Saturday, 21 July 2012

Types of stroke.

Hello my dear reader's!!!!!!!

Today Stanford will tell you about the types of strokes in our brain. Just watch the video below:

Here are the notes that you can revise after watching the video:

Neurons communicate through Ions. Ions are passed through the cell membrane and the inside of the cell is negatively charged while the outside is positively charged. The neurons send electric signals to communicate known as action potential. The difference between the cell's inside and outside atmosphere is maintained by the proteins in the cell membrane.
They do so by pumping certain ions inside and certain ions outside,this pumping actino requires energy.
Neurons only work in aerobic conditions and they don't have their own energy stores. Brain only costs 2% of body weight, but requires about 20% of cardiac output, and 15% of oxygen take from the lungs. The blood to the brain reaches from the aorta is taken up to the brain by the carotid artery,
which takes 70% of it. The other 30% is taken up by basilar artery and verebral artery. This two artery are joined the base
of the skull and are then divided into six parts (2 parts each) -

1. Anterior Cerebral Artery.
2. Middle Cerebral Artery.
3. Posterior Cerebral Artery.

The Circle of Willis is the place where all these arteries join to provide the brain with blood. This circle joined the right and left artries so that if one artery (either left or right) is not working, then the brain will still receive the blood instead of no blood. Now there are also many other deeper parts in our brain, this parts will get supplied by different arteries. If this arteries don't work properly, that certain part might not be able to function properly.
For example, if the blood does not reach the Broca's and Wernickel's area, this parts will stop working and that person might suffer from Broca's Affesia, a disease in which that person will have language related problems.

A stroke is defined to be an abrupt onset of focal or global neurological symptoms, caused by ischemia or hemorrhage.
Ischemia means restriction of blood in Greek. And it is usually caused due to factors in blood vessels, with resultant damage in tissues. Tissue damage is caused by shortage of O2 or Glucose.

Hamorrhage is discharge of blood from blood vessels AKA bleeding. Bleeding in the tissue or around the brain. Their are 3 types of strokes, Ischemic stroke, Intracerebral Hemorrhage, Subarachnoid Hemorrhage. Ischemic Strokes are usually caused by blood clotting in the brain which will result to no O2 and glucose supply to the brain. Intracerebral Hemorrhage is bleeding in the tissues and Subarachnold Hamorrhage is bleeding around the brain.

Warning signs of Stroke:

1. Sudden Numbness on the face or any other body part, especially on the one side of body.
2. Sudden Problems in speaking or understanding.
3. Sudden, severe headache with no known cause.
4. Sudden trouble walking, loss of balance or coordination, dizziness.
5. Sudden trouble seeing with one or both of our eyes.

If a patient walks in and says he/she has a stroke, we can do the image studying of the brain to confirm that, the images show us what type of stroke it is or either it has an other cause such as tumor, infection, epilepsy. Imaging also tells us how better the brain is getting blood from the blood vessels. Their are two methods of Imaging, MRI an CT scan.

We can also use the cerebral angiography scan to determine the stroke. The main symptomes of strokes are usually seen in people with High blood pressure, diabetes, people who smoke, drink or intake tobacco.

Ischemic stroke is caused when the thrombus is formed which leads to vessel occulsion leading to O2 depletion leads to membrane ion failure which leads to cell swelling and then cell death. Some thrombi take time to form but there are some other thrombi that are formed in the heart and are then sent to the brain from the heart. Some strokes can also be temporary but we must remember that they may be a sign of a stroke. tPA is a method to diagnose the deficits of stroke, but it is not very much effective. The occulsion of a cerebral vessel is followed by formation of a central irreversible infarct, with a peripheral zone, the penumbra, where the tissue is variable due to partial preservation of blood supply via collateral vessels. CT Perfusion shows up the penumbra and infracted area. CT Scanning uses the X-Rays to make a
photo of the brain, the X-Rays are projected to the patient by the X-Ray generator which rotates around the patient to get a good view of the brain, the image of the brain is regerated by a process known as Back Projection as the X-Rays are changed in velocity when they interact with the tissues. MRI works with the help of the photon molecules or molecules containing photons, the MRI take advantage of the photon as they spin at a certain frequency at certain chemical environment, so we use different photons for different tissues, the photons when are bought in an magnetic field, then releases some enery as protons which we can record as they pass through the tissue to get an image of the brain. Rcently, Stanford University and other Universities have made a device that can go through the artery and the surgeon will pass the
device until the surgeon see's the thrombus, afterward's, the device will pull out a string through the clot, and will then turn the string into spiral shape so that the thrombus is stuck in it without any problem and will then just drag the thrombus with the help of the string and take it out. Another thrombactic device is also there that can relatively suck the clot in it and then the device can be taken out of the artery. If the thrombus is sent through the heart, after it is removed, there are sligth chances that the heart might send another thrombus again, which would again cause the ischemia. To make sure that this does not happen, the patient is passed through certain medication after the thrombus is removed from the artery.
The cerebrovascular system is the only route for energy supply to the brain. Blood vessels are lining organs that are under constant state of vascular remodeling. Acquired and cognital problems of this system are important causes of stroke.
In hamorrhage, the blood vessels spell the blood in or around the brain, and as a result of that, that particular vessel does not supply that particular brain part with which it is associated and this leads to ischemic stroke. More people die because of hamorrhagic stroke than the ischemic stroke. The causes of hamorrhage are divided into Primary and Secondary causes, primary cause of hamorrhage is hypertension etc. Ischemic stroke can also be converted to hamorrhage as in
ischemic stroke the blood is not able to reach in the brain which can make the vessel blast as the thrombus won't allow the blood to pass through the artery and then the artery will not be able to take on the blood pressure and will blast off.
Ischemia can also lead to hypertension which would lead to hamorrhage. Surgery is the best way to treat hamorrhage but there are chances of accident in surgery which can lead to brain damage. Aneurysms are the defect in blood vessels where the blister's form. We don't know why the aneurysms occur. The people who suffer from aneurysms have brother's and sister's who also suffer from this aneurysms, this makes us think that there is some genetic problems related with it. The larger the aneurysms the bigger the chance to blow. There are several causes of SAH (Subarachnoid Hamorrhage) such as hypertension, alcohol, pregnancy, drug or cocaine, smoking.

Aneurysms usually happen where two arteries join. Aneurysms can be found in a Stroke, Seizure, or a headache pain.
We can tell if a patient has SAH if he is reporting a very worst headache of his/her life, nausia, vomiting, photophobia, neck pain, less control over eye or face, altered level of consciousness, sential headaches (warning leaks) may proceed major, clinically divastating SAH as in half of the cases. First thing to diagnose a SAH is to get an angiographic study of it. We can also do a 3D angiogram. We can treat aneurysms by surgery and enduvascular coiling. In the surgery, we first make a small window in the scalp to look inside the brain, and then we look through a microscope in it, find the aneurysms and then tie a clip around the aneurysms, this would not allow the blood to get into the aneurysms and so the aneurysms
will not bleed out. In endovascular coiling, we tie the aneurysms from the bottom to the top so that the blood can't enter into the aneurysms. The coil comes of different types and sizes. The endovascular coiling can be done with the Primary treatment, Ballon assisted treatment, and Stent assisted treatment. In primary treatment where the neck is not to much large, we just coil the aneurysms, but in ballon assisted aneurysms, we need to use a ballon so that the coil did not fall back to the vessel. There is a device known as flow diverter that can divert the flow of the blood into other blood vessel so that the surgeon can perform the surgery. Arteriovenous Malformations is an abnormal collection of blood vessels wherein
the arterial blood flow directly into the veins without proper capillary beds. Cognitial , but may enlarge with age, this may involve an abnormality or dysregulation of vascular development or remodelling. Usually in AVM's, they are seen like very large capillaries and the veins in AVM usually loss the two layers of their walls, as well as we are not able to see the brain tissue between them, this condition is named as enciephalomalacia. This may be due ischemia at that place or due to the hamorrhage as the veins are carrying blood at high pressure and they are not accustomed to it. This disease usually
is diagnosed at the adulthood as it starts creating problems at that time and it is a rare disease (1-2 people per 100,000)
We use CT (CT Angiography),MRI (MR Angiography), or angiogram to find AVM's. We can cure AVM's by using microneurosurgery, which is very good method for curing the less sophisticated AVM's as well as which are located on the upper side if the brain. AVM's might have been in the patient from their birth or it might have been developed with age but it usually is within the patients at their time of birth. The AVM usually occur when the capallaries are not able form the correct way and they grow thicker and thicker with the time. The AVM can also be treated with the help of Stereotactic Radiosurgery, in this process the AVM is cured with the help of radiation and this is only done when we usually cannot acces the AVM
surgically. We use Endovascular Embolization to make the microsurgey or the Stereotactic Radiosurgery more effective and this all is known as Multimodality approach,i.e., using two or three methods together to cure the Anteriovenous Malformation. The CyberKnife Radiosurgery is made by the Stanford Scientists and it is used to target the particular area directly by an image guided robot. Embolization helps us to get a 3d graph of the brain or the Anteriovenous Malformation as well as helping us to decide weather it is okay or not to do an surgery. We can also know about the risks of performing
a surgery there and also introduce flow-directed micro catheters to the patient's body so that will be assisting in the furture processes as well as to inject liquid in the blood which can literally block that portion of the blood vessel(AVM).
Galen AVM is a type of Anteriovenous Malformation in which the AVM is much dilated than the usual.

No comments:

Post a Comment