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Assessment of Cerebral Lateralization in Children using Functional Transcranial Doppler Ultrasound fTCD
Published on: September 27, 2010
Transcranial Doppler and Magnetic Resonance in Tanzanian Children With Sickle Cell Disease
Edward N Kija1,2, Dawn E Saunders3, Emmanuel Munubhi1
1From the Muhimbili Wellcome Programme, Dar es Salaam, Tanzania (E.N.K., E.M., D.S., J.K., D.A.N., S.E.C., C.R.J.C.N.).
Insights
Neurological complications are common in Tanzanian children with sickle cell disease. Abnormal cerebral blood flow velocity (CBFv) on transcranial Doppler indicates high risk for stroke and requires further MRI/MRA evaluation.
Area of Science:
- Pediatric Neurology
- Hematology
- Vascular Imaging
Background:
- Sickle cell disease (SCD) is a common genetic disorder in many parts of Africa, including Tanzania.
- Neurological complications, such as stroke and silent infarcts, are significant causes of morbidity and mortality in children with SCD.
- Early detection of at-risk individuals is crucial for timely intervention.
Purpose of the Study:
- To determine the prevalence of neurological complications, vascular abnormalities, and infarction in Tanzanian children with sickle cell disease.
- To assess the association between cerebral blood flow velocity (CBFv) and clinical outcomes.
- To evaluate the utility of transcranial Doppler (TCD), magnetic resonance imaging (MRI), and magnetic resonance angiography (MRA) in this population.
Main Methods:
- Consecutive enrollment of children with SCD for transcranial Doppler (TCD) screening.
- Children with abnormal CBFv (elevated, low, or absent) were invited for brain MRI and MRA.
- Clinical data, including history of seizures, weakness, and painful crises, were collected.
Main Results:
- 11% of children had a history of seizures, and 8% had unilateral weakness.
- 14% had elevated CBFv and 20% had low/absent CBFv, both associated with lower hemoglobin levels.
- 43% of children with abnormal TCD findings had infarction on MRI, and 50% had abnormal MRA findings.
- Children with previous seizures had significantly higher rates of infarction (91%) compared to others.
- Absent/low CBFv was associated with increased risk of stroke, recurrent stroke, and mortality.
Conclusions:
- Approximately one-third of Tanzanian children with SCD have abnormal CBFv, linked to frequent painful crises and low hemoglobin.
- Half of the children exhibit abnormal vascular findings on MRA.
- Screening with TCD is recommended for African children with SCD, with abnormal results warranting MRI/MRA to detect and manage neurological complications.
Abstract:
Background and Purpose- We determined prevalences of neurological complications, vascular abnormality, and infarction in Tanzanian children with sickle cell disease. Methods- Children with sickle cell disease were consecutively enrolled for transcranial Doppler; those with slightly elevated (>150 cm/s), low (<50 cm/s) or absent cerebral blood flow velocity (CBFv) were invited for brain magnetic resonance imaging and magnetic resonance angiography. Results- Of 200 children (median age 9; range 6-13 years; 105 [2.5%] boys), 21 (11%) and 15 (8%) had previous seizures and unilateral weakness, respectively. Twenty-eight (14%) had elevated and 39 (20%) had low/absent CBFv, all associated with lower hemoglobin level, but not higher indirect bilirubin level. On multivariable analysis, CBFv>150 cm/s was associated with frequent painful crises and low hemoglobin level. Absent/low CBFv was associated with low hemoglobin level and history of unilateral weakness. In 49 out of 67 children with low/absent/elevated transcranial Doppler undergoing magnetic resonance imaging, 43% had infarction, whereas 24 out of 48 (50%) magnetic resonance angiographies were abnormal. One had hemorrhagic infarction; none had microbleeds. Posterior circulation infarcts occurred in 14%. Of 11 children with previous seizure undergoing magnetic resonance imaging, 10 (91%) had infarction (5 silent) compared with 11 out of 38 (29%) of the remainder ( P=0.003). Of 7 children with clinical stroke, 2 had recurrent stroke and 3 died; 4 out of 5 had absent CBFv. Of 193 without stroke, 1 died and 1 had a stroke; both had absent CBFv. Conclusions- In one-third of Tanzanian children with sickle cell disease, CBFv is outside the normal range, associated with frequent painful crises and low hemoglobin level, but not hemolysis. Half have abnormal magnetic resonance angiography. African children with sickle cell disease should be evaluated with transcranial Doppler; those with low/absent/elevated CBFv should undergo magnetic resonance imaging/magnetic resonance angiography.
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