L7 Diagnosis, Treatments and Prevention of Stroke

Question 1

Describe how a stroke is diagnosed.

Answer 1

Diagnosing a stroke takes 5 broad steps;
1 - Has a stroke occurred? (or is it migraine)
2 - What type of stroke is it? (Ischaemic/Haemorrhagic)
3 - How severe is the damage? (widespread or localised)
4 - Can it be treated? (unblock artery or stop bleeding)
5 - What was the cause? (Lifestyle or trauma)

If someone notices the early signs of stroke (dizziness, confusion, headache, numbness on one side, vison problems) then acting quickly is essential.

Procedure:

• The patient will be admitted to hospital with a suspected stroke
• A medical professional will immediately do a quick medical background check to identify whether this person is ‘at risk’ or whether it is likely to be a separate medical issue eg migraines
• The doctor will also conduct a quick neurological examination to asses whether there is any cognitive impairment (a sign of stroke) by asking the patient their name, the date, what time of day it is etc
• As soon as possible, the patient is given a CT scan which is used as a brain imaging method to guide treatment
• This CT scan can detect Haemorahgic strokes immediately but only detects Ischaemic strokes roughly 24hours post-stroke (because it doesn’t detect blood flow changes)
• (CT’s are used because other brain imaging techniques take longer and are less readily available)
• If bleeding is detected then a Haemorrhagic stroke is diagnosed, if not then they assume an Ischaemic stroke has occurred.

Question 2

Why is it essential that both Haemoragghic and Ischaemic strokes are treated ASAP?

Answer 2

Hemorrhagic strokes such as Epidural Haemorrhages or Subarachnoid Haemorraghes involve immediate danger, as they raise the pressure in the skull which causes the brain step to be restricted. This can stop a person heartbeat, breathing and swallowing.

Ischaemic strokes are important to treat quickly because the ischaemic core (irreparably damaged tissue) can grow if blood flow is not reintroduced. The penumbra is defined reigns which have <20% of normal blood flow but can benefit from treatment if blood supply is reintroduced within three hours.

Question 3

What are the drug treatments for an Ischaemic stroke? Evaluate these.

Answer 3

Drug treatments:
-used as a first treatment as they can be effective and incur relatively low risk

1. Aspirin (+ Clopidogrel)
   - a drug commonly used as a primary treatment to prevent further blood clotting
   - works by suppressing platelet activity
   - Wang et al (2013) did a clinical drug trial with 5100 patients who had suffered a TIA (likely to suffer an ischaemic stroke within a month). found that the use of Asprin alongside Clopidogrel (another antiplatelet drug) lowered the risk of a second stroke when compared to Asprin alone (8% compared to 11%), which poses a more effective drug treatment in preventing further strokes post-TIA.
2. Tissue Plasminogen Activator (tPA)
   - a drug which converts plasminogen into plasmin; an enzyme which actively breaks down blood clots

Evaluation of drug treatments:

(Limitations)

• A small window of opportunity to work/ needs to be given within 3-4 hours otherwise there is no therapeutic benefit (penumbra will have become part of ischaemic core)
• need to consider other medications taken by the person/ other health problems before giving them
• can increase the risk of Haemorraghic stroke by removing bodies ability to form blood clots

(Strengths)

• effectively reduce further clotting
• tPA can unblock vessels

Question 4

What are the surgical treatments for an Ischaemic stroke? Evaluate these.

Answer 4

Surgical treatments:
-used as a last resort treatment, can be extremely risky and dangerous

1. MERCI Retriever
   - stands for Mechanical Embolus Removal in Cerebral Ischemia (MERCI)
   - is a mechanical tool which is inserted into a blocked vessel
   - once inside, a rod is passed through the clot and coils on the other side
   - this acts as a net to mechanically remove the clot
2. Suction Removal
   - another mechanical tool
   - this one has a vacuum type end with a sharp cutting rod
   - rod breaks down the clot and then is sucked up through the tool

Evaluation of surgical treatments:

(strengths)
-can be a useful last resort therapy when drugs fail

(Limitations)

• Extremely risky
• only appropriate for ‘healthy’ patients (young, good BMS)

Question 5

What are the surgical treatments for a Haemorrhagic stroke? Evaluate these.

Answer 5

surgical treatments:

1. Aneurysm Clipping
   - this is done when an aneurysm is detected
   - involves surgically clipping off the ballooned artery wall
   - this prevents it from bursting causing a haemorrhage
   - can be done after haemorrhage
2. Coil Embolisation
   - preventative treatment
   - involves inserting a rough-surfaced coil into the Aneurysm before it ruptures
   - coil then helps form an Embolism clot which closes off the artery wall

Evaluation of surgical treatments:

(strengths)
-can be a useful last resort therapy

(Limitations)

• Extremely risky
• only appropriate for ‘healthy’ patients (young, good BMS)
• is the only option

Question 6

Current treatments for stroke are poor. Discuss the preventative approach and outline what Non-modifiable and Modifiable risk factors are involved.

Answer 6

Because treatments are relatively inadequate, time-sensitive and risky, special emphasis has been put on preventing risk factors known to increase the likelihood of stroke. Some we can modify, others we cannot.

Non-modifiable risk factors:

• Age (older = weaker and stiffer artery walls)
• Ethnicity (some cultures have a higher incidence)
• Gender (Robin et al (2009) Men at greatest risk, research suggests progesterone is protective [stroke incidence increases post-menopause + administration of progesterone in men has been linked to lower incidence of Ischaemic stroke])

Modifiable risk factors:

• High salt diet (salt causes hypertension/ increases blood pressure = higher artery pressure on walls = thicker more rigid walls = greater risk of Aneurysm and Haemorrhage)
• Diabetes and high blood sugar levels (sugar damages epithelial layer on artery walls, makes them weaker)
• High LDL cholesterol diet (LDL causes the buildup of plaques in artery walls, increases the chance of Embolism formation and increases hypertension which increases wall thickness and rigidity, increases risk of stroke)
• Smoking (chemicals within smoked tobacco damage artery walls, break down elastic tissue making artery more Ridgid
• Excercise (sedentary lifestyle without exercise increases plaque build up in arteries

O’donnell et al (2009)

• looked at factors common in 3000 + people in 22 countries who had suffered a stroke
• looked at risk factors by comparing them and their lifestyles to healthy controls
• found significant modifiable risk factors;
  
  • history of hypertension
  • current smoker
  • high BMI
  • diabetes
  • poor diet (high salt, fat & sugar)
  • depression
  • stress
  • alcohol intake
  • lack of physical exercise
• Found these risk factors combined were accountable for 90% of the strokes in these patients

Question 7

what is Hankey et al’s (1999) research about?

Answer 7

Wanted to identify the efficacy and cost-effectiveness of current therapeutic interventions in the prevention of secondary stokes. Did this by applying current evidence to a hypothetical sample of 1,000,000 individuals over a year, of which statistically speaking, 2400 would suffer a stroke. Compared effectiveness in terms of lives saved, availability of intervention, cost per treatment, and reduction in the probability of post-stroke care dependance.

Found;

STROKE TREATMENT UNITS - found to be specialized and effective at reducing risk of death or secondary stroke. Cost as much as admission to a general hospital so cost-effective, the main cost is hotel type costs eg cleaning feeding etc so varies relative to the length of stay. If used in all cases of stroke, would prevent 56/2400 from either dying or being dependent post-stroke. However, under available; only 55% of stroke sufferers are treated in a stroke treatment unit in the UK.

ASPRIN - an antiplatelet drug used post-stroke to prevent the formation of clots, reduces the risk of secondary stroke. Not tolerated in 5% of the population, so only useful for 95%, even then only Ischaemic strokes. Would prevent 51/2400 from death or post-stroke dependence. Costs very little, as much as 1$ a day per patient.

tPA - tissue plasminogen activator, turns plasminogen into plasmin; a blood clot digesting enzyme. is found to be effective in the treatment of Ischaemic strokes however widely inappropriate for use as it has to be administered within 3-4 hours. 80% of stroke patients Ischaemia diagnosed after this time zone, limiting its use. cost-effectiveness is okay, If it could get to each Ischaemic case, would cost 3200$ per life saved, and could probably be used to treat only 15/1000 strokes due to time sensitivity.

Preventative lifestyle changes;

REDUCTION IN BLOOD PRESSURE - interventions designed to decrease blood pressure through changes in exercise and diet would half the chances of secondary stroke and would save 132/2400 stroke patients. mainly due to lifestyle change so cost relatively little

REDUCTION IN CIGARETTES - smokers who continue to smoke post-stroke increase the risk of secondary stroke by 1.5x. If all smoking stroke survivors stopped then it would save 84/2400 from death or dependence. although alternatives like gum or patches would be needed, relatively inexpensive. 20,000$ would treat 43 for 3 months.

REDUCTION IN LDL - high-fat increases chances of Ischaemic and reduce chances of Haemorrhagic stroke due to thickening of artery walls. the reduction in LDL would reduce chances of secondary stroke by 24% in Ischaemic type stroke survivors.