Cerebral Infarction Flashcards
What percentage of strokes are ischaemic and what percentage are hemorrhagic?
85% ischaemic
15% haemorrhagic
Causes of ischaemic stroke
Large artery atherosclerosis
Cardioembolic event e.g. atrial fibrillation
Small artery occlusion
Cryptogenic
Rarer causes e.g. arterial dissection, venous sinus thrombosis
Causes of haemorrhagic stroke
Primary intracerebral haemorrhage
Secondary haemorrhage
Subarachnoic haemorrhage
Arteriovenous malformation
What causes ischaemia in the brain?
Failure of cerebral blood flow to a part of the brain, caused by an interruption of the blood supply resulting in varying degrees of hypoxia
Effects of hypoxia in the brain
Stresses brain metabolism
Causes anoxia if prolonged
Anoxia causes infarction which results in the clinical presentation of stroke
Modifiable risk factors for stroke
Hypertension Smoking Hypercholesterolaemia Diet High BMI Sedentary lifestyle Excessive alcohol consumption Oral contraceptive pill
Non-modifiable risk factors for stroke
Previous stroke
Increasing age
Male
Family history
Impaired cardiac function e.g. recent MI
Hyper-coagulable states e.g. due to malignancy/genetics
How can hypertension cause a stroke?
Chronic hypertension worsens atheroma and affects small distal arteries
Major risk for hemorrhagic stroke
How does smoking increase the risk of stroke?
Smokers have a 2-fold increased risk of cerebral infarction and 3-fold increased risk of subarachnoid haemorrhage
Smoking may also worsen cardiac risk factors
How does hyperlipidaemia increase the risk of stroke?
Increased serum lipids cause blood vessel wall atheroma
Increased plasma levels of LDLs result in excessive amounts within the arterial wall
How does alcohol increase the risk of stroke?
Small amounts decrease risk, but heavy drinking increases the risk by a 2.5-fold
Possible aetiologies for stroke
Atherosclerotic narrowing Embolic - cardiac source Artery - arterial embolism Hypercoagulable state Arterial dissection Venous sinus thrombosis
What is a stroke?
Sudden onset of focal or global neurological symptoms caused by ischaemia or haemorrhage, lasting more than 24 hours
What is a transient ischaemica attack?
Sudden onset of focal or global neurological symptoms which resolves within 24 hours
Clinical presentation of anterior cerebral artery occlusion
Contralateral paralysis of foot and leg
Contralateral sensory loss over foot and leg
Contralateral impairment of gait and stance
Clinical presentation of middle cerebral artery occlusion
Contralateral paralysis of face, arm and leg
Contralateral sensory loss of face, arm and leg
Contralateraly homonymous hemianopia
Gaze paralysis to opposite side
Aphasia if stroke occurs on dominant side
Unilateral neglect and agnosia for hal of external space if non-dominant stroke
Clinical presentation of right hemisphere stroke
Left-sided hemiplegia Left-sided homonymous hemianopia Left-sided neglect syndromes Visual agnosia Sensory agnosia Anosagnosia Prosopagnosia
Clinical presentation of lacunar stroke syndromes
Devoid of cortical signs - no dysphasia, neglect, hemianopia Pure motor stroke Pure sensory stroke Dysarthria Ataxic hemiparesis
Anatomy involved in posterior circulation stroke
Brainstem
Cerebellum
Thalamus
Occipital and medial temporal lobes
Clinical presentation of posterior circulation stroke
Coma Vertigo Nausea Vomiting Cranial nerve palsies Ataxia Hemiparesis Hemisensory loss Crossed sensorimotor deficits Visual field defects
Acute ischaemic stroke therapies
Restore blood supply Prevent extension of ischaemic damage Protect vulnerable brain tissue CT head Aspirin Heparin Neuroprotectant Tissue plasminogen activator Intra-arterial therapy e.g. thrombectomy
What are the criteria for tissue plasminogen activator use in acute ischaemic stroke?
< 4.5 hours from symptom onset
Disabling neurological deficit
Symptoms present > 60 minutes
Consent
Exclusion criteria for use of tissue plasminogen activator in acute ischaemic stroke
Blood on CT Recent surgery Recent episodes of bleeding Coagulation problems BP > 185 systolic or > 110 diastolic Glucose < 2.8 or > 22mmol/L
When is it best to use thrombectomy?
For removal of large vessel occlusive/ischaemic stroke
Treatment for symptomatic internal carotid artery stenosis
Cardiac endarterectomy
Investigations for stroke
FBC, glucose, lipids, ESR CT/MRI head ECG Echo Carotid doppler ultrasound Cerebral angiogram/venogram Hyper coagulable blood screen
Agents used in secondary prevention of stroke
Antihypertensives Anti-platelets Lipid lowering agents Warfarin for AF Carotid endarectomy
Differential diagnoses for stroke
Post-ictal states e.g. Todd's paralysis Hypoglycaemia Intracranial masses Vestibular disease Bell's palsy Functional hemiparesis Migraine UTIs in patients with dementia
Management of stroke after initial medical/surgical intervention
Prevention of recurrence
Prevention of complications
Rehabilitation
Re-integration into community
Objectives of stroke care
Reduce mortality
Reduce residual disability amongst survivors
Improve psychological status of patients and care-givers
Improve patient/carer knowledge
Maximise quality of life
Who might be involved in the rehabilitation of a stroke patient? (members of multidisciplinary team)
Clinical staff Specialised stroke nurses Physiotherapists Speech and language therapists Occupational therapists Dietician Psychologist Orthoptist
