Pathology of the Brain Flashcards

1
Q

What commensal bacteria is normally found in the central nervous system?

A

NONE

CNS is normally sterile!

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2
Q

How can microorganisms gain entry the CNS?

A

Direct Spread

middle ear infection / basal skull #
(photo shows abcess from middle ear inf)

Haematogenous Spread

sepsis / infective endocarditis

Iatrogenic

V-P shunt / lumbar puncture

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3
Q

What are the leptomeningies and how are they affected in meningitis?

A

inner two meningeal layers
(arachnoid and pia mater)

inflammed in meningitis with collection of pus (neutrophil infiltration)

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4
Q

Patients with meningitis must always have a non-blanching rash?

TRUE / FALSE

A

FALSE

meningitis can exist with or without a septicaemia (causing a non-blanching rash)

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5
Q

What are the common causative organisms of meningitis in the following age groups:

Neonates

2-5 Years (toddlers)

5-30 Years (adolescents)

Over 30 Years (older adult)

A

Neonates

  • E. coli

2-5 Years (toddlers)

  • H. influenzae type B (HiB)

5-30 Years (adolescents)

  • N. meningitidis (gm -ve diplococci, intracellular)

Over 30 Years (older adult)

  • S. pneumoniae
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6
Q

Why may patients with chronic meningitis caused by TB present with cranial nerve palsies?

A

TB causes granulomatous inflammation

meningies become fibrosed/scarred

cranial nerves become compressed as they exit the foramina

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7
Q

What are 3 potential complications of meningitis?

A

Death

Raised ICP

Cerebral Infarction

Cerebral Abscess

Subdural Empyema

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8
Q

What pathogen commonly causes encephalitis?

A

Viruses

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9
Q

What is the underlying pathology in encephalitis?

A

disease of brain parenchyma
(not meningies)

neuroncal cell death cause by virus replication and cell rupture

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10
Q

How may a patient present with encephalitis?

A

Headache

Nausea and Vomiting

Confusion

Seizures

Neurological Deficit

Altered Level of Consciousness

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11
Q

What is a prion?

A

a protein

normal constituent of synapse with unclear function

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12
Q

How do mutated prions cause disease and how can they get into the body?

A

mutated prions can occur via 3 mechanisms:

  1. sporadic mutation
  2. familial inheritance
  3. ingested

mutated prions interact with normal prions and cause a post translational conformational change

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13
Q

What is the effect of the post translational conformational change that occurs following fusion of a prion with a mutated prion?

A

aggregations form within neuronal cells that lead to cell death

holes appear in grey matter of the brain

(spongiform encephalopathies - due to appearance)

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14
Q

Give two examples of prion disease

A

BSE
in Cows

Variant Creutzfeld-Jacob Disease (vCJD)
in humans

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15
Q

Provide a definition of dementia

A

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

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16
Q

Give two examples of types dementia

A

Alzheimer’s Dementia

Vascular Dementia

Lewy Body Dementia

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17
Q

Outline the role of Tau proteins in Alzheimer’s disease

A

loss of cortical neurones due to abnormally phosphorylated tau proteins that would normally stabalise microtubules in neurones

abnormal tau aggregates to form collections witin neurones > then unable to function and die

18
Q

What are senile plaques seen on histological sample of patients with Alzheimer’s disease?

A

plaques around neurones, formed of aggregated amyloid protein

19
Q

Other than Tau protein, name another protein that can build up in cells and vessels that contributes to Alzheimer’s disease

A

Amyloid

due to abnormal mutations on 3 genes on chromosome 21

20
Q

What is the normal range for intracranial pressure?

A

0 - 10mmHg

21
Q

How can the body’s normal physiological responses help to reduce ICP?

A

Reduced Blood Flow/Volume to Brain
(can compensate up to an ICP <60mmHg)

Reduced CSF Volume

Brain Atrophy
(longer term)

22
Q

What is Cushing’s reflex?

A

Significant Hypertension

&

Reflex Bradycardia
(due to compression of medulla)

all in response to a rising ICP > in an attempt to maintain perfusion

23
Q

What are 3 potential anatomical effects of a space occupying lesion in the skull?

A

displacement of midline structures

deformation or destruction of brain around lesion

internal herniation

24
Q

What is a subfalcine herniation?

A

cingulate gyrus pushed under the free edge of the falx cerebri

causes ischaemia of medial parts of brain in frontal and parietal lobe

25
Q

Which cerebral artery is typically damaged in a subfalcine herniation?

A

Anterior Cerebral Artery

26
Q

Which area of the brain moves significantly during a tentorial herniation?

A

uncus/medial part of parahippocampal gyrus moves over the tentorial notch

27
Q

Which strucutres are at signifcant risk with a tentorial herniation?

A

occulomotor nerve (CN III)

posterior cerebral and superior cerebellar arteries

28
Q

What is a Duret haemorrhage that frequently occurs with a tentorial herniation?

A

secondary haemorrhage into the brainstem (midbrain/pons)

29
Q

What is a tonsillar herniaton?

A

cerebellar tonsils are pushed into the foramen magnum > compressing the brianstem

30
Q

Why are primary brain tumours rare in adults?

A

CNS contains permenant tissue > therefore as it does not divide, tumours do not commonly occur

(this is not the case in children due to growth and development)

31
Q

Is a meningioma a malignant or benign neoplasm?

A

Benign

32
Q

Which supporting cells in the CNS commonly cause malignant neoplasms?

A

Astrocytes

(cause astrocytomas)

33
Q

What is the most common cause of malignany neoplasms in the CNS?

A

metastasis

commonly from colon or lung

34
Q

What are the two broad classifications of stroke?

A

Cerebral Infarction (ischameic)

Cerebral Haemorrhage

35
Q

What common risk factors are shared between stroke and MI, and why?

A

common risk factors as both are vascular diseases

Hyperlipidaemia

Hypertension

Diabetes

Male

36
Q

What are 2 pathological processes that can lead to an interupted blood supply to the brain and cause stroke?

A

Embolism
(mural thrombus, atrial fibrillation)

Thrombosis
(forming over an atheromatous plaque in carotid arteries)

e.g. thrombus occuring in basilar artery

37
Q

Within which 2 locations can a cerebral haemorrage cause stroke?

A

Intracerebral Haemorrhage

Subarachnoid Haemorrahe

38
Q

What condition prediposes patients to intracerebral haemorrhages?

A

Hypertension
(hypertensive vessel damage)

Deposition of Amyloid
(cause vessels walls to become weakened)

39
Q

What is the common source of bleeding in a subarachnoid haemorrhage?

A

rupture of ‘berry’ aneurysms

found at branching points of the Circle of Willis

40
Q

How many a patient present with a subarachnoid haemorrhage?

A

DEATH

Thunderclap Headache

Loss of Consciousness

Sentinal Headache
(worsening due to rising ICP/bleeding)