S8) Neuropathology Flashcards Preview

(LUSUMA) Clinical Neuroscience > S8) Neuropathology > Flashcards

Flashcards in S8) Neuropathology Deck (36)
Loading flashcards...
1
Q

The CNS is normally sterile. However, microorganisms gain entry by 3 possible routes.

Identify them

A
  • Direct spread e.g. middle ear infection, base of skull fracture
  • Blood-borne e.g. sepsis, infective endocarditis
  • Iatrogenic e.g. ventricular-peritoneal shunt, surgery, lumbar puncture
2
Q

What is meningitis?

A
  • Meningitis is the inflammation of the leptomeninges, with/without septicaemia
  • Prompt diagnosis and treatment is life saving
3
Q

What are the causative organisms of meningitis in patients of various ages?

A
  • Neonates – E. Coli, L. monocytogenes
  • 2 - 5 years – H. influenzae type B (HiB)
  • 5 - 30 years – N. Meningitides (types)
  • Over 30 years – S. pneumoniae
4
Q

Describe, in three steps, how chronic meningitis might occur

A

M. tuberculosis:

⇒ Granulomatous inflammation

⇒ Fibrosis of meninges

⇒ Nerve entrapment

5
Q

Identify five complications of meningitis

A
  • Death (swelling → RICP)
  • Cerebral Infarction → neurological deficit
  • Cerebral abscess
  • Subdural empyema
  • Epilepsy
6
Q

What is encephalitis?

A
  • Encephalitis is the classically viral inflammation of the brain parenchyma due to infection
  • Neuronal cell death by virus occurs, with the inclusion bodies
7
Q

Identify the causative organisms for encephalitis in the following areas:

  • Temporal lobe
  • Spinal cord motor neurons
  • Brain stem
A
  • Temporal lobe e.g. herpes virus
  • Spinal cord motor neurons e.g. polio
  • Brain stem e.g. rabies
8
Q

How might mutated prion proteins enter the body?

A
  • Sporadic mutation
  • Familial mutation
  • Ingested
9
Q

What is the effect of the mutated PrP on the body?

A

Mutated PrP interacts with normal PrP to undergo a post translational conformational change

10
Q

What occurs in prion disease?

A

PrPSC aggregates leading to neuronal death and holes in grey matter

11
Q

What is dementia?

A

Dementia is the acquired global impairment of intellect, reason and personality without impairment of consciousnes

12
Q

Identify four common forms of dementia

A
  • Alzheimer’s (50%)
  • Vascular dementia (20%)
  • Lewy body
  • Picks disease
13
Q

Describe some defining features of Alzheimer’s Disease

A

Exaggerated aging process due to:

  • Loss of cortical neurones – ↓ brain weight, cortical atrophy
  • neuronal damage – neurofibrillary tangles, senile plaques
14
Q

In three steps, describe how neuronal damage occurs in AD due to neurofibrillary tangles

A

⇒ Intracellular twisted filaments of Tau protein

⇒ Tau normally binds and stabilises microtubules

⇒ Tau becomes hyperphosphorylated in AD

15
Q

In two steps, describe how neuronal damage occurs in AD due to senile plaques

A

⇒ Foci of enlarged axons, synaptic terminals and dendrites

Amyloid deposition in vessels in centre of plaque

16
Q

In Down’s syndrome, there is early onset AD.

Explain why

A
  • Mutations of 3 genes on chromosome 21:

I. Amyloid precusor protein (APP) gene,

II. Presenilin (PS) genes 1 and 2 code for components of secretase enzyme

  • Leads to incomplete breakdown of APP and amyloid is deposited
17
Q

What is the value for normal intracranial pressure?

A

0 - 10mmHg

18
Q

Which physiological mechanisms increase ICP?

A

Coughing and straining increase ICP to 20 mmHG

19
Q

Identify the three compensation mechanisms that maintain normal pressure

A
  • Reduced blood volume
  • Reduced CSF volume
  • Spatial – brain atrophy
20
Q

How are vascular mechanisms affected by ICP?

A

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

21
Q

State the three effects of an expanding lesion in the brain

A
  • Deformation/destruction of the brain around the lesion
  • Displacement of midline structures – loss of symmetry
  • Brain shift resulting in internal herniation
22
Q

What occurs in a subfalcine herniation?

A
  • In a subfalcine herniation, the cingulate gyrus is pushed under the free edge of the falx cerebri
  • Ischaemia of medial parts of frontal lobe, parietal lobe and corpus callosum due to compression of anterior cerebral artery → infarction
23
Q

What occurs in a tentorial herniation?

A
  • In a tentorial herniation, the uncus / medial part of the parahippocampal gyrus herniates through the tentorial notch
  • Ipsilateral occulomotor nerve damage and occlusion of posterior cerebral and superior cerebellar arteries
  • Often fatal due to secondary haemorrhage into the brainstem (duret haemorrhage)
24
Q

What occurs in a tonsillar herniation?

A

In a tonsillar herniation, the cerebellar tonsils are pushed into the foramen magnum compressing the brainstem

25
Q

CNS tumours are very rare.

Regardless, identify some

A
  • Benign – meningioma
  • Malignant – astrocytoma
  • Others – neurofibroma, ependymoma, neuronal e.g. medulloblastoma
26
Q

What is a stroke?

A

A stroke is a sudden event producing a disturbance of CNS function due to vascular disease

27
Q

What are the two broad categories of strokes?

A
  • Cerebral infarction (85%)
  • Cerebral haemorrhage (15%)
28
Q

Identify three risk factors for stroke

A
  • Hyperlipidaemia
  • Hypertension
  • Diabetes mellitus
29
Q

Describe the pathogenesis of a stroke from an embolism (most common)

A
  • Heart – atrial fibrillation, mural thrombus
  • Atheromatous debris (carotid atheroma)
  • Thrombus over ruptured atheromatous plaque
  • Aneurysm
30
Q

Describe the pathogenesis of a stroke from a thrombosis

A

Thrombosis – over atheromatous plaque

31
Q

Identify and describe two types of infarct in the brain

A
  • Regional – named cerebral artery or carotid
  • Lacuna – Associated with hypertension (commonly affect the basal ganglia)
32
Q

What are the two types of intracerebral haemorrhages?

A
  • Intracerebral haemorrhage (10% of all strokes)
  • Subarachnoid haemorrhage (5% of all strokes)
33
Q

Describe the occurrence of intracerebral haemorrhages

A
  • Associated with hypertensive vessel damage
  • Deposition of amyloid around cerebral vessels in the elderly
  • Produces space occupying lesion
34
Q

Describe how a subarachnoid haemorrhage usually presents

A
  • Sudden severe headache
  • Loss of consciousness
  • Often instantly fatal
35
Q

Describe the pathogenesis of subarachnoid haemorrhages

A

Pathogenesis poorly understood:

  • Male sex
  • Hypertension
  • Atheroma
  • Links to other diseases
36
Q

What causes a subarachnoid haemorrhage?

A

A subarachnoid haemorrhage is caused by the rupture of ‘berry’ aneurysms