MRI abnormalities of the brain in one-year-old children with sickle cell anemia

Background. Sickle cell anemia (SCA) frequently results in damage to the central nervous system (CNS), but the age of onset of these effects is uncertain. We performed MRI examinations of the brain in infants with SCA, who were evaluated as part of the multicenter randomized double-blinded Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG). Methods. Determination of eligibility for enrollment in the trial originally required baseline MRI and magnetic resonance angiography (MRA) of the brain. A standardized imaging protocol was utilized across eight clinical centers. MRI/MRA exams were reviewed by a panel of three neurology/neuroradiology readers and interpretations reported to the coordinating center. Results were correlated with patient age, gender, history, WBC count, platelet count, hemoglobin (Hb), HbF level, score on the Bayley Scales of Infant Development, and velocity on transcranial Doppler ultrasonography (TCD). Results. Twenty-three subjects with HbSS were examined at average age 13.7 months (range 10-18 months); 13 were male. Three (13%, CI: 3-34%) had silent infarcts on MRI, two in the right frontal area and one bilaterally. None had MRA abnormalities. The lesions were correlated with increased right-sided TCD velocity and low HbF level, but not with age, history, Hb level, developmental score, or left-sided velocity. Conclusions. Silent brain infarcts occur in a small but significant number of infants with SCA as early as a year of age. This finding indicates a need for thorough evaluation of the CNS very early in life in children with SCA in order to develop timely intervention strategies.