Introduction
The prevention and treatment of strokes has undergone significant changes over the past decade. What was previously considered a devastating but untreatable condition is now viewed more as a 'brain attack', a condition which requires emergency assessment to see if patients may benefit from new treatments such as thrombolysis.
Epidemiology
- Incidence: 230.00 cases per 100,000 person-years
- Peak incidence: 70+ years
- Sex ratio: 1:1
Condition | Relative incidence |
---|---|
Stroke | 1 |
Bell's palsy | 0.10 |
Central venous thrombosis | 0.004 |
<1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Pathophysiology
There are two main types of strokes:
- ischaemic: these can be further subdivided between into episodes which last greater than 24 hours (termed an ischaemic stroke) and episodes where symptoms and signs last less than 24 hours (transient ischaemic attacks, TIAs, sometimes termed 'mini-strokes' by patients)
- haemorrhagic
Clinical features
Features include:
- motor weakness
- speech problems (dysphasia)
- swallowing problems
- visual field defects (homonymous hemianopia)
- balance problems
Cerebral hemisphere infarcts may have the following symptoms:
- contralateral hemiplegia: initially flaccid then spastic
- contralateral sensory loss
- homonymous hemianopia
- dysphasia
Brainstem infarction
- may result in more severe symptoms including quadriplegia and lock-in-syndrome
Lacunar infarcts
- small infarcts around the basal ganglia, internal capsule, thalamus and pons
- this may result in pure motor, pure sensory, mixed motor and sensory signs or ataxia
Whilst symptoms alone cannot be used to differentiate haemorrhagic from ischaemic strokes, patients who've suffered haemorrhages are more likely to have:
Investigations
- CT
- MRI
Management
Selected points relating to the management of acute stroke include:
- blood glucose, hydration, oxygen saturation and temperature should be maintained within normal limits
- blood pressure should not be lowered in the acute phase unless there are complications e.g. Hypertensive encephalopathy*
- aspirin 300mg orally or rectally should be given as soon as possible if a haemorrhagic stroke has been excluded
- with regards to atrial fibrillation, the RCP state: 'anticoagulants should not be started until brain imaging has excluded haemorrhage, and usually not until 14 days have passed from the onset of an ischaemic stroke'
- if the cholesterol is > 3.5 mmol/l patients should be commenced on a statin. Many physicians will delay treatment until after at least 48 hours due to the risk of haemorrhagic transformation
Thrombolysis for acute ischaemic stroke
Thrombolysis with alteplase should only be given if:
- it is administered within 4.5 hours of onset of stroke symptoms (unless as part of a clinical trial)
- haemorrhage has been definitively excluded (i.e. Imaging has been performed)
Contraindications to thrombolysis:
Absolute | Relative |
---|---|
- Previous intracranial haemorrhage - Seizure at onset of stroke - Intracranial neoplasm - Suspected subarachnoid haemorrhage - Stroke or traumatic brain injury in preceding 3 months - Lumbar puncture in preceding 7 days - Gastrointestinal haemorrhage in preceding 3 weeks - Active bleeding - Pregnancy - Oesophageal varices - Uncontrolled hypertension >200/120mmHg | - Concurrent anticoagulation (INR >1.7) - Haemorrhagic diathesis - Active diabetic haemorrhagic retinopathy - Suspected intracardiac thrombus - Major surgery / trauma in the preceding 2 weeks |
Thrombectomy for acute ischaemic stroke
Mechanical thrombectomy is an exciting new treatment option for patients with an acute ischaemic stroke. NICE incorporated recommendations into their 2019 guidelines. It is important to remember the significant resources and senior personnel to provide such a service 24 hours a day. NICE recommend that all decisions about thrombectomy take into account a patient's overall clinical status:
- NICE recommend a pre-stroke functional status of less than 3 on the modified Rankin scale and a score of more than 5 on the National Institutes of Health Stroke Scale (NIHSS)
Offer thrombectomy as soon as possible and within 6 hours of symptom onset, together with intravenous thrombolysis (if within 4.5 hours), to people who have:
acute ischaemic stroke and
- confirmed occlusion of the proximal anterior circulation demonstrated by computed tomographic angiography (CTA) or magnetic resonance angiography (MRA)
Offer thrombectomy as soon as possible to people who were last known to be well between 6 hours and 24 hours previously (including wake-up strokes):
- confirmed occlusion of the proximal anterior circulation demonstrated by CTA or MRA and
- if there is the potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
Consider thrombectomy together with intravenous thrombolysis (if within 4.5 hours) as soon as possible for people last known to be well up to 24 hours previously (including wake-up strokes):
- who have acute ischaemic stroke and confirmed occlusion of the proximal posterior circulation (that is, basilar or posterior cerebral artery) demonstrated by CTA or MRA and
- if there is the potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
Secondary prevention
NICE also published a technology appraisal in 2010 on the use of clopidogrel and dipyridamole
Recommendations from NICE include:
- clopidogrel is now recommended by NICE ahead of combination use of aspirin plus modified release (MR) dipyridamole in people who have had an ischaemic stroke
- aspirin plus MR dipyridamole is now recommended after an ischaemic stroke only if clopidogrel is contraindicated or not tolerated, but treatment is no longer limited to 2 years' duration
- MR dipyridamole alone is recommended after an ischaemic stroke only if aspirin or clopidogrel are contraindicated or not tolerated, again with no limit on duration of treatment
With regards to carotid artery endarterectomy:
- recommend if patient has suffered stroke or TIA in the carotid territory and are not severely disabled
- should only be considered if carotid stenosis > 70% according ECST** criteria or > 50% according to NASCET*** criteria
*the 2009 Controlling hypertension and hypotension immediately post-stroke (CHHIPS) trial may change thinking on this but guidelines have yet to change to reflect this
**European Carotid Surgery Trialists' Collaborative Group
***North American Symptomatic Carotid Endarterectomy Trial