CHICAGO—In patients with unruptured aneurysms, surgery reduces the long-term mortality from aneurysmal subarachnoid hemorrhage (SAH) overall, according to data from the International Study of Unruptured Intracranial Aneurysms. The study was discussed at a plenary here at the annual meeting of the American Association of Neurological Surgeons.
But the investigators also reported that a low and continuous risk of hemorrhage and co-morbidities mandate long-term follow-up in these patients.
“The overall outcome of these patients is worse because of risk factors and comorbidities that not only effect aneurysmal development but also other diseases,” said co-principal investigator James Torner, PhD, professor and head of the department of epidemiology at the University of Iowa in Iowa City. He emphasized that morbidity was primarily caused by other risk factors, such as smoking and hypertension.
The study, co-led by Dr. Torner and Robert Brown, MD, professor of neurology at the Mayo Clinic in Rochester, MD, prospectively evaluated the outcomes of 1,917 patients at 61 medical centers who had surgical clipping for an unruptured aneurysm.
Among findings, the risk of hemorrhage during surgery was 4 percent and the risk of hemorrhage after surgery was 0.1 percent per year (50 percent of these were due to untreated or new aneurysms). Overall, only 0.5 percent of the patients died from a subsequent SAH over an 8.5-year average follow-up.
Commenting on the study, Robert Solomon, MD, chair and director of the neurosurgical service in the department of neurosurgery at Presbyterian Medical Center in New York City, said the findings reinforce the need for long-term data — for at least 10 years — to show a benefit of surgery compared to the natural history of the disease.
“The exact subgroups that will benefit from surgery are still to be established, but it appears that patients under the age of 50 with non-giant anterior circulation aneurysms do better with surgery than either coiling or conservative management.”
The patients in the study were not stratified by size of aneurysms, Dr. Torner noted. But he added that in data from another study, which he described in February at the American Stroke Association annual meeting, there was a low hemorrhage rate for anterior circulation aneurysms smaller than 6 mm.
Figure. Typical site...Image Tools
“Clinical equipoise exists between treatment and no treatment for anterior circulation aneurysms between 5 to 10 mm and posterior circulation aneurysms between 3 and 10 mm,” he said. “For aneurysms larger than that, treatment has a lower morbidity and mortality compared to observation.” He added that the findings will be confirmed with the release of data from an upcoming study.
Because of the high rate of comorbidities and risk factors in these patients, Dr. Torner said medical management should address issues including hypertension and cigarette smoking.
• Torner J, et al. Long-term follow-up in patients surgically treated for an unruptured intracranial aneurysm. Annual meeting of the American Association of Neurological Surgeons. April 29, 2008. Abstract 705.