comd 474 PPT 10 PT 1 Cerebrovascular Accidents & Circle of Willis

Aphasia

A group of disorders/syndrome that affects the verbal communication caused by damage to the brain that have multimodal characteristics

Cerebrovascular Accidents  - Occlusion

This is an arterial blood vessel that has been occluded, reducing or stopping the flow of blood to the brain

Thrombosis occlusions

The formation of a blood clot inside a blood vessel or the heart, which blocks or slows down normal blood flow 

Embolism occlusions

A sudden blockage in a blood vessel caused by a traveling piece of material that gets lodged in a vessel too small for it to pass through 

Arteriosclerosis occlusions

The thickening or hardening of an arterial wall, enlarging the walls.

Embolic occlusions

This is when extraneous material has occluded a vessel. An embolus breaks away, travels through the vessels, and becomes lodged, stopping or disrupting the flow of blood.

TIA: Transient Ischemic Attack occlusions

This is a mini stroke that mimics stroke symptoms, but the disruptions are temporary. The neurological signs are transient, last about an hour, and resolve within 24 hours. This is a warning sign!

Hemorrhage from Trauma occlusions

The damage to this can be subdural or subarachnoid

Subdural

The space between the dura mater and the arachnoid mater

Subarachnoid

The narrow gap between the brain and the thin tissues that cover it.

Hemorrhage from rupture of a blood vessel (without trauma) occlusions

This would be an aneurysm rupture. 85% are found in the internal carotid artery system. Many are congenital but some may never rupture. Some of the larger types of aneurysms can cause symptoms before rupture.

Hemorrhage from Arteriovenous Malformation (AVM) occlusions

This happens when the capillary network between arteries and veins is absent causing the vessels to be twisted and tangled. This is congenital.

Risk Factors for Cerebrovascular Accidents (CVA)

This includes high blood pressure (hypertension), hardening of the arteries (arteriosclerosis), obesity, lack of physical activity, high cholesterol, family history, diabetes, stress, and smoking. These factors can increase the risk of blood vessel damage or blockage, leading to a stroke.

Symptoms of cerebrovascular accidents

This is sudden weakness or paralysis and loss of sensation on one side of the body. Others include difficulty speaking or understanding language, vision loss, double vision, and dizziness. These require immediate medical attention because a stroke is a medical emergency.

Diagnosis of Cerebrovascular Accident

• CAT or CT (Computerized

  Tomography)

• MRI (Magnetic Resonance Imaging)

• EEG (electroencephalogram)

CAT or CT scans to diagnose CVA

This uses X-rays to create detailed cross-sectional images of the brain to identify abnormalities. It is relatively inexpensive, widely available, noninvasive (does not require surgery), and useful for detecting several brain conditions.

CAT or CT scan to diagnose CVA preference

This is preferred for detecting sudden bleeding in the brain (acute hemorrhage) and is used when a patient cannot have an MRI. However, it shows the brain's physical structure rather than how the brain functions.

MRI scan to diagnose CVA

This uses strong magnetic fields and radio waves, not X-rays, to create detailed images (slices) of the brain by detecting signals from molecules in the body. It is noninvasive and provides detailed images of brain structures. However, it may not be safe for people with certain metal implants or objects in their bodies.

MRI scan to diagnose CVA preference

This is preferred for identifying brain damage caused by blocked blood flow (infarcts), tumors, and abnormalities in individual blood vessels.I t examines the brain's physical structure rather than directly measuring its function.

Diagnosis of Cerebrovascular Accident - EEG

This measures the electrical activity of the brain, not its structure, but is not as accurate

Circle of Willis 

This is made of three cerebral arteries, originating from a circular arterial system at the base of the brain, anterior to the brainstem, including small communicating arteries and is supplied on both sides by arteries in the neck.

Lower neck portion of the circle of Willis

The left and right common carotid arteries become the internal and external carotid arteries on each side of the larynx and spinal column. The internal arteries proceed to the Circle of Willis and at the base of the brain, the Internal Carotid Artery splits into 2 directions":

• outward: Middle Cerebral Artery (MCA)

• forward: Anterior Cerebral Artery (ACA)

Arteries running up the neck in the circle of Willis

A pair of arteries run up the neck posterior to the carotids. The left and right Vertebral Arteries join to become the Basilar Artery

Anterior boundary for the circle of Willis

The anterior communicating artery links the anterior cerebral arteries creating the ___.

Posterior boundary for the circle of Willis

The basilar artery divides into the posterior cerebral arteries creating the ___.

Lateral boundary for the circle of Willis

The posterior cerebral arteries connect to the internal carotid arteries by the posterior communicating arteries creating the __.

Circle of Willis is made of -

• 2 anterior cerebral arteries

• 1 anterior communicating branch

• 2 posterior cerebral arteries

• 2 posterior communicating branches

Internal carotid artery

This is a major artery that supplies blood to the front of the brain and gives rise to the anterior cerebral artery and the middle cerebral artery.

Anterior cerebral artery (ACA)

This supplies the medial (inner) surface of the brain, including areas involved in movement and sensation.

Middle cerebral artery (MCA) in the circle of Willis

This supplies the lateral (side) surface of the brain, including motor and sensory areas involved in speech, hearing, and language. It travels through the Sylvian fissure and divides into superior and inferior branches.

Posterior communicating artery (PCoA)

This connects the internal carotid circulation to the posterior circulation.

Vertebral arteries

These carry blood toward the back of the brain and join to form the basilar arteries

Basilar arteries

This is a major artery formed by two vertebral arteries that eventually divide into the posterior arteries

Posterior cerebral artery (PCA)

This supplies the medial surface of the occipital lobe and the base of the temporal lobe, including the primary visual area.

Acute phase recovery

This is defined as the 5 days or up to 4-6 weeks post-onset

Spontaneous recovery

This is hours, weeks, or months immediately following the onset, varying depending on the severity of the symptoms 

Sparing of function

This is a failure to detect a loss of function due to undamaged regions of the brain

Recovery

This is the restitution of function lost or the implementation of strategies to achieve the goal of the function (substitutions).

Ischemic stroke

This stroke is caused by occlusion, accompanied by swelling, and typically diminishes during the first week after onset. The causes increase intracranial pressure and compress brain structures, affecting the hemisphere contralateral to the infarction. Reducing swelling is considered responsible for recovery so soon after onset, which is why it’s classified as an acute phase.

Thromboembolic occlusion

This type of occlusion may be temporary due to “spontaneous recanalization” and “collateral circulation”.

Spontaneous recanalization

The natural process where a previously blocked or severed blood vessel, or reproductive tube, reopens or reconnects on its own without direct surgical intervention. 

Collateral circulation

This is your body's network of alternate or "backup" blood vessels that can take over when a main artery or vein becomes blocked, narrowed, or damaged

Determining prognosis

This depends on how much brain swelling decreases and whether blood flow returns through recanalization (reopening a blocked artery) or collateral circulation (alternative blood vessels supplying blood to the brain). Because the patient's condition may be unstable at first, a clearer understanding of the extent of damage and language difficulties can usually be determined about one month after the stroke.