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For Patients and Caregivers
TCD Screening and Sickle Cell Disease
Transcranial Doppler (TCD) ultrasound measures the speed of blood flowing in
arteries inside the head. The narrower an artery is, the faster the blood
flows through it, and the higher the risk of blockage and brain injury. TCD
is a proven tool for identifying children 2-16 years old with sickle cell
disease who are at risk for stroke.
TCD was used in the STOP study.1 In that study, chronic blood transfusion
reduced stroke risk by 90%. The National Heart, Lung, and Blood Institute
recommends that all children with sickle cell disease receive screening with
TCD and that transfusions be considered for children at high risk for
stroke.
TCD is:
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Proven to predict stroke risk
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Non-invasive
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Painless
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Fast (exam takes 30-45 minutes)
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Convenient (can be done same day as clinic visit)
A TCD examines intracranial vessels (middle cerebral artery and
distal internal carotid artery). Greater attention is paid to these vessels
because stenosis (blockage) is normally found in these vessels, especially the
middle cerebral artery.
In the STOP study, TCDs were read as either normal, conditional, abnormal, or
inadequate, based on time-averaged maximal mean velocities:
Reading Velocities Risk Level
Normal - Under 170 cm/sec, Low risk of stroke
Conditional - 170-199 cm/sec, Moderate risk of stroke
Abnormal - 200 cm/sec or higher, High risk of stroke
Inadequate - Unreadable or incomplete, Unknown
Why Is TCD Important?
Stroke is an important complication of sickle cell disease. The rate of stroke
in children with sickle cell disease is 300 times higher than children without
sickle cell disease.2 Strokes can lead to physical and neuro-psychological
impairment which can affect motor skills, school performance, and overall
quality of life.
The symptoms of stroke are:
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Paralysis on one side of the body
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Difficulty with speech or vision
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Numbness on one side of the body
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Sudden severe headache with possible loss of consciousness
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Seizures, particularly partial seizures.
More information about stroke and sickle cell disease can be
obtained from the Sickle Cell Information
Center.
Where Can Children Get A TCD?
TCD is performed vascular ultrasound laboratories that are usually located in Radiology and Neurology Departments at many major medical
centers. The availability of this service varies by state. Most major sickle
cell disease clinics offer TCD or know where TCD can be obtained.
Another source of information is the
Intersocietal Commission for the Accreditation of Vascular Labs (ICAVL), an agency that
ensures quality standards for vascular laboratories. Labs which perform
intracranial exams are identified in the ICAVL Website.
Click here
for a list of TCD Exam Locations in North America.
Please contact us for more information:
Robert J. Adams, MS, MD
Regents Professor of Neurology
Medical College of Georgia
1429 Harper Street, HF-1154
email: rjadams@mcg.edu
phone: (706) 721-4670
What Research Is Going On Now?
In the STOP II study, the goal is to learn whether children who are receiving
long-term transfusions to prevent strokes can safely stop those transfusions
when their TCDs show that they have a lower risk of stroke.
This study could provide valuable information for patients and their physicians.
While chronic blood transfusions are effective in preventing strokes, they also
have serious side effects including iron overload. If it can be proved that
transfusions do not need to be given indefinitely, this will reduce the burden
on children and their families.