Raised ICP, Space Occupying Lesions & Trauma Flashcards
what can cause a raised ICP?
increased CSF production (hydrocephalus) focal lesion in brain (SOL) diffuse lesion in brain (oedema) increased venous volume physiological (hypoxia, hypercapnia, pain)
what is responsible for re-absorption of CSF?
arachnoid granulations
what should normal CSF contain and not contain?
contain small amount of protein and lymphocytes and glucose
no neutrophils or RBCs
what is the difference between non-communicating and communicating hydrocephalus?
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
what happens if hydrocephalus occurs before cranial sutures close?
cranial enlargement
what is hydrocephalus ex vacuo?
dilation of ventricular system - increase in CSF volume
due to loss of brain parenchyma (eg in alzheimer’s disease)
what are the effects of raised ICP?
intracranial shifts and herniation
pressure on cranial nerves
impaired blood flow (CPP = MAP - ICP)
reduced level of consciousness
describe how the brain can shift and herniate in raised ICP and what each shift can compress?
subfalcine = moves under falx cerebri, can squish anterior cerebral artery
tentorial = squishes CNIII - blown out pupil
cerebellar = compresses brainstem
transcalvarial = moves through skull fracture
what are main clinical signs of raised ICP?
papilloedema
headache
neck stiffness (due to dura compression)
N&V
what SOLs can be responsible for raised ICP?
tumour
abscess
haematoma
local swelling (eg oedema around infarct)
where do tumours arise in children vs adults in relation to tentorium cerebelli?
children = tumours below TC adults = tumours above TC
what types of cancer most commonly metastasise to brain?
breast bronchus kidney thyroid colon
where in the brain are metastases most likely to present?
often seen at boundaries between matter
what type of malignant primary tumour is most common in adults vs children?
adults = astrocytoma
children = medulloblastoma
what type of benign brain tumour is most common in adults?
meningioma
what type of grade 1 astrocytomas do children normally develop?
pilocytic
what signs can be seen on histology which point towards a higher grade tumour?
abnormal cells
mitotic features (proliferation)
anaplasia
neoangiogenesis
how do medulloblastomas appear on histology and why is this significant clinically?
cells are primitive undifferentiated embryonic cells
respond well to radiotherapy
where do medulloblastomas usually occur in brain?
occurs in midline of cerebellum
describe the different in cause of a single abscess vs multiple abscesses?
single - usually adjacent to source eg mastoiditis infection, next to fracture site
multiple - haematogenous spread eg pneumonia, endocarditis
how are abscesses diagnosed?
CT or MRI
aspiration for culture and treatment (weeks of antibiotics)
how does bacterial meningitis cause raised ICP?
inflammation of meninges irritates the arachnoid granulations - prevents them from reabsorbing CSF
describe what is meant by a penetrating (missile) injury?
focal damage
lacerations in region of damage
haemorrhage
cavitation depending on high / low velocity
what is a blunt or non-missile injury?
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
what can cause blunt / non-missile injury?
RTAs
falls
assaults
alcohol
primary injury is usually irreversible - true or false?
true - damage to neurones means they cant regenerate
preventative measures (seatbelts, crashmats) can be used to increase contact time
what are the croup and contra-croup injuries?
croup - occurs at point of impact
contra-croup - occurs opposite of impact, due to rebound, often worse than initial injury
a linear fracture across the squamous part of the temporal bone would cause which artery to rupture?
middle meningeal artery - would cause extradural haematoma
what is diffuse axonal injury?
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
what injury often causes extradural haematoma and what are the consequences of this?
fracture in tempero-parietal (middle meningeal artery)
immediate brain damage often minimal
untreated = midline shift (compression and herniation)
what causes a subdural haematoma and what are the complications of this?
disruption of bridging veins
swelling of cerebrum on side of haematoma
non-treated non fatal haematomas become liquefied and form a yellow neomembrane (chronic)
