13) Neuropathology

Question 1

How can micro-organisms gain entry to the CNS?

Answer 1

Direct spread - middle ear infection, base of skull fracture
Blood borne - sepsis, endocarditis
Iatrogenic - V-P shunt, surgery, LP

Question 2

What is meningitis?

Answer 2

Inflammation of the leptomeninges (pia and arachnoid)

Question 3

What are some symptoms of meningitis?

Answer 3

Headache, photophobia, neck stiffness

Question 4

Why is a prompt diagnosis of meningitis needed?

Answer 4

Risk of sepsis and swelling of the brain

Question 5

What are the likely causative organisms of meningitis in neonates?

Answer 5

E. coli
L. monocytogenes
Group B strep

Question 6

What are the likely causative organisms of meningitis in 2-5 year olds?

Answer 6

H. influenzae type B (vaccine against this now)

Question 7

What is the likely causative organism of meningitis in 5-30 year olds?

Answer 7

N. meningitidis

Question 8

What is the likely causative organism of meningitis in >30 year olds?

Answer 8

S. pneumoniae

Question 9

What is ‘chronic meningitis’?

Answer 9

Caused by M. tuberculosis, granulomatous inflammation causing fibrosis of meninges leading to cranial nerve entrapment

Question 10

What are some complications of meningitis?

Answer 10

Death - RICP
Cerebral infarction 
Cerebral abscess
Subdural empyema
Epilepsy

Question 11

What is encephalitis?

Answer 11

Usually a viral infection affecting brain parenchyma

Question 12

List some viruses that can infect the brain:

Answer 12

Herpes virus
Polio
Cytomegalovirus
Rabies

Question 13

What are prions?

Answer 13

Infectious agents composed entirely of protein material that can fold in multiple ways that are transmissible to other prion proteins

Question 14

What are the normal and mutated forms of prions?

Answer 14

Normal is PrPc

Mutated or diseased is PrPsc

Question 15

How do mutated prions cause neuronal death?

Answer 15

Interact with normal prions to undergo post translational conformational changes. Build up of protein causes death of the neurone

Question 16

What is the name given to prion diseases in the brain? Give some examples.

Answer 16

Spongiform encephalopathies

Scrapie, Kuru, variant Creutzfeld-Jacob disease

Question 17

What is dementia?

Answer 17

Acquired global impairment of intellect, reason and personality without impairment of consciousness

Question 18

Name some types of dementia:

Answer 18

Alzheimer’s, vascular, Lewy body, Pick’s disease

Question 19

What is the mechanism behind Alzheimer’s disease?

Answer 19

Exaggerated ageing process causing loss of cortical neurones due to neuronal damage by neurofibrillary tangels and senile plaques

Question 20

What are neurofibrillary tangles?

Answer 20

Intracelullar twisted filaments of Tau proteins which can’t be metabolised

Question 21

What are senile plaques?

Answer 21

Foci of enlarged axons, synaptic terminals and dendrites. Amyloid deposition in vessels at centre of the plaque

Question 22

What condition is linked to early onset Alzheimer’s disease?

Answer 22

Down’s syndrome

Question 23

What mutations on chromosome 21 predispose to Alzheimer’s?

Answer 23

Amyloid pre-cursor protein gene

Presenilin genes 1+2

Question 24

What is normal intracranial pressure?

Answer 24

0-10mmHg

Question 25

What are some compensation mechanisms against raised ICP?

Answer 25

Reduced blood pressure Reduced CSF volume Brain atrophy

Question 26

What is Cushing's reflex?

Answer 26

Increased systolic pressure, decreased HR and irregular respiration

Question 27

What is a subfalcine herniation?

Answer 27

Cingulate gyrus pushed under free edge of falx cerebri on same side as mass

Question 28

What are the complications of a subfalcine herniation?

Answer 28

Causes compression of ACA so can lead to ischemia in medial frontal and parietal lobes and corpus callosum

Question 29

What is a tentorial herniation?

Answer 29

Uncus herniates through the tentorial notch

Question 30

What are the complications of a tentorial herniation?

Answer 30

Damages oculomotor nerve on same side and occlusion of blood flow in posterior cerebral and superior cerebellar arteries

Question 31

What is Duret's haemorrhage?

Answer 31

Secondary haemorrhage into brainstem after downward displacement of brainstem

Question 32

What is a tonsillar herniation?

Answer 32

Cerebellar tonsils pushed into foramen magnum, compressing brainstem

Question 33

What are some benign tumours of the brain?

Answer 33

Meningioma, schwannoma, pituitary adenoma

Question 34

What are some malignant tumours of the brain?

Answer 34

``` Astrocytoma Neurofibromas Ependymoma Medulloblastoma Lymphoma Metastasis ```

Question 35

How does an astrocytoma spread, and therefore often present?

Answer 35

Spread along nerve tracts and through sub-arachnoid space | Often presents with spinal secondary

Question 36

What is a stroke?

Answer 36

Sudden event producing a disturbance of CNS function due to vascular disease

Question 37

What are the types of stroke?

Answer 37

``` Cerebral infarction (85%) Cerebral haemorrhage (15%) ```

Question 38

What are some risk factors for stroke?

Answer 38

Hyperlipidemia Hypertension Diabetes

Question 39

What is the pathogenesis of a cerebral infarction?

Answer 39

Usually from embolism: heart (AF), carotid atheroma, aneurysm or from thrombus

Question 40

What is the pathogenesis of a cerebral haemorrhage?

Answer 40

Spontaneous: abnormal or friable vessels | Associated with hypertensive vessel disease

Question 41

What is the cause of a sub-arachnoid haemorrhage?

Answer 41

Rupture of berry aneurysm

Question 42

What are the risk factors for a subarachnoid haemorrhage?

Answer 42

Male, hypertensive, atheroma

Question 43

What are the symptoms of a subarachnoid haemorrhage?

Answer 43

Sudden severe headaches, sentinel headache (builds up), loss of consciousness