Buchanan Iris D, James-Herry Anne, Osunkwo Ifeyinwa
*Morehouse School of Medicine, Department of Pediatrics ‡Division of Hematology/Oncology, Department of Pediatrics, Emory University §Aflac Cancer Center and Blood Disorder Services of Children Healthcare of Atlanta †Sickle Cell Consortium, Atlanta, GA.
J Pediatr Hematol Oncol. 2013 Oct;35(7):543-6. doi: 10.1097/MPH.0b013e318279caae.
The prevalence of cerebrovascular events in sickle cell disease (SCD) can be as low as 10% by the age of 18 for overt cerebral infarction or strokes, up to 35% for silent cerebral infarction, and as high as 43/100 patient years for acute silent cerebral ischemic events. These events typically occur during childhood with a peak incidence between the age of 4 and 7 years. The cumulative risk of central nervous system events in SCD increases with age. Transcranial Doppler (TCD) ultrasonography is an established screening tool for detecting children with SCD at highest risk for stroke by measuring the flow velocity in the large intracranial vessels. Velocities are considered abnormal with readings >200 cm/s and chronic red cell transfusions are recommended to reduce further risk or progression. Red cell transfusions have reduced the rate of cerebrovascular accidents by 90%. We describe the case of 5 children with sickle cell anemia, whose antecedent screening TCD velocities were measured to be ≤70 cm/s in the study. All patients developed some form of cerebral insults, an overt cerebral infarctions, silent stroke or transient ischemic attack, and are now receiving chronic transfusion to prevent further progression. On the basis of these cases, low TCD velocities may identify another group of children at risk for cerebrovascular disease. We suggest TCD velocities <70 cm/s in major vessels (MCA, ACA, and ICA) be considered another type of "abnormal," prompting more sensitive evaluations (such as a brain MRI and MRA) for the presence of central nervous system disease, and, if negative, decrease intervals between subsequent TCD assessments.
镰状细胞病（SCD）中脑血管事件的患病率，18岁时显性脑梗死或中风的患病率可低至10%，无症状脑梗死的患病率高达35%，急性无症状脑缺血事件的患病率高达43/100患者年。这些事件通常发生在儿童期，4至7岁时发病率最高。SCD中枢神经系统事件的累积风险随年龄增加。经颅多普勒（TCD）超声检查是一种成熟的筛查工具，通过测量颅内大血管中的血流速度来检测SCD中中风风险最高的儿童。读数>200 cm/s时，血流速度被认为异常，建议进行慢性红细胞输血以降低进一步的风险或病情进展。红细胞输血使脑血管意外的发生率降低了90%。我们描述了5例镰状细胞贫血患儿的病例，在研究中，他们之前的筛查TCD血流速度测量值≤70 cm/s。所有患者均出现了某种形式的脑损伤，即显性脑梗死、无症状性中风或短暂性脑缺血发作，目前正在接受慢性输血以防止病情进一步进展。基于这些病例，低TCD血流速度可能会识别出另一组有脑血管疾病风险的儿童。我们建议，主要血管（大脑中动脉、大脑前动脉和颈内动脉）的TCD血流速度<70 cm/s应被视为另一种类型的“异常”，这促使对中枢神经系统疾病的存在进行更敏感的评估（如脑部MRI和MRA），如果结果为阴性，则缩短后续TCD评估的间隔时间。
