Causes

There are different causes for each type of stroke.
Transient Ischemic Attack
Ischemic
Hemorrhagic

Transient Ischemic Attack

Ischemic

Ischemic stroke is caused by several diseases

  • Atherosclerosis (hardening of the arteries), caused by a cholesterol deposition that narrows the blood vessels is the most common cause of ischemic stroke. As arteries narrow, blood cells may collect and form blood clots. These blood clots can block the artery where they are formed (thrombosis), or can dislodge and become trapped in arteries closer to the brain (embolism). Refer to Dr. Ruth McPherson’s information
  • Blood clots in the heart can occur as a result of irregular heartbeat, atrial fibrillation, heart attack, patent foramen ovale or abnormalities of the heart valves.
  • Use of street drugs (cocaine)
  • Blood clotting disorders, like Lupus, Factor V Leiden or Antiphospholipid syndrome.
  • Carotid or vertebral artery dissection
  • Unusual cardiac sources — like infections
  • Vasculitis/Arteritis/Phlebitis

 

While these are the most common causes of ischemic stroke, there are many other possible causes. Especially in younger people, it is important to look for the uncommon causes. There may be multiple causes of the stroke as well. For example in young women – migraine and taking birth control pills or a patent foramen ovale complicated by APS ( a clotting disorder).

Hemorrhagic
Hemorrhagic stroke is usually caused by one of the following:

  • High Blood Pressure (hypertension). High blood pressure causes no symptoms, so people are unaware that they have high blood pressure, and it is not treated. 70% of all strokes (not just hemorrhagic strokes) are related to high blood pressure. Tighter control of blood pressure in diabetics especially reduces the risk of stroke. A blood pressure reading of 120/80 is best for diabetics.
  • Aneurysm
  • Arteriovenous malformations
  • Trauma
  • Infections
  • Tumours
  • Blood clotting problems
  • Use of anticoagulants, such as Coumadin or heparin
  • Amyloid angiopathy (associated with Alzheimer’s disease)

Other Classification of Hemorrhagic Stroke

Petechial Hemorrhages – The passage of a clot through an infarction (blockage) can lead to a localized hemorrhage. In the gray matter of the brain, these are petechial hemorrhages and in the white matter they are pale, ischemic hemorrhages. Infarctions caused by long-standing hypertension are often of the type called “lacunes.” Lacunes are small cystic infarcts and are the most common type of infarction. They result from the occlusion of perforating arteries.

Intracerebral Aneurysms – Aneurysms are weaknesses in the wall of your arteries that may be present at birth. They are usually at points of bifurcation (the splitting off of one vessel from another). Aneurysms are thin-walled sacs which are dilated (enlarged). Aneurysms can become a problem when the dilated (enlarged) sac.

  • Acts as a space occupying lesion (and presses on part of the brain)
  • Ruptures (breaks and bleeds)
  • Impairs the circulation of the blood beyond the aneurysm

Fusiform Dilations and Hemorrhages – Fusiform dilations occur in the Basilar Artery. These dilations are caused by atherosclerosis. The atherosclerosis creates enlarged tortuous (meaning with many twists and turns) vessels which can compress structures next to them creating ischemia or infarctions.

Basilar hemorrhages – May be caused by ruptures of the medial or lateral branches of the Basilar Artery. In these cases, there may be bleeding into the area of the Pons. According to Fitzgerald, the symptoms are very severe and will affect both sides of the body because of the swelling (edema) that results. Some of the symptoms that may result are coma, the inability to use all four arms and legs, pin-point pupils, body temperatures rising to 106 degrees over several days, and periodic respiratory arrest.

Subarachnoid hemorrhage
Subarachnoid hemorrhage is most often caused by:

  • Cerebral Aneurysms; abnormalities of the arteries at the base of the brain where there are small areas of rounded or irregular swellings in the arteries. Where the swelling is most severe; the blood vessel wall become weak and prone to rupture, or
  • Arteriovenous Malformations; a congenitally malformed tangle of thin-walled blood vessels.