Neuropathology

Question 1

By what routes can MO gain entry into the CNS?

Answer 1

Direct spread = middle ear infection, base of skull fracture

Blood-borne = sepsis, infective endocarditis

Iatrogenic = V-P shunt, surgery, lumbar puncture

Question 2

What is meningitis?

Answer 2

Inflam of the leptomeninges – 2 inner layers

With/without septicaemia

Prompt diagnosis and treatment is life saving

Question 3

What organisms can cause meningitis?

Answer 3

Neonates – E. Coli, Listeria. monocytogenes

2 -5 years – H. influenzae type B (HiB)

5 -30 years – N. Meningitides (types)

Over 30 years – S. pneumoniae

Question 4

Describe chronic meningitis

Answer 4

M. Tuberculosis of the meninges

Granulomatous inflam

Fibrosis of meninges

Nerve entrapment – present with cranial N palseys

Question 5

Outline the complications of meningitis

Answer 5

Death – swelling = RICP

Cerebral Infarction = neurological deficit

Cerebral abscess

Subdural empyema = diff to treat as no direct blood supply so need to go into surgery

Epilepsy

Systemic = rashes

Question 6

What is encephalitis?

Answer 6

Brain tissue itself is infected - classically viral

Neuronal death – inclusion bodies

Temporal lobe = herpes virus

Spinal cord motor neurones = polio

Brainstem = rabies

Question 7

What is a prion?

Answer 7

Protein present in synapses

Question 8

What is prion disease?

Answer 8

Sporadic mutation – abnormal protein development

Genetic - produce abnormal protein

Become ingested

Normal prions interact with abnormal prions = all become abnormal prions = aggregation = cell death

Question 9

What is vCJD?

Answer 9

Variant Cretzfeld-Jacob disease

Causes prion disease

Question 10

Define dementia

Answer 10

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

Question 11

What types of dementia are there?

Answer 11

Alzheimer’s (50%) – Sporadic/Familial, Early/Late

Vascular dementia (20%) = neurones undergo ischaemic damage

Lewy body

Picks disease

Question 12

What is Alzheimer’s disease?

Answer 12

Loss of cortical neurones at an increased rate = decreased brain weight

Neuronal damage = neurofibrillary tangles of hyperphosphorylated Tau, senile plaques

Question 13

What mechanisms maintain normal pressure inside the skull?

Answer 13

Reduced blood volume

Reduced CSF volume

Spatial - brain atrophy

Question 14

Outline the cushing reflex

Answer 14

When ICP raises

The systemic circulation = hypertension in order to delivery enough blood to the brain

Low HR, low RR

May indicate imminent brain herniation

Question 15

What are space occupying lesions?

Answer 15

Oedema

Tumour

Question 16

What can result from space occupying lesions?

Answer 16

Deformation or destruction of the brain around the lesion

Displacement of midline structures – loss of symmetry

Brain shift resulting in internal herniation

Question 17

Outline a subfalcine herniation

Answer 17

Same side as mass

Cingulate gyrus pushed under free edge of the falx cerebri

Ischaemia of medial parts of frontal/parietal lobe and corpus callosum due to compression of anterior cerebral artery = Infarction

Question 18

Outline a tentorial herniation

Answer 18

Uncus/medial part of the parahippocampal gyrus through the tentorial notch

Damage to occulomotor N on same side (clinical sign)

Occlusion of blood flow in posterior cerebral and superior cerebellar arteries

Question 19

Online a tonsilar herniation

Answer 19

Cerebellar tonsils pushed into the foramen magnum compressing the brainstem

Question 20

Why are tumours in the brain rare?

Answer 20

As cells in the brain don’t divide

Question 21

What types of tumours within the skull can occur?

Answer 21

Meningeal = meningioma (benign)

Astrocyte = astrocytoma

Neurofibroma

Ependymoma

Neuronal = medulloblastoma

Most common = metastasis

Question 22

How can stroke be categorised?

Answer 22

Infarction = 85%, regional or lacuna (less than 1cm, commonly in the basal ganglia)

Haemorrhage = 15%, intracerebral (hypertensive vessel damage) or subarachnoid (ruptured berry aneurysms)

Question 23

What are the risk factors for stroke?

Answer 23

Hyperlipidaemia

Hypertension

DM

Vascular disease

Question 24

Outline the pathogenesis of stroke

Answer 24

Embolism = most common, AT, carotid atheroma, aneurysm

Thrombosis = atheromatous plaque