CEREBROVASCULAR DISEASE
Cerebrovascular disease refers to a group of conditions that affect blood flow and the blood vessels in the brain. Problems with blood flow may occur from stenosis (narrowing of blood vessels), embolism (blockage of artery), thrombosis (formation of clot) or hemorrhage (rupture of blood vessel). Lack of sufficient blood flow (referred to as ischemia) affects brain tissue and may cause a stroke.
Cerebrovascular Conditions
Cerebrovascular conditions include:
Arteriovenous Fistula (AVF) An abnormal connection between an artery and a vein in which blood flows directly from an artery into a vein, bypassing some capillaries. An arteriovenous (AV) fistula is an abnormal connection between an artery and a vein
Aneurysms - An aneurysm refers to a weakening of an artery wall that creates a bulge, or distention, of the artery. Most aneurysms do not show symptoms and are not dangerous.
Carotid Stenosis - Carotid stenosis is a narrowing of the carotid arteries, the two major arteries that carry oxygen-rich blood from the heart to the brain. Also called carotid artery disease, carotid stenosis is caused by a buildup of plaque (atherosclerosis) inside the artery wall that reduces blood flow to the brain
Arteriovenous malformations (AVM) - An arteriovenous malformation (AVM) is an abnormal tangle of blood vessels connecting arteries and veins, which disrupts normal blood flow and oxygen circulation. Arteries are responsible for taking oxygen-rich blood from the heart to the brain.
TIA and Stroke - A transient ischemic attack (TIA) is a temporary period of symptoms similar to those of a stroke. A TIA usually lasts only a few minutes and doesn't cause permanent damage. Often called a ministroke, a transient ischemic attack may be a warning.
Cerebral cavernous malformations (CCM) - Cerebral cavernous malformations are collections of small blood vessels (capillaries) in the brain that are enlarged and irregular in structure. These capillaries have abnormally thin walls, and they lack other support tissues, such as elastic fibers, which normally make them stretchy
Carotid-Cavernous Fistula - Carotid-cavernous fistula (CCF) is an abnormal connection between the carotid artery and/or its branches and a large vein called the cavernous sinus. The cavernous sinus is located behind the eye and receives blood from brain, orbit, and pituitary gland.
Optimal treatment of these varied cerebrovascular disorders requires experience with a wide spectrum of techniques, including complex cranial microsurgery, and minimally invasive techniques such as endovascular surgery and radiosurgery.
Whatever the condition and cause, the goal will be to maintain or restore proper blood flow and oxygen delivery to the brain as soon as possible.
TYPES
Stroke, Transient ischemic attack (TIA), and subarachnoid hemorrhage are types of cerebrovascular disease. Aneurysms and hemorrhages might cause severe health problems. Blood clots can form in the brain or travel there from other parts of the body, causing a blockage.
Different types of cerebrovascular disease include:
Ischemic stroke: These occur when a blood clot or atherosclerotic plaque blocks a blood vessel that supplies blood to the brain. A clot, or thrombus, may form in an artery that is already narrow. A stroke occurs when the lack of blood supply results in the death of brain cells.
Embolism: An embolic stroke is the most common type of ischemic stroke. An embolism occurs when a clot breaks off from elsewhere in the body and travels to the brain to block a smaller artery. People who have arrhythmias, which are conditions that cause an irregular heart rhythm, are more prone to developing this condition.
A tear in the lining of the carotid artery, which is found in the neck, can lead to ischemic stroke. The tear will allow blood to flow between the layers of the carotid artery, narrowing it, and reducing blood supply to the brain.
Hemorrhagic stroke: This occurs when a blood vessel in part of the brain weakens and bursts open, causing blood to leak into the brain.
The leaking blood puts pressure on the brain tissue, leading to swelling caused by the body's tissues (edema), which damages brain tissue. The hemorrhage can also cause nearby parts of the brain to lose their supply of oxygen rich blood.
Cerebral aneurysm or subarachnoid hemorrhage: These can result from structural problems in the blood vessels of the brain. An aneurysm is a bulge in the walls of the artery that can rupture and bleed.
A subarachnoid hemorrhage occurs when a blood vessel ruptures and bleeds between two membranes surrounding the brain. This leaking of blood can damage brain cells.
CAUSES OF CEREBROVASCULAR DISEASE
Cerebrovascular diseases can either be acquired later in life, and that may be preventable by the control of certain risk factors, or due to congenital defects that predispose or are directly causative of cerebrovascular damage.
Acquired cerebrovascular diseases are interconnected with advancing age and can be directly related to the onset of atherosclerosis, aneurysms, and embolisms. The narrowing, rupturing or clotting within vessels can be caused by key risk factors including hypertension, obesity, type 2 diabetes, and smoking.
The consequences of these acquired changes to cerebral vessels lead to the reduced oxygenation and the delivery of blood to the whole brain or some regions of the brain. There are, however, some risk factors such as advanced age, being male, being of black or South Asian descent and prior heart attack or stroke history that cannot be controlled for.
Genetically inherited, or congenital diseases can disrupt the integrity of cerebral arteries from birth, this would increase the likelihood of developing cerebrovascular incidents in life.
Other conditions that can lead to cerebrovascular incidents include;
Arteriovenous malformations, in which abnormally formed blood vessels have a higher rate of bleeding than a normal one, this substantially increases the risk of hemorrhage.
Moyamoya disease is a progressive disease of the carotid arteries that can lead to irreversible blockage and hence blood flow to the brain. The patients with this disease tend to have higher incidences of strokes, vascular dementia and cognitive decline, seizures, and motor impairments.
When blood flow to the brain is disrupted even for a few seconds, the brain tissue parenchyma can suffer from inadequate blood supply (ischemia), for a short while. If the ischemia only lasts for a short time and blood supply can be restored, then a silent stroke (a transient ischemic attack - TIA) can occur.
If unfortunately, the ischemia lasts several minutes or longer, the brain parenchyma suffers from tissue death (permanently).
SIGNS AND SYMPTOMS
The signs and symptoms of cerebrovascular disease depend on which blood vessels in the brain are affected and how much blood flow is involved.
Signs and symptoms of cerebrovascular stenosis do not usually become apparent until a trans ischemic attack or stroke occurs.
Warning signs of a trans ischemic attack or stroke may include the sudden onset of some or all the following symptoms:
- Facial weakness or droop, especially on one side
- Disorientation
- Loss of balance
- Memory loss
- Abnormal or slurred speech
- Confusion
- Loss of coordination
- Loss of vision or difficulty with sight
- Dizziness, nausea, and/or vomiting
- Unusually severe headache
- Difficulty with comprehension
- Numbness or weakness of an arm or leg
- Loss of the ability to walk
Small aneurysms do not usually have any symptoms, but larger ones may cause localized pain or headaches, and very large aneurysms can exert pressure on adjacent brain tissue or nerves thus causing;
- Sensitivity to light
- Problems with vision
- Numbness or weakness of an arm or leg
- Difficulty with memory or speech
- Fainting, or seizures.
If an aneurysm ruptures, it may cause:
- Head and neck pain
- Cold, clammy skin
- Dizziness, nausea or vomiting
- Rapid heart rate
- Low blood pressure
- Shock
Some cerebrovascular malformations may indicate as blood-filled bulges visible under the skin and are sometimes painful but rarely have other symptoms. When symptoms do occur, they can include:
- Seizures
- Headaches
RISK FACTORS
There are eight major risk factors for cerebrovascular diseases (CBVD). They are:
- High blood pressure (hypertension)
- Smoking
- Diet
- High blood cholesterol
- Lack of exercise
- Being overweight and obese
- Diabetes
- Excessive alcohol consumption
These are described below.
High blood pressure
Hypertension (High blood pressure), is one of the most significant risk factors for developing CVBD. This is because the increase in blood pressure damages the walls of the arteries in the brain, making it more likely that a blood clot will form or an artery will rupture (split open). Both of which can trigger a stroke.
A person who has high blood pressure is four times more likely to have a stroke than someone with healthy blood pressure.
Smoking
Smoking is a major risk factor for developing CBVD because the toxins in tobacco can damage and narrow the blood vessels in the brain. Smoking also causes high blood pressure.
Diet
A diet that's high in saturated fat and salt can cause high blood pressure, high blood cholesterol levels and narrowing of the arteries, all of which are risk factors of CBVD.
High blood cholesterol
High blood cholesterol can cause the arteries to narrow and increase the risk of developing a blood clot.
Lack of exercise
People who don't exercise regularly usually would have higher cholesterol levels, high blood pressure and possibly high levels of stress. They're also more likely to be overweight or obese.
Being overweight or obese
Being overweight or obese increases one's risk of developing diabetes and high blood pressure. Overweight and obese people also often have poor diets and don't exercise enough.
Diabetes
The high blood glucose (sugar) levels that are associated with type 1 diabetes or type 2 diabetes can damage the arteries. People with type 2 diabetes are also often overweight or obese.
Excessive alcohol consumption
Drinking excessive amounts of alcohol can increase both cholesterol and blood pressure levels.
Please note that many of the risk factors for CBVD are linked, which means that if a person has one, they're likely to have others as well.
COMPLICATIONS
When a cerebral blood vessel becomes partially or totally blocked, or a blood vessel or aneurysm ruptures, it can cause serious complications such as:
Stroke: A stroke occurs when part of the brain loses blood supply due to a blockage or rupture in one of the arteries, causing permanent damage.
Trans ischemic attack: A trans ischemic attack occurs when the blood supply to part of the brain is temporarily cut off by a clot, however, the clot would quickly dislodge itself and does not result in lasting brain damage.
Vascular dementia: Damage to the brain cells, that is caused by a shortage of blood supply can result in a widespread and persistent loss of mental ability known as vascular dementia.
DIAGNOSIS AND MANAGEMENT
In order to determine if a person has cerebrovascular disease, the physician will begin by reviewing the symptoms, risk factors, and family and medical histories, as well as perform a physical exam. In most cases, the physician will also order one or more diagnostic imaging tests that allow vascular specialists to view the brain and the arteries and vessels around it.
These tests may include:
Angiogram: A thin tube (catheter) would be inserted into a blood vessel and a dye is injected to make the blood vessel visible during an X-ray. This may reveal any blood clots or other blood vessel issues.
Ultrasound: An ultrasound device can measure blood pressure on various points of the patient's limbs. This will help the physician to determine if there are any blockages and how quickly blood flows through the arteries.
Computed tomographic angiography (CT): This a non-invasive test can show the arteries in the abdomen, pelvis and legs. This test is particularly useful in patients with pacemakers or stents.
Electroencephalogram (EEG): During this test, special electrodes that are attached to different spots on the scalp send electrical impulse data from the brain to a special recording machine. The machine converts the impulses to a visual pattern that is saved to a computer.
Lumbar puncture (spinal tap): This diagnostic test will make use of a needle to remove a sample of cerebrospinal fluid from the space surrounding the spinal cord. This test can be helpful in detecting bleeding caused by a cerebral hemorrhage.
Magnetic resonance imaging (MRI): A large magnet, radio waves and a computer are used to produce pictures of the heart and blood vessels.
TREATMENT
The specific treatment will depend on the type of cerebrovascular disease that the patient has. The treatment will however center on improving the brain's blood flow. The doctor will choose among several treatment options based on what caused the loss of blood flow. The most effective treatment will depend on the extent of the loss of blood flow. Most cases of cerebrovascular disease are treated with medications. These medications may include:
- Blood pressure medications
- Cholesterol medications
- Blood thinners
Medications are usually given to people whose arteries are less than 50 percent blocked or narrowed. In more severe cases, surgery may be required to remove plaque or blockages, or to insert a stent.
If brain function has already been reduced or altered by a cerebrovascular disease, then the patient may need to have physical therapy, occupational therapy, and speech therapy as a critical part of the recovery process.
Careful Monitoring
To ensure that an aneurysm does not grow or show signs of leakage the doctor may recommend careful monitoring. In actual fact, those with small aneurysms are generally at low risk for a rupture. Similarly, most cerebrovascular malformations do not pose a major risk, but are difficult to remove, and will grow back if not removed completely. Therefore, surgery may only be recommended if the risk from the malformation is serious or the symptoms are unbearable and cannot be otherwise treated.
Cerebral Angiography
Depending on the location of the aneurysm, malformation or narrowing caused by stenosis, minimally invasive treatment options (i.e. neurointerventional or neuroradiological procedures), may be recommended. Initially, a catheter would be threaded into the artery, and the aneurysm, malformation, or stenosis is located by injecting a special dye that helps create a clear picture of the cerebrovascular system on an X-ray.
For some cases, especially of cerebrovascular stenosis, a balloon may be used to widen a narrowed artery, followed by the placement of a stent to keep the artery open and prevent clotting.
Neurosurgery
Any surgery on the brain and surrounding blood vessels is inherently risky. Therefore open neurosurgery is generally recommended only in cases where there is already leakage or hemorrhaging, or more serious symptoms begin to occur and cannot be treated with a cerebral angiography. Most aneurysms and malformations that require surgery are treated with a process known as surgical clipping, which cuts off the blood supply to the affected area.
For minor arteries, a donor artery that normally supplies blood to the face and scalp can be rerouted to supply blood to the brain.
Recovery after Surgery
Depending upon the surgical procedure and how the body heals, the patient will be in the hospital for four to six days, sometimes for several weeks.
For those who have experienced a stroke or permanent damage related to complications from cerebrovascular disease, physical and cognitive rehabilitation programs can help restore or improve some speech and cognitive functions among others. Damaged brain tissue cannot be repaired, but new skills can be learned as other parts of the brain are trained to take on some of the functions of the damaged area.
REHABILITATION
As a cerebrovascular event can cause permanent brain damage, people may experience temporary or permanent disability.
For this reason, they may require a range of supportive and rehabilitative therapies so as to be able to retain as much function as possible.
These might include:
Psychological therapy: Physical disability can create unexpected emotional demands and require intensive readjustment. A person may benefit from consulting a psychiatrist, psychologist, or counselor after a cerebrovascular event if they feel incredulous.
Physical therapy: This aims at restoring as much as possible mobility, flexibility, and limb function.
Speech therapy: This will go a long way to help people communicate more clearly and regain speech after a stroke or cerebrovascular attack.
Occupational therapy: This may help a person access facilities that support a return to work and daily life.
PREVENTION
Although cerebrovascular disease is a fairly common medical condition, there are things one can do to help prevent it.
Several health behaviors are associated with reducing stroke risk:
- Not smoking or quitting if they already smoke
- Reducing alcohol intake
- Losing weight if already overweight
- Following a heart- healthy and balanced diet
- Effectively controlling high blood pressure
- Lowering blood cholesterol
- Exercising regularly
- Being aware of the risks of hormone replacement therapies
- Visiting their doctors regularly for checkups
- Lowering stress levels
Preventing cerebrovascular disease must always a paramount goal. However, if anyone suspects that they, or someone around them is having stroke-like symptoms, call the local emergency numbers immediately.
Getting immediate medical attention will help give the best chance for full recovery.