Neuropathology 3 Flashcards
(121 cards)
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
2
Q
What does increased brain volume lead to?
A
Increased ICP
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)
4
Q
What is hydrocephalus?
A
An accumulation of excessive CSF with the ventricular system of the brain
5
Q
What is CSF produced by?
A
Choroid plexus in the lateral and fourth ventricles of the brain
6
Q
What is CSF absorbed by?
A
Arachnoid granulations
7
Q
How much CSF is normal?
A
120-150ml
8
Q
How much CSF would there be in hydrocephalus?
A
500ml
9
Q
CSF fluid looks…
A
CLEAR
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
11
Q
What does CSF not contain?
A
RBC’s
12
Q
What 3 things can hydrocephalus be due to?
A
- Obstruction
- Decreased resorption
- Overproduction
13
Q
What can cause obstruction to CSF?
A
- Inflammation
- Pus
- Tumours
14
Q
What can cause decreased resorption to CSF?
A
- Post- SAH
* Meningitis
15
Q
What causes an overproduction of CSF?
A
Tumours of the choroid plexus
16
Q
Hydrocephalus can be either?
A
Communicating OR Non-communicating
17
Q
In non-communicating hydrocephalus, where does the obstruction to flow of CSF occur?
A
Within the ventricular system and CANNOT exit
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
19
Q
What happens if hydrocephalus occurs before closure of the cranial sutures?
A
Cranial enlargement
20
Q
At what age does closure of the cranial sutures occur?
A
2-3 years old
21
Q
What happens if hydrocephalus develops after the closure of the cranial sutures?
A
There is expansion of ventricles and increasing ICP
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
23
Q
In what condition would you see hydrocephalus ex vacuo? Why?
A
Alzheimer’s
- due to brain atrophy
24
Q
What is ‘coning’?
A
Tonsillar herniation of the cerebellum into the foramen magnum
25
Why does coning occur?
Due to raised ICP
26
What 5 things occur due to raised ICP?
* Intracranial shifts and herniations
* Midline shifts
* Distortion and pressure on cranial nerves and vital neurological centres
* Impaired blood flow
* Reduced level of consciousness
27
Name the 4 main types of herniations.
1 – Subfalcine
2 – Tentorial
3 – Cerebellar/Tonsillar
4 – Transcalvarial
28
Describe subfalcine herniations.
Displacement of the brain (typically the cingulate gyrus) beneath the free edge of the falx cerebri due to raised intracranial pressure
- MOST COMMON
29
Describe cerebellar/tonsillar herniations.
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
30
What are the 4 main symptoms or raised ICP?
* Papilloedema
* N+V
* Neck stiffness
* Headache
31
What causes papilloedema?
Pressure on the optic disc
32
Describe the headache in raised ICP.
Worse when lying down, coughing, straining and sneezing
33
How does raised ICP cause N+V?
Pressure on vom centre in pons and medulla
34
How does raised ICP cause neck stiffness?
Pressure on the dura around the brainstem and cerebellum
35
Give examples of SOL's.
* Tumour (primary or mets)
* Abscess
* Haematoma
36
What are the common signs when a patient has a brain tumour?
* Focal deficit
| * Papilloedema
37
What are the common symptoms when a patient has a brain tumour?
* Focal sx (68%).
* Headache (54%)
* Vomiting.
* Seizures (26%).
* Visual disturbances.
38
Why are headaches in relation to brain tumours worse in the morning?
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
39
Where do 70% of brain tumours in children occur?
Below the tentorium cerebelli
40
Where do 70% of brain tumours in adults occur?
Above the tentorium cerebella
41
Where do 70% of brain tumours in adults occur?
Above the tentorium cerebelli
42
What are the commonest cancers to metastasise to the brain?
Breast, bronchus, kidney, thyroid and colon carcinomas
Malignant melanomas
43
Where are brain mets most often seen?
At the boundaries between grey and white matter
44
What is the most common brain tumour in adults?
Astrocytoma
45
What is the most common benign brain tumours in adults?
Meningioma
46
What can some high grade tumours secrete? What does this lead to?
VEGF
| Increased vascularity
47
What is the most common brain tumour in children?
Pilocytic astrocytomas
48
What is the 2nd most common brain tumour in children?
Medulloblastoma
49
Describe the cells in medulloblastoma.
Poorly differentiated/embryonal (look like primitive undifferentiated embryonal cells).
50
Where do medulloblastomas occur?
In the midline of the cerebellum
51
What is the prognosis of a medulloblastoma if untreated?
AWFUL
52
A medulloblastoma is very ___________
RADIOSENSITIVE
53
Where can a medullablastoma occupy?
4th ventricle
54
What are the 2 main ways in which a brain abscess can arise?
* Local extension e.g mastoiditis
| * Direct implantation e.g skull fracture
55
Where do single brain abscesses tend to occur?
Adjacent to the brain
56
How do multiple abscesses arise?
Due to haematogenous spread ie. bronchopneumonia, bacterial endocarditis., lung abscess, left to right shunt of the heart, PWID
57
Where do multiple abscesses tend to arise?
At the grey and white matter boundary
58
What symptoms are associated with abscesses?
* Fever
* Raised ICP
* Symptoms of underlying cause
59
How are abscesses diagnosed?
CT or MRI
60
What kind of lesions do abscess appear as on CT/MRI?
ENHANCING
61
Aside from CT and MRI, what other investigations are done?
Aspiration - for culture and treatment
62
How are brain abscesses treated?
Weeks of ABx
63
What is the definition of 'meningitis'?
Inflammation of the leptomeninges and CSF within the subarachnoid space
64
What does meningitis frequently cause?
Severe oedema and raised ICP
65
How is meningitis usually derived?
Haematogenous spread
66
What are the results of an LP in someone with meningitis?
* Low glucose
| * LOTS of polymorphs
67
What can arachnoiditis later cause?
Lack of CSF absorption, hydrocephalus and raised ICP
68
Sometimes things that are not SOL's can cause oedema and thus become SOL's
TRUE
69
What organism is most commonly found in neonates with meningitis?
E coli
70
What organism is most commonly found in infants and children with meningitis?
H. influenzae
71
What organism is most commonly found in young adults with meningitis?
N. meningitidis
72
What organism is most commonly found in older adults with meningitis?
S. pneumonia
73
What organism is most commonly found in elderly with meningitis?
L. monocytogenes
74
What are the 2 categories of head trauma?
Penetrating or blunt
75
What 3 things can head trauma cause?
* Skull fractures
* Parenchymal injury
* Vascular injury
76
Describe a penetrating head injury.
* Focal damage
* Laceration at site
* Haemorrhage
* High/Low velocity
77
What does blunt head injury occur due to?
Sudden acceleration/deceleration of the head
78
What is the relationship between contact time and force?
The smaller the contact time, the larger the force
79
What happens to the brain in a blunt trauma injury?
The brain moves within the cranial cavity, and makes contact with the inner table of the cranium and bony protrusions
80
Suggest causes of blunt brain trauma.
Road traffic collisions (RTC’s)
Falls
Assaults
Alcohol
81
Describe PRIMARY brain injury.
* Occurs at time of injury
* Irreversible
* Preventative measures
82
Describe SECONDARY brain injury.
* Haemorrhage
* Oedema
* Potentially treatable
* Exacerbates injury
83
What are the 3 different types of skull fracture?
* Linear
* Compound
* Depressed
84
Describe a linear skull fracture.
Straight, sharp fracture line that may cross sutures (diastatic fracture).
85
Describe a compound skull fracture.
Associated with full thickness scalp lacerations
| – compound ones are open and carry as risk of bacterial infection
86
Describe a depressed skull fracture.
* Higher risk of intracranial bleeding and haemotomas
| * Base of skull fractures
87
Where do coup injuries occur?
To the brain on the side of the impact
88
Where do contra-coup injuries occur?
Diametrically opposite the point of impact
89
Contra-coup injuries are worse than coup injuries
TRUE
90
Why are contra-coup injuries worse than coup injuries?
* 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
When does diffuse axonal injury occur?
At the moment of injury
92
What is diffuse axonal injury?
Widespread tearing of axons at the moment of injury
93
What kind of pattern does diffuse axonal injury have?
Uniform
94
Where does diffuse axonal injury usually affect?
Central areas of the brain
95
What can diffuse axonal injury lead to?
Reduced consciousness + coma.
| Vegetative state.
96
Why does diffuse axonal injury occur?
Because of shearing strains
97
Outline the cellular events that lead to secondary injury.
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
What are the most important mechanisms of excitotoxicity?
Glutamate and oxygen free radical formation, bringing about CALCIUM influx
99
What does Ca2+ influx bring about?
Apoptosis and necrosis
100
What causes glutamate release?
Depolarisation
101
Name the 3 main types of oedema.
* Cytotoxic
* Ionic/osmotic
* Vasogenic
102
When does cytotoxic oedema occur?
Intoxication, Reye’s and severe hypothermia
103
When does ionic oedema occur?
Hyponatraemia + excess water intake ie. in SIADH
104
When does vasogenic oedema occur?
Trauma, tumours, inflammation, infection and hypertensive encephalopathy
105
When does haemorrhagic conversion occur?
* 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
The majority of intracranial haematomas are _______
INTRADRUAL
107
What are the 3 main categories of intradural haematomaS?
* 13% subdural
* 15% intracerebral haematomas
* 3% subarachnoid
108
What is a 'burst lobe' intradural haemorrhage?
A subdural in continuity with intracerebral haematoma particularly in frontal and temporal lobe
109
What happens with age?
Brain atrophy
110
What do traumatic extradural haematomas occur as a complication of?
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
What happens if a traumatic extradural haematoma is left untreated?
Midline shift, resulting in compression and herniation
112
What is a subdural haemorrhage?
Collections of blood between the internal surface of dura mater and arachnoid mater.
113
What are subdural haemorrhages caused by?
Disruption of bridging veins that extend from the surface of the brain into the subdural space
114
What are subdural haemorrhages mostly caused by?
Trauma
115
Who are subdural haemorrhages most common in? Why?
Elderly
| - as you get older you get brain atrophy so there is more space for bridging veins to stretch and avulse
116
What is preserved in subdural haemorrhages? Why?
Gyral contours – pressure is evenly distributed
117
Where does the swelling of the cerebellum in subdural haemorrhages occur?
On the side of the haematoma
118
What happens to non-treated and non-fatal haematomas?
They become liquefied, and form a yellowish neomembrane
119
What are chronic subdural haemorrhages associated with?
Brain atrophy
120
What are chronic subdural haemorrhages not less associated with?
Trauma
121
What are chronic subdural haemorrhages composed of?
Liquefied blood/yellow-tinged fluid, separated from inner surface of dura mater and underlying brain by ‘neomembrane.’
