Raised ICP, Space Occupying Lesions & Trauma

Question 1

what can cause a raised ICP?

Answer 1

increased CSF production (hydrocephalus)
focal lesion in brain (SOL)
diffuse lesion in brain (oedema)
increased venous volume 
physiological (hypoxia, hypercapnia, pain)

Question 2

what is responsible for re-absorption of CSF?

Answer 2

arachnoid granulations

Question 3

what should normal CSF contain and not contain?

Answer 3

contain small amount of protein and lymphocytes and glucose

no neutrophils or RBCs

Question 4

what is the difference between non-communicating and communicating hydrocephalus?

Answer 4

non communicating = obstruction to flow of CSF occurs within ventricular system

communicating = obstruction to flow of CSF outside of ventricular system eg in subarachnoid space or at arachnoid granulations

Question 5

what happens if hydrocephalus occurs before cranial sutures close?

Answer 5

cranial enlargement

Question 6

what is hydrocephalus ex vacuo?

Answer 6

dilation of ventricular system - increase in CSF volume

due to loss of brain parenchyma (eg in alzheimer’s disease)

Question 7

what are the effects of raised ICP?

Answer 7

intracranial shifts and herniation
pressure on cranial nerves
impaired blood flow (CPP = MAP - ICP)
reduced level of consciousness

Question 8

describe how the brain can shift and herniate in raised ICP and what each shift can compress?

Answer 8

subfalcine = moves under falx cerebri, can squish anterior cerebral artery

tentorial = squishes CNIII - blown out pupil

cerebellar = compresses brainstem

transcalvarial = moves through skull fracture

Question 9

what are main clinical signs of raised ICP?

Answer 9

papilloedema
headache
neck stiffness (due to dura compression)
N&V

Question 10

what SOLs can be responsible for raised ICP?

Answer 10

tumour
abscess
haematoma
local swelling (eg oedema around infarct)

Question 11

where do tumours arise in children vs adults in relation to tentorium cerebelli?

Answer 11

children = tumours below TC
adults = tumours above TC

Question 12

what types of cancer most commonly metastasise to brain?

Answer 12

breast
bronchus 
kidney 
thyroid 
colon

Question 13

where in the brain are metastases most likely to present?

Answer 13

often seen at boundaries between matter

Question 14

what type of malignant primary tumour is most common in adults vs children?

Answer 14

adults = astrocytoma

children = medulloblastoma

Question 15

what type of benign brain tumour is most common in adults?

Answer 15

meningioma

Question 16

what type of grade 1 astrocytomas do children normally develop?

Answer 16

pilocytic

Question 17

what signs can be seen on histology which point towards a higher grade tumour?

Answer 17

abnormal cells
mitotic features (proliferation)
anaplasia
neoangiogenesis

Question 18

how do medulloblastomas appear on histology and why is this significant clinically?

Answer 18

cells are primitive undifferentiated embryonic cells

respond well to radiotherapy

Question 19

where do medulloblastomas usually occur in brain?

Answer 19

occurs in midline of cerebellum

Question 20

describe the different in cause of a single abscess vs multiple abscesses?

Answer 20

single - usually adjacent to source eg mastoiditis infection, next to fracture site

multiple - haematogenous spread eg pneumonia, endocarditis

Question 21

how are abscesses diagnosed?

Answer 21

CT or MRI

aspiration for culture and treatment (weeks of antibiotics)

Question 22

how does bacterial meningitis cause raised ICP?

Answer 22

inflammation of meninges irritates the arachnoid granulations - prevents them from reabsorbing CSF

Question 23

describe what is meant by a penetrating (missile) injury?

Answer 23

focal damage
lacerations in region of damage
haemorrhage
cavitation depending on high / low velocity

Question 24

what is a blunt or non-missile injury?

Answer 24

sudden acceleration / deceleration of head
the smaller the contact time is, the larger the force
brain moves within cranial cavity and makes contact with the cranium and bony protrusions

Question 25

what can cause blunt / non-missile injury?

Answer 25

RTAs falls assaults alcohol

Question 26

primary injury is usually irreversible - true or false?

Answer 26

true - damage to neurones means they cant regenerate preventative measures (seatbelts, crashmats) can be used to increase contact time

Question 27

what are the croup and contra-croup injuries?

Answer 27

croup - occurs at point of impact contra-croup - occurs opposite of impact, due to rebound, often worse than initial injury

Question 28

a linear fracture across the squamous part of the temporal bone would cause which artery to rupture?

Answer 28

middle meningeal artery - would cause extradural haematoma

Question 29

what is diffuse axonal injury?

Answer 29

occurs at moment of injury and affects central areas sheering of axons - electrical signals cant transfer causes reduced consciousness and coma and axons become axonal bulbs

Question 30

what injury often causes extradural haematoma and what are the consequences of this?

Answer 30

fracture in tempero-parietal (middle meningeal artery) immediate brain damage often minimal untreated = midline shift (compression and herniation)

Question 31

what causes a subdural haematoma and what are the complications of this?

Answer 31

disruption of bridging veins swelling of cerebrum on side of haematoma non-treated non fatal haematomas become liquefied and form a yellow neomembrane (chronic)