According to the findings of a study presented at the Society of Interventional Radiology's 31st annual scientific meeting, carotid stenting with filter protection can prevent neurocognitive deficit. The purpose of this study was to test the hypothesis that carotid stenting with filter protection can prevent the neurocognitive deficit due to emboli causing trauma if they reach the brain. The study used the Acculink stent and the Accunet embolic protection filter (Guidant), which captures microemboli that be dislodged during the procedure.

The study involved very sophisticated neurocognitive measures including IQ, handling of spatial relationships, memory and other executive functions. Patients were tested for memory and executive function five times before and an additional four times after the procedure. The tests include the ability to respond to a command, integrating the command, and providing an answer in return. Functions such as word memory, number memory and assembling sequences were also tested. These functions improved, even in patients with a lower degree of stenosis, and the improvement was statistically significant. These are the interim results and analyses in 26 patients at six months in this ongoing study.

The study measured pre- and post neurocognitive effects of carotid stenting and showed that patients with narrowed carotid arteries displayed neurocognitive deficits involving memory and executive functions, and that these deficits improved after the interventional treatment. This study corroborates results from two previous small studies from the US and Germany. Study author, Dr Rodney Raabe, Sacred Heart Medical Center, Spokane, WA, said that the study results indicated that patients could benefit from being treated earlier in their disease than currently thought and that the stenting procedure improves brain function in symptomatic patients. Furthermore, he was quick to add that the biggest gain was seen in asymptomatic patients.

"We know from previous studies that carotid stenting can prevent a stroke in those at high risk, but what we didn't know is that the treatment makes people's brains function better. Their memory improves, some say they see colours brighter and they can think better," said Raabe.

Currently, asymptomatic patients are generally treated if their carotid artery is more than 80% stenosed. Symptomatic patients, those who have had a stroke or are exhibiting transient ischaemic attacks, are also treated to prevent future stroke. In this study, the patients in the asymptomatic category improved the most in neurocognitive function, most likely because they have not suffered previous injury to the brain from strokes or mini-strokes. Though all those studied showed improvement, the younger patients did better. They have more neurocognitive reserve and exhibited the biggest gains in neurocognitive function. The improvement was due to the increase in blood flow to the brain, as shown on magnetic resonance imaging after the procedure.

"We know when patients have a coronary bypass operation with aortic clamping, that there is a memory and cognitive decline from microemboli that reach the brain and cause permanent damage to brain function. We thought microemboli that might break loose during stenting could cause the same effect and wanted to see if filter protection would prevent this," says Raabe.

The study shows that using the embolic protection filter did save patients from neurocognitive decline and the author concludes that an embolic protection device is beneficial and should be used during carotid stenting procedures. "We set out to show that the protection filter would protect the brain, and expected to prove it by showing that the patient's brain function did not worsen after carotid stenting. We never expected to see brain function improve. These patients are seeing better and thinking better, and those with least degree of disease had the greatest gain," Raabe concluded.