Cerebrovascular Disease and Trauma Flashcards
What is cerebral oedema
Excess accumulation of fluid in the brain parenchyma
What are the two main types of cerebral oedema (2)
Vasogenic - disruption of the blood brain barrier
Cytotoxic - secondary to cellular injury (e.g. hypoxia/ischaemia)
What does cerebral oedema result in
Raised ICP
How is cerebral oedema cleared from the parenchyma (3)
Into subarachnoid CSF
Into ventricles
Into bloodstream
What does cerebral oedema look like on CT
Loss of differentiation of brain parenchyma
What is a non-communicating hydrocephalus
Involves obstruction of flow of CSF
What is a communicating hydrocephalus
Involves no obstruction, but problems with reabsorption of CSF into venous sinuses
What is ICP measured in
mmHg
What is the normal ICP at rest
7-15mmHg for a supine adult
What can cause a rise in ICP (3)
Space occupying lesions
Oedema
Or both!
What are the consequences of raised ICP
Increased pressure forces brain against unyielding bony wall of skull - results in herniation of brain structures where space is available
What are the three areas of brain herniation (3)
Subfalcine herniation
Transtentorial herniation
Tonsillar herniation
What is the third largest cause of death in the UK
Stroke
How many people does stroke affect every year
More than 100,000 people
What is the definition of a stroke (WHO)
A stroke is a clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal, and at times global loss of cerebral function, with symptoms lasting more than 24 hours or leading to death, with no apparent cause other than that of vascular origin.
What causes of stroke does the WHO definition include (4)
Cerebral infarction.
primary intracerebral haemorrhage
Intraventricular haemorrhage
Most cases of subarachnoid haemorrhage
What causes of stroke does the WHO definition exclude (4)
Subdural haemorrhage
Epidural haemorrhage
Intracererbral haemorrhage
Infarction caused by infection or tumour
What is a transient ischaemic attack (TIA)
A temporary blockage of a cerebral artery by a clot - this is a warning stroke that should be taken very seriously
How long does a TIA typically last
Less than 5mins, on average lasting 1min
What are the consequences of a TIA
There is usually no permanent injury to the brain
What proportion of people with get a TIA will suffer a significant infarct within 5 years
1/3rd
What is a good predictor of future infarcts
TIA
What is a haemorrhagic stroke
A haemorrhage into the substance of the brain, due to the rupture of a small intraparenchymal vessel
What is the most common location of haemorrhagic strokes
Basal ganglia
What is a risk factor for a haemorrhagic stroke (2)
Hypertension - present in over 50% of bleeds
Arteriovenous malformations
How does a haemorrhagic stroke present (4)
Severe headache
Vomiting
Rapid loss of consciousness
Focal neurological signs
Where do arteriovenous malformations occur within the CNS
Anywhere
When do arteriovenous malformations become symptomatic
Anywhere between the 2nd and 5th decade (mean age 31.2 years)
How do arteriovenous malformations present (4)
Haemorrhage
Seizures
Headache
Focal neurological deficits
What is high pressure within an ateriovenous malformation associated with
Massive bleeding
How can you visualise AV malformations
Angiography
What is the morbidity after rupture of an AV malformation
53-81%
What is the mortality of an AV rupture
10-17.6%
What is the treatment for a ruptured AV malformation (3)
Surgery
Embolization
Radiosurgery
What is an arteriovenous malformation
A malformation in which blood passes quickly from the artery to the vein, bypassing the normal capillary network
What is a cavernous angioma
A well-defined malformative lesion composed of closely packed vessels with no parenchyma interposed between vascular spaces
Where are cavernous angiomas found
Anywhere in the CNS
When do cavernous angiomas become symptomatic
Usually after age 50
How do cavernous angiomas present (4)
Headache
Seizures
focal deficits
haemorrhage
What is associated with recurrent bleeds of a cavernous angioma
Low pressure
What is the treatment for a cavernous angioma
Surgical
What does a target sign in a T2 weighted head MRI indicate
Cavernous angioma
What is the most common cause of sub-arachnoid haemorrhage
Rupture of a berry aneurysm - present in 1% of the general population
What is the pathogenesis of sub-arachnoid haemorrhages (3)
80% - internal carotid artery bifurcation
20% - occur withint he vertebro-basilar circulation
30% - multiple aneurysms
What is associated with the greatest risk of rupture of a berry aneurysm
Diameter > 6-10mm
What is the presentation of a subarachnoid haemorrhage (3)
Sudden onset of severe headache (worst headache ever)
Vomiting
Loss of consiousness
What is the treatment fo berry aneurysm
Endovascular treatment - coil
What is an infarction (CNS)
Tissue death due to ischaemia
What is the most common form of cerebrovascular disease
Ischaemia
What proportion of strokes are ischaemia
70-80%
What is the most common cause of CV ischaemia
Cerebral atherosclerosis
What are some risk factors for cerebral ischaemia (3)
Hypertension
Smoking
Diabetes
What does the term focal cerebral ischaemia mean
Defined vascular territory
What does the term global cerebral ischaemi mean
Systemic circulation failure
What vessels is cerebral ischaemia worst in
Larger vessels - e.g. extracerebral arteries
What are larger vessels prone to
Thrombosis
What are the most common sites of thrombosis (2)
Near carotid bifucation
In Basilar artery
What is the most common cause of intra cerebral ischaemia
Emboli
Where do cerebral emboli usually originate (2)
Heart
Atherosclerotic plaque
What artery is most commonly affected by emboli
Middle cerebral artery branches
What are the three vascular territories of the brain
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
What are the pathological features of CNS infarcts (4)
Tissue necrosis (stains)
Rarely haemorrhagic
Permanent damage in the affected area
No recovery of tissue
What are the pathological features of CNS haemorrahagic events (5)
Bleeding. Dissection of parenchyma Fewer macrophages Limited tissue damage (periphery) Partial recovery possible
What is the single largest cause of death in people under 45
Trauma
What proportion of trauma deaths can be attributed to TBI
25%
What is the morbidity associated with TBI (2)
19% vegetative or severely disabled
31% good recovery
What are the different forms of brain trauma (6)
Non-missile and missile. Non-missile. Acceleration/deceleration. Rotation. RTA, falls and assaults. Focal or diffuse.
What are the clinical features of a skull fracture (4)
Fissure fractures often extend into the base of the skull.
May pass through the middle ear or anterior cranial fossa.
Otorrhoea or rhinorrhoea.
Infection risk
Where does bruising occur in skull fractures (2)
Behind ears
Racoon eyes
What is a contusion
Brain in collision with the skull - surface bruising
What is a brain laceration
A contusion with torn pia mater
What areas of the brain are bruised in a contusion (2)
Lateral surfaces of hemispheres
Inferior surfaces of frontal and temporal lobes
What are the two types of brain contusion
Coup
Contrecoup
What is diffuse axonal injury
Shear and tensile forces of TBI affect axons (stretching) during head injury
What does diffuse axonal injury occur
At the time of head injury
What is particularly vulnerable in diffuse axonal injury
Midline structures are particularly affected (e.g. corpus callosum, rostral brainstem and septum pellucidum)