Neurology Flashcards
(545 cards)
Define Stroke
Stroke is defined as an acute neurological deficit lasting more than 24 hours and caused by cerebrovascular aetiology.
It is also referred to as a cerebrovascular accident
Epidemiology of Stroke
- Stroke is the third leading cause of mortality in the US and the UK
- The average age for a stroke is 68 to 75 years old
- Stroke rates are higher in Asian and black African populations than in Caucasians
- M>F
Aetiology of Ischaemic stroke
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Ischaemic (80%)
- Reduction in cerebral blood flow due to arterial occlusion or stenosis. Typically divided into lacunar (affecting blood flow in small arteries), thrombotic and embolic
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Cardiac:
- Atherosclerotic disease: smoking, hypertension, diabetes, high cholesterol
- Atrial fibrillation
- Paradoxical embolism due to septal abnormality, such as a patent foramen ovale
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Vascular
- Aortic dissection
- Vertebral dissection
- Vasculitides
-
Haematological
- Hypercoagulability, such as antiphospholipid syndrome
- Sickle cell disease
- Polycythaemia
Aetiology of Haemorrhagic stroke
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Haemorrhagic (20%)
- Ruptured blood vessel leading to reduced blood flow
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Intracerebral: bleeding within the brain parenchyma
- Trauma
- Arteriovenous malformation
- Cerebral amyloid
- Hypertension
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Subarachnoid: bleeding between the pia mater and arachnoid mater
- Trauma
- Berry aneurysm
- Arteriovenous malformation
- Intraventricular: bleeding within the ventricles
RF for Stroke
- Hypertension
- Age: the average age for a stroke is 68 to 75 years old
- Smoking
- Diabetes
- Hypercholesterolaemia
- Atrial fibrillation
- Vasculitis
- Family history
- Haematological disease: such as polycythaemia
- Medication: such as hormone replacement therapy or the combined oral contraceptive pill
Pathophysiology of Stroke
Patients typically have a focal neurological deficit which corresponds to the region of the brain that’s affected e.g.
- An anterior cerebral artery stroke affects the feet and legs.
- A middle cerebral artery stroke affects the hands, arms, face, and the language centers in the dominant hemisphere, including Broca’s and Wernicke’s area.
- A posterior cerebral artery stroke primarily affects the visual cortex, which affects a person’s ability to see clearly.
Both motor and sensory fibres may be affected:
- Damage to motor pathways: flaccid paralysis develops almost immediately. And then over the following days to weeks, there’s spastic paralysis and hyperreflexia due to the hyperexcitable stretch reflex.
- Damage to sensory pathways: numbness, reduced pain and vibration sensation.
Both motor and sensory symptoms usually happen on the side that’s contralateral from the stroke, except in rare cases of brain stem stroke, where both sides are affected.1
General stroke symptoms
Usually sudden onset followed by gradual decline
Specific symptoms depends on anatomical site of stroke
S/S of Anterior cerebral artery stroke
- Contralateral hemiparesis and sensory loss with lower limbs > upper limbs
S/S of Middle cerebral artery stroke
- Contralateral hemiparesisandsensorylosswith upper limbs > lower limbs
- Homonymous hemianopia
- Aphasia: if affecting the ‘dominant’ hemisphere (the left in 95% of right-handed people)
- Hemineglect syndrome: if affecting the ‘non-dominant’ hemisphere; patients fail to be aware of items to one side of space
S/S of Posterior cerebral artery Stroke
- Contralateral homonymous hemianopiawithmacular sparing
- Contralateralloss of pain and temperature due to spinothalamic damage
S/S of Vertebrobasilar artery stroke
- Cerebellarsigns
- Reduced consciousness
- Quadriplegiaorhemiplegia
S/S of Weber’s syndrome (midbrain infarct)
Oculomotor palsy and contralateral hemiplegia
S/S of Lateral medullary syndrome (Posterior inferior cerebellar artery occlusion)
- Ipsilateralfacial loss of pain and temperature
- IpsilateralHorner’s syndrome: miosis (constriction of the pupil), ptosis (drooping of the upper eyelid), and anhidrosis (absence of sweating of the face)
- Ipsilateralcerebellar signs
- Contralateralloss of pain and temperature
Assessment using ROSIER scale
Recognition of Stroke in the Emergency Room (ROSIER) scale is a variation of FAST (Face, Arm, Speech, Time) and is used to differentiate acute stroke from stroke-mimics
A stroke is possible if the score is > 0 and requires an urgent non-contrast CT head. Once hypoglycaemia has been excluded, assess the following:
Loss of consciousness or syncope: -1
Seizure activity: -1
Asymmetric facial weakness: +1
Asymmetric arm weakness: +1
Asymmetric leg weakness: +1
Speech disturbance: +1
Visual field defect: +1
Primary investigations for stroke
- Non-contrast CT head:first-line imaging.
- ECG:assess for AF
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Bloods:
- Screen for risk factors includingHba1c, lipids, clotting screenand rule out stroke mimics such ashypoglycemia and hyponatraemia
- In younger patients, consider ESR, autoantibody and thrombophilia screen
- CT angiogram (CTA):identifies arterial occlusion and should be performed in all patients who are appropriate for thrombectomy
- MRI head:MRI is an alternative to non-contrast CT head; MRI is more sensitive but CT is safer and easier to obtain
Differentials for stroke
- Stroke mimics e.g.
- Hypoglycaemia
- Hyponatraemia
- Hypercalcaemia
- Uraemia
- Hepatic encephalopathy
- Brain tumours
- Seizures
- Complicated migraine
Management of Ischaemic stroke
Maintain stable blood glucose levels, hydration status and temperature
Blood pressure should not be lowered too much during a stroke because this risks reducing the perfusion to the brain.
- Antiplatelets: aspirin given as soon as possible once haemorrhage is excluded
- Thrombolysis: alteplase (tissue plasminogen activator) to reestablish blood flow; given if < 4.5 hours of symptom onset and haemorrhage excluded on imaging
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Thrombectomy: must score > 5 on NIH Stroke Scale/Score (NIHSS) and pre-stroke functional status < 3 on the modified Rankin scale
- Confirmation of stroke requires CTA or MR angiogrampriorto thrombectomy
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Anticoagulation
- If atrial fibrillation is the cause, anticoagulation should not be started until 14 days post-stroke.
Prevention of stroke
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Clopidogreldaily lifelong is first-line
- Offeraspirin75 mg daily +MR dipyridamoleif clopidogrel is contraindicated
- OfferMR dipyridamole aloneif aspirin and clopidogrel are contraindicated
- High-dose statin e.g. atorvastatin
- Carotid endarterectomy or stenting in patients with carotid artery disease
- Manage hypertension, diabetes, smoking and other cardiovascular risk factors
Management of Haemorrhagic stroke
The exact management of haemorrhagic stroke depends on the subtype (refer to haemorrhage topics)
- Admit to neurocritical care:patients will need intensive monitoring due to the risk of raised intracranial pressure and airway compromise
- If features of raised intracranial pressure: consider intubation with hyperventilation, head elevation (30°) and IV mannitol
- Surgical intervention:decompression may be needed
Complications of Stroke
- Deep vein thrombosis: due to immobility
- Aspiration pneumonia: due to dysphagia
- Neurological sequelae: such as weakness, impaired mobility, MCA syndrome and seizures
- Requirement for nutritional support: such as nasojejunal feeding
- Depression
Prognosis of stroke
For ischaemic stroke, the prognosis depends on the severity. A total anterior circulation stroke confers the poorest prognosis. Regarding thrombolysis, if administered within 3 hours, patients are 30% more likely to have minimal or no disability.
In general, mortality for haemorrhagic stroke is significantly higher than for ischaemic stroke and can be as high as 40%.
What are the common types of ischaemic stroke
Large vessel disease (50%), Small vessel disease (25%), Cardioembolic (20%), Cryptogenic/rarities (5%)
Notes on neuronal transmission in relation to epilepsy
Neuronal communication is controlled through neurotransmitters and receptors.
Neurotransmitters bind to the receptors and tell the cell to either open up the ion channels and relay the electrical message, called excitatory neurotransmitters, or close the ion channels and stop the electrical message, called inhibitory neurotransmitters.
The main excitatory neurotransmitter in the brain is glutamate, and NMDA is the primary receptor that responds to glutamate by opening ion channels that let calcium in.
The main inhibitory neurotransmitter in the brain is GABA, which binds to GABA receptors that tell the cell to inhibit the signal by opening channels that let in chloride ions.
Define epilepsy
Epilepsy is an umbrella term for a condition where there is a tendency to have seizures. Seizures are transient episodes of abnormal electrical activity in the brain.
There are many different types of seizures.