Table 3: Risk factors for stroke in sickle cell disease.

(i) high blood flow velocity on transcranial Doppler
(ii) low hemoglobin value
(iii) high HbS level
(iv) high white cell and platelet counts
(v) hypertension
(vi) silent brain infarction
(vii) history of chest crisis, transient ischemic attacks, meningitis, seizures, surgery, priapism, acute anemia, and transfusion within 2 weeks before the stroke