Stroke and Thrombosis

A stroke is sudden death of brain cells due to lack of oxygen. It can be caused by blockage of blood flow due to a clot or rupture of an artery that supplies blood in the brain.

When this happens, the cells of the brain in the affected area become damaged. If the flow is interrupted for too long, the cells may die because they don't get the oxygen they need. When this happens, the child is at risk for long-term damage and may even risk losing his or her life.

There are three types of strokes:

• Arterial ischemic stroke
• Hemorrhagic stroke
• Cerebral sinus vein thrombosis

Arterial ischemic stroke occurs when the flow of blood going into an area of the brain is interrupted by an occlusion of a blood vessel, usually by a clot. This type of stroke is usually related to:

• Lack of oxygen
• A heart defect present at birth
• Diseases that increase blood clotting
• Injury to a blood vessel that brings blood to the brain (for example dissection)
• Dehydration
• Abnormal arteries in the brain like moyamoya
• An infection such as meningitis or chicken pox
• Pregnancy related factors: mother with high blood pressure, diabetes, drug abuse or placenta or problems during delivery

Hemorrhagic stroke occurs when a blood vessel in the brain leaks or bursts causing flooding of the brain with blood and damaging brain cells. This type of stroke can be caused by:

• A head injury
• Arteriovenous malformation, a condition in which the blood vessels in the brain do not connect properly
• An aneurysm or weakness in an artery wall
• Bleeding disorder

Cerebral sinus vein thrombosis is a stroke that occurs when a blood clot forms in the brain's venous sinuses (veins drain blood from the brain towards the heart). Rather than preventing blood from flowing into the brain, it blocks blood from flowing out. This may result in increased pressure inside the brain or blood leaking into the brain, resulting in a hemorrhagic or ischemic stroke. This type of stroke can be caused by:

• Dehydration
• Severe iron deficiency anemia
• Trauma
• Acute or chronic head and neck disorder
• Blood clotting abnormalities
• Sickle cell anemia
• Severe head or neck trauma
• Dehydration
• Certain medications, including those used for cancer treatment

The causes and types of stroke in children are very different from those in adults. For children, common causes are often related to:

• Diseases of the arteries
• Heart disease – both congenital and acquired
• Infection in the body or brain (meningitis)
• Acute or chronic head and neck disorders
• Blood clotting abnormalities
• Sickle cell anemia
• Severe head or neck trauma
• Dehydration
• Certain medications, including those used for cancer treatment

While it can be extremely difficult to recognize symptoms of stroke in an adult, it is even more so in children. It is not uncommon for some types of strokes to go unnoticed. The brain is divided into two parts, the left and the right.

The left side of the brain controls the right side of the body as well as speech and language. If your child has experienced a stroke in the left side of his or her brain you may notice difficulty with speaking or reading or weakness on the right side of the body.

The right side of the brain controls the left side of the body. If your child has suffered a stroke on the right side of the brain, the left side of the body will be affected along with perception and motor skills. In this case your child may have difficulty with simple tasks such as buttoning a shirt or may be clumsy due to loss of perception and an inability to judge things like distance.

In addition, children may experience the following symptoms and warning signs:

• Seizures, especially in newborns
• Worsening or sudden headaches

Children often cannot clearly describe the way they feel. Newborns and infants have no way of expressing their symptoms. If your child has been diagnosed with a disorder, illness or genetic disease or is undergoing certain treatments where stroke could be a possible complication, it is very important to discuss a plan of action with your pediatrician and/or specialist. It is also critical to know these signs and take swift action if you believe your child is having a stroke. It could save his or her life.

Time is crucial. Recognize stroke with this simple acronym:

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Strokes are very serious and cause long-term and life-threatening damage. Because the brain is like a "command center" signaling all the functions of our bodies, a stroke affects other parts of the body.

The American Stroke Association reports that between 20 percent and 40 percent of children die after experiencing a stroke, and of those who survive, 50 percent to 80 percent may have permanent neurological deficits. Some include:

• Changes in behavior or personality
• Cognitive and sensory impairments – bumping into or dropping things due to difficulty judging distance, size, or space
• Epilepsy or seizures
• Hemiparesis – weakness on one side of the body
• Hemiplegia – paralysis of one side of the body
• Resultant cerebral palsy
• Difficulty speaking, remembering, solving problems
• Visual disturbances

Stroke is diagnosed through several testing techniques. Your doctor will perform a complete physical exam and check for problems with vision, movement, feeling, reflexes, speaking and ability to understand what is being said. The doctor will also listen for an abnormal sound in the carotid arteries in the neck. This sound, called a bruit, is caused by irregular blood flow. Additional tests may include:

• Electroencephalogram (EEG)
• Blood tests which may include bleeding time, cholesterol, sugar, clotting, and a complete blood count.
• CT scans
• MRI scans
• Doppler ultrasound
• Conventional Angiography of the brain

Just as the causes for stroke are very different in children than adults, so is treatment. Your child's plan of care will depend on the specific cause of the stroke, as well as other important factors such as age, size and other medical problems. The management of acute stroke in children, teens and young adults includes:

• Supportive care to maintain normal body temperature, proper hydration and normal blood sugar levels
• Controlling high blood pressure
• Detecting and treating seizures with EEG monitoring and anticonvulsant medication
• Managing intracranial pressure
• Clot-busting drugs or Interventional Radiology mechanical clot retrieval (early strokes)
• Clinical trials
• Antithrombotic therapy – medications used to prevent blood clots from forming or growing
• Surgery
• Rehabilitation services
• Movement Disorders Program

For some children with sickle cell disease, blood transfusions may prevent strokes from occurring or recurring. Your doctor will discuss any risks and help to determine if this course of treatment is the right one for your child.

The stroke and thrombosis team at Cook Children's has an outstanding track record in helping patients to recover and to regain as much of their mental and motor skills as possible. An amazing team with extensive knowledge of disorders and issues that can cause stroke and treating those disorders in the tiniest of patients to young adults provides early prevention of recurrence.

Cook Children's Stroke Program is a proud member of the International Pediatric Stroke Society (IPSS) which is an international network of several large pediatric institutions that are current world leaders in therapy and research in the field of pediatric stroke and thrombosis. Membership in IPSS has allowed Cook Children's to participate in international research trials that offer the opportunity to participate in the most recent advances to treat acute ischemic stroke in children, including the novel use of a "clot busting" medication for children, that helps to reopen the obstructed cerebral artery and offer the best chance for children to have full recovery.

Thrombosis is when a blood clot forms inside a vein, artery or within the heart.

Deep vein thrombosis (DVT) is when a blood clot forms inside one of the deep veins of the body obstructing the drainage of blood from an extremity or an organ into the heart. This is a very serious problem because it will cause congestion and tissue damage, and in certain cases, it can affect the function of an important organ of the body (such as the kidneys, liver, spleen, etc). In addition, if blood clots in the veins break loose and travel through your bloodstream, they may lodge in your lungs blocking blood flow to the lungs from the heart (pulmonary embolism) which can be a fatal complication. Rarely, the loose blood clot will not go to the lungs but go to the brain causing a stroke (condition known as a paradoxical embolism).

Arterial thrombosis is when a blood clot forms inside an artery of the body. It is a rare problem and it usually happens in newborns or in hospitalized patients with multiple medical problems.

Intracardiac thrombosis is when a clot forms inside one of the heart chambers or over the valves of the heart. This is a very rare thrombotic problem and, as arterial thrombosis, it usually happens in hospitalized patients.

Thrombosis can occur from anything that keeps blood from flowing smoothly within the blood vessel. Inflammation, infection, presence of a foreign object within a large blood vessel such as a central catheter, pressure over the blood vessel by surrounding tissue in the case of trauma, “thick blood” (congenital or from medications or underlying disease), will cause turbulent flow or slow flow of blood, that will subsequently provoke clot formation.

Certain factors can increase the risk of blood clots such as:

• Blood clotting disorder: Antiphospholipid syndrome, Factor V Leiden mutation, Prothrombin gene mutation, Protein C, S or Anti thrombin III deficiency, hyperhomocystenemia
• Autoimmune or rheumatological diseases
• Use of oral contraceptives
• Severe dehydration
• Trauma
• Cancer
• Congenital heart disease
• Long hospital stay, bed rest or paralysis
• Severe infections of bone or skin
• Major surgery
• Being overweight
• Smoking
• Inflammatory bowel disease

The symptoms of blood clots are:

• Swelling in affected leg/arm
• Pain in leg
• Red or discolored skin of the leg/arm
• Feeling warm to touch on affected leg/arm
• Sudden shortness of breath
• Chest pain that worsens with a deep breath or cough
• Rapid pulse
• Coughing up blood

The Cook Children's Stroke and Thrombosis Program is involved with a prompt, up to date, safe and efficacious treatment of patients with thrombotic complications. In addition, an evaluation of the potential causes/factors that triggered the thrombotic problem takes place to determine the length of anticoagulation therapy needed and to assess the risk of a second thrombotic event once anticoagulation has been stopped.

Treatments available include:

• Blood thinners
• Medications to “dissolve the clots” known as thrombolytics
• New generation blood thinners
• Mechanical and chemical (thrombolytics) removal of the blood clot by Interventional Radiology

Cook Children's Stroke and Thrombosis program participates actively in research and investigation for the use of new Anti-thrombotic (blood thinners) therapy for children. In addition, Cook Children's Medical Center is an active member of a national initiative to decrease the number of thrombotic complications in Children's Hospitals.

• Pediatric Stroke Warriors
• Fight the Stroke
• American Heart Association
• Children's Hemiplegia and Stroke Association