Acute Silent Cerebral Ischemia Occurs More Frequently Than Silent Cerebral Infarction In Children with Sickle Cell Anemia

• Published in: Blood 2010-11, Vol.116 (21), p.268-268
• Main Authors: Quinn, Charles T., McKinstry, Robert C., Dowling, Michael M., Ball, William S., Kraut, Michael A., Casella, James F., Dlamini, Nomazulu, Ichord, Rebecca N., Jordan, Lori C., Kirkham, Fenella J., Noetzel, Michael J., Roach, E. Steve, Hirtz, Deborah, DeBaun, Michael R.
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V116.21.268.268

Abstract 268 Children with sickle cell anemia (HbSS) are at high risk of overt stroke and clinically silent cerebral infarction (SCI). SCI is an infarct-like lesion visualized on magnetic resonance imaging (MRI) of the brain that produces no corresponding motor or sensory deficits. The prevalence of SCI in HbSS is approximately 20 – 30% by 16 years of age, but less is known about its incidence. The Cooperative Study of Sickle Cell Disease (CSSCD) found the incidence of new or more extensive SCI in children with HbSS to be 7 events per 100 patient-years. Given that SCI is clinically silent, the only way to determine its incidence (the number of new events occurring in a specific time-period) is to screen with two sequential MRIs of the brain. MRI can also detect acute cerebral ischemia in asymptomatic patients using diffusion-weighted imaging (DWI). The incidence of acute silent cerebral ischemic events (ASCIEs) is not known. A clinical trial setting provides a unique opportunity to determine the incidence of ASCIEs and SCI in children with HbSS. To determine the incidence rates of (1) ASCIEs in children with HbSS without prior evidence of focal neurological deficits and (2) new, recurrent SCI in children with HbSS who have pre-existing SCI. We studied a cohort of children with HbSS and sickle-β0-thalassemia who had brain MRIs for the Silent Infarct Transfusion Trial. All participants had no prior history of overt stroke, seizures, or transient ischemic attacks. ASCIE was defined as an infarct-like lesion on brain MRI without corresponding motor or sensory deficits that appeared as a focus of T2 hyperintensity with restricted diffusion on DWI sequences. SCI was defined an infarct-like lesion without corresponding motor or sensory deficits that appeared as a focus of T2 hyperintensity without restricted diffusion. Given that acute cerebral ischemia appears as a focus of restricted diffusion on DWI for 10 days, we assumed that each MRI scan provided 10 patient-days of observation for detecting ASCIE. Therefore, the incidence of ASCIEs was calculated using a single MRI per patient. The incidence of new or more extensive SCI in children with pre-existing SCI was determined in those who had two MRIs each (screening and pre-randomization). We statistically compared the incidence rates of ASCIEs and SCI obtained by these two different methods. For all ASCIEs and new SCI events, a medical history tool was completed at the local site at the time of MRI of the brain.