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An unresolved issue in sickle cell disease is treatment in the
presence of Moyamoya syndrome.
Case report: We present a 10 year old child from Central
Africa who suffers from homozygous sickle cell disease
(SCD). Cerebral MRI showed multiple, clinically silent ischemic
infarctions while diffusion weighted imaging (DWI) was negative
for acute lesions. The neurological examination revealed normal
clinical findings without an evident neurological deficit. In colourcoded
duplex sonography high peak flow velocities in the left
middle cerebral artery up to 300 cm/s and in the right posterior
cerebral artery up to 200 cm/s could be detected. Peak flow
velocities in the extracranial internal carotid arteries were slightly
elevated. MR angiography showed high grade stenosis of the
middle cerebral artery on both sides, of the right posterior
cerebral artery and middle grade stenosis of the left posterior
cerebral artery and of the anterior cerebral artery on both sides.
MR angiography showed a secondary moyamoya syndrome with
collateralisation via the leptomeningeal vessels.
Discussion: Children with SCD are at a high risk for ischemic
strokes. In essence, the strokes are the result of large-vessel
occlusive disease. Moyamoya disease is described as an
angiographic pattern which is due to large-vessel occlusions
resulting in progressive development of collaterals. As
moyamoya collaterals reflect the degree of large vessel occlusive
disease, it is a surrogate marker for higher risk of recurrent
strokes in these subjects similarly as elevated peak flow
velocities (>200 cm/s) in the terminal segment of internal carotid
artery or proximal middle cerebral artery as measured with
duplex sonography. Chronic transfusion therapy that is
administered to keep HbS levels below 30% has been thought to
reduce the risk of recurrent stroke, but there are studies which
showed progression of the disease despite chronic transfusions
in the presence of collaterals. Prevention of collaterals by chronic
transfusion therapy and the effect of bone marrow transplantation
are other unresolved issues. Therefore, regular monitoring by
MRA and colour-coded duplex sonography may help to indentify
subjects at high risk for stroke and evaluate treatment regimes.