Primary and secondary stroke prevention strategies
The dire consequences of stroke in this patient population underline the importance of primary stroke prevention, which requires the use of transcranial Doppler (TCD) ultrasound. It has been validated as a tool to screen for initial stroke risk in children with no history of stroke. High velocity measured on TCD indicates a narrowed blood vessel or elevated blood that is compensating for anemia. It adds up to a “struggling brain,” said Dr. Jordan, during her talk. If the TCD ultrasound velocity is greater than 200 cm/sec (or 170 cm/sec, depending on nonimaging versus imaging TCD), the TWiTCH trial showed that seven monthly transfusions is the number needed to treat to prevent one stroke. After 1 year, patients can be switched from transfusions to hydroxyurea if the patient has no significant intracranial stenosis. Hydroxyurea boosts both fetal and total hemoglobin, and also counters inflammation.
Following an acute stroke or transient ischemic attack, patients should receive a transfusion within 2 hours of presenting in the health care setting. American Society of Hematology guidelines recommend exchange transfusion rather than a simple transfusion. A simple transfusion can be initiated if an exchange transfusion is not available within 2 hours and hemoglobin values are less than 8.5 g/dL, to be followed by performance of exchange transfusion when available.
For chronic secondary stroke prevention, transfusions should be performed approximately monthly with the goal of maintaining hemoglobin above 9 g/dL at all times, as well as suppressing hemoglobin S levels to 30% or less of total hemoglobin.
Sudden, severe headache is a potential harbinger of complications like aneurysm, which occurs 10-fold more often among patients with sickle cell disease than the general population. It could also indicate increased intracranial pressure or cerebral venous sinus thrombosis.
Treatment of acute headache in sickle cell disease should avoid use of triptans, since vasoconstriction can counter the increased cerebral blood flow that compensates for anemia. Gabapentin and amitriptyline are good treatment choices.
New-onset seizures are a potential sign of stroke or posterior reversible leukoencephalopathy (PRES) in patients with sickle cell disease. Urgent MRI should be considered for all new-onset seizures. If blood pressure is high, PRES may be present. Seizures may also be an indicator of a previous brain injury.
Dr. Jordan has no relevant financial disclosures. Dr. Lance has served on an advisory board for Novartis.