MR Image Infarction in the (SCA) Superior Cerebellar Artery.
Brainstem and the Posterior Cerebral Artery (PCA).
MR Image showing a Left Sided Posterior Inferior
Cerebellar Artery (PICA) Infarction
The two above images both illustrate a cerebrovascular accident (CVA) or ‘Stroke’ caused by an infarction. An infarct is an area of tissue or cellular death caused by an interruption in blood supply to that particular area.
Cerebrovascular Accident (CVA) or Stroke
Cerebrovascular Accident (CVA) and ‘Stroke’ are both terms that apply to a medical situation whereby the blood supply to the brain is interrupted resulting in injury and eventual death of the cerebral brain cells (infarction) due to lack of oxygen and essential nutrients. There are two main classifications of CVA:-
- Ischemic CVA: Caused by a blockage of the blood vessel
- Hemmorhagic CVA: Caused by a breakage of the blood vessel
Ischemia can be defined as:-
“Deficient supply of blood to a body part (as in the heart or brain) that is due to obstruction
of the inflow of arterial blood (as by the narrowing of arteries by spasm or disease)(1)”
The Ischemic Category of CVA is caused when a thrombosis (blood clot in a blood vessel) blocks the blood supply in an artery that supplies oxygen and nutrients to the brain. There are two types of thrombosis.
- Cerebral Thrombosis: This is where a thrombosis or blood clot forms within the blood vessel leading to the brain.
- Cerebral Embolism: This is where a blood clot has formed elsewhere in the body and travels and lodges in the artery supplying blood to the brain. This type of thrombosis can be secondary to a Myocardial Infarction (heart attack) or a Deep Vein Thrombosis (DVT) for example.
The two classifications are a little confusing because a hemorrhagic stroke is also ischemic in nature in that the oxygen supply is interrupted to the brain, but in this case the blood vessel to the brain ruptures and bleeds (hemorrhages) into surrounding tissue causing additional damage. Hemorrhagic CVA (sudden bleeding) account for only around 10 % of total strokes(2). Although they are less common than the Ischemic stroke caused by thrombosis they are more deadly as the tissue damage is further exacerbated by the bleeding into the brain.
Hemorrhagic strokes are categorized by how and where they occur.
Intracerebral hemorrhage (ICH): The bleeding occurs in this type of stroke within the brain tissue.
Subarachnoid hemorrhage (SAH): The bleeding occurs in this type of stroke when a blood vessel around the brain’s surface ruptures and leaks blood into the subarachnoid space. The subarachnoid space is the area between the brain and the skull. These types of bleeds can be caused by the rupture of an aneurysm, this is a ballooning or ‘bulging’ of an artery wall resulting in a weakened vessel structure that is prone to bursting.
patient could also have had an aneurysm with a subarachnoid hemorrhage and that’s a different disease altogether.
Transient Ischemic Attack (TIA)
A Transient Ischaemic Attack (TIA) or mini stroke as it is sometimes called, is characterised by a temporary disruption in the blood supply to part of the brain, normally caused by a small clot. This disruption leads to a lack of oxygen to the brain which causes symptoms similar to those of a stroke. The difference in diagnosis is that the symptoms last a short time, (often around 5 minutes and sometimes only a minute) and are completely resolved within a 24 hour period.
Transient Ischemic Attacks should not be ignored as they are often a warning sign of a bigger, more devastating event to come. While the vast majority of strokes are not preceded by TIA around a third of people who experience Transient Ischemic Attacks go on to have a stroke within a year(3)
Life Saving Tips
CVA or stroke is the Number four cause of death in the United States, it is also the leading cause of adult disability. Each year in the US there are 795,000 cases of strokes, 610,000 of which are first strokes(4). The long term outcome and prognosis following a stroke is directly linked to the time lapse between the onset of symptoms and hospital treatment. The first three hours are key for effective treatments which include the use of thrombolytic (blood clot dissolving) medications and TPA which is a natural enzyme of the blood which aids in the dissolving of blood clots.
The largest meta-analysis to date to investigate the thrombolytic drug Altplase took place in August 2014 and involved over 6700 stroke patients. The findings show that more stroke patients could benefit from treatment but it has to be given as quickly as possible following the first symptoms. The odds of a good outcome were seen to be 75% higher for patients who received the drug Alteplase within 3 hours of the onset of symptoms of a stroke. Benefits were still evident (although reduced) if the drug was given up to 4.5 hours after the symptoms but the more time that elapses before treatment the worse the long term prognosis(5).
To help you identify somebody having a stroke as soon as possible. Remember F.A.S.T (as in act Fast) you could save a life or somebody from living with a severe disability.
F is for Face Ask the patient to smile look at the face. Is there any drooping?
A is for Arms Ask the patient to raise both arms. Does one arm drift down?
S is for Speech Ask the patient to say a simple sentence. Is the speech slurred or strange?
T is for Time Think ‘time is of the essence’ If in any doubt call your emergency services immediately.
1. Merriam Webster
2. University of Maryland Medical Centre
3. Dr. E. Matarese St. Mary’s Medical Center in Langhorne
4. RTH Stroke Foundation
5. The Lancet August 5 2014 ‘Alteplase given promptly after stroke reduces long-term disability, even in older people, and those with severe stroke’.