ASNR: Most Brain Aneurysms in Children Arise Spontaneously

CHICAGO, June 14 -- Most intracranial arterial aneurysms in children appear to arise spontaneously in the anterior circulation, reported researchers here.

The origins of most of these aneurysms are not, as commonly believed, the result of trauma, infections, or vascular malformations, said Todd Abruzzo, M.D., of the University of Cincinnati, and colleagues, at the American Society of Neuroradiology meeting here.

Studying 58 children and adolescents with a total of 71 intracranial aneurysms, they found that 43 were idiopathic, and only 10 children with idiopathic lesions had known risk factors.

They found that the middle cerebral artery was the single most common parent artery affected in children with idiopathic aneurysms, and that the most frequent presentation was subarachnoid hemorrhage. These children are at increased risk for developing new intracranial aneurysms, said the authors.

"This is very significant because it provides insight into the mechanisms of aneurysm formation," said Dr. Abruzzo. "Most cerebrovascular specialists believe that aneurysms arise from mechanical fatigue of the arterial wall -- resulting from wear and tear caused by a lifetime of excessive blood pressure and flow on thin-walled cerebral arteries."

Their findings suggest that unidentified environmental exposures, genetics, or an interplay between the two could be risk factors for aneurysm development, Dr. Abruzzo said.

He and colleagues conducted a retrospective study of the anatomical, pathological, and clinical characteristics of intracranial arterial aneurysms in 58 patients under the age of 19 who were treated in three tertiary centers in Ohio from 1993 through 2006.

The authors extracted cases from radiology reporting databases, neurosurgery clinic registries, and neuroangiography log books, and reviewed each record for epidemiological, anatomical, pathological, and clinical characteristics of the aneurysm.

They identified a total of 71 intracranial arterial aneurysms in 58 patients. The median patient age was 10.5 years old, range eight months to 18 years. Fifteen of the aneurysms occurred in children under the age of five years, 13 in five- to 10 year-olds, and 36 in preteens and adolescents (11 to 18).

Sixteen of the aneurysms occurred in the posterior circulation, all intradural. The remaining 55 aneurysms occurred in the anterior circulation, 36 intradural and 19 extradural.

Among the aneurysms occurring in the posterior circulation, three affected the basilar artery, five were in the posterior cerebral artery, three in the vertebral artery, one in posterior inferior cerebellar artery, two in the anterior inferior cerebellar artery, and one was in an arteriovenous malformation (AVM) nidus.

Of the aneurysms occurring in the anterior circulation, seven involved the petrous internal carotid artery (ICA), 11 were in the cavernous ICA, one occurred in the ophthalmic artery, three affected the terminal ICA, five involved the anterior communicating artery, 17 affected the middle cerebral artery, eight occurred in the anterior cerebral artery, and two in the posterior communicating artery.

The etiology of 28 aneurysms were identified in the records. Five were mycotic in origin, 16 because of trauma, one was related to vasculitis, two to neoplasms, and four were attributable to flow irregularities secondary to AVM.

The remaining 43 aneurysms were idiopathic, and occurred in children in all three age groups. Of these children, only 10 had known or potential risk factors for aneurysms, including tuberous sclerosis in two patients, neurofibromatomasis-1 in one patient, autosomal dominant polycystic kidney disease in one, sickle cell disease with moya and hypertension occurring in one patient with five aneurysms, one each occurring in patients with hypertension alone, end stage renal disease with hypertension and cystinosis, growth hormone deficiency, cutis marmorata telangiectasia congenital, and congenital absence of the internal carotid artery.

Among the children with idiopathic aneurysms, nine of the 43 had a subarachnoid hemorrhage. One patient with an idiopathic aneurysm suffered a subarachoid hemorrhage from rupture of a de novo intracranial aneurysm that occurred six years after the child had undergone therapeutic carotid occlusion for treatment of the index aneurysm.

"It turns out the aneurysms not only occurred in different places in children compared to adults, but there also appeared to be a difference in the way the disease develops," said Dr. Abruzzo. "These differences merit further investigation to give neurorradiologists the knowledge they need to develop ongoing treatment and strategies for monitoring this at-risk population."