LOS ANGELES – Evidence from a preliminary study suggests that the arteriopathy called fibromuscular dysplasia appears differently in children than in adults.
In fact, what most neurologists diagnose as fibromuscular dysplasia in children with arterial ischemic stroke might not be fibromuscular dysplasia at all, but is more likely to be transient cerebral arteriopathy (TCA) of childhood, Dr. Adam Kirton said at the conference.
Little is know about the causes of arteriopathy, the most common cause of childhood arterial ischemic stroke. One cause is fibromuscular dysplasia, a group of idiopathic, noninflammatory arteriopathies that classically involve cerebral and renal vessels in whites.
"There’s never been a systematic look at the role of fibromuscular dysplasia in childhood stroke," said Dr. Kirton, director of the pediatric stroke program at Alberta (Calgary) Children’s Hospital. He and his associates analyzed data from 81 cases of childhood stroke that had references to fibromuscular dysplasia or renal artery disease.
Of the 15 cases obtained from two large Canadian registries and 66 cases gleaned from the medical literature, 27 had pathologically proven fibromuscular dysplasia, 31 were clinically diagnosed, and the remaining 23 cases were grouped as "other" diagnoses.
The records provided sufficient detail on 19 of the 27 pathologically proven cases to show that 17 of the 19 (89%) were classified as intimal fibroplasia, a type that is rarely seen in adults. Angiography of these patients showed nonspecific findings such as focal narrowing or stenosis, he said at the meeting, sponsored by the American Heart Association.
The other 2 of the 19 cases were classified as medial hyperplasia, and the remaining 8 cases could not be classified. Notably, none of the 19 had medial fibroplasia or dysplasia, the type typically seen in adults with stroke. "This is the one you learn about in medical school" that has a unique "string of beads" appearance on angiography, he said.
Conventional angiography was performed in 26 of 27 children with pathologically-proven fibromuscular dysplasia. Only 5 (20%) showed a "string of beads" appearance, compared with more than half of the clinically diagnosed group, a significant difference. The pathologically-proven group, however, had significantly higher rates of the moyamoya intake pattern and of renal artery stenosis or renal hypertension than did the clinically diagnosed group.
Of 21 children in the pathologically-proven group who underwent systemic evaluations, 16 (76%) had evidence of systemic arteriopathy outside of the brain and kidneys, "supporting the idea that a lot of fibromuscular dysplasia is really a systemic arterial disease in children," Dr. Kirton said.
There was no evidence of the female predominance for fibromuscular dysplasia that has been observed in adult cases. Nine children in the pathologically-proven group (33%) first presented with neurological symptoms in the first year of life, compared with only three children in the clinically diagnosed group (10%).
Children in the pathologically proven group were significantly more likely to have poor outcomes, to have disease recurrence, and to die, compared with the clinically diagnosed group.
Among 23 patients with pathologically proven fibromuscular dysplasia who were followed for an average of 43 months, 15 had poor outcomes (65%), 8 had recurrences (35%) and 10 died (43%). "There’s a selection bias here, because some of these children died before they could get to pathology," Dr. Kirton noted.
Among 30 children in the clinically diagnosed group who were followed for an average of 22 months, 10 had poor outcomes (33%), 2 had recurrences (7%) and 1 died (3%).
The clinically diagnosed cases more closely resembled TCA than fibromuscular dysplasia, he suggested. The former were more likely to be previously healthy patients with unilateral disease that had a "string of beads" appearance, less likely to have renal artery stenosis or hypertension, and less likely to develop recurrence.
"We are not able to accurately diagnose fibromuscular dysplasia clinically," Dr. Kirton said. "If you see a ‘string of beads,’ it doesn’t necessarily mean fibromuscular dysplasia. In fact, our data would argue that it suggests something else."
Dr. Kirton said the investigators have no relevant conflicts of interest.