Extracranial Internal Carotid Arterial Disease in Children with Sickle Cell Disease.

Sickle cell anemia (HbSS) is the commonest cause of stroke in children. It is associated with narrowing of the middle cerebral or distal intracranial carotid arteries. The significance of extracranial internal carotid artery (ICA) disease in children with sickle cell disease (SCD) is not known. Abnormalities of the extracranial ICA are well described in cerebrovascular disease in adults without SCD. Approximately 25% of ischemic strokes in adults are associated with abnormalities of the extracranial ICA, and the ICA is routinely assessed using Doppler ultrasound in adults with symptoms of cerebrovascular disease. For the last 6 years children with SCD at our hospital have undergone annual transcranial Doppler (TCD) scanning, which has also included Doppler ultrasound assessment of the extracranial ICA. We have reviewed this data to assess the importance of extracranial internal carotid artery (ICA) disease in this population.

All measurements were performed as part of routine clinical care at King's College Hospital (KCH), London, United Kingdom. The data were collected as part of an audit of TCD scanning at KCH to assess the additional value of extracranial ICA measurement in children with SCD. Doppler ultrasound assessment of extracranial ICAs was assessed in 236 children with HbSS and 56 with HbSC. The results were compared with clinical and laboratory data. 17 of the children had previously had a stroke. The links between extracranial ICA measurements, laboratory and clinical parameters were assessed using the statistical programme SPSS 17.0 (Chicago, Il).

The median of the extracranial ICA peak systolic velocity was 148cm/s (5^th centile 84, 95^th centile 236). Lower velocities occurred in older children with decreased rates of hemolysis. 14 (5.9%) had tortuous extracranial ICAs and 13 (5.4%) had stenosis. None of the children with tortuous vessels but 8 of those with stenosis had previously had a stroke; the presence of stenosis was strongly associated with overt clinical stroke (OR 35.9, 95% C.I. 9.77 – 132, P<0.001). In 6 children, extracranial stenosis was part of extensive intracranial vasculopathy, but in 2 there was no evidence of intracranial disease. Stenosis seemed to be more common in older children.

Extracranial ICA stenosis is strongly associated with stroke in children with HbSS. Our data suggest that Doppler ultrasound of the extracranial ICA is potentially useful and should be included in the routine TCD assessment of stroke risk recommended in all children with HbSS. If stenosis is detected, full brain imaging should be organised and consideration given to stroke prevention. In some cases extracranial ICA disease seems to be an extension of overt intracranial vasculopathy, although it can also occur in isolation; preliminary data from our study suggests that it affects older children and is not obviously related to increased hemolytic rates.

No relevant conflicts of interest to declare.