Neuropathology 3 Flashcards

1
Q

If the brain enlarges (e.g due to an SOL), what must escape the cranial vault to avoid rise in pressure

A
  • CSF

* Blood

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2
Q

What does increased brain volume lead to?

A

Increased ICP

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3
Q

Suggest causes of raised ICP.

A
  • Increased CSF (hydrocephalus)
  • Focal lesion in brain (SOL)
  • Diffuse lesion in brain (e.g. oedema)
  • Increased venous volume
  • Physiological (hypoxia, hypercapnia, pain)
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4
Q

What is hydrocephalus?

A

An accumulation of excessive CSF with the ventricular system of the brain

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5
Q

What is CSF produced by?

A

Choroid plexus in the lateral and fourth ventricles of the brain

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6
Q

What is CSF absorbed by?

A

Arachnoid granulations

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7
Q

How much CSF is normal?

A

120-150ml

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8
Q

How much CSF would there be in hydrocephalus?

A

500ml

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9
Q

CSF fluid looks…

A

CLEAR

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10
Q

What does CSF contain?

A
Lymphocytes <4 cells/ml
Neutrophils 0 cells/ml
Protein <0.4g/l
Glucose >2.2mmol/l
No RBCs
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11
Q

What does CSF not contain?

A

RBC’s

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12
Q

What 3 things can hydrocephalus be due to?

A
  • Obstruction
  • Decreased resorption
  • Overproduction
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13
Q

What can cause obstruction to CSF?

A
  • Inflammation
  • Pus
  • Tumours
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14
Q

What can cause decreased resorption to CSF?

A
  • Post- SAH

* Meningitis

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15
Q

What causes an overproduction of CSF?

A

Tumours of the choroid plexus

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16
Q

Hydrocephalus can be either?

A

Communicating OR Non-communicating

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17
Q

In non-communicating hydrocephalus, where does the obstruction to flow of CSF occur?

A

Within the ventricular system and CANNOT exit

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18
Q

In communicating hydrocephalus, where does the obstruction to flow of CSF occur?

A

Goes outside of the ventricular system ie. in subarachnoid space, or at the arachnoid granulations
i.e it is communicating with something outwith the ventricular system

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19
Q

What happens if hydrocephalus occurs before closure of the cranial sutures?

A

Cranial enlargement

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20
Q

At what age does closure of the cranial sutures occur?

A

2-3 years old

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21
Q

What happens if hydrocephalus develops after the closure of the cranial sutures?

A

There is expansion of ventricles and increasing ICP

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22
Q

What is hydrocephalus ex vacuo?

A

Dilatation of the ventricular system, and a compensatory increase in CSF volume, secondary to a loss of brain parenchyma

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23
Q

In what condition would you see hydrocephalus ex vacuo? Why?

A

Alzheimer’s

- due to brain atrophy

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24
Q

What is ‘coning’?

A

Tonsillar herniation of the cerebellum into the foramen magnum

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25
Q

Why does coning occur?

A

Due to raised ICP

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26
Q

What 5 things occur due to raised ICP?

A
  • Intracranial shifts and herniations
  • Midline shifts
  • Distortion and pressure on cranial nerves and vital neurological centres
  • Impaired blood flow
  • Reduced level of consciousness
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27
Q

Name the 4 main types of herniations.

A

1 – Subfalcine
2 – Tentorial
3 – Cerebellar/Tonsillar
4 – Transcalvarial

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28
Q

Describe subfalcine herniations.

A

Displacement of the brain (typically the cingulate gyrus) beneath the free edge of the falx cerebri due to raised intracranial pressure

  • MOST COMMON
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29
Q

Describe cerebellar/tonsillar herniations.

A

Transforaminal herniation, or “coning”, the cerebellar tonsils move downward through the foramen magnum possibly causing compression of the lower brainstem and upper cervical spinal cord as they pass through the foramen magnum

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30
Q

What are the 4 main symptoms or raised ICP?

A
  • Papilloedema
  • N+V
  • Neck stiffness
  • Headache
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31
Q

What causes papilloedema?

A

Pressure on the optic disc

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32
Q

Describe the headache in raised ICP.

A

Worse when lying down, coughing, straining and sneezing

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33
Q

How does raised ICP cause N+V?

A

Pressure on vom centre in pons and medulla

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34
Q

How does raised ICP cause neck stiffness?

A

Pressure on the dura around the brainstem and cerebellum

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35
Q

Give examples of SOL’s.

A
  • Tumour (primary or mets)
  • Abscess
  • Haematoma
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36
Q

What are the common signs when a patient has a brain tumour?

A
  • Focal deficit

* Papilloedema

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37
Q

What are the common symptoms when a patient has a brain tumour?

A
  • Focal sx (68%).
  • Headache (54%)
  • Vomiting.
  • Seizures (26%).
  • Visual disturbances.
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38
Q

Why are headaches in relation to brain tumours worse in the morning?

A

We tend to become slightly hypercapneic, retaining CO2 while we sleep
This leads to increased blood flow, and a commensurate increases the size of the brain.
And as a result the headache can improve slightly as we blow off CO2

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39
Q

Where do 70% of brain tumours in children occur?

A

Below the tentorium cerebelli

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40
Q

Where do 70% of brain tumours in adults occur?

A

Above the tentorium cerebella

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41
Q

Where do 70% of brain tumours in adults occur?

A

Above the tentorium cerebelli

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42
Q

What are the commonest cancers to metastasise to the brain?

A

Breast, bronchus, kidney, thyroid and colon carcinomas

Malignant melanomas

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43
Q

Where are brain mets most often seen?

A

At the boundaries between grey and white matter

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44
Q

What is the most common brain tumour in adults?

A

Astrocytoma

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45
Q

What is the most common benign brain tumours in adults?

A

Meningioma

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46
Q

What can some high grade tumours secrete? What does this lead to?

A

VEGF

Increased vascularity

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47
Q

What is the most common brain tumour in children?

A

Pilocytic astrocytomas

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48
Q

What is the 2nd most common brain tumour in children?

A

Medulloblastoma

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49
Q

Describe the cells in medulloblastoma.

A

Poorly differentiated/embryonal (look like primitive undifferentiated embryonal cells).

50
Q

Where do medulloblastomas occur?

A

In the midline of the cerebellum

51
Q

What is the prognosis of a medulloblastoma if untreated?

A

AWFUL

52
Q

A medulloblastoma is very ___________

A

RADIOSENSITIVE

53
Q

Where can a medullablastoma occupy?

A

4th ventricle

54
Q

What are the 2 main ways in which a brain abscess can arise?

A
  • Local extension e.g mastoiditis

* Direct implantation e.g skull fracture

55
Q

Where do single brain abscesses tend to occur?

A

Adjacent to the brain

56
Q

How do multiple abscesses arise?

A

Due to haematogenous spread ie. bronchopneumonia, bacterial endocarditis., lung abscess, left to right shunt of the heart, PWID

57
Q

Where do multiple abscesses tend to arise?

A

At the grey and white matter boundary

58
Q

What symptoms are associated with abscesses?

A
  • Fever
  • Raised ICP
  • Symptoms of underlying cause
59
Q

How are abscesses diagnosed?

A

CT or MRI

60
Q

What kind of lesions do abscess appear as on CT/MRI?

A

ENHANCING

61
Q

Aside from CT and MRI, what other investigations are done?

A

Aspiration - for culture and treatment

62
Q

How are brain abscesses treated?

A

Weeks of ABx

63
Q

What is the definition of ‘meningitis’?

A

Inflammation of the leptomeninges and CSF within the subarachnoid space

64
Q

What does meningitis frequently cause?

A

Severe oedema and raised ICP

65
Q

How is meningitis usually derived?

A

Haematogenous spread

66
Q

What are the results of an LP in someone with meningitis?

A
  • Low glucose

* LOTS of polymorphs

67
Q

What can arachnoiditis later cause?

A

Lack of CSF absorption, hydrocephalus and raised ICP

68
Q

Sometimes things that are not SOL’s can cause oedema and thus become SOL’s

A

TRUE

69
Q

What organism is most commonly found in neonates with meningitis?

A

E coli

70
Q

What organism is most commonly found in infants and children with meningitis?

A

H. influenzae

71
Q

What organism is most commonly found in young adults with meningitis?

A

N. meningitidis

72
Q

What organism is most commonly found in older adults with meningitis?

A

S. pneumonia

73
Q

What organism is most commonly found in elderly with meningitis?

A

L. monocytogenes

74
Q

What are the 2 categories of head trauma?

A

Penetrating or blunt

75
Q

What 3 things can head trauma cause?

A
  • Skull fractures
  • Parenchymal injury
  • Vascular injury
76
Q

Describe a penetrating head injury.

A
  • Focal damage
  • Laceration at site
  • Haemorrhage
  • High/Low velocity
77
Q

What does blunt head injury occur due to?

A

Sudden acceleration/deceleration of the head

78
Q

What is the relationship between contact time and force?

A

The smaller the contact time, the larger the force

79
Q

What happens to the brain in a blunt trauma injury?

A

The brain moves within the cranial cavity, and makes contact with the inner table of the cranium and bony protrusions

80
Q

Suggest causes of blunt brain trauma.

A

Road traffic collisions (RTC’s)
Falls
Assaults
Alcohol

81
Q

Describe PRIMARY brain injury.

A
  • Occurs at time of injury
  • Irreversible
  • Preventative measures
82
Q

Describe SECONDARY brain injury.

A
  • Haemorrhage
  • Oedema
  • Potentially treatable
  • Exacerbates injury
83
Q

What are the 3 different types of skull fracture?

A
  • Linear
  • Compound
  • Depressed
84
Q

Describe a linear skull fracture.

A

Straight, sharp fracture line that may cross sutures (diastatic fracture).

85
Q

Describe a compound skull fracture.

A

Associated with full thickness scalp lacerations

– compound ones are open and carry as risk of bacterial infection

86
Q

Describe a depressed skull fracture.

A
  • Higher risk of intracranial bleeding and haemotomas

* Base of skull fractures

87
Q

Where do coup injuries occur?

A

To the brain on the side of the impact

88
Q

Where do contra-coup injuries occur?

A

Diametrically opposite the point of impact

89
Q

Contra-coup injuries are worse than coup injuries

A

TRUE

90
Q

Why are contra-coup injuries worse than coup injuries?

A
  • Denser CSF moves to impact (coup) side first, forcing brain to contra-coup side 1st. In this situation the contra-coup would have the higher energy
  • Cavitation – low pressure in brain moving away from zone opposite the impact side. Low pressure creates cavitation bubbles, which damage parenchyma
91
Q

When does diffuse axonal injury occur?

A

At the moment of injury

92
Q

What is diffuse axonal injury?

A

Widespread tearing of axons at the moment of injury

93
Q

What kind of pattern does diffuse axonal injury have?

A

Uniform

94
Q

Where does diffuse axonal injury usually affect?

A

Central areas of the brain

95
Q

What can diffuse axonal injury lead to?

A

Reduced consciousness + coma.

Vegetative state.

96
Q

Why does diffuse axonal injury occur?

A

Because of shearing strains

97
Q

Outline the cellular events that lead to secondary injury.

A
  1. Injury to microvasculature and the blood brain barrier occurs.
  2. Oedema
  3. Hypoxia
  4. Glutamate release -> Excitotoxicity
  5. Increased intracellular Ca2+
  6. Hypoxia also increases oxidative stress, causing mitochondrial injury and free radical formation
  7. These processes bring about apoptosis and necrosis
  8. To an extent, further tissue disruption can exacerbate the situation creating positive feedback loops of enhancing local injury
98
Q

What are the most important mechanisms of excitotoxicity?

A

Glutamate and oxygen free radical formation, bringing about CALCIUM influx

99
Q

What does Ca2+ influx bring about?

A

Apoptosis and necrosis

100
Q

What causes glutamate release?

A

Depolarisation

101
Q

Name the 3 main types of oedema.

A
  • Cytotoxic
  • Ionic/osmotic
  • Vasogenic
102
Q

When does cytotoxic oedema occur?

A

Intoxication, Reye’s and severe hypothermia

103
Q

When does ionic oedema occur?

A

Hyponatraemia + excess water intake ie. in SIADH

104
Q

When does vasogenic oedema occur?

A

Trauma, tumours, inflammation, infection and hypertensive encephalopathy

105
Q

When does haemorrhagic conversion occur?

A
  • Occurs when endothelial integrity is completely lost and blood can enter the extracellular space.
    Such extravasation of RBCs occurs in as many as 30 to 40% of ischaemic strokes
106
Q

The majority of intracranial haematomas are _______

A

INTRADRUAL

107
Q

What are the 3 main categories of intradural haematomaS?

A
  • 13% subdural
  • 15% intracerebral haematomas
  • 3% subarachnoid
108
Q

What is a ‘burst lobe’ intradural haemorrhage?

A

A subdural in continuity with intracerebral haematoma particularly in frontal and temporal lobe

109
Q

What happens with age?

A

Brain atrophy

110
Q

What do traumatic extradural haematomas occur as a complication of?

A

A fracture in the squamous portion tempero-parietal region that involves the middle meningeal artery. – leakage into extradural space, resulting in a tearing of the dura away from the skull

111
Q

What happens if a traumatic extradural haematoma is left untreated?

A

Midline shift, resulting in compression and herniation

112
Q

What is a subdural haemorrhage?

A

Collections of blood between the internal surface of dura mater and arachnoid mater.

113
Q

What are subdural haemorrhages caused by?

A

Disruption of bridging veins that extend from the surface of the brain into the subdural space

114
Q

What are subdural haemorrhages mostly caused by?

A

Trauma

115
Q

Who are subdural haemorrhages most common in? Why?

A

Elderly

- as you get older you get brain atrophy so there is more space for bridging veins to stretch and avulse

116
Q

What is preserved in subdural haemorrhages? Why?

A

Gyral contours – pressure is evenly distributed

117
Q

Where does the swelling of the cerebellum in subdural haemorrhages occur?

A

On the side of the haematoma

118
Q

What happens to non-treated and non-fatal haematomas?

A

They become liquefied, and form a yellowish neomembrane

119
Q

What are chronic subdural haemorrhages associated with?

A

Brain atrophy

120
Q

What are chronic subdural haemorrhages not less associated with?

A

Trauma

121
Q

What are chronic subdural haemorrhages composed of?

A

Liquefied blood/yellow-tinged fluid, separated from inner surface of dura mater and underlying brain by ‘neomembrane.’