Introduction

Strokes represent an important cause of morbidity and mortality. In the UK alone there are over 150,000 strokes per year, with over 1.2 million stroke survivors. Stroke is the fourth largest cause of death in the UK and kills twice as many women than breast cancer each year.

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
Stroke1
Bell's palsy0.10
Central venous thrombosis0.004
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Pathophysiology

A stroke (also known as cerebrovascular accident,CVA) represents a sudden interruption in the vascular supply of the brain. Remember that neural tissue is completely dependent on aerobic metabolism so any problem with oxygen supply can quickly lead to irreversible damage.

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

Stroke is defined by the World Health Organization as a clinical syndrome consisting of 'rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 hours or leading to death with no apparent cause other than that of vascular origin'. In contrast, with a TIA the symptoms and signs resolve within 24 hours.

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:
  • decrease in the level of consciousness: seen in up to 50% of patients with a haemorrhagic stroke
  • headache is also much more common in haemorrhagic stroke
  • nausea and vomiting is also common
  • seizures occur in up to 25% of patients

Investigations

Patients with suspected stroke need to have emergency neuroimaging. The main cause for urgency is to see whether a patient may be suitable for thrombolytic therapy to treat early ischaemic strokes. The two types of neuroimaging used in this setting are:
  • CT
  • MRI

Management

The Royal College of Physicians (RCP) published guidelines on the diagnosis and management of patients following a stroke in 2004. NICE updated their stroke guidelines in 2019.

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