Adding extracranial internal carotid artery evaluation via the submandibular window to transcranial Doppler sonograpy allowed us to detect 10.3% patients at risk for extracranial internal carotid arteriopathy. Further studies are needed to evaluate the prognosis of these anomalies.
Background: Cerebral arteriopathy in patients with sickle cell anemia mainly affects the intracranial anterior circulation. However, the extracranial internal carotid artery (eICA) can also be stenosed and responsible for ischemic lesions. In children with sickle cell anemia, we perform routine annual Doppler ultrasound assessment of the eICA and magnetic resonance imaging with 3-dimensional time-of-flight magnetic resonance angiography of the Willis circle and neck arteries in those with abnormal velocity. Our aim was to report the evolution of eICA stenoses from 2011 to the present as a function of therapy in a retrospective case-series study. We hypothesized that chronic transfusion (CTT) would be more effective than hydroxyurea and simple observation on the evolution of eICA stenosis. Methods: Eligibility criteria were a history of eICA velocity ≥160 cm/s with a minimum Doppler and magnetic resonance imaging follow-up of 1 year. eICAs were graded for stenosis according to NASCET (The North American Symptomatic Carotid Endarterectomy Trial). Magnetic resonance imaging was investigated for ischemic lesions. Treatment with hydroxyurea and CTT were obtained from the chart review. Results: Fifty-four patients were included. Eight patients had a stroke history. The median (range) follow-up was 4.7 years (1.1–9.2 years). On the first neck magnetic resonance angiography, stenosis was present in 48/54 (89%) patients. Kinking was found in 39/54 (72%) patients. On the last neck magnetic resonance angiography, the proportion of patients with eICA stenosis decreased to 39/54 (72%). ICA occlusion occurred in 5 patients despite CTT. Three patients had carotid webs without intracranial stenosis. The proportion of patients with improvement in stenosis score was 8% with no treatment intensification, 20% with hydroxyurea, and 48% with CTT ( P =0.016). The mean (SD) change per year in stenosis score was 0.40 (0.60) without intensification, 0.20 (0.53) with hydroxyurea, and −0.18 (0.55) with CTT ( P =0.006). Ischemic lesions were present initially in 46% of patients, and the incidence of progressive ischemic lesions was 2.5 events/100 patient-years. Cox regression analysis showed that the initial score for eICA stenosis was a significant predictive factor for the risk of new silent cerebral infarct events. Conclusions: Our study reinforces the need to assess cervical arteries for better prevention of cerebral ischemia and encourage initiation of CTT in sickle cell anemia children with eICA stenosis.
88 Background. Strokes are a well-known complication of sickle-cell anemia (SCA), and are largely due to intracranial arteriopathy, detected by routine transcranial Doppler (TCD). Adams et al. showed in the STOP I trial (N Engl J Med, 1998) the efficiency of transfusion programs for primary stroke prevention in patients identified by TCD as being at risk of stroke. We recently reported in the CHIC newborn cohort (Bernaudin et al., Blood, 2011) that early TCD imaging (TCDI) screening significantly reduces the risk of stroke by age 18 from the previously reported 11% to only 1.9%, but has not allowed adequate prevention of silent infarcts, with a risk of 37.1% by age 14, suggesting that TCDI does not distinguish all SCA-patients at risk of silent infarcts. Extracranial internal carotid artery (eICA) vasculopathy is considered rare and has not been routinely assessed; however, several recent cases of stroke with extracranial arteriopathy prompted the inclusion of eICA evaluation in routine screening. The aim of the study was to establish the ranges of eICA velocities in SCA-patients, to determine the cut-off limits of velocities predictive of eICA stenoses by extracranial MRA, to evaluate the prevalence of abnormal eICA velocities and to determine their association with intracranial stenoses and/or silent infarcts by MRI. Methods. Since June-2011, all stroke-free SCA patients from the CHIC and Debre cohorts who had routine yearly TCDI for intracranial arteries were also systematically assessed for eICA using submandibular windows (Gorman et al., Neurology 2009) and the same 2Mhz TCDI transducer probe. Time-averaged mean of maximum velocities (TAMMV) were obtained for intra and extracranial cerebral arteries. By color Doppler mapping, the course of eICA was considered as straight, or as tortuous if the artery changed direction with an angle > 120° between adjacent segments. Extracranial cervical MRA was added to routine intracranial MRI/MRA, performed every 2 years or as soon as abnormal velocities were found. Results. Between June 2011 and January 2012, 435 consecutive SCA-children from the two cohorts (202M, 233F) were assessed by Doppler at the median age of 8.5 years (range: 1.3–18.7). MRI/intra and extracranial MRA was performed in 104 patients. At time of Doppler assessment, mean±SD hemoglobin was 9.1±1.6 g/dl. eICA velocities were significantly correlated with middle cerebral arteries (MCA) velocities (r=0.234, p<0.001), and were about 25–30% lower than MCA velocities (mean:95±38 vs 127±32 cm/sec). As for MCA, eICA velocities were maxima between 3–7 years of age. eICA tortuosities were echo-detected in 25% cases (107/435), and were more frequent in boys (65/202; 32%) than in girls (42/233; 18%), p<0.001. Regression logistic analysis showed that tortuosities were not associated with age, but significantly associated with males (OR:2.2, 95%CI:1.4–3.4, p=0.001). Cervical MRA found stenoses in 40/104 patients. ROC curve showed that eICA velocities ≥ 160 cm/sec were highly predictive of stenoses on eMRA (100% specificity, 80% sensitivity). The prevalence of eICA velocities ≥ 160 cm/sec was 10.3% (45/435), and was significantly higher in males (14.9% vs 6.4%; p=0.004). Low hemoglobin (OR:2.6/1g/dl decrease, 95%CI:1.4–4.6; p=0.002) and tortuosities (OR:14.5, 95%CI:4.1–50; p<0.001) were significant and independent risk factors for eICA velocities ≥ 160cm/sec. Intracranial stenoses were detected in 29/104 patients, while 40/104 patients had extracranial stenoses with 31/40 showing no intracranial stenoses. Silent infarcts were detected in 35/104 patients, and were highly associated with the presence of intra and/or extracranial stenoses (30/35: 86%, p<0.001). Intra (OR:5.1,95% CI:1.9–13.8, p=0.002) and extracranial (OR:4.5, 95% CI:1.7–11.6; p=0.002) stenoses were significant and independent risk factors for silent infarcts. Conclusion. This study shows for the first time that in cohorts previously assessed early by TCDI for intracranial arteries, about 10% stroke-free patients have eICA vasculopathy. Moreover, we show that intra and/or extracranial stenoses are significant risk factors for silent infarcts. These data may explain why silent infarcts still occurred in patients early assessed by TCDI exploring only intracranial arteries. Thus, extracranial Doppler assessment should be routinely done with TCD to evaluate the full extent of cerebral vasculopathy in SCA. Disclosures: No relevant conflicts of interest to declare.
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