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Radiosurgery for unruptured arteriovenous malformations shows promise
The benefits of gamma knife radiosurgery for treatment of unruptured arteriovenous malformations outweigh the risk for complications, according to new data published in Stroke.
Contrary to findings from ARUBA and a Scottish cohort study, results of a new retrospective study conducted by Dale Ding, MD, from the department of neurosurgery at the University of Virginia, and colleagues suggest that treatment with radiosurgery may not be as risky as the current conservative approach of no treatment at all.
“These findings strongly suggest that patients who are younger are going to be far more likely to benefit from treatment than people who may be diagnosed late on in their life,” Jason Sheehan, MD, PhD, neurosurgeon and director of the Gamma Knife Center at the University of Virginia Health System, said in a press release. “If patients have at least a 10-year life expectancy, this new study strongly suggests treatment.”
In total, 509 patients (mean age 40 years) underwent arteriovenous malformation (AVM) radiosurgery between 1977 and 2014. Patients received MRI or CTA every 6 months for the first 2 years after surgery, and then once a year until the end of the follow-up period. The mean follow-up period was 86.2 months.
The primary endpoint was favorable outcome measured as a composite of AVM obliteration, no post-radiosurgery hemorrhage and no permanent radiation-induced changes.
The most common symptoms upon presentation were seizure (20.2%), headache (16.9%) and focal neurological deficit (7.1%). More than two-thirds (69.2%) of the AVMs were located in the eloquent brain areas and 68% had deep venous drainage.
AVM obliteration occurred in 75% of the patients. Smaller malformation diameter (P = .012) and higher radiosurgical margin dose (P = .001) were associated with successful obliteration.
After surgery, 32 patients (6.3%) experienced 34 AVM hemorrhages with two of the patients having two each. In addition, radiation-induced changes were observed in 138 patients (27.1%), but were only symptomatic in 57 (11.2%) and permanent in 13 (2.6%). The researchers reported low percentages of patients who either died (4.3%) or were left with permanent neurological morbidity (4.5%).
Seventy percent (n = 354) of the patients met the primary endpoint. Multivariate analysis suggested that size, location, nidus volume and margin dose were all predictors of favorable outcome. Patients with malformations smaller in diameter (P = .035) that were not located in the eloquent brain areas (P = .023) were more likely to have a favorable outcome, according to the researchers. Nidus volume less than 4 cm3 and a radiosurgical margin dose of at least 18 Gy also were independent predictors.
The researchers calculated the annual post-radiosurgery hemorrhage rate to be 0.9%.
Sheehan said, in a 10-year period, a patient can have a 10% to 30% risk for stroke. “The stroke risk, even if it’s low on an annual basis, really begins to add up when you consider 10-year or more life expectancy. And in many of these patients, they exhibit 50 or more years of life expectancy,” he said in the release.
Ding and colleagues wrote that clinical trials comparing radiosurgery to the conservative approach are needed to better understand the risks and benefits involved. – by Tracey Romero
Disclosure: One researcher is a stockholder and serves on the board of directors of Greater Michigan Gamma Knife and another is a consultant and stockholder in Elekta.