Changes in Transcranial Doppler Flow Velocities in Children with Sickle Cell Disease: The Impact of Hydroxyurea Therapy Samuel Ademola Adegoke, MD, MPH, PhD,* , † Rejane de Souza Macedo-Campos, MD,‡ Josefina Aparecida Pellegrini Braga, MD, PhD,§ Maria Stella Figueiredo, MD, PhD,* and Gisele Sampaio Silva, MD, MPH, PhD‡ , ‖ Background and Objectives: Hydroxyurea (HU) was recently described as a sub- stitute for chronic transfusion for children with sickle cell disease (SCD) and abnormal transcranial Doppler (TCD) velocities who have received at least 1 year of trans- fusions. However, the role of HU in reverting elevated TCD velocities in patients not treated with transfusion is still debatable. The objective of the study was to examine whether HU influences the progression of TCD velocities in children with SCD. Patients and Methods: Children with SCD with at least 2 TCDs not less than 6 months apart were evaluated over 51 months. Time-averaged maximum mean (TAMM) velocities for the initial and the last transcranial Doppler examinations were noted and differences compared between HU and HU-naive groups. Results: Overall, 68.8% of the HU-group with elevated TCD velocities compared with 40.0% of the HU-naive experienced TCD reversal (P = .047). A higher proportion of the HU-naive group, 7 (14.3%) versus 9.8% of the HU group experienced TCD con- version. Those with initial conditional velocities in the HU-group experienced a significant reduction in TAMM velocities (from 176.8 ± 5.3 to 162.7 ± 13.9 cm/s, difference of 14.1 cm/s; P = .001) unlike those in the HU-naive group (176.3 ± 5.3 to 170.0 ± 18.6 cm/s, difference of 6.3 cm/s; P = .148). The change in the TAMM velocities was also significantly higher among the HU-group (14.1 ± 12.4 cm/s versus 6.3 ± 18.5 cm/s, P = .015). Conclusion: Our data suggest a beneficial role of HU in TCD velocity reduction in patients not treated with chronic transfu- sions, particularly among those with initial conditional TCD velocities. Key Words: Children—chronic blood transfusions—hydroxyurea—sickle cell disease—transcranial Doppler. © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved. From the *Haematology and Blood Transfusion Division, Universidade Federal de São Paulo, São Paulo, Brazil; †Department of Pediatrics and Child Health, Obafemi Awolowo University, Ile-Ife, Nigeria; ‡Department of Neurology and Neurosurgery; §Department of Pediatrics, Universidade Federal de São Paulo, São Paulo, Brazil; and ‖Programa Integrado de Neurologia, Hospital Israelita Albert Einstein, São Paulo, Brazil. Received May 9, 2017; revision received July 30, 2017; accepted September 17, 2017. Address correspondence to Samuel A. Adegoke, MD, MPH, PhD, Department of Paediatrics and Child Health, Obafemi Awolowo University, P.M.B. 013, Ile-Ife, Nigeria. E-mail: adegoke2samade@yahoo.com. 1052-3057/$ - see front matter © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jstrokecerebrovasdis.2017.09.020 ARTICLE IN PRESS Journal of Stroke and Cerebrovascular Diseases, Vol. ■■, No. ■■ (■■), 2017: pp ■■–■■ 1