Intracranial Aneurysms in Children with Sickle-Cell Anemia

Intracranial aneurysms in sickle-cell anemia (SCA) have been reported in about 50 adult patients, mostly presenting with subarachnoid hemorrhage (SAH). Aneurysms in those patients tend to be multiple (50%), to involve the posterior circulation more frequently than in the general population (33% vs 14%) and to be diagnosed at a younger age. In pediatric SCA patients, SAH has scarcely been reported, without evident link with stenotic cerebral vasculopathy. An associated intracranial aneurysm has only been demonstrated once in a teenager.

We report the cases of 2 children with sickle-cell anemia (HbSS) with intracranial aneurysms. The first patient was a 5-year old girl with abnormal transcranial Doppler (TCD) screening for cerebral vasculopathy: left middle cerebral artery time-averaged mean velocity (MCA TAMV) 208cm/sec, right MCA TAMV 196cm/sec. She had normal neurological assessment. On her brain MRA, no stenotic lesion was found within the Circle of Willis and the Internal Carotid arteries. A 6mm distal left posterior cerebral artery unruptured saccular aneurysm was observed. The brain MRI revealed a left thalamic lacunar infarction likely due to asymptomatic embolic infarction from the aneurysm. Longitudinal MR imaging showed spontaneous but incomplete thrombotic aneurysm occlusion. The second patient, an 11 year-old boy with slight cognitive delay and normal annual TCD procedures, presented with a non-traumatic SAH. Brain MRI showed several small silent cerebral infarctions in the white matter watershed territories. Brain MRA revealed multiple aneurysms without any stenotic lesion. A ruptured aneurysm was located on the basilar artery termination. Four unruptured aneurysms were found: 3 on the posterior cerebral arteries (1 right, 2 left) and 1 on the ophthalmic artery ostium. Endovascular coil embolization resulted in angiographic occlusion of the 2 accessible aneurysms. Clinical outcome was excellent.

Hemorrhagic strokes are more frequent than ischemic strokes in young adult SCA patients. Two main mechanisms are described: intracerebral or intraventricular hemorrhage due to major occlusive vasculopathy (moyamoya syndrome) or subarachnoid hemorrhage due to aneurysm rupture or leak. Our pediatric patients have no evidence for moyamoya syndrome. Their intracranial aneurysms bear similar characteristics with adult SCA patients': possibility of multiple aneurysms and posterior circulation involvement. They are observed at a very young age and are associated with mild cerebral vasculopathy: abnormal TCD without MRA stenosis in one case, silent cerebral infarcts without MRA stenosis in the other case. These findings plead for a possible concurrent development of vascular lesions leading either to ischemic or hemorrhagic stroke. This hypothesis is supported by similar histopathological findings in both aneurysms and cerebrovascular occlusive lesions in SCA: intimal hyperplasia, smooth-muscle layer hyalinization and elastic lamina fragmentation. This challenges the supposedly sequential pathophysiology of strokes in SCA, based on the high prevalence of infarctive strokes in children and hemorrhagic strokes in young adults.

This report of pediatric intracranial aneurysms, associated with mild cerebral vasculopathy in both patients, supports the hypothesis of a common pathophysiological mechanism and the possible concurrent development of stenotic lesions and dilatations. This is also the first report of successful coil embolization in a pediatric SCA patient.

No relevant conflicts of interest to declare.