This procedure in being tested in monkeys now because humans and monkeys are the only two species which get PD naturally. If it is proven to be safe and efficient, spinal cord stimulation will be a potential alternative to DBS since it requires no risky invasive surgery to plant electrodes deep in the brain. It may be effective for some of the 70% of severely impaired PDers who do not qualify for deep brain stimulation.
This could represent a major paradigm shift in available treatments. It is not without drawbacks-tradeoffs, however since one side effect is reported to be a never-ending mini-vibration described by Dr Ali Rezai, director of the Cleveland Clinic Center for Neurological Restoration as "pins and needles."
Read more:
http://www.nytimes.com/2009/03/20/health/20spinal.html?_r=1&ref=health