What is childhood stroke?

A stroke happens when the blood supply to part of the brain is cut off, killing brain cells. Damage to the brain can affect how the body works. It can also change how you think and feel.

There are two main types of stroke, ischaemic and haemorrhagic.

In adults, 85% of strokes are caused by a blockage and 15% by a bleed in the brain. But in children, both types of stroke are equally common.

Children can also have a transient ischaemic attack (TIA or mini-stroke). A TIA is the same as a stroke, except that the symptoms last for a short amount of time. TIA is a major warning sign for stroke, and should always be taken seriously.

Although it's very rare, babies can have a stroke in the womb or just after birth. Find out more about perinatal stroke, which is the name for stroke in a baby from week 20 of pregnancy until 28 days after birth.

Ischaemic strokes are caused by a blockage in the blood supply to the brain.

A main cause of ischaemic stroke in adults is the arteries becoming stiff and narrowed, and fatty deposits collecting inside the blood vessels. This is a process that tends to happen as we get older, and does not affect babies and children. For children, stroke due to a clot can happen for a number of other reasons.

Causes in babies

Stroke in unborn babies and newborns up to 28 days old (known as pre- and perinatal stroke) may be caused by clots travelling from the placenta to the child's brain. It can also be due to a blood clotting disorder that the mother or baby may have.

Causes in children

Strokes in children from 28 days to 18 years are often associated with existing conditions mostly commonly, congenital heart disease and sickle cell disease. Other risk factors are infectious diseases, trauma to the head or neck, vascular problems and blood disorders.

Strokes can also affect previously healthy children and in some cases, there can be no apparent cause.

There are several different conditions which can make children more likely to have an ischaemic stroke. These fall mainly into four categories

• Heart disorders.
• Blood disorders.
• Infections.
• Vascular disorders.

Heart disorders

Heart disorders increase the risk of ischaemic strokes in children. Some children are born with a heart problem, known as congenital heart disease, and heart problems that develop in childhood are known as acquired heart disease. Sometimes a heart disorder is only diagnosed after a stroke.

Heart surgery and stroke

If a child has surgery for a heart condition, this can raise the risk of a stroke. But the outcome of any serious operation depends on the individual child and their unique health needs. If your child needs heart surgery, the doctor should explain the likely risks and benefits of the operation. If your child had a stroke after heart surgery, your medical team can help you understand why this happened. They can also support you and your child with recovery.

Blood disorders: sickle cell disease (SCD)

Sickle cell disease is an inherited condition affecting red blood cells. These are the blood cells that carry oxygen around your body. In sickle cell disease, some red blood cells change shape from round to a narrow sickle (half moon) shape. The damaged cells are less able to carry oxygen around the body. They can also block blood vessels and cause clots in the brain. SCD can also lead to a bleed in the brain, but this is rare in children under 18.

SCD is most common among Black Caribbean, Black African and Black British people. It affects males and females alike.

You can find more information on sickle cell disease in our 'What is stroke' section of the website.

Blood clotting disorders

Some types of rare blood clotting disorders make it more likely for clots to form, raising the risk of a stroke. Sometimes known as 'sticky blood' disorders, they may be diagnosed after a stroke.

Infections

Chickenpox is linked to an increased risk of childhood stroke for around six months after the infection. Although chickenpox is a very common childhood illness in the UK, stroke is an extremely rare complication. Other serious infections affecting the brain and other organs may cause a stroke, such as bacterial meningitis, encephalitis, sepsis and brain abscess.

Vascular disorders

Vascular disorders are problems with blood vessels in the body which can affect the blood flow. In children vascular problems can be caused by an injury, as well as malformations or inflammation. The type of vascular problems leading to stroke in adults tend to be changes due to age, and fatty deposits accumulating in the arteries, which do not affect children in the same way.

Arterial dissection

A cervical arterial dissection happens when a tear develops in the lining of one of the large arteries in the neck. The tear lets blood in between the layers of the blood vessel wall. Blood or a clot can leak into the brain, causing a stroke. It is one of the leading causes of stroke in children and young adults.

It can happen after an injury, or an activity like sport. It can also be related to an infection or a health condition such as Ehlers-Danlos and Marfan syndrome. A spontaneous dissection means there is no apparent cause. An arterial dissection does not always have symptoms. However, it can cause headaches, pain in the face and neck, and stroke-like symptoms such as a drooping eyelid and speech problems. It's important to get medical help if you suspect a dissection or a stroke.

Moyamoya syndrome

In Moyamoya syndrome, the main arteries in the brain become narrowed. To compensate for the reduced blood flow in the main vessels, a network of small blood vessels grows inside the brain. Moyamoya means 'puff of smoke' in Japanese, referring to the appearance of the abnormal blood vessels in the brain scan image.

It does not always have symptoms, but it can cause headaches and muscle weakness, as well as learning difficulties. It can lead to strokes and TIA in some children. Moyamoya syndrome has been found in children with sickle cell disease, Down syndrome and neurofibromatosis. It sometimes occurs in otherwise healthy children, when it is known as Moyamoya disease.

It is very rare, with an estimated one person per million in the UK affected. It is more common among people from Japan and some other East Asian countries.

Vasculitis

A rare condition in which the blood vessels inside the brain become inflamed, known as central nervous system vasculitis, can lead to a stroke or TIA in children.

Cerebral venous thrombosis

Large veins drain the blood away from the brain through spaces under the brain known as the venous sinuses. If a clot (thrombosis) develops in this space it can cause stroke symptoms such as headaches, seizures and blurred vision. It is known as a cerebral sinovenous thrombosis (CVST) or a cavernous venous thrombosis. It can be due to conditions including blood-clotting disorders, infections and heart disease.

Haemorrhagic strokes occur when blood leaks from a burst blood vessel into the brain.

Up to 50% of strokes in children are haemorrhagic. They can be due to problems with the blood vessels in the brain and other conditions.

Arteriovenous malformation (AVM)

In an AVM, the blood vessels carrying blood to and from the brain grow together in a cluster, often in the brain or spine. An AVM can reduce the blood flow in the brain, and compress the surrounding brain tissue. The blood flow can be diverted from arteries into veins, damaging the veins and sometimes causing bleeding.

Aneurysm

An aneurysm is a weakness in an artery wall which can sometimes burst, causing bleeding in the brain. In children, this can happen for several reasons including head injury, connective tissue disorders, and heart conditions. Sometimes it may not be possible to find a cause.

Cavernous malformation or cavernoma

A cavernous malformation is a small cluster of abnormal blood vessels in the brain often said to look like a raspberry. It is made up of a series of connected 'bubbles', or caverns, filled with blood. Often these don't cause any symptoms unless the structure is pressing on the surrounding brain tissues. But if the walls of the caverns are weak, blood can leak out or a large bleed can happen. Symptoms of a cavernoma or a bleed can include seizures, headaches and slurred speech.

Some of the disorders that have already been mentioned including moyamoya syndrome, some types of vasculitis, SCD and blood clotting disorders are also known risk factors for haemorrhagic stroke in children.

It's important to remember that stroke symptoms that last a short amount of time can be a transient ischaemic attack (TIA or mini-stroke). In a TIA, a blood vessel in the brain gets blocked, but the blockage clears by itself. A TIA is a major warning sign of a stroke, and you should call 999.

The FAST test can be used to identify strokes in children:

• Face: Can the young person smile? Has their face fallen on one side?
• Arms: Can they raise both arms and keep them there?
• Speech: Can they speak clearly and understand what you say? Is their speech slurred?
• Time: If you see any one of these three signs, it's time to call 999.

However, children and young people may also have other symptoms including:

• Sudden, severe headache.
• Seizures (fits).
• New and sudden vertigo or dizziness, neck pain or stiffness.
• Nausea/vomiting, fever or loss of consciousness.
• Sudden blurred vision or loss of sight in both eyes.
• Weakness or numbness on one side of the body.
• Changes in sensation, like pins and needles in arms or legs.

In babies up to 28 days old, seizures are a common symptom of stroke. It may also be the case that a stroke in a baby is only identified later, when problems arise with their learning and development. They may have difficulties with movement on one side, known as hemiplegia.

It's important to remember that stroke symptoms that last a short amount of time can be a transient ischaemic attack (TIA or mini-stroke). In a TIA, a blood vessel in the brain gets blocked, but the blockage clears by itself. A TIA is a major warning sign of a stroke, and you should call 999.