Stroke/TIA Flashcards
Anatomy of blood supply to the brain
Recieves blood from two pairs of vessels, which interconnect in the cranial cavity to produce a cerebral circle of Willis
- vertebral arteries
- internal carotid arteries
Vertebral arteries enter cranial cavity through foramen magnum (inferior to the pons) and fuse to form the basilar artery
Internal carotids enter cranial cavity through carotid canals on either side
Describe the circle of willis
Left and right vertebral arteries join to form the basilar artery
- this ends in a bifurcation, giving rise to two posterior cerebral arteries
The internal carotid arteries give off the opthalmic artery, posterior communicating artery, middle cerebral artery and the anterior cerebral artery after entering the cerebral cavity
The circle of willis is formed as the posterior communicating artery connects the interior carotid artery and the posterior cerebral artery. While the anterior communicating artery connects the two anterior cerebral arteries
Which parts of the brain are supplied by which blood vessels
Anterior cerebral artery - frontal and parietal lobes
Middle cerebral artery - temporal lobe
Posterior cerebral artery - occipital lobe
Blood supply to the cerebellum
Superior cerebellar artery - cerebellar cortex, the cerebellar nuclei, and the superior cerebellar peduncles
Anterior inferior cerebellar artery - anterior inferior cerebellum, middle cerebellar peduncles, CNVII and CNVIII
Posterior inferior cerebellar artery - posterior inferior portion of the cerebellum and the inferior cerebellar peduncle
Pathological process that causes stroke
A stroke occurs when blood supply to part of the brain is interrupted or reduced - depriving the tissue of oxygen and nutrients
- brain cell death
Damage is caused when blood flow to the brain is at 50% of healthy normal
Causes of stroke
Small vessel occlusion/cerebral microangiopathy or thombosis in situ
- thrombosis
- cardiac embolism (AF, endocarditis)
- atherothromboembolism e.g. from carotids
CNS bleeds
- hypertension
- trauma
- aneurysm rupture
- anticoagulation
- thrombolysis
Rarer causes include carotid artery dissection, vasculitis, SAH, venous sinus thrombosis, antiphosphlipid syndrome, thrombophilia, Fabry diseas and CADASIL (genetic cause of stroke)
Risk factors for cerebrovascular disease
Hypertension Male gender Smoking Sedentary lifestyle Age >65 Diabetes mellitus Heart disease - valvular, ischaemic, AF Peripheral vascular disease Carotid bruit Obesity OSA Family history <55yr Combined OCP Hyperlipidaemia High alcohol use Increased clotting
Clinical presentation of stroke/TIA
TACS - total anterior circulation infarct
- higher cortical dysfunction
- homonymous hemianopia
- partial motor/sensory defect
PACS - partial anterior circulation infarct (1 of)
- higher cortical dysfunction
- partial motor/sensory defect
AND homonymous hemianopia
POCS - posterior circulation infarct (any of)
- cranial nerve palsy, bilateral motor/sensory defect, eye movement dysfunction and cerebellar dysfunction
OR isolated hemianopia
- brainstem/cerebellar signs
LACS - lacunar infarction
- pure motor stroke, pure sensory stroke, mixed sensorimotor stroke, hemiparesis, ataxic hemiparesis, dysarthria and/or clumsy hand
General symptoms
- hemiparesis
- hemiplegia + facial weakness
- hypotonic and absent reflexes
- aphasia - dominant hemisphere affected
What are the possible brainstem/cerebellar signs in a POCS or LACS stroke
Hemi/tetraparesis Sensory loss Diploplia Facial numbness Facial weakness Nystagmus Vertigo Dysphasia/dysarthria Horner's syndrome - hemianhydrosis, ptosis & miosis Altered conciseness Coma Locked-in syndrome
Differential diagnosis for stroke/TIA
Head injury Hypo/hyperglycaemia Subdural haemorrhage Intracranial tumours - SOL Hemiplegic migraines Post-ictal CNS lymphona Wernicke's encephalopathy Hepatic encephalopathy Encephalitis Toxoplasmosis Cerebral abscess Drug overdose Mycotic aneurysm
Typical onset of a vascular cause of weakness
Sudden-onset
Investigations for ?stroke/TIA
Bloods - FBC, ESR, CRP, lipids, glucose Urinarlysis - sugar presence Blood culture - if endocarditis suspected ECG - arrhythmia or MI CXR - neoplasia/heart failure CT - ASAP after admission MRI - if required
Role of CT, MRI and vascular imaging in the assessment of stroke
CT - differentiate infarctions and heamorrhages (new ischaemic stroke may not appear on CT, but can be identified due to lack of haemorrhage)
MRI - lesions of the cerebellum and brainstem as this area poorly visualised in CT
- also if there is a small stroke, not visible on CT
MR angiography
- blood vessels in the head and neck (vertebral, internal and external carotids)
- shows stenosis and thrombus formation (and aneurysms)
Further investigations of patients with stroke
Carotid doppler
- demonstrates internal carotid stenosis
- when thromboembolism is suspected, or carotid bruit heard
- carotid endarterectomy performed if >70% stenosed
Angiography
- not used as commonly
- used for localising intracerebral aneuryms and diagnosing cerebral vasculitides
72-hour ambulatory ECG
- identification of AF as cause of stroke
Acute management of stroke/TIA
Protect airway - hypoxia/aspiration
BP - needs to be <185/110 if thromboylsis considered
CT within 1 hour
Thromboylsis - alteplase
Anti-platelets if thrombolysis contraindicated
- 300mg continued for two weeks before being switched to long-term DAPT
Thrombectomy for large artery occlusion
- not very common
When would a CT be required within an hour for a stroke admission?
Thrombolysis considered High haemorrhagic risk - decreased GCS - raised ICP - headache - anticoagulated Unusual presentation e.g. fluctuating conciousness, fever Otherwise can wait up to 24 hours
Indications for thrombolysis
Ischaemic stroke confirmed on CT
Onset of symptoms <4.5 hours ago
Patient has no contraindications
Contraindications for thrombolysis
CT shows haemorrhage Mild/non-disabling deficit Recent surgery or trauma (<2 weeks) Previous CNS bleed AVM/aneurysm Severe liver disease, varices or portal hypertension Seizures at presentations BM<3 or >22 Stroke/serious head injury <3 months GI/urinary tract haemorrhage History of intracranial neoplasm Rapidly improving symptoms Known clotting disorder Anticoagulants or INR >1.7 Platelets <100x10^9/l BP >180/105mmHg
Role of the MDT in the management of stroke (PT, SALT)
Physiotherapy
- prevents risk of immobility (pressure sores, aspiration penumonia, constipation and contractures)
- avoids further injury and minimises fall risk
- Barthel’s index of activities in daily living allows assessment of a patients QoL and whether they need any extra help at home
SALT
- stroke can affect a patients ability to swallow, increasing risk of aspiration pneumonia
- swallow assessment and NG tube placement if required
Other
- incontinence requires bladder/bowel care ?early catheter
- positioning can minimise spasticity
- emotional lability and depression are common (due to failure of cortical inhibition of limbic system
Secondary prevention and management of risk factors in stroke/TIA
Antiplatelets after stroke - aspirin 300mg 2 weeks, then clopidogrel monotherapy Anticoagulation after AF stroke - CHA2DS2VASc score Carotid endarterectomy if >70% stenosis BP management Statin Lifestyle management - smoking cessation - stop thrombogenic drugs e.g. OCP - control diabetes - reduce alcohol consumption - improve diet and lose weight
Investigation of ?stroke in young adult
Bloods
- FBC, LFTs, glucose, U&Es, ECR, CRP, and syphilis serology
- very detailed coagulation screen for cause of thrombosis
- fibrinogen, ANA, lipid panel, lipoprotein A, serum protein elctrophoresis and sickle cell assay
ECG
CT
MRI and/or MRA
- distinguish irreversible injured tissue from that which is salvageable
Angiography of cerebral and neck vessels for patients with suspected dissection, or no other cause is found
Transcranial doppler ultrasound
CSF analysis if suspicion of infection
What is a TIA
Ischaemic (usually embolic) neurological event with symptoms lasting <24 hours
- without intervention, one in 12 will have a stroke within a week
Signs of a TIA
Specific to arterial territory (see stroke)
Amaurosis fugax
- retinal artery occlusion, causing unilateral progressive vision loss
Global events e.g. syncope and dizziness
- not common
Single or many highly stereotyped attacks (crescendo TIAs)
- may suggest critical intrancranial stenosis
- commonly the superior division of MCA
Management of TIA
Control CV risk factors - optimise blood pressure, lipids and glucose control Antiplatelet therapy - aspirin 300mg for 2 weeks, then clopidogrel 75mg Anticoagulation - if AF is cause Carotid endarterectomy - within 2 weeks if >70% stenosed Driving prohibited for a month
Assessment of TIA prognosis
ABCD^2 score
A: age >60 year (1) B: BP >140/90mmHg (1) C: clinical features - unilateral weakness (2) - isolated speech disturbance (1) D: duration of symptoms - greater than 1 hour (2) - 10-59 mins (1) D: diabetes (1)
Score 4 or more: high risk of early stroke
Score 6 or more: strongly predicts stroke
