I spoke recently to a member of our local Mountain Rescue Team (MRT) who had been called out to help a fell runner who had collapsed during a race. On reaching him it was clear that something serious was wrong. Despite being conscious and unhurt, he was unable to speak clearly and had lost the use of his left arm and leg. The MRT members diagnosed a potential stroke and quickly made arrangements to transport him to the roadside and an awaiting ambulance. Impressively, the time taken from call out to hospital arrival was just over 1 hour.
85% of strokes are ischaemic and caused by an obstruction to blood flow - either a thrombus formed over a ruptured atherosclerotic plaque in the brain or an embolism originating from another part of the body. Early signs of an ischaemic stroke on CT are typically caused by the swelling of damaged cells - loss of grey-white differentiation (arrow on left), loss of cortical sulci (arrows on right) and compression of the ventricular system (arrows on right) are common.
Stroke is by far the most common serious neurological condition seen in the UK and occurs in 100,000 people each year. Unfortunately, two thirds leave hospital with a disability. Recent studies have shown that rapid assessment and treatment can make an enormous difference when treating those with an ischaemic stroke. Despite a 5-6% risk of intracerebral haemorrhage, thrombolysis given within 4.5 hours has been shown to double the chances of a good outcome. These odds are further improved by treating the patient even quicker.
Recombinant tissue plasminogen activator (alteplase) is the only agent licensed for thrombolysis treatment of ischaemic stroke in the UK. The dose is 0.9mg/kg. 10% is given as a bolus and 90% is infused over 1 hour.
In this man’s case, a CT scan identified an ischaemic stroke. Due to the position of the clot (proximal middle cerebral artery) the decision was made to give thrombolysis and for an interventional radiologist to undertake an endovascular thrombectomy to try and remove the clot. This was undertaken with a stent retriever under local anaesthetic.
A stent retriever with a clot removed from an ischaemic stroke victim.
Twenty four hours later a further CT scan was performed to look for evidence of intracranial haemorrhage. This was “all clear” and aspirin treatment was begun. Further medications for hypertension and hyperlipidaemia were added. Four days later the patient was discharged home. His symptoms had completely resolved.
Strokes are common. The vast majority are ischaemic and can be treated successfully with either thrombolysis, thrombectomy or a combination of both. For the best possible results this needs to be done quickly. Therefore those who might encounter stroke victims in the mountains need to make the diagnose promptly and organise a rapid transfer to a treatment centre.
The picture used at the start of this post is by Sue Slack. Details of her upcoming exhibition can be found here.
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