A stroke occurs when the blood supply to the brain is interrupted, due to blockage or a bleed on the brain. Since blood carries oxygen and nutrients, brain cells that have a completely interrupted blood supply will usually die.
An Ischaemic Stroke occurs when there is a blockage in an artery carrying blood to the brain, usually by a clot. Brain infarction occurs where blockage causes the brain tissue supplied by that artery to die. This infarction becomes a scar on the brain, and damage begins within a few minutes of stroke onset. In some instances, blood supply may not be completely cut off, and the brain cells may sustain themselves for a bit longer. If rapid diagnosis and treatment occurs in the minutes to hours after a stroke, there is a chance to recover some of the damaged cells and reduced permanent brain damage.
A Haemorrhagic Stroke is caused by a bleed in the brain, usually due to a rupture blood vessel. This either occurs within the space surrounding the brain (subarachnoid haemorrhage) or within the brain (intracerebral haemorrhage).
Both kinds of strokes present themselves very similarly, so a proper diagnosis must be made quickly by a physician to begin the appropriate treatment.
The symptoms of stroke usually come on quite quickly and may include;
- Sudden severe headache with an unknown cause
- Weakness on one or both sides of the body, such as a drooping face or inability to move limbs
- Blurring or sudden loss of vision
The FAST test is an easy way to remember the signs of stroke; Check their Face, is their mouth drooping, can they lift both Arms, is their Speech slurred, Time is critical for treatment so call emergency services.
Cognitive issues associated with Stroke
The specific deficits associated with stroke depend on the extent of the brain damage acquired; this includes the severity of the infarct, and whether it occurred in the left or right side of the brain, the brain stem, or the cerebellum. General cognitive effects of stroke may include difficulties with thinking and remembering things, trouble reading or writing, as well as producing or comprhedning language., It can also include weakness in movement, or paralysis, and difficulty regulating emotions. Depression and fatigue are two common outcomes associated with a stroke, both of which have a quite a large impact on quality of life.
Effects of stroke in the left hemisphere
The right side of the body is controlled by the left side of the brain, meaning a stroke in this part of the brain often causes motor problems and weakness in the opposite side of the body. It may also affect the visual ability to the right, if damage is located further in the back of the brain near the occipital lobes. The left side of the brain also controls a lot of language abilities and speech. A stroke in this side of the brain may cause aphasia (broadly an inability to either produce or comprehend language or both).
Effects of stroke in the right hemisphere
Often a stroke in the right hemisphere will cause some weakness or paralysis in the left side of the body and face. Individuals may also experience hemi-spatial neglect, whereby damage to the right-hand side of their brain has caused a neglect, or inability to attend to the things on their left. This could be anything to the left of their body, information in their left visual field. For example, when asked to draw a clock, someone may leave out the whole left side of the clock face altogether. Right hemisphere strokes can cause deficits in visuo-spatial abilities, such as misjudging distances.
Effects of stroke in the cerebellum
The cerebelllum sits below and behind the larger brain. The cerebellum is responsible for most of one's balance and coordination, as well as basic reflexes. Stroke damage to this area can cause imbalance and coorodination problems.
Effects of stroke in the brain stem
The brain stem is responsible for a lot of our automatic responses such as regulating our breathing, heart beat, our ability to swallow, as well as some control over eye movement and hearing. The brain stem is also responsible for relaying messages from the brain through the spinal cord to the limbs. Stroke damage to the brain stem can be particularly debilitating, or even, fatal due to its important role in these functions.