Table of Contents
Patients, Families and Friends
Health Care Providers
|Transcranial Doppler Ultrasonography|
|Health Care Providers - Care Paths And Protocols - Children & Adolescents|
Stroke, defined as an acute, clinically apparent neurological event, occurs in 8-11% of children with Hb SS. Most strokes are ischemic events caused by stenosis or occlusion of large cerebral arteries such as the intracranial internal carotids and middle cerebrals. Stroke typically occurs without warning and causes significant long-term neurologic sequelae in at least 50% of cases. Chronic transfusion after a first stroke reduces markedly the high risk of recurrent stroke, but this is a suboptimal approach because it does not prevent the initial neurologic injury.
Transcranial Doppler (TCD) ultrasonography provides a non-invasive method for identifying children with Hb SS who are at high risk for developing a first stroke. High risk patients are those with increased blood velocity in large cerebral vessels, indicative of vascular narrowing. Patients with mean blood-flow velocity in the internal carotid or middle cerebral artery of >200cm/second are at highest risk. A prospective randomized study demonstrated that chronic transfusions reduce the risk of first stroke in such high risk patients. These data have led some to recommend routine TCD screening of children with sickle cell anemia, and the initiation of a chronic transfusion program for those with abnormal screening tests.
The use of TCD and chronic transfusions to prevent first stroke is an exciting development. However, a number of important issues continue to limit the implementation of this approach:
Thus, our group feels that it is premature to recommend that all sickle cell anemia patients with sickle cell anemia be routinely screened with TCD. Screening requires that the method be reproducibly established at individual centers according to the protocol established for children with sickle cell disease (details available at http://www.neuro.mcg.edu/cvhp/stop). Once standardized, TCD screening can be offered to families, with disclosure of pros and cons and alternatives to chronic transfusions for children with positive results. This approach will facilitate informed decision-making by families. Chronic transfusions should be discussed with families of children at high risk for stroke, but data are currently insufficient to recommend that all such patients be transfused indefinitely. Finally, we recognize that information about this issue is rapidly evolving, and that approaches to TCD screening will vary among institutions.