Last updated 12/11/23

ESSENTIALS

Cardiovascular Accident (Stroke)

A stroke is characterised by the sudden loss of blood circulation to an area of the brain, resulting in a corresponding loss of neurologic function. Strokes are also known as cardiovascular accidents (CVA). There are two main types of stroke: ischaemic and haemorrhagic.

Ischaemic stroke, which accounts for about 80% of cases, is caused by a blockage inside an artery in the brain. This may be due to a blood clot that travels in the blood stream from another part of the body and lodges in a blood vessel in the brain (called a cerebral embolus). Another mechanism is similar to that which occurs with a heart attack, where the blockage is from a plaque of fatty material caused by the process called arteriosclerosis.

A haemorrhagic stroke occurs when a blood vessel inside the brain ruptures. This accounts for the other cases of stroke.

History

Contrary to common belief, a stroke can strike at any age. One third occur in people under 65 years.

More common in the following:

• Older people

• Previous stroke or TIA (“mini stroke” – see below)

• High blood pressure (hypertension)

• Smokers

• Diabetics

• High cholesterol

• Atrial fibrillation* (irregular heartbeat)

• People with known atherosclerosis (“hardening of the arteries”)

• Other circulation problems

• The physically inactive

• The obese

• Alcohol users (excessive)

• Oral contraceptive pill

*NB Atrial fibrillation (AF) is a cause of an irregular heart beat. It is not usually a threat to life, though a person with it will not be able to exercise as much as a person with a normal heart rhythm. Most importantly, AF is not the same as ventricular fibrillation, which is a cause of cardiac arrest.

Symptoms and Signs

Symptoms will come on suddenly.  The casualty may be unable to describe the problem themselves. It is important to question any accompanying person.

The first thing to remember with stroke is to think and act F.A.S.T.  Remember this is a pass / fail test. If they have any one symptom, the whole test is positive and they need urgent evacuation for treatment.

F – Face, fallen to one side, can they smile?

A – Raise their arms. Do they stay there?

S – Slurred speech?

T – Record the time of the stroke as clot busting drugs are only effective in the first 3- 4.5 hours.

Other symptoms and signs are:

Effects on consciousness and mental processes

• Sudden loss of consciousness

• Confused or agitated

• Seizures (can be characterised by spasms or convulsions)

• Uses incorrect words, or cannot understand you at all

• Severe headache

• Motor & sensory problems

Dizziness, balance and coordination problems

• Weakness. This may be of the face, arm, leg or foot, or the whole side of the body
  In some cases, the person complains of sudden loss of sensation to half the body

• Difficulty swallowing (may be apparent as drooling)

• Tongue deviates to one side if they attempt to stick it out

• Visual disturbance e.g. cannot see the half of the visual field; double vision

• Pupils may be abnormal when examined

• Loss of consciousness indicates a more extensive stroke.

On Site Management

Confirm the diagnosis

• History of what happened (usually from other people present)

• Previous medical history e.g. blood pressure, known irregular heart rate, diabetes, seizures, medications

• Look for the features described above

• In younger patients, ask about trauma, drugs (esp cocaine because it can cause very high blood pressure), migraine, contraceptive pill

• Ask about diabetes and insulin/ drugs and check BM. Hypoglycaemia can mimic a stroke

• Important – after some strokes, the victim may be unable to understand you or to speak.

URGENT EVACUATION TO HOSPITAL IS THE PRIORITY
Clot busting drugs are available for some types of stroke, but are only effective in the first 3-4.5 hours.  It is safest to treat anyone with stroke symptoms accordingly.

MR Interventions

• Provide airway and breathing support if required or the casualty is unconscious

• Keep them warm to minimise oxygen demand

• Check blood pressure. Stroke is more common in casualties with high blood pressure. This cannot be treated on the mountain but is a useful clinical sign.

• Treat persistent seizures if they occur in the usual way (midazolam).

• Do NOT give aspirin as this could exacerbate a haemorrhagic stroke

It is not necessary to give supplementary oxygen if:

• SpO2 94% or greater

• The patient has a normal body temperature (i.e. not cold and shivering);

• The patient’s hands are warm so that you can easily get a good reading with the pulse oximeter and the saturation is 94% or more; and

• There is no other reason for them to need oxygen (e.g. the stroke caused them to fall and sustain significant trauma)

If the casualty is unconscious check for other causes:

• Hypoglycemia

• Hypothermia

• Head injury

• Drug overdose

What else could it be?

A number of conditions occasionally mimic a stroke:

• Hemiplegic migraine (stroke symptoms can occasionally occur during a migraine headache)

• Some types of seizures

• Brain tumour

• Hypoglycaemia

Transient Ischaemic Attack (TIA)

Often called a mini-stroke because it shares the sames causes and symptoms as strokes. TIA is the result of a temporary disruption of cerebral blood flow.  80% resolve within 60 minutes, but they can last for 24 hours. Importantly, 10% of people who have a TIA will have a full blown stroke within 90 days. Half of these occur within two days of the TIA so it is imperative that these people have medical review as soon as possible. A TIA has the features of a full blown stroke but these wear off completely.

ADDITIONAL INFORMATION

As TIA is a risk factor for a stroke that could occur at any time, the casualty should be placed on oxygen (if required) and evacuated urgently to hospital.

Additional Info

Infographics from the Wellcome Trust about strokes in the UK.