G38 CHANGE OF CEREBRAL BLOOD FLOW OVER TIME IN CHILDREN WITH SICKLE CELL DISEASE

K. Kotecha, D. E. Saunders, F. J. Kirkham. Institute of Child Health & Great Ormond Street Hospital, London

Around 10% of children with sickle cell disease (SCD) have a stroke by the age of 20 and a further 24% have silent infarction (SI). Non-invasive methods of imaging such as transcranial Doppler (TCD) have been used to diagnose vasculopathy in SCD. Cerebral blood flow velocities (CBFV) >170 cm/sec are associated with higher risk of subsequent stroke, potentially preventable by blood transfusion. In adults, low CBFV is associated with SI.

This study has examined the natural history of CBFV as measured by TCD in a cohort of 64 patients who were not on a regular transfusion programme. Highest recorded average CBFV was measured on both sides of the internal carotid and middle cerebral arteries in 1991–1993 (time point 1) and again in 1996–1999 (time point 2). A score was given for each TCD measurement as follows: 0 = normal CBFV, 1 = CBFV>200 cm/sec, 2 = CBFV<50 cm/sec. The median age at time point 1 was 7 (range 1.4–15 years).

Thirty nine patients remained normal throughout and 15 with initially normal velocities changed to velocity <50 cm/s at time point 2. Of the 5 (8%) patients with velocities >200 cm/s at time point 1, 4 had velocities <50 cm/s at time point 2 and 4/5 patients with velocities <50 cm/s at time point 1 remained low at time point 2. Patients with abnormally high or low CBFV at time point 1 were more likely to have abnormally low CBFV at time point 2 (χ², p = 0.007). Although clinical stroke was commoner in those with abnormal TCD (χ² = 0.003) and SI, the latter relationship was not significant (χ², p = 0.397).

There is progressive CVD in children with SCD over time as evidenced by an increase in …