The therapy, known as active nerve cell cluster stimulation, was used on patients within 24 hours of an ischemic stroke. This most common type of “brain attack” is often caused by a clot that blocks a blood vessel and so prevents blood flow in the brain. Within minutes of such a blockage, brain cells begin to die, leading to potential mental and physical disabilities.
The study, published Friday in the medical journal The Lancet, was funded by BrainsGate Ltd., the manufacturer of the stimulation device.
The treatment consists of a small electrode that actively stimulates a cluster of nerve cells behind the nose. (This temporary neurostimulator, which is implanted through the roof of the mouth, requires only local anesthesia.)
Stroke is the fifth leading cause of death in the United States, where nearly 800,000 people experience a new or recurrent stroke each year, according to the National Stroke Association. Worldwide, stroke claims 6.2 million lives each year — more than AIDS, tuberculosis and malaria put together, the World Stroke Organization says.
A safe alternative?
There are just two US Food and Drug Administration-approved treatments for ischemic stroke: a clot-dissolving drug and a device that threads through arteries to capture and remove blockages. The drug does not work for all patients and becomes less effective as minutes pass after a stroke, while the device requires an expertise that is usually found only in major medical centers.
Research has shown that nerve stimulation can dilate undamaged arteries, increasing blood flow in the brain. Neurostimulation also preserves the blood-brain barrier, which prevents brain swelling, while improving the ability of brain cells to form new connections.
The new study included more than 1,000 people who had experienced an acute ischemic stroke and were randomly assigned to receive either the experimental therapy or a placebo therapy. Half of the 536 people who had the real nerve stimulation had favorable outcomes — defined as better-than-expected disability levels three months after their strokes — versus 40% of the 519 people who received the fake stimulation.
These results are not considered “significant” by statistical standards, but when findings from earlier studies are combined with the new data, they suggest that the therapy can be effective for ischemic stroke patients if used within 24 hours.
No differences in deaths or side effects were seen between the two groups of patients. The proportion of patients with a positive outcome increased from 40% to 70% when neurostimulation was applied at low- to midrange intensity, yet it fell back to 40% when high intensity was used, the researchers noted.
The experimental neurostimulation treatment could be a safe and effective alternative to medication for some stroke patients, the researchers concluded. Future studies will look at how effective the treatment is when paired with clot-dissolving medications and clot-retrieving devices.
The future of stroke therapy
Seth Hays, a neuroscientist and assistant professor in the Department of Bioengineering at the University of Texas at Dallas, said the study was “well-designed” and “very large.”
“Stimulation with the device didn’t raise any safety concerns, which is a clear strength,” said Hays, who was not involved in the study but has done his own research in this area.
One major caveat was that the researchers could not statistically prove that receiving the therapy worked better than not receiving it, even if they used additional data from previous research to show benefits, Hays said. “This tempers my enthusiasm.”
New treatments are definitely needed for stroke patients, Hays said: “Although remarkable advances have been made in acute stroke treatment, stroke is still a leading cause of disability.” Additionally, some patients are ineligible for existing treatments, but neurostimulation may be used with a large population, he said.
“Nerves are highly responsive to electrical stimulation, and capitalizing on this with clever techniques represents a largely untapped potential strategy to treat stroke and other neurological disorders,” Hays said. Continued improvements in the devices and their implementation is likely to “really impact treatment of neurological disorders in the near term,” he said: “I think devices are the future for the treatment of neurological disorders.”