Screenings Aim to Prevent Stroke for Children with Sickle Cell Disease

By Jean Yaeger

Sickle cell disease (SCD) can cause damage to blood vessels in the brain, putting children as young as age 2 at risk for stroke.

That’s why patients with certain types of SCD need preventive screenings called transcranial doppler ultrasound. The ultrasound measures how fast blood is flowing in the brain’s arteries, an indicator of stroke risk.   

SCD is a genetic disorder that causes red blood cells to be sticky, stiff and sickled – shaped like crescent moons, in other words. Sickled cells don’t move easily in the blood vessels, which causes pain and possibly anemia or stroke. Sickle cell disease affects people of African, Central and South American, Middle Eastern, Asian, Indian and Mediterranean descent. An estimated 1 in 365 Black newborns have SCD, a lifelong condition.

September is National Sickle Cell Awareness Month, a time to highlight the tools to treat children and teens with the disorder. Cook Children’s serves about 400 patients with SCD. About 5-10% of that population have the genes that make stroke more likely. They need ultrasound screenings at least once a year from age 2-16.

“The main patients that we are concerned about with stroke are the patients who have hemoglobin SS and sickle beta-zero thalassemia, which are severe types of SCD,” said Cassandra Wallace, RN, BSN in the Hematology and Oncology Center at Cook Children’s. “Those patients typically have a higher percentage of sickled cells and more damage done to the blood vessels in the brain. That’s what causes the changes to the blood flow and puts then a higher risk for stroke.”

Hematologist Clarissa Johnson, M.D. heads up the Sickle Cell Program at Cook Children’s, which includes testing, diagnosis, treatment and research. Ultrasound screening is one component of the program.   

Dr. Johnson said the ultrasound screenings allow the medical team to intervene before a stroke happens. Depending on the results of the ultrasound, the medical team might order further tests, adjust the patient’s medication, or start the patient on monthly blood transfusions. If the blood flow is normal, the ultrasound will be repeated in a year.

Screening for Stroke

Most SCD patients at Cook Children’s get their screenings done at the Dodson Specialty Clinics building. It’s a painless process that typically takes about 30 minutes.

Technicians target specific blood vessels on both sides of the patient’s head to measure the rate of blood flow. If inflammation has caused the vessels to narrow, the blood flows faster.

Dr. Johnson says ultrasound results fall into three categories:

• Normal
• Conditional yellow zone (slightly high rate)
• Elevated red zone (high rate)

Depending on what the ultrasound finds, follow-up care might include getting an MRI, starting on a medication, or adjusting the dose. Another treatment option is monthly blood cell transfusions to lower the percentage of sickled cells. 

Wallace said Cook Children’s keeps track of when SCD patients are due for their next ultrasound as part of their ongoing checkups. What’s the outcome? Better management of stroke risk.

“The changes that occur in the brains of sickle cell patients are not visible,” Wallace said. “We do the screening to pick up on minute changes that we may not otherwise see had we not done the transcranial doppler.”

Know the Signs

Another component of SCD care at Cook Children’s is educating patient families about the warning signs of stroke. A stroke occurs whenever the blood supply to the brain is disrupted, causing a loss of oxygen. It can happen at any age. The damage can be permanent.   

Sometimes a stroke happens “silently” and can only be detected later by MRI. Silent strokes occur in as many as 39% of children with SCD before they turn 18, according to the American Stroke Association. Silent strokes can cause learning difficulties and other cognition problems.

Overt strokes, meanwhile, cause slurred speech, facial droop, weakness in the arms and legs, difficulty walking and confusion. If your child has these symptoms, call 911.

“We try to push the parents to know that ‘Time is Brain.’ We want them to remember that it’s very important that they seek treatment right away to save as much brain tissue as we can,” Wallace said.

To spot the signs of stroke, remember the acronym BE FAST:

Balance - Is there a sudden loss of balance or coordination?

Eyes - Is there blurred or lost vision?

Face - Is one side of the face drooping or numb?

Arm - Is there weakness, numbness or loss of movement in the arms, legs or one side of the body?

Speech - Is speech slurred?

Time - If you or someone you know is experiencing any of these symptoms, call 911 immediately.

The most important thing to know is that strokes happen in children. If something is different or off about your child, seek emergency care.

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