Definitions
- TIA (Transient ischemic attack)
- Transient neuronal dysfunction secondary to focal ischemia (of brain, spinal cord, or retina) without (permanent) acute infarction
- Note: obsolete operational definitions used an arbitrary 24-hour cut off for duration of symptoms
- 10–15% of patients with TIA have a stroke within 3 months, 50% of which occur within 48 hours.
- Risk of stroke after TIA (NASCENT data)
- 26% over 2 years → carotid endarterectomy reduce risk 9%
- Stroke
- Permanent (i.e., irreversible) death of neurons caused by inadequate perfusion of a region of the brain or brainstem.
- Watershed infarct
- Ischemic infarction in a territory located at the periphery of two bordering arterial distributions due to a disturbance in flow in one or both of the arteries.
Aka
- Acute ischemic stroke (AIS)
- Cerebral infarction.
- Cerebrovascular accident (CVA) Obsolete term
Number
- Ischaemic stroke accounts for approximately 87% of all cerebrovascular accidents (CVA)
- Global Burden of Disease working group
- Reduction in the incidence of ischaemic stroke in high income countries (1990 → 2010)
- Western Europe: 127.65/100 000 dropping to 102.39/100 000
- Persistently high incidence in low to middle income countries
- Sub Saharan central Africa: 136.36/100 000 → 166.69/100 000
- Due to rates of smoking and increasing life expectancy
- 13% hemorrhagic stroke
- 10% ICH
- 3% SAH
- 87% ischaemic stroke
- 15-30% secondary to extracranial ICA stenosis
Aetiology
- Common
- Thrombotic ischaemic (more common)
- Atherosclerosis
- Carotid artery bruits, often atherosclerotic in nature, become audible when the residual vessel lumen diameter approaches 2.5 to 3 mm; they later disappear as the lumen is thinned to 0.5 mm
- Embolic ischaemic
- Where do the clots come?
- The Heart - 30%
- Neck Vessels - 30% (together with brain vessels)
- Brain Vessels - 30% (together with neck vessels)
- Atherosclerosis
- Dissection
- Unknown Cause - 30%
- Rare Causes - 5%
- Extracranial atherosclerosis of the aorta or carotids.
Cardioembolic – AF, infectious, metal valve replacement
- Rare
- Prothrombotic vascular anomalies – carotid web, fibromuscular dysplasia
- Thrombotic stroke
- Cerebral venous sinus thrombosis or hypercoagulopathic states (inherited and acquired)
- Traumatic occlusion
- Dissection of vessels
- Traumatic space occupying lesions leading to mass effect →
- Subfalcine herniation → anterior cerebral artery (ACA) infarction
- Transtentorial herniation → posterior cerebral artery (PCA) infarction
- Vasogenic occlusive causes
- Migraine or vasospasm
- Inflammatory vasculitides
- Occlusive disease processes such as the
- Delayed effects of radiation
- Moya fibromuscular dysplasia
- Cerebral amyloid angiopathy
- CADASIL
- Haemorrhagic
- Hypertension/Idiopathic
- Bleeding diathesis
- Vascular malformation
- Cerebral amyloid angiopathy
- Tumour
Risk factors
- Nonmodifiable
- Age
- Sex
- Race
- Family history
- Genetics.
- Modifiable
- Hypertension: Most important
- Smoking
- Double risk
- Diabetes
- Dyslipidaemia
- Diet
- AF
- Most common cardiogenic cause
- Etoh
- Ischaemic and haemorrhagic
Differential for stroke
- Differentiating TIA/ Stroke (Perth) from other disease
- Favour stroke
- Sudden
- Negative symptoms
- Vascular risk factors
- Favours other diagnosis
- Not sudden
- Positive/other symptoms
- No vascular risk factors
- Positive findings for another diagnosis
Stroke mimics
Single/multiple cortical/subcortical lesions with restricted diffusion | Cardioembolic infarcts | WM lesions with restricted diffusion e.g. embolic/borderzone | Deep grey nuclei + cortex e.g. hypoxic-ischaemic encephalopathy | Apparent subacute ischaemia |
MELAS; Hypoglycaemia; Seizures; Hemiplegic migraine; NMDA-R; Encephalitis; Venous infarct | Fat emboli – fracture/bone marrow infarcts; Metal emboli; Lung metastases | Splenial lesions – CLOCCS; Central pontine myelinolysis; Methotrexate toxicity; CADASIL Susac's | CJD; Wernicke's; CO poisoning; Metabolic; Vigabatrin | High grade glioma |
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