Many long-time sufferers of Parkinson’s disease are finally getting the help they need with the implantation of  Deep Brain Stimulators.  During implantation, neurosurgeons aim for an exact location in the brain, but how close to this ideal spot are they really getting, and how much does it matter? Drs. Robert Goodman and Guy McKhann from our Center for Movement Disorders set out to answer this question in a retrospective study published recently in the Journal of Clinical Neuroscience.

Deep Brain Stimulation: Image Source

Parkinson’s Disease is a chronic degenerative disease of the brain that causes the body to sort of freeze up, making limbs stiff and movement slow.  People with Parkinson’s often have a tremor when they are resting and initiating purposeful movement (like walking) takes quite a bit longer than usual. You can’t rush someone with Parkinson’s nor should you because often the disease affects their balance and they have an increased risk for falling.

In the nineteen sixties the drug L-Dopa was introduced and radically changed the lives of many Parkinson’s sufferers by almost eliminating their symptoms.  Unfortunately, this drug doesn’t help everyone all the time.  Sometimes after years of working well, with progression of the disease , the drug no longer helps.  For these patients, the authors say that implanting a deep brain stimulator in a part of the brain called the  Subthalamic Nucleus (STN), “is the most beneficial surgical intervention.”

With deep brain stimulation (DBS) surgery, a small electrode is placed in the critical parts of the brain that help to control movement. The electrode is attached to a small battery in the chest wall and is connected by wires that are placed under the skin. The stimulator is then turned on and interrupts the normal flow of information in the brain and can help to decrease symptoms of Parkinson’s disease. Columbia Neurosurgery

The STN in the brain is tiny and implanting an electrode in the part of it that controls movement can be tricky and takes a lot of preparation. The area is targeted using sophisticated imaging techniques, then they pick the safest part of the brain to enter and with incredible precision aim right at the spot they want.  This way, they can go straight in without disrupting any more of the brain than they have to.

The authors of this study  wanted to look at patients who had already had this surgery and see how close to the target their surgeons had gotten and if the distance away had any effect on the outcome.  In particular they looked at whether it affected movement in the legs.

Impressively, what these authors found was that surgeons were consistently within two millimeters of their target.  Also, the distances from the target were not related to how the patient fared.  In other words, even when they didn’t hit the target exactly, the patient wasn’t the worse for it.

To learn more see the authors’ paper, Typical Variations of Subthalamic Electrode Location do not Predict Limb Motor Function Improvement in Parkinson’s Disease in the Journal of Clinical Neuroscience, Volume 16, Issue 6, June 2009, Pages 771-778