Researchers have effectively delivered drugs to primate brain stems and monitored how the drugs spread inside the brain, providing hope for improving treatment of brain stem tumours and other brain conditions, according to a study in the October 2002 issue of the Journal of Neurosurgery.
Current drug treatments of brain stem tumours are largely unsuccessful because the drugs often fail to bypass the blood vessel lining, called the blood-brain stem barrier, protecting the brain stem.
In the new study, researchers at the National Institute of Neurological Disorders and Stroke (NINDS) used a technique called convection-enhanced delivery (CED), which was developed at the National Institutes of Health, to deliver a tracer molecule to the primate brain stem. They then used magnetic resonance imaging (MRI) to track the tracer's movement throughout the brain.
NINDS neurosurgeon and researcher Dr Russell Lonser said:
"It's difficult to safely treat the brain stem with available techniques because it's so intricate and complex, and because of the blood-brain stem barrier. These findings suggest that we can reach the brain stem to treat diseases, and we can ensure that treatment is targeted to the critical region by monitoring it in real time."
Co-author Dr Edward Oldfield, chief of the Surgical Neurology Branch at NINDS, and colleagues developed CED in 1994. The technique uses small differences in pressure to make infused molecules flow through solid tissue. This enables large molecular weight molecules, such as those used in drugs, to penetrate the brain stem. Researchers have refined and expanded the uses of CED during the past 8 years, but until now, there has been no way to track precisely where the drugs were going and therefore no way to predict or prevent adverse side effects.
If proven safe and effective, drug delivery imaging with CED may ultimately be used to treat other neurological diseases, such as Parkinson's disease, other tumours, epilepsy, and pain disorders.