BOF: General (Haemoglobinopathy)

Which ONE of the following has been identified as a risk factors for HAEMORRHAGIC stroke in sickle cell disease?

a) Absent moyamoya vasculature on cerebral angiography

b) Age greater than 40 years

c) Chronic hydroxyurea therapy

d) Increased steady state haemoglobin

e) Reduced steady state leucocyte count

Answer:

d) Increased steady state haemoglobin

Explanation:

Stroke causes considerable morbidity in sickle cell disease. The risk of stroke is around 25% by 50 years with more than half of these occurring before the age of 30, and is usually ischemic in children and older adults, with an increased in haemorrhagic stroke in those presenting in their twenties. Overall 30% of strokes are haemorrhagic and may be associated with Moyamoya collateral vessel development in the circle of Willis secondary to chronic stenosis. Risk is increased in those with frequent veno-occlusive events particularly recent chest crisis and in those with lower Hb, increased WCC and haemolysis. Vascular occlusion is attenuated by the thalassemias because of a reduction in HbSS concentration in the erythrocytes and this reduces stroke. At risk patients can be identified with transcranial Doppler ultrasound and chronic transfusion programmes are effective at reducing recurrence risk, and probably primary stroke risk in high risk patients by these criteria. However, compliance is often poor, iron overloading needs to be addressed, and it is not clear when therapy can be discontinued since the risk probably persists. Hydroxyurea may offer an acceptable alternative with evidence of its efficacy in addressing the surrogate markers of stroke risk (increasing fetal haemoglobin, reducing white cell count and reducing trascranial Doppler flow rates), and in reducing stroke risk clinically.

Reference:

Kassim A, Galadanci N, Pruthi S & DeBaun M. How I treat and manage strokes in sickle cell disease. Blood May 2015, 125 (22) 3401-3410v