Explainers

Different Types of Strokes


Many people have a preconceived misperception when they think of someone following a stroke.

They might automatically envision mobility difficulties and hemiplegia, or maybe swallowing problems, or even being unable to speak and communicate. When, in reality, there are different types of strokes and therefore, different types of symptoms, so it is important to know exactly what type of stroke your patient has had in order to predict some of these symptoms.

A stroke, which is also known as a cerebrovascular accident, is defined as ‘a non-traumatic brain injury that is caused by disruption of blood flow to part of the brain’ (Mauk 2012, pp. 216).

This disruption of blood flow means that this specific part of the brain is being deprived of the nutrients and oxygen it needs to survive, so it results in cell death to that area of the brain. Therefore, anyone who has had a stroke is also now classed as having an acquired brain injury.

There are 2 main types of strokes: ischaemic and haemorrhagic.

types of strokes

Ischaemic Strokes

An ischaemic stroke occurs when a thrombus or embolus impairs cerebral blood flow.

One of the most common causes of ischaemic strokes are those that are associated with atherosclerosis, in which the lumen of arteries are narrowed, leading to a thrombus forming. This thrombus then occludes the vessel which, when occurring in the brain, results in the cerebral ischaemia – otherwise known as a thrombotic stroke (Koutoukidis et al. 2016).

An embolic stroke can also occur when a thrombus breaks away and becomes an embolus. This embolus can then be carried to the brain from another part of the body and occlude a cerebral blood vessel causing cerebral ischaemia (Koutoukidis et al. 2016).

Haemorrhagic Strokes

A haemorrhagic stroke occurs when there is a rupture in a cerebral blood vessel that causes bleeding in the brain.

The main cause of haemorrhagic strokes is hypertension, but they can also be brought on by anatomical defects such as aneurysms, arteriovenous malformations (AVMs) or degenerative changes occurring in arterial walls (Koutoukidis et al. 2016).

An aneurysm occurs when there is a weakened part of a blood vessel wall that balloons out.  This section of the blood vessel wall can continue to weaken until it eventual ruptures and bleeds into the brain.

It is estimated that 1.5-5% of the population has or will develop a cerebral aneurysm, but most people will be asymptomatic with only 3% of this number eventually suffering from it bleeding and causing a stroke (American Heart Association 2017).

AVMs occur when there is a cluster or a tangle of abnormally formed blood vessels. These blood vessels bypass normal brain tissue and divert the blood from the arteries to the veins. When these AVMs rupture they then cause bleeding.

Cerebral AVMs occur in less the 1% of the population and symptoms will vary depending on the location of the AVM (American Heart Association 2017).

Manifestations of Strokes

The manifestation of a stroke will depend on many factors. When a stroke occurs, areas of the brain are deprived of their oxygen supply which causes necrosis of cerebral tissue and results in the neurological deficits seen in these patients.

The deficits that may present will depend on the area of the brain involved (Koutoukidis et al. 2016).

Left and Right Hemisphere Strokes

With any stroke, it is important to make note of what brain hemisphere it has occurred in.

The side that the stroke occurred in will tell you a lot about the individual’s potential neurological deficits, which may have resulted from the cerebral tissue necrosis.

Generally, the patient will experience hemiplegia on the opposite side of the area of stroke. For example, if they had a stroke in the left hemisphere of the brain they will experience right-sided weakness or hemiplegia (Koutoukidis et al. 2016).

There are also other differences between strokes that occur to the left and right hemispheres, such as:

Left Hemisphere

  • Receptive, expressive or global aphasia (impairment of production and comprehension of language
  • Intellectual impairment
  • Slow behaviour
  • Deficits in right visual fields

Right Hemisphere

  • Spatial and perceptual deficits
  • Impulsive behaviour and the tendency to be distractible
  • Poor judgment and the individual appears to be unaware of deficits
  • Deficits in left visual fields

(Koutoukidis et al. 2016)

types of strokes

Middle Cerebral Artery (MCA) Stroke

A middle cerebral artery (MCA) stroke occurs when the middle cerebral artery, which supplies the frontal lobe and lateral surface of the temporal and parietal lobes with blood, becomes blocked (Mauk 2012).

It is important to remember that individuals with the same type of stroke will often display different symptoms depending on the precisely where and how much of the brain was deprived of oxygen and where cerebral tissue necrosis has occurred.

This is especially important to remember in those who have had an MCA stroke because the middle cerebral artery supplies such a vast area of the brain, the deficits it leaves are dependent on the areas most damaged.

A MCA stroke can have many implications for the individual. These include:

  • Deficits in movement and sensation (contralateral hemiplegia and hemianesthesia)
  • Difficulty swallowing (dysphagia)
  • Uninhibited neurogenic bladder
  • Impaired language ability, including global aphasia, Broca’s aphasia, and Wernicke’s aphasia
  • Impaired vision and partial blindness (hemianopia)
  • Poor awareness of deficits
  • Headaches
  • Inability to turn eyes towards the affected side

(Koutoukidis et al. 2016; Mauk 2012).

Anterior Cerebral Artery Stroke

The anterior cerebral artery supplies most of the anterior section of the interhemispheric cortical surface of the frontal and parietal lobes. So therefore the deficits left following this type of stroke may include:

  • Deficits in movement and sensation (contralateral hemiplegia and hemianesthesia) with the lower limb often worse than the upper limb
  • Foot drop
  • Flat affect
  • Impulsivity
  • Reduction in speech, motivation or movement (abulia)
  • Decreased auditory comprehension
  • Mental state impairments such as confusion, amnesia, apathy, short attention span

(Koutoukidis et al. 2016; Mauk 2012).

Posterior Cerebral Artery Stroke

Strokes in the posterior cerebral artery will effect the temporal and occipital lobes, impacting the sight of the individual.

Many individuals with this type of stoke will potentially experience blindness in half their vision field (hemianopia) or the inability to identify colours (colour agnosia).

They may also experience dyslexia, memory deficits, involuntary eye movements (nystagmus) and pupillary dysfunction (Koutoukidis et al. 2016; Mauk 2012).

The Future

Statistically, if you have had a stroke, you are more likely to experience another one in the future with 1 in 5 stroke survivors having another stroke within 5 years.

This is quite significant considering that this second stroke is often more severe than the first, therefore leaving the individual with more deficits (Mauk 2012).

Implementing stroke prevention strategies and decreasing known risk factors for the individual are essential in the treatment following a stroke, as well as providing education to the individual on reducing their risk of another stroke.

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