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
