Space Occupying Lesions Flashcards by Louise Emerson

what happens when the brain enlarges

some blood +/‐
CSF must escape from cranial vault
to avoid rise in pressure.
• Once this process is exhausted,
venous sinuses are flattened and
there is little or no CSF.
• Any further increase in brain volume
results in rapid increase in ICP

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what can cause raised ICP

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

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what is hydrocephalus

accumulation of excessive CSF within the ventricular system of the brain

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what is the normal volume of CSF

120-150 mls

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how much CSF is made per day

500ml

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where is CSF produced

by the choroid plexus in the lateral and fourth ventricles of the brain

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what absorbs CSF

arachnoid granulations

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what does the CSF usually contain

lymphocytes <4 cells 
neutrophils 0
protein < 0.4 g/l
glucose >2.2 mmol/l
no RBCs

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what does increased lymphocytes in CSF mean

inflammation/ infection

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what does increased polymorphs in CSF mean

bacterial meningitis

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what can cause hydrocephalus

obstruction to CSF flow (inflammation, pus and tumours)
decreased resorption of CSF (post SAH, meningitis)
overproduction of CSF (v. rare: tumours of choroid plexus)

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what is non communicating hydrocephalus

obstruction of flow of CSF occurs within ventricular system

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what is communicating hydrocephalus

obstruction to flow of CSF outside of the ventricular system (e.g. in subarachnoid space or at the arachnoid granulations)

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what happens if hydrocephalus occurs before/ after the closure of cranial sutures

before- cranial enlargement

after- expansion of ventricles and increased in ICP

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what is hydrocephalus ex vacuo

dilatation of the ventricular system and a compensatory increase in CSF volume secondaryto loss of brain parenchyma (e.g. in alzheimers)

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what are the physical effects of raised ICP

• Intracranial shifts and
herniations – “Coning”
•Midline shift
•Distortion and pressure on cranial nerves and vital
neurological centres
• Impaired blood flow
• Cerebral Perfusion Pressure =
MAP – ICP
•Reduced level of consciousness

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what are the causes of raised ICP

infections
tumours
stroke
aneurysm
epilepsy
seizures
hydrocephalus
hypoxemia
meningitis
haemorrhage

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describe a tentorial herniation

when medial aspect of temporal lobe herniates over the tentorial cerebellum

=compression of CN 3 (pupillary dilatation and impaired eye movements on side of lesion)

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describe a subfalcine herniation

unilateral expansion of cerebral hemisphere which displaces the singular gyrus underneath the falx cerebri= weakness and sensory loss on opposite side

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describe a cerebellar herniation (uncal)

inferior descent of cerebellar tonsils below the foramen magnum (aka coning)
=puts pressure on brain stem

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describe a central herniation

the diencephalon and parts of the temporal lobes of both of the cerebral hemispheres are squeezed through a notch in the tentorium cerebelli

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describe a transcalvarial herniations

herniation through any defect in the skull (e.g. following fracture)

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what are the clinical signs of raised ICP

papilloedema
headache
neck stiffness
N&V

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what are the most common space occupying lesions

tumours
abscess
haematomas
localised swelling (swelling and oedema around cerebral infarct)

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what are the most common clinical presentations of tumours

``` focal symptoms headache (worse in morning) vomiting seizures visual disturbances papilloedema ```

where do most brain tumours in children occur

below the tentorium cerebelli

where do most brain tumours in adults occur

above the tentorium cerebelli

what are the commonest cancers to mets to brain

breast, bronchus, kidney, thyroid, colon, malignant

how are brain tumours graded

``` mitosis neovascularisation necrosis atypia cellularity ```

what are the most common types of malignant primary brain tumour

astrocytomas oligodendrogliomas medulloblastoma (most common in children)

what is the most common type of benign primary brain tumour

meningioma schwannoma craniopharyngioma pituitary adenoma

why are astrocytomas hard to resect

insidious brain infiltration

what is a glioblastoma

grade 4 astrocytoma

do grade 1 astrocytomas become malignant

what are the features of a astrocytoma (grades 2+)

``` nuclear atypia mitosis necrosis (4) neovascularisation (4) proliferation anaplasia palisading ```

what is the most common tumour in children

medulloblastoma

what are the features of a medulloblastoma

poorly differentiated embryonal occurs in midline of cerebellum very radiosensitive- good prognosis

what are the causes of single brain abscesses

``` local extension (e.g. mastoditis) direct implantation (e.g. skull fracture) ``` (tend to occur adjacent to the source)

what are the causes of multiple abscesses

haemotogenous spread (bronchopneumonia, bacterial endocarditis, congenital heart disease, IV drug use) (tend to occur at grey and white matter boundary)

what are the symptoms of an abscess

fever raised ICP + symptoms of underlying cause

what investigations and Tx for brain abscess

CT/ MRI to diagnose apsirate for culture and Tx weeks of antibiotics (hard to get into CNS)

what is bacterial meningitis

inflammation of the leptomeninges | and CSF within the subarachnoid space

how does bacterial meningitis cause raised ICP

severe oedema

what is seen in CSF in bacterial meningitis

polymorphs | low glucose

what can arachnoiditis cause

lack of CSF absorption = hydrocephalus = raised ICP

e coli: | what type of bacterial is it and who does it cause bacterial meningitis

gram -ve rod | neonates

H influenza: | what type of bacterial is it and who does it cause bacterial meningitis

gram -ve cocco-bacilli | infants and children

n meningitidis: | what type of bacterial is it and who does it cause bacterial meningitis

gram -ve diplococci | adolescents and young adults

s pneumoniae: | what type of bacterial is it and who does it cause bacterial meningitis

gram +ve cocci in chains | older adults or children

L monocytogenes: | what type of bacterial is it and who does it cause bacterial meningitis

gram +ve rods | older adults

what are missile and non missile injuries

missile= penetrating | non missile- blunt

what can penetrating brain injuries cause

focal damage lacerations in region of brain damage haemorrhage

does a high or low velocity penetrating brain injury cause more damage

high

what is a non missile injury and what determines the extend of its damage

sudden acceleration/ deceleration of head smaller the contact time the larger the force

what is a primary brain injury

* Injury to neurones * Irreversible * Preventative measures (hallmark is change in consciousness immediately)

what is a secondary brain injury

* Haemorrhage * Oedema etc * Potentially treatable

what are the types of scalp lesions

bruising (contusions) lacerations bleeding (route for infection)

what are the types of skull fracture

• Linear ‐ straight sharp fracture line, that may cross sutures (diastatic fracture) •Compound ‐ associated with full thickness scalp lacerations •Depressed if base of skull fracture then compound or open as damage to paranasal sinus

what is coup and contra coup

in the context of brain surface contusions and lacerations: - Coup- brain hits side of injury - Contra coup- hits opposite side, tend to be worse than coup

what is a diffuse axonal injury

Occurs at moment of injury a blunt trauma puts a shearing strain on axons which tear affects central areas causes reduced consciousness and coma can lead to vegetative state

what can cause secondary injury to the brain

``` -Intracranial haematoma • Reduced cerebral blood flow • Hypoxic brain damage • Excitotoxicity • Oedema • Raised ICP • Infection ```

what does Ca2+ influc do to protease and phospholipase

activates them- causing lipid membrane disruption

where are most traumatic intracranial haematomas

intradural (sub dural, intracerebral, subarachnoid)

what are traumatic extradural haematomas like

``` •Usually a complication of fracture in tempero‐parietal region that involves middle meningeal artery • Immediate brain damage often minimal •But untreated, midline shift – compression and herniation ```

what is a subdural haemorrhage and what causes it

• Collections of blood between the internal surface of dura mater and arachnoid mater • Caused by disruption of bridging veins that extend from the surface of the brain into subdural space

what is the pressure put on the brain by a subdural haemorrhage like

Gyral contours preserved – | pressure evenly distributed

what are chronic subdural haemorrhages associated with

brain atrophy less associated with trauma will present subtly

Space Occupying Lesions Flashcards

(67 cards)