Neuro pathology part 2 Flashcards
Ischaemic stroke causes
Sudden cessation of adequate blood flow to region of brain- occlusion of artery supply
Blood vessel disease - Large artery stenosis, small vessel disease
Thrombosis of blood vessel
Embolism e.g. Cardio-embolism
Hypoperfusion e.g. post MI
Ischaemic stroke risk factors
same as those for atherosclerosis: hypertension, diabetes, age, obesity, smoking, hypercholesterolaemia, genetic/ethnic factors
ischaemic stroke development of infarction
Infarction due to disrupted blood flow
Hypoxia > Neurons irreversibly damaged after 5-7 minutes
Cells swell up – cytotoxic oedema
Necrosis (infarct core) with surrounding ischemic area (penumbra)
If blood supply restored, penumbra can recover
Eventually necrotic area becomes a fluid-filled cavity (“pseudocyst”)
Acute stroke imaging NICE guidelines 2019
indications for thrombolysis (breaking down of clot) or (removal of clot) thrombectomy
on anticoagulant treatment
a known bleeding tendency
a depressed level of consciousness (GCS below 13)
unexplained progressive or fluctuating symptoms
Papilloedema (raised intracranial pressure), neck stiffness or fever
severe headache at onset of stroke symptoms.
CT scan within 24 hours otherwise
If thrombectomy (removal of thrombus) indicated, a CT angiogram (CTA) and CT perfusion imaging are added
Ischaemic stroke: stroke and prognosis
Dedicated stroke care unit
Neurosurgical interventions
Reperfusion therapy
Dedicated stroke care unit
Dedicated stroke care unit – aim to prevent complications of neurological impairment (e.g. aspiration, pneumonia, pressure ulcers)
Neurosurgical interventions examples
decompressive craniotomy- reducing intracranial pressure
Reperfusion therapy
Intravenous or intra-arterial thrombolysis
Mechanical thrombectomy
How does imaging help with treatment and prognosis
Exclude intracranial haemorrhage as this precludes thrombolysis
Demonstrate early signs of ischaemia
Exclude stroke mimics –e.g. tumour
Ischaemic stroke on non contrast CT early signs
Early signs are subtle – hyperdense vessel, or loss of grey/white matter differentiation
Ischaemic stroke on non contrast CT later signs
seen as a low-density area corresponding to vascular territory affected (e.g. wedge-shaped MCA as shown here) and mass effect
Ischaemic stroke on non contrast CT- low density is due to
Low density is due to cytotoxic oedema (swollen cells)
Later, as swelling reduces, and area is replaced by glial cells, a low-density area will remain
Diffusion weighted imaging (DWI)
Used in MRI and can be used to see ischaemic stroke earlier- however, is not used routinely
consequences depend on the affected vessel
Transient Ischaemic attack (TIA)
a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction.
Transient Ischaemic attack (TIA) localised symptoms
similar to stroke (FAST criteria) usually no more than 1-2 hours. Usually, conscious
Transient Ischaemic attack (TIA) causes
Temporary localised reduction in blood flow to the brain.
Stenosis of the artery (e.g. internal carotid artery or intracranial arteries)
Small embolus
bifurcation of the carotid artery is the most common site
Transient Ischaemic attack (TIA) risk factors
same as for ischaemic stroke
Imaging in TIA and non disabling stroke following rapid assessment in TIA clinic (2019 NICE guidelines) brain imaging
diffusion-weighted imaging
blood sensitive sequences….
Types of Brain bleeds
Intra-axial – within the brain parenchyma
Extra-axial – outside of the brain but within the skull
Intra-axial bleed:Intracerebral Haemorrhage (ICH) causes
hypertension; occasionally due to aneurysm or arteriovenous malformation
usually basal ganglia, pontine, or cerebellar
Intra-axial bleed: Intracerebral Haemorrhage (ICH) symptoms
same as for ischemic stroke, but frequently more severe. Headaches and coma are more commonly associated. Raised Intracranial pressure +++
Intra-axial bleed: Intracerebral Haemorrhage (ICH) treatment
medical – reduce hypertension and aim to prevent secondary cerebral injury. Surgical if large
imaging of ICH
CT is very sensitive for fresh blood
Well circumscribed hematoma seen within the brain parenchyma
High density indicating fresh blood
Often surrounded by oedema (low density - vasogenic rather than cytotoxic)
trauma may show fractures too
Head injury
GCS less than 13 on initial assessment in the emergency department.
GCS less than 15 at 2 hours after the injury on assessment in the emergency department.
Suspected open or depressed skull fracture.
Any sign of basal skull fracture (‘panda’ eyes, cerebrospinal fluid leakage from the ear or nose, Battle’s sign).
Post-traumatic seizure.
Focal neurological deficit.
More than 1 episode of vomiting.
Extra-axial bleeds
extradural
subdural
subrachnoid
extradural haematoma
Collection of blood between inner surface of skull and outer layer of dura
Usually associated with hx of trauma (RTC/sports)> gradual LOC
Commonly caused by rupture of the middle meningeal artery, often associated with skull fracture
Coma > Invariably lethal if unrecognized
Prompt blood clot extraction (if large enough)>best prognosis
extradural haematoma CT appearances
Acute hemorrhage has high density (HU 50-100)
Lentiform (bi-convex) in shape
Can cause mass effect and herniation
Bone windows may identify underlying fracture
Subdural haematoma
Collection of blood in subdural space – between dura and arachnoid mater > Caused by tearing of bridging veins
Occur in any age group:
Infants (SPA)- suspected physical abuse
Young adults (RTC)
Elderly (falls)
Typically present with depressed conscious state; focal deficits develop
In elderly > confusion>pseudodementia following minor trauma
subdural haematoma CT appearances
Crescent-shaped collection - blood tracking between dura and the arachnoid mater
High density if acute, low density if chronic; often mixed
Subarachnoid Haemorrhage
Bleeding between arachnoid and pia mater
Type of stroke (3-5% of all strokes). High mortality
Typical older middle age patients <60
usually spontaneous
Rupture of berry aneurysms 70%,
Arteriovenous malformations (AVM) (10%)
Other e.g. bleeding disorders, tumours, trauma
Subarachnoid Haemorrhage
Symptoms: Thunderclap headache, neck stiffness (irritation of meninges); acute confusion, neurological signs and reduced consciousness.
Subarachnoid Haemorrhage treatment
– bed rest, and reduce hypertension; if berry aneurysm – endovascular coil may be indicated
Subarachnoid Haemorrhage CT appearances
High density (fresh blood) within basal cisterns, cerebral fissures and sulci (indicating that it is within the subarachnoid space) Most commonly around COW (circle of willis) which is where most berry aneurysms occur
