Neurology - Stroke Flashcards
What is a stroke?
A sudden interruption in the vascular supply of the brain, resulting in irreversible damage to neural tissue.
Types of stroke.
- ischaemic (85%)
- haemorrhagic (15%)
Subtypes of ischaemic stroke.
- thrombotic stroke (ie. thrombosis from large vessels)
- embolic stroke (atrial fibrillation is risk factor)
Risk factors for ischaemic stroke.
- age
- hypertension
- smoking
- hyperlipidaemia
- diabetes mellitus
- atrial fibrillation
Subtypes of haemorrhagic stroke.
- intracerebral haemorrhage (bleeding within the brain)
- subarachnoid haemorrhage (bleeding on the surface of the brain)
Risk factors for haemorrhagic stroke.
- age
- hypertension
- arteriovenous malformation
- anticoagulation therapy
Stroke by anatomy.
Anterior cerebral artery infarct.
Contralateral hemiparesis
Sensory loss (more pronounced in lower extremities)
Stroke by anatomy.
Middle cerebral artery infarct.
Contralateral hemiparesis
Sensory loss (more pronounced in upper extremities)
Contralateral homonymous hemianopia.
Aphasia.
Stroke by anatomy.
Posterior cerebral artery infarct.
Contralateral homonymous hemianopia (macula sparing)
Visual agnosia
Stroke by anatomy.
Posterior inferior cerebellar artery infarct.
Ipsilateral:
- facial pain
- temperature loss
Contralateral:
- limb / torso pain
- temperature loss
Ataxia / nystagmus
Stroke by anatomy.
Anterior inferior cerebellar artery.
Ipsilateral:
- facial paralysis / pain
- deafness
Contralateral:
- limb / torso pain
- temperature loss
Ataxia / nystagmus
Stroke by anatomy.
Basilar artery infarct.
Locked in syndrome:
The body and most of the facial muscles are paralysed, but consciousness remains.
Types of stroke (Oxford Stroke Classification)
- total anterior circulation infarcts (TACI)
- partial anterior circulation infarcts (PACI)
- posterior circulation infarcts (POCI)
- lacunar infarcts (LACI)
Features of TACI.
MCA and ACA affected, causing all of:
- contralateral hemiparesis
- contralateral homonymous hemianopia
- dysphasia
Features of PACI.
Branches of the ACA / MCA are affected, causing two of:
- contralateral hemiparesis
- contralateral homonymous hemianopia
- dysphasia
Features of POCI.
Vertebrobasilar arteries affected, causing one of:
- cerebellar or brainstem syndromes
- loss of consciousness
- contralateral homonymous hemianopia (macular sparing)
What areas of the brain do the lacunar arteries supply?
- internal capsule
- thalamus
- basal ganglia
Features of LACI.
Involves perforating arteries around the internal capsule, thalamus and basal ganglia, causing one of:
- unilateral weakness
- pure sensory stroke
- ataxic hemiparesis
Which symptoms of stroke are more suggestive of haemorrhagic stroke?
- reduced consciousness
- headache
- nausea and vomiting
- seizure
BEFAST mnemonic for stroke.
Positive predictive value of 78%.
Imaging for stroke.
Non-contrast CT head scan is the first line investigation for a suspected stroke.
CT findings.
Ischaemic stroke.
- areas of low density
- hyperdense artery sign
CT findings.
Haemorrhagic stroke.
- hyperdense material (blood)
- oedema
When is thrombolysis for acute ischaemic stroke indicated?
Thrombolysis with alteplase is given if:
- administered within 4.5 hours of onset of stroke symptoms
- haemorrhage has been excluded
Absolute contraindications to thrombolysis of an acute ischaemic stroke.
- previous intracranial haemorrhage
- seizure at onset of stroke
- intracranial neoplasm
- active bleeding
- pregnancy
- oesophageal varices
- malignant hypertension
When is thrombectomy for acute ischaemic stroke indicated? (6 hours)
Offer thrombectomy within 6 hours of symptom onset, alongside IV thrombolysis, to people who have:
- acute ischaemic stroke
- confirmed occlusion of the proximal anterior circulation
How can occlusion of the proximal anterior circulation be confirmed?
Computed tomographic angiography (CTA) or magnetic resonance angiography (MRA).
When is thrombectomy for acute ischaemic stroke indicated? (24 hours)
Offer thrombectomy within 24 hours of symptom onset to people who have:
- confirmed occlusion of proximal anterior circulation
- potential to salvage brain tissue
How is the potential to salvage brain tissue by thrombectomy decided?
CT perfusion scan of the head.
When is carotid artery endarterectomy performed?
Recommended if a patient has suffered a stroke or TIA in the carotid territory and has performance status <3, where carotid stenosis is severe.
Management of haemorrhagic stroke.
Surgical management where deemed appropriate (PS).
Supportive management.
What is a transient ischaemic attack (TIA)?
A transient episode of neurological dysfunction caused by focal brain, spinal cord or retinal ischaemia, without acute infarction.
Clinical features of TIAs.
Similar clinical features to a stroke, with resolution within an hour.
What is the role of the ABCD2 score?
Estimates the risk of stroke after a TIA.
Management of TIA.
- 300mg aspirin immediately
- continue aspirin until specialist review
Imaging for TIA.
MRI used to determine the territory of ischaemia.
Secondary prevention of stroke.
- Clopidogrel
- High intensity statin
What is a subarachnoid haemorrhage?
An intracranial haemorrhage that is defined as the presence of blood within the subarachnoid space.
Causes of subarachnoid haemorrhage.
- head injury
- intracranial berry aneurysm
- infective aneurysm
Presentation of subarachnoid haemorrhage.
- severe, thunderclap headache (occipital)
- nausea and vomiting
- meningism
- coma
- seizure
Why are ECG changes seen in subarachnoid haemorrhage?
ECG changes including ST elevation may be seen, secondary to:
- autonomic neural stimulation from hypothalamus
- elevated levels of circulating catecholamines
Investigations of subarachnoid haemorrhage.
- non-contrast CT within 6 hours
- lumbar puncture if CT not performed within 12 hours
Role of lumbar puncture in subarachnoid haemorrhage.
Perform LP 12 hours following the onset of symptoms to allow the development of xanthochromia (billirubin 2° haemolysis).
Xanthochromia helps distinguish true SAH and traumatic tap.
Management of subarachnoid haemorrhage.
Supportive:
- bed rest
- analgesia
- VTE prophylaxis
- reverse anticoagulation
Refer to intervention neuroradiology for coil fitting.
Complications of subarachnoid haemorrhage.
- re-bleeding
- hydrocephalus
- vasospasm
- hyponatraemia
- seizures
Predictive factors in subarachnoid haemorrhage.
- conscious level on admission
- age
- amount of blood visible on CT scan
Types of traumatic brain injury following trauma.
- extradural haematoma
- subdural haematoma
- subarachnoid haemorrhage
- intracerebral haematoma
Features of extradural haematoma.
Rupture of middle meningeal artery results in bleeding into the space of the dura mater and the skull.
Patients often exhibit a lucid interval of a few hours.
Features of subdural haematoma.
Bleeding into the outermost meningeal layer, most commonly occuring around the frontal and parietal lobes.
Slower onset of symptoms than an extradural haematoma, with fluctuating consciousness.
Features of a intracerebral haematoma.
A collection of blood within the brain parenchyma causes patient to present similarly to ischaemic stroke.
Signs of raised intracranial pressure.
NB: hypertension occurs as when ICP is above MAP, brain can no longer receive oxygen. This activated sympathetic nervous system to raise blood pressure.
Pupillary findings in head injury.
Unilateral dilated pupil with sluggish light response.
Oculomotor nerve compression secondary to tentorial herniation.
Pupillary findings in head injury.
Unilateral dilated pupil with cross-reactive light response.
Optic nerve injury
ie. constricts when light shone in contralateral eye; no response when light shone in dilated pupil.
Pupillary findings in head injury.
Bilaterally dilated pupils with sluggish light response.
- poor CNS perfusion
- bilateral oculomotor nerve palsy
Pupillary findings.
Bilaterally constricted pupils.
- opiates
- pontine lesions
- metabolic encephalopathy
Pupillary findings.
Unilateral constricted pupils with preserved light response.
Sympathetic pathway disruption.
Indications of CT head within 1 hour following head injury.
- GCS <13 on initial assessment
- suspected open or depressed skull fracture
- signs of basal skull fracture
- post-traumatic seizure
- focal neurological deficit
- episodes of vomiting
Signs of base of skull fracture.
Indications of CT head within 8 hours following head injury.
- age >65 years
- anticoagulant use
- history of bleeding / clotting disorders
- dangerous mechanism of injury
- > 30 minutes retrograde amnesia of events before the head injury