Question 14

What is the pathophysiology of alzheimers disease?

Answer 14

Loss of cortical neurones causing cortical atrophy. This is due to increased neuronal damage from neurofibrillary tangles of tau protein (which is a normal constituent of cell) and senile plaques ( foci of enlarged axons, synaptic terminals and dendrites- amyloid deposition)

Question 15

Which genetic condition can predispose to alzheimers disease?

Answer 15

Trisomy 21

Question 16

What is normal intracranial pressure?

Answer 16

0-10mmHg. Coughing and straining cause it to raise to 20mmHg.

Question 17

What compensatory mechanisms do we have to reduce ICP?

Answer 17

Reduce blood volume
Reduce CSF volume
Spatial- brain atrophy

Question 18

How is blood flow to the brain maintained in raised ICP?

Answer 18

Vascular mechanisms maintain cerebral blood flow as long as ICP < 60mmHg.

Question 19

What is a subfalcine herniation?

Answer 19

Cingulate gyrus is pushed under free edge of falx cerebri.

This causes ischaemia of medial parts of the frontal and parietal lobe and corpus callosum due to compression of anterior cerebral artery.

Question 20

What is a tentorial herniation?

Answer 20

Uncus/ medial part of parahippocampal gyrus is pushed through the tentorial notch.

This causes damage to the occulomotor nerve on the same side and occludes blood flow in the posterior cerebral and superior cerebellar arteries.

This is frequently fatal due to secondary haemorrhage into the brainstem.

Question 21

What is tonsilar herniation?

Answer 21

Cerebellar tonsils are pushed into the foramen magnum compressing the brainstem

Question 22

What is a common benign brain tumour?

Answer 22

Meningioma

Question 23

What are the most aggressive and malignant brain tumours?

Answer 23

Astrocytoma- spreads along nerve tracts and through sub arachnoid space

Question 24

What less common brain tumours can occur?

Answer 24

Neurofibroma
Ependyoma
Medulloblastoma
Lymphoma
Metastasis from other tissues (most common)