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Andy Blatz wrote: > > Dear All, > Periodically, someone has a question about "electrical brain stimulation" > for PD and other movement disorders. Here is a simplified picture of the > current state of the surgery: > > There are currently three types of "electrical brain stimulation for > movement disorders". The only current commercial source of the implanted > device, which is essentially a high-powered heart pacemaker, is Medtronic > Inc., although another company is currently preparing to enter the market. > All three implants may be placed unilaterally (one side of the brain to > control symptoms on opposite side of body) or bilaterally (both sides of > brain to control symptoms on both sides of body). In all cases, the > electrode is a flexible cable with four metal contacts at the end, which is > guided into the brain using stereotactic techniques just like for ablative > (destructive) surgery like pallidotomy and thalamotomy. Either on the same > day as the brain implant is performed or a few days later, the stimulator > (about the size of a "Mint Patty" candy bar is surgically placed below the > skin in the chest. Although the goal of the stimulators is to stimulate, > as opposed to destroy tissue, there is some tissue damage as the electrode > is guided to the correct location deep inside the brain. Nobody knows why > it works. The most accepted hypothesis is that the stimulating electrode > over-stimulates nerve cells in the target area, which makes them incapable > of functioning. Thus, the results are very similar to destroying the > cells, except that the stimulator can be turned off, unlike a heat lesion > made in ablative surgery. Depending on the amount of use, the batteries > need changing (minor surgery) every few years. The three different targets > are: > > 1. Thalamic Implant: Stimulating electrode is placed into the thalamus. > Controls tremor only. Approved in Europe and USA. > 2. Pallidal Implant: Stimulating electrode is placed in the globus > pallidus. Controls dyskinesias, slowness, lack of movement, tremor. > Effects very similar to pallidotomy. Approved in Europe, not in USA. > Clinical trials ongoing in USA. > 3. STN Implant: Stimulating electrode is placed in the subthalamic nucleus > (this is distinct from the thalamus). Controls dyskinesias, slowness, lack > of movement, tremor. Effects similar to pallidotomy. Approved in Europe, > not in the USA. Clinical trials ongoing in USA. > > There is currently debate as to whether the STN or the globus pallidus is > the best spot to stimulate for major PD symptoms. My guess is that all > forms of stimulation will be approved in Europe and USA within one year. > > Hope this helps, > Andy I believe it will, and thanks a lot for your authoritative description. I'd add one comment about turning the device off: This feature puts the patient in charge, not only to conserve battery life but also to use the stimulator only when he feels the need. Cheers, Joe -- J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks, CA 91403-5013