Drug Implant Halts Stroke Complication
Medicinal pellets prevent postoperative spasm
THURSDAY, April 4, 2002 (HealthDayNews) -- A middle-aged woman collapses on the street. A blood vessel in her brain has burst. In an emergency operation, a neurosurgeon repairs the damage, placing a patch over the break. A few days later, the blood vessel goes into spasm, a violent contraction that causes brain damage that can be crippling or even fatal.
Neurologists have a variety of treatments for this vasospasm, but they have not been as successful as hoped. Now, Japanese neurologists say they have found a solution to this problem.
A report in tomorrow's issue of the journal Stroke says they have virtually eliminated vasospasm in these patients by implanting tiny pellets containing a calcium-channel blocking drug in the blood vessels after surgery.
The calcium-channel blocker nicardipine (Cardene), used in capsule form for high blood pressure, relaxes blood vessels and keeps them from going into spasms, explains Dr. Hidetoshi Kasuya, a senior lecturer in the neurosurgery department at Tokyo Women's Medical University and lead author of the study.
The journal paper reports on 20 patients, none of whom developed damaging vasospasm.
"Since October of 1999, we now have 54 patients, and just two have experienced vasospasm," Kasuya says. "And there have been no side effects of the treatment."
As he explains it, use of the pellets was a logical evolution of earlier attempts to prevent vasospasm.
"Ten years ago, we tried injecting the drug into the system, but the effects of the drug disappear soon," Kasuya says. "So I thought, if I could develop a system for delivering the drug for a longer period, it would work very well."
The system uses tiny pellets, two millimeters in diameter and 10 millimeters long, impregnated with nicardipine. Between two and 10 of the pellets are placed parallel to the affected artery and next to blood clots identified during surgery.
The pellets release the drug slowly, with 7 percent of the nicardipine released in the first three days, and 46 percent in the three days after that. Vasospasm rarely occurs before the fourth day after surgery, with the risk peaking at about the eighth day, when 70 percent of patients have some narrowing of the arteries, Kasuya says.
"This finding could change the method used to deliver drugs to patients who are suffering from the effects of a ruptured aneurysm [weak spot in a blood vessel]," says Dr. J.P. Mohr, a spokesman for the American Academy of Neurology.
Use of calcium-channel blockers to prevent vasospasm is not new, Mohr says, but "the notion that any of this family of compounds could be directly inserted into the fluid spaces around the brain is new."
If the Japanese results stand up, the pellet method could be adopted widely, Mohr says. That will not happen quickly, in part because the pellet method of delivery does not have approval by the U.S. Food and Drug Administration.
Japanese neurologists "have been leading the way in methods of putting medications into spaces in the brain," Mohr says.
What To Do
You should know the symptoms of a stroke and seek help quickly, since early intervention can limit the damage.