Stroke in Newborns: More Common Than We Think

Sherene Chen-See
Medical writer/editor
AboutKidsHealth.ca

Most parents think of stroke as a disease of old age. But did you know that newborns have as high a risk of stroke as the elderly? Stroke in the first 28 days of life, called the newborn period, is much more common than parents realize. Yet stroke in this fragile age group remains largely unrecognized and thus untreated.

What is stroke and how common is it?
A stroke is a sudden stoppage or decrease in the flow of blood in the brain, severe enough that it causes damage to the brain. There are two types of stroke: ischemic and hemorrhagic. Ischemic stroke is when the blood flow to the brain is diminished, usually because of a clot, called a thrombus, in one of the blood vessels in the brain. There are two types of ischemic stroke that occur in children, especially newborns: sinovenous thrombosis, where there is a clot in one of the veins in the brain, and arterial ischemic stroke, where the clot is in an artery in the brain. Hemorrhagic stroke is when a blood vessel in or near the brain ruptures, causing bleeding in the brain.

Types of Stroke
The incidence of stroke in the newborn period is very high compared to infancy and childhood. Sinovenous thrombosis occurs in one out of 6000 newborns, arterial ischemic stroke in one of 4000 newborns, and hemorrhagic stroke in one of 4000 newborns, according to Dr. Gabrielle deVeber, Director of the Children’s Stroke Program and staff neurologist at the Hospital for Sick Children (SickKids). After the newborn period, the risk of stroke drops significantly, and remains low until old age.

Why do strokes occur in newborns?
“Strokes that are diagnosed in newborns often occur in fetal life,” says Dr. Hilary Whyte, a neonatologist at SickKids. In pregnancy, proteins come across the placenta from mother to fetus, which help to decrease the risk of bleeding. However, this puts the fetus at higher risk for clotting and stroke, says Dr. deVeber. Also, sometimes clots can form in the placenta and travel to the fetus’ blood circulation. These clots may eventually make their way to the baby’s brain and cause a stroke.

Labour and delivery is another common time when stroke can occur in newborns. Childbirth can cause tremendous strain on the baby’s head. Stress on the arteries and veins in the baby’s head may lead to clot formation and stroke.

In addition, newborns come into the world with thicker blood than the rest of us – twice as many red blood cells as an adult – and this in itself can lead to clotting. In the first few days after birth, dehydration can be a problem, which can also cause the blood to clot.

What are the symptoms of stroke in newborns?
Stroke in newborns is essentially a "silent entity," according to Dr. Whyte. Because there are usually no clinical symptoms, the problem often goes unrecognized and thus untreated until the baby is much older. The usual symptoms seen in older children and adults, such as speech problems, numbness on one side, or imbalance, are difficult or impossible to detect in a newborn.

Of the newborns who do show symptoms, the vast majority present with a seizure, says Dr. deVeber. Seizure is the most recognizable sign of stroke in this age group. The symptoms of seizure are sometimes difficult to spot in newborns, and they include the following:

repetitive facial movements, including sucking, chewing, or eye movements
unusual bicycling or pedaling movements
staring
apnea, or pauses in breathing associated with slowing of the heart
rhythmic jerking movements involving the muscles of the face, tongue, arms, legs, or other regions
stiffening or tightening of muscle groups
quick, single jerks involving one arm or leg or the whole body

One major sign of stroke in adults is weakness on one side of the body. However, the newborn brain is immature, and thus the newborn’s ability to show weakness on one side of the body is not yet developed, says Dr. deVeber. As a result, this symptom may not appear in a newborn victim of stroke. Generally, about 15% of newborn stroke victims show less movement on one side of their body. One-sided weakness becomes easier to recognize as the baby gets older.

"Handedness" is a symptom of stroke that may arise some time after the newborn period, from around six weeks to six months of life, says Dr. Whyte. These babies may favour their left or right hand and reach out more with that hand. Some parents mistake this as meaning that the baby is advanced for his or her age, when really it is a sign of stroke. In healthy children, handedness does not normally appear until about 12 months.

What are the risk factors for stroke in newborns?
There are a number of factors that can put a newborn at higher risk for stroke. If the newborn has a birth defect that involves a hole in the heart, it is easier for clots to pass from other parts of the body, through the heart, and up to the brain. If there is a family history of clotting problems, the risk of stroke is higher in the newborn. Serious infections such as sepsis and meningitis can also lead to clotting. Other risk factors are those previously described, such as dehydration and childbirth.

How is newborn stroke diagnosed?
Sometimes stroke can be diagnosed while the baby is still in the womb. Generally this occurs if a birth defect is suspected and the mother is given a test called fetal magnetic resonance imaging (MRI). The fetal MRI is very effective at detecting stroke in the fetus. In some fetuses, if the stroke is particularly severe, it can be detected on a normal ultrasound during pregnancy. Once the baby is born, further imaging of the brain can be done to confirm the diagnosis.

In addition, all newborns who have a seizure should be given an ultrasound and CT of the head. They may also be given an MRI. The MRI is more sensitive but any stroke of significance would be seen on a CT, says Dr. Whyte. In an ideal world, an MRI would be done first, followed by other tests called a magnetic resonance arteriogram (MRA) and a magnetic resonance venogram (MRV), to look more closely at the blood vessels in the brain.

How is newborn stroke treated?
Although stroke can be diagnosed during pregnancy, the fetus cannot actually be treated for the condition until after he is born. Once the baby is born, it is not possible to reverse the damage that has been caused by the stroke. However, sometimes a medication called an anticoagulant can be given to prevent the clot from getting worse. An anticoagulant decreases the clotting ability of the blood. If the baby has had an ischemic stroke, and there is no evidence of bleeding in the brain, an anticoagulant can be used to stop the clot from getting worse.

New research led by Dr. Mahendra Moharir, a stroke fellow in the Children’s Stroke Program at SickKids, has shown that the use of an anticoagulant is safe in the treatment of sinovenous thrombosis with no bleeding in the brain; almost one-quarter of newborns with this type of stroke who do not receive an anticoagulant have a worsening of their blood clot. On the other hand, newborns who have arterial ischemic stroke generally do not need an anticoagulant unless there is an additional blood clot in the heart that could move up to the brain, says Dr. deVeber.

If the baby has had a hemorrhagic stroke, which means that there is bleeding in the brain, an anticoagulant should not be used because it will make the bleeding worse.

What are the outcomes of stroke in newborns?
The newborn brain is "plastic," and therefore it is more amenable to recovery after stroke than an adult brain. The nerve cells in the newborn brain are still forming connections, and this makes it easier for the baby to transfer important functions to other parts of the brain, says Dr. Whyte. For example, if the stroke occurred in the part of the brain that controls speech, as the baby gets older, he might be able to transfer control of this function to the other side of the brain. Because of the plasticity of the newborn brain, a newborn may have a significant stroke and still be neurodevelopmentally normal.

With that said, there are a number of common complications that can arise from stroke in newborns. Cerebral palsy is the most common complication. Epilepsy, language problems, cognitive or behavioural problems, headache disorders, and seizure disorders can all emerge as a result of newborn stroke. These conditions require special care over the long term, to ensure the best possible quality of life for the child.

What precautions can be taken to prevent stroke in newborns?
Because many newborn strokes actually occur in pregnancy, every precaution should be taken to make sure the fetus receives healthy blood flow while in the womb. Expectant mothers should eat properly, refrain from cigarette smoking, and avoid becoming dehydrated, says Dr. deVeber.

If an expectant mother has a history or family history of clotting disorders, she should be tested to see if she carries a genetic problem called Factor V Leiden, which can cause clotting in the baby. If doctors know that the baby may have this condition, they can take the necessary steps to manage it.

If a baby has too many red blood cells, which can arise if there is a problem during pregnancy or childbirth, the newborn may be prone to developing clots. Stroke can sometimes be prevented in these newborns by giving them a "partial exchange" blood transfusion where the blood is diluted with saline, says Dr. Whyte.

Once the baby is born, dehydration can sometimes cause the blood to clot. Bring your newborn in to see a doctor if you notice any of the following signs of dehydration:

dry mouth
less than six wet diapers per day
tearless and sunken eyes
a sunken fontanel, which is the ‘soft spot’ at the top of your newborn’s head
dry skin

It is important for parents to be aware of stroke in the newborn period. If you think that something is wrong with your baby, bring her to the family doctor. Do not worry that you are over-reacting. It is better to be safe than sorry. If your family doctor agrees that your baby could have had a stroke, he will refer your baby to a paediatrician who will launch an investigation.

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