Stroke and sickle cell anemia

Here are the facts:

  • 1 in 10 children with sickle cell anemia have a stroke before college.
  • Almost 1 in 4 children with sickle cell anemia have “silent strokes” before college.
  • Approximately 100,000 Americans have sickle cell anemia.
  • Patients with sickle cell anemia are at greater risk of chronic pain, opioid dependence, HIV and hepatitis C.
  • Sickle cell disease and its complications can be managed, and often prevented.

Want more? Hear what Dr. Erica Jones has to say on the matter in this week’s broadcast:

To start, sickle cell disease is a group of hemoglobin disorders that mostly affects people from sub-Saharan Africa, India, or the Mediterranean. People with sickle cell anemia inherit a particular mutated Beta globin –S gene from both parents resulting in a dysfunctional hemoglobin molecule which distorts the shape of red blood cells, causing a chronic hemolytic anemia as well as a relative hypercoagulable state.

My interview with Dr. Jones.

Other than the hypercoagulable stroke, sickle cell disease can cause cerebrovascular disease by way of fat embolism from infarcted bone, venous sinus thrombosis, complications of HIV, and

Suzuki grade III/IV Moyamoya with characteristic “smokey smoke” appearance on vessel imaging.

the Moyamoya syndrome. Moyamoya tends to be progressive and preferentially affects the anterior circulation leading to large territory strokes or watershed infarcts due to hypoperfusion. Hemorrhagic strokes become more common in sickle cell patients as they become adults, and it is thought to be due to the fragility of those collateral vessels that form as a part of moyamoya or even aneurysms caused by the abnormal circulation.

Treatment is indicated when there are clinical signs of decreased blood flow such as stroke, TIA, or cognitive decline or if there is decreased cerebral blood flow on imaging. Many patients with moyamoya are started on daily aspirin therapy but there has not been strong evidence for its efficacy in preventing stroke. Surgery is also an option:

Superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass surgery.

  1. Direct revascularization involves connecting a branch of the external carotid—the superior temporal artery—to middle cerebral artery and is used more in adults (the STA-MCA bypass).
  2. Indirect revascularization involves pial synangiosis, whereby a surgeon connects a tissue supplied by the ECA or the ECA itself to the dura of the brain in order to promote angiogenesis.

Hopefully you don’t need to surgerize many Moyamoya patients these days. In fact, a number of clinical trials have demonstrated safety and efficacy in routine exchange transfusions for specific patients. And this should reduce the need for these neurosurgical procedures. The STOP 1 trial in the 90s determined that children with abnormal TCD velocities (>200 cm/s), who had previously been found to be at significantly higher risk for stroke, had a reduced stroke risk from chronic blood transfusions every 3-4 weeks with goal HbS < 30%. In an attempt to prevent the complications of chronic transfusion, the STOP 2 trial evaluated the risk of stroke once chronic transfusion therapy was discontinued. Unfortunately, patients randomized to STOPPING the red blood cell transfusions were more likely to develop higher TCD velocities OR stroke.

But what do you do when a sickle cell patient is experiencing an acute stroke? To make a long story short here, there are few exceptions to the management of a typical stroke patient when you are seeing a stroke patient with a history of sickle cell disease. A head CT is always important to start with in order to rule out hemorrhage. Next, the most important acute treatment is RBC transfusion to a hemoglobin goal of 10 mg/dL. Exchange transfusion is ideal but if it can’t be arranged right away simple transfusion is also recommended. tPA should still be considered, as should endovascular therapy for candidates with proximal vessel occlusions. Secondary stroke prevention with anti-platelets and statins can also be given like any other patient. And so on… Don’t stroke out when you see these patients. Do the work up, weigh the treatment options, and make your decision–remembering that BrainWaves is here to provide education not medical advice!


[Jim Siegler]


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