Nancy A. Melville

May 08, 2015

Washington, DC — The detection of new intracranial aneurysms (IA) among patients with a history of aneurysm through radiographic screening is exceptionally low, only about 1%, indicating that such surveillance in most cases is likely not justified, according to new research.

"We conclude that the low 1.14% per-person-per-year risk of de novo intracranial detection with the small lesion size at the time of detection cannot be used to justify surveillance in all patients with a personal history of intracranial aneurysms," said lead author Judy Huang, MD, a professor of neurosurgery in the Division of Cerebrovascular Neurosurgery at Johns Hopkins University School of Medicine, Baltimore, Maryland.

"The at-risk population has yet to be defined but we think that imaging surveillance can be considered in current smokers."

The findings were presented here at the American Association of Neurological Surgeons (AANS) 83rd Annual Meeting.

Unruptured Aneurysm

The risk for a de novo IA after an earlier aneurysm ranges from 0.37% to 13%, with risk factors including female sex, hypertension, and cigarette smoking, Dr Huang explained.

The knowledge that treatment of unruptured aneurysms prevents subarachnoid hemorrhage may motivate some to provide surveillance as a means of catching any new developments early.

With limited studies showing the benefits of surveillance, Dr Huang and colleagues retrospectively evaluated data on 2153 patients with IAs.

They found that overall, 26 (1.2%) patients developed de novo IAs.

Among the patients, 185 had routine imaging surveillance, defined as follow-up imaging performed once in the first 1 to 2 years after treatment for the initial aneurysm and imaging performed every 1 to 3 years thereafter.

In the surveillance group, 9 (4.9%) patients developed de novo IA compared with 17 patients (0.86%) of the 1967 who did not have surveillance, including 5 who were detected upon a repeat subarachnoid hemorrhage (P < .001).

The rate of de novo IA rate per person year of 10 years of follow-up in the surveillance group was 1.14%.

The lesions detected in the surveillance group were significantly smaller (with surveillance: 3.8±1.8 mm, without: 7.0±4.4mm, mean ± standard deviation; P = .026).

"This was not surprising — if you look hard enough, you will find them," Dr Huang said.

In looking at baseline patient characteristics, the data showed that patients who had surveillance tended to have a family history of aneurysm, a history of hypertension, a history of smoking, alcohol consumption, or multiple aneurysms.

Patients who did undergo surveillance were followed for an average of 3.3 years.

Among risk factors for de novo IA, there was a trend toward an association of tobacco use and de novo IA detection within 10 years (P = .06), with 6 (23.1%) of the 26 patients with de novo IA having a history of tobacco use.

All 6 of the patients continued to smoke up to the detection of the de novo IA, which were detected in an average of 2.5 years.

"Screening patients who continue to smoke after the treatment of their initial aneurysm will most likely yield the most amount of benefit," she said. Otherwise, surgeons should consider key criteria when deciding on routine imaging for patients with aneurysm, she added.

"To justify routine imaging surveillance for de novo IA in patients with a personal history of IA, there should be evidence that the risk of de novo IA development is significant, that there is a significant risk of subarachnoid hemorrhage from de novo IA, and treatment of these lesions results in improved outcomes."

Routine Surveillance

Important limitations of the study include the relatively small percentage of patients who actually had surveillance and their relatively short follow-up time, noted Kevin M. Cockroft, MD, an associate professor of neurosurgery, radiology and public health sciences and co-director of the Penn State Hershey Stroke Center, Pennsylvania, in discussing the study.

"The main problem with this study is that the majority of patients didn't actually have routine surveillance and those that did only had it for a relatively short time," he told Medscape Medical News.

"Aneurysms are a lifelong problem, so to get a better idea of the rate of new aneurysm formation you really need long-term follow-up of 10 to 20 years or more, which is obviously very hard to obtain."

In terms of screening patients without risk factors, Dr Cockcroft agreed that surveillance is likely not necessary, but the evidence is still not as clear with risk factors.

"I think in terms whether to screen patients with risk factors, what the study shows is a resounding maybe," he said. "In terms of selecting patients for screening, I think factors should include family history, hypertension, smoking and perhaps multiple aneurysms."

He noted that, with low detection rates, screening can have its own negative effects, ranging from cost to unnecessary stress on the patient.

"There is good data to suggest that the risk of rupture from some types of very small aneurysms is exceedingly low, yet patient and physician anxiety can sometimes lead to potentially unnecessary treatment and subsequent risk of treatment-related morbidity, and even mortality," he said.

Dr Huang has disclosed no relevant financial relationships. Dr Cockroft has been a consultant for Covidien Neurovascular and Actuated Medical Inc.

American Association of Neurological Surgeons (AANS) 83rd Annual Meeting. Abstract 603. Presented May 4, 2015.

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