Sickle Cell Disease Patients Are at a Higher Risk for Stroke
Stroke is defined as an acute neurological syndrome caused by cerebral infarction (blocking of an artery in the brain due to sickled cells) or a hemorrhage (large bleed) with resultant ischemia (tissue death) and signs and symptoms such as headache, seizure, weakness, slurred speech, or confusion.
In general, hemorrhagic strokes occur in older persons with sickle cell disease while cerebral infarctions occur in younger groups.
It is now understood that the cause of vessel blockage in sickle cell disease is likely a combination of a buildup of sickled red blood cells, narrowing of the blood vessels, and blood clots. Bone marrow or fat emboli secondary to bone marrow infarction has also been known to cause strokes among patients with sickle cell disease.
Most patients who have strokes have HbSS disease or HbSβ-0; however, it can occur in other genotypes.
Signs and Symptoms of Stroke
Signs and symptoms of stroke include:
- sleepiness and confusion
- acute severe headache
- weakness or numbness usually on one side of the body
- slurred speech or aphasia
- visual or auditory changes
- painless limp
- cerebral infarcts (“silent strokes”) often lead to psychological problems and learning delays
Strokes occur in about 10% of children under age 20 with sickle cell disease. It is rarely seen under the age of one. The incidence is highest between ages 2 and 16 years. In children with sickle cell disease, the internal carotid and middle cerebral arteries are the most common areas of infarction.
Children who had a stroke are treated with transfusion therapy to maintain a HbS of less than 30%. This reduces the risk of repeated strokes. Chronic transfusion therapy ultimately requires medications to reduce iron overload.
Transcranial Doppler ultrasound is primarily used as a screening tool to identify children with sickle cell disease who may be at increased risk for stroke. The Transcranial Doppler ultrasound measures the flow of blood through the cerebral arterial circulation, particularly in the internal carotid and middle cerebral arteries.
An increased flow velocity (measured in cm/seconds) is linked to the presence of a narrowed vessel or segment. Flow velocities of greater than 200 cm/sec are strongly associated with increased risk of stroke. If two studies are abnormal, the family should be offered prophylactic chronic transfusion and iron overload therapy. A Transcranial Doppler ultrasound screening is recommended for children with sickle cell disease ages 2 to 16.