Pathology of Cerebro-Vascular Disease Flashcards
What are the major blood vessels of the brain?
Right and left internal carotid arteries
Right and left vertebral arteries
Basilar artery
Right and left anterior cerebral arteries
Right and left middle cerebral arteries
Right and Left posterior cerebral arteries
Anterior communicating artery
Right and left posterior communicating arteries
What does the right middle cerebral artery supply?
Left body strength
Left body sensation
What does the left middle cerebral artery supply?
Right body strength
Right body sensation
Language
What does the right posterior cerebral artery supply?
Perception of the left visual field
What does the left posterior cerebral artery supply?
Perception of the right visual field
What is the cerebellum supplied by (Arteries)?
Posterior inferior, anterior inferior and superior cerebellar arteries
Presentation of brain aneurysm
Severe headache
Vomiting
Extremely sudden presentation
Possible coma
Investigation of brain aneurysm
Unenhanced CT
LP
What does LP stand for?
Lumbar puncture
Where do most intracranial aneurysms arise from?
Branch points of the circle of willis
Treatment of ruptured intracranial aneurysm
Endovascular coil embolisation
Surgical clipping
Prevalence of aneurysms
2%
Complications of intracranial aneurysm
Hydrocephalus
Vasospastic infarcts
Disability
Lobes of the brain
Frontal
Parietal
Temporal
Occipital
Do the veins of the brain accompany the arteries?
No
Definition of stroke
Focal neurological deficit (loss of function affecting a specific region of the CNS) due to disruption of blood supply
Pathological mechanism of stroke
Interruption of supply of O2 and nutrients, causing damage to brain tissue
Causes of interruption to supply of oxygen to brain causing stroke
Vessel wall abnormality - atheroma - vasculitis - outside pressure Blood flow - decreased - increased BP Blood constitutents - thrombosis of arteries and rarely veins - bleeding due to anticoagulation, reduced platelets and clotting factors
3 main causes of localized interrupted blood supply
- ATHEROMA AND THROMBOSIS of the artery causing ischaemia
- THROMBOEMBOLISM causing ischaemia
- RUPTURED ANEURYSM of a cerebral vessel causing haemorrhage
Internal carotid artery thrombosis typically causes ischaemia where?
Middle cerebral artery territory
Definition of ischaemia
A relative or absolute lack of blood supply in a tissue or an organ
What does TIA stand for?
Transient ischaemic attack
What is the viability of the tissues in a TIA?
Still viable tissues
What is the viability of the tissues in a stroke?
Infarcted tissue
Pathogenesis of ischaeimc stroke
Brain very sensitive to oxygen ischaemia
A few minutes hypoxia or anoxia will cause brain ischaemia
Can lead to infarction
What is a localized area of brain death called?
Regional cerebral infarct
Histology of infarcted brain tissue
Loss of neurones
Foamy macrophages
Repair process leading to gliosis
What is gliosis the CNS equivalent of?
Fibrosis
What two factors can cause an aneurysm to form?
Weakening of wall
HTN
2 common sites of ruptured vessels causing haemorrhagic stroke
Basal ganglia
- microaneurysms form in HTN patients
Circle of willis
- berry aneurysms form in HTN patients
Causes of generalised problem with blood supply or hypoxia affecting the brain
- Low O2 in blood
- CO poisoning
- near drowning
- resp arrest e.g. pneumonia - Inadequate supply of blood (blood flow not occurring)
- cardiac arrest with immediate resolution
- Hypotension
- brain swelling e.g. trauma due to compressed vessels - Inability to use O2 (RARE)
- e.g. cyanide poisoning
What are watershed zones?
Areas of the brain that are poorly perfused
What % of strokes occur in patients over 65 y/o?
75%
Two types of stroke
Ischaemic
Haemorrhagic
Causes of ischaemic stroke
Large artery atherosclerosis (35%) Cardioembolic e.g. AF (25%) Small artery occlusion e.g. lacune (25%) Undetermined/cryptogenic (10-15%) Rare causes (<5%) - arterial dissection - venous sinus thrombosis
What % of strokes are ischaemic?
85%
What % of strokes are haemorrhagic?
15%
Types of haemorrhagic stroke
Primary intracerebral haemorrhage 70%
Secondary haemorrhage 30%
- SAH
- AV malformation
Stoke risk increases with what?
Age
What is the public awareness campaign for stroke?
FAST
- Facial weakness
- Arm weakness
- Speech problems
- Time to call 999
Risk factors for stroke
HTN Smoking DM Cholesterol Diet Activity High BMI / Sedentary lifestyle Alcohol Previous stroke Older Male Family history Impaired cardiac function - recent heart attack - AF Oral contraceptives (with oestrogen) HRT Hypercoagulable states - malignancy - genetic
What is the most important modifiable risk factor for stroke?
HTN
Where does HTN tend to cause the damage in stroke?
Small end arteries in the basal ganglia and brain stem
Why does increased serum lipid levels lead to increased risk of stroke?
Blood vessel wall atheroma
Increased plasma level of low density lipoprotein (LDL) results in excessive amounts of LDL within the arterial wall
What contributes to LDL-C deposition in arterial walls?
HTN
Smoking
DM
What colour is brain tissue on CT?
Black
What colour is CSF on CT?
Black
What colour on bone on CT?
White
Which of MRI and CT is easier to pick up smaller strokes?
MRI
What arteries make up the anterior circulation to the brain?
2 internal carotid arteries
- 2X ACA
- 2 MCA
What arteries make up the posterior circulation to the brain?
2 vertebral arteries - 1 basilar
- 3 pairs of cerebellar arteries
- 2 posterior cerebral arteries
Symptoms of ACA occlusion
Contralateral
Paralysis of foot and leg
Sensory loss over foot and leg
Impairment of gait and stance
Symptoms of MCA occlusion
Contralateral
- paralysis of face/arm/leg
- sensory loss of face/arm/leg
Homonymous hemianopia
Gaze paralysis to opposite side
Loose visual fields on same side as the paralysis
Aphasia if stroke on dominant (left) side
Unilateral neglect and agnosia for half of external space if non dominant stroke (usually right side)
Symptoms of damage to the left hemisphere
Hemiplegia
Homonymous hemianopia
Dysphagia
Symptoms of damage to the right hemisphere
Left hemiplegia
Homonymous heminaopia
Neglect syndromes (agnosia)
Types of neglect syndromes (agnosia)
Visual
Sensory
Anosagnosia
Prosphanosia
What is anosagnosia?
Denial of hemiplegia - unawareness that have had stroke
What is prosophanosia?
Failure to recognise faces
What is a feature of main lacunar stroke syndromes?
Devoid of ‘cortical signs
Affects deep pathways in the brain so dont cause cortical syndromes e.g. no dysphagia, neglect, hemianopia
What does a lacunar stroke syndrome usually present as?
Weakness
Clumsiness
Numbness
Ataxic hemiparesis
Symptoms of posterior circulation damage to the brain
Depends on where affected
- brain stem
- cerebellum
- thalamus
- occipital and medical temporal lobes
Symptoms of brainstem dysfunction
Coma Vertigo Nausea and vomiting CN palsies Ataxia Hemiparesis Hemisensory loss Crossed sensorimotor deficits Visual deficits
Types of stroke
Total anterior circulation stroke (TACS)
Partial anterior circulation stroke (PACS)
Lacunar stroke (LACS)
Posterior circulation stroke (POCS)
Which of the types of stroke has the worst prognosis?
TACS
Which of the types of stroke has the best prognosis?
LACS / POCS
What % of patients with a TIA have stroke recurrence within the 1st 2 weeks?
10%
Treatment of TIA
Antiplatelets
Anti HTNs
Statins
Endarterectomy
Causes of TIA
Athersclerotic narrowing Embolic-cardiac source (AF, recent MI) Hypercoagulable state Arterial dissection Venous sinus thrombosis
What should acute ischaemic stroke therapies do?
Restore blood supply
Prevent extension of ischaemic damage
Protect vulnerable brain tissue
What does TPA stand for?
Tissue plasminogen activator
What does TPA do?
It is involved in the breakdown of blood clots
What is the strict criteria for TPA use?
< 4.5 hours from symptom onset
Disabling neurological deficit
Symptoms present > 60 mins
Consent obtained
Exclusion criteria for IV TPA
Anything that increases the possibility of haemorrhage - blood on CT scan - recent surgery - recent episodes of bleeding - coagulation problems BP > 125 systolic or > 110 diastolic Glucose < 2.8 or > 22 mmol/L
What does the benefit of TPA decline with?
Time
What is the effective treatment in symptomatic internal carotid artery stenosis?
Carotid endarterectomy
What can be used in secondary prevention of stroke?
Anti HTNs Anti platelets Lipid lowering agents Warfarin for AF Carotid endarectomy
After the acute phase has settled, what is the management of acute stroke?
Prevention of stroke recurrence
Prevention of complications related to stroke
Rehabilitation
Re-integration into the community
What are the objectives of stroke care?
Reduce mortality
Reduce residual disability amongst survivors
Improve psychological status of patients and care givers
Improve patient/care giver knowledge
Maximize quality of life
Investigations for stroke
Routine blood tests - FBC - glucose - lipids - ESR CT or MRI ECG Carotid doppler USS Cerebral angiogram/venogram Hypercoagulable blood screen
Definition of stroke
Is the sudden onset of focal or global neurological symptoms caused by ischemia or haemorrhage and lasting more than 24 hours
What % of strokes are ischaemic?
85%
Definition of TIA
Sudden onset of focal or global neurological symptoms if the symptoms resolve within 24 hours
How quickly do most TIAs resolve?
1 - 60 mins
Definition of ischaemia
Failure of the cerebral blood flow to a part of the brain, caused by an interruption of the blood supply to the brain
How much of the metabolic rate does the brain use at rest?
20%
Pathology of stroke
Varying degrees of hypoxia (decreased O2)
Hypoxia stresses the brains metabolism - this is especially important in ischaemic pneumbra
If prolonged the hypoxia leads to anoxia
Anoxia leads to infarction (complete cell death leading to necrosis)
Definition of anoxia
No oxygen
What further damage can occur after necrosis in stroke?
Oedema
Secondary haemorrhage
What arteries do lacunar infarcts involve?
Perforating arteries around the internal capsule, thalamus and basal ganglia
A stroke of the anterior cerebral artery will cause what?
Contralateral hemiparesis and sensory loss
LL > UL
A stroke of the middle cerebral artery will cause what?
Contralateral hemiparesis and sensory loss, UL > LL
Contralateral homonymous hemianopia
Aphasia
A stroke of the posterior cerebral artery will cause what?
Contralateral homonymous hemianopia with macular sparing
Visual agnosia
A stroke of the basillar artery causes what?
Locked in syndrome
What is webers syndrome and what does it result in?
Stroke of the branches of the posterior cerebral artery that supply the midbrain
Ipsilateral CN III palsy
Contralateral weakness of upper and lower extremity
What does a stroke of the posterior inferior cerebellar artery?
Ipsilateral facial pain and temp loss
Contralateral limb/torso pain and temp loss
Ataxia
Nystagmus
What does a stroke of the anterior inferior cerebellar artery cause?
Symptoms similar to posterior inferior cerebellar artery stroke but also
ipsilateral facial paralysis and deafness
What does a stroke of the retinal / ophthalmic artery result in?
Amaurosis fugax
What does a lacunar stroke present with?
Isolated hemiparesis, hemisensory loss or hemiparesis with limb ataxia
What do lacunar strokes have a strong association with?
HTN
What is conduction aphasia?
Speech is fluent but repetition is poor
Aware of the errors they are making
Comprehension is normal
What causes conduction aphasia?
Stroke affecting the arcuate fasiculus (the connection between wernickes and brocas)
What % of patients with intracranial venous thrombosis have sagittal sinus thrombosis?
50%
Features of intracranial venous thrombosis
Headache (may be sudden onset)
Nausea and vomiting
Presentation of sagittal sinus thrombosis
Seizures
Hemiplegia
Headache
N and V
Causes of cavernous sinus syndrome
Cavernous sinus thrombosis
Local infection (e.g. sinusitis)
Neoplasia
Trauma
Presentation of cavernous sinus thrombosis
Headache
N and V
Periorbital oedema
Ophthalmoplegia (6th nerve damage occurs before 3rd and 4th)
If trigeminal nerve involvement - hyperaesthesia of upper face and eye pain
Central retinal vein thrombosis
What does lateral sinus thrombosis typically cause?
6th and 7th CN palsies
Treatment of ischaemic stroke due to occlusion of anterior circulation presenting < 4.5 hours ago
Thrombolysis AND thrombolectomy
What is the tool to assess patients with stroke symptoms in an acute setting and what does this stand for?
ROSIER
Recognition of stroke in the emergency room
Patients following an ischaemic stroke should receive what?
Aspirin 300mg once daily for 14 days before considering anticoagulant treatment
If have had TIA or a stroke, how long can you not drive for?
4 weeks
Secondary prevention of stroke
1st line - clopidogrel
2nd line - aspirin in combination with modified release dipyridamole
Criteria for thrombectomy
- 6 - 24 hours. If potential to salvage brain tissue - as shown by CT perfusion or diffusion weighted MRI sequences showing limited infarct core volume AND confirmed occlusion of proximal anterior circulation
- ASAP and within 6 hours. If confirmed proximal anterior circulation stroke demonstrated by CTA or MRA
What does an anterior cerebral artery stroke cause and NOT cause?
Would CAUSE - leg weakness
Would NOT CAUSE - Face weakness or speech impairment
Criteria for carotid endarectomy
Suffered stroke or TIA in the carotid territory and are not severely disabled
Who have carotid stenosis > 70% (ECST criteria) or > 50% (NASCET criteria)
What is the first line radiological investigation for suspected stroke and what does it rule out?
Non contrast CT head
Rules out haemorrhagic event
What tests must be done if < 55 y/o with no obvious cause of the stroke?
Autoimmune and thrombophilia screening
What is the scale tool used to measure disability or dependence in activities of daily living in stroke patients?
Barthel index
What is characteristic of brain stem infarcts?
‘Crossed findings’ - with cranial findings IPSILATERAL to the lesion and motor or sensory findings on the CONTRALATERAL side of the body
What is webers syndrome?
Midbrain stroke syndrome
- involves fascicles of the oculomotor nerve resulting in an ipsilateral CN III palsy and contralateral hemiplegia or hemiparesis
What is the most commonly survived stroke which affects the brainstem? What is this syndrome called?
Stroke affecting the posterior inferior cerebellar artery (PICA) - called lateral medullary syndrome
Presentation of lateral medullary syndrome
Facial and contralateral body loss of sensation along with nystagmus and ataxia
What is a feature of lacunar infarct?
Isolated hemisensory loss
What does pontine haemorrhage commonly occur secondary to?
Chronic HTN
Presentation of pontine haemorrhage
Life threatning Reduced GCS Quadraplegia Miosis Absent horizontal eye movements
A stroke of where can cause aphasia?
Dominant hemisphere middle cerebral artery strokes
What does a cerebellar stroke present similarly to?
Vestibular neuritis