Deep Brain Stimulation at St. John’s
By Alan Scarrow, M.D.

Since the spring of 2005, St. John’s has offered deep brain stimulation (DBS) as a therapy for patients with medically refractory Parkinson’s disease and essential tremor. 

DBS involves high frequency, pulsatile electrical stimulation of the deep brain nuclei such as the thalamus, globus pallidus or subthalamic nucleus that suppresses or inhibits local neurons passing close to those areas. 

The electrical stimulus is delivered through 2 mm wide electrodes that are attached to a pulse generator placed underneath the skin typically on the anterior chest wall.  Stimulation can be activated, deactivated and controlled with an external magnet that the patient carries with them.

There are 50-60,000 new cases of Parkinson’s disease diagnosed each year in the United States.  Of those, approximately 10-20 percent are candidates for DBS.  In order to be a candidate for DBS, the patient must have bradykinesia and either rest tremor or rigidity.  The patient should also have had a good response to Sinemet (levodopa) in the past but may have developed adverse effects such as dyskinesia or cognitive deficits at higher doses. 

Even more common than Parkinson’s disease, essential tremor affects hundreds of thousands of patients in the U.S.  Fortunately most of these patients can be controlled with beta-blockers. However for those that are refractive to that treatment, DBS may be a good option for them.  Patients with dystonia, often seen in cerebral palsy, are also good candidates for DBS treatment.

The procedure for placing DBS is done in three parts.  The first stage involves placement of the electrodes by a neurologist and neurosurgeon team in the operating room.  This typically takes 3-5 hours and is done with neurophysiologic monitoring while the patient is awake.  The neurosurgeon placing the electrodes is assisted by the use of infrared stereotactic guidance in the operating room.  The combination of neurophysiology feedback, stereotactic guidance and patient response provides a ‘belt and suspenders’ approach to assuring proper placement of the electrode.  (See Figure 1)  The second stage is done approximately one week later and unlike the first stage is performed with the patient under a general anesthesia.  At this stage the electrodes are connected via 30 cm leads to a pulse generator battery. 

Typically one battery is placed on each side just below the clavicle.  Once these batteries are placed, the patient is discharged home and follows up with the neurologist in 1-2 weeks for an initial programming session.  During the programming session, the settings of the pulse generator are optimized for the individual patient by altering amplitude, frequency, pulse width, and the combination of contacts on the electrode to be turned on.

For patients receiving DBS, studies with the largest number of patients indicate that between 82 and 91 percent of patients report total or clinically significant reduction in the amount of tremor while their rigidity and bradykinesia decrease by at least 50 percent.  Symptom relief persists over a 5 year period in most cases.  The more common complications include intracranial hemorrhage (3 percent) and infection in ~10 percent. 

At St. John’s we have placed DBS in 15 patients, 12 with Parkinson’s disease and 3 with essential tremor.  Patient ranged in age from 45 to 90 years.  Our results for symptom relief have been consistent with these larger studies.  Our complications have included one patient who did not achieve good symptom control during surgery and thus did not have permanent placement of the electrode, three infections, and one case with dysphasia following placement. 

The cost of DBS actually compares quite favorable to medical treatment.  In a 1997 study looking at the average annual cost to Medicare for a Parkinson’s patient was $16,634 (the average cost for a Medicare patient in that year was $6,711) which included the cost of medications, hospitalization and rehabilitation.  Hospital and rehabilitation costs in this patient population are often due to falls.  In comparison the total cost of DBS (Part A and Part B) for a Parkinson’s patient (in 2007 dollars) is $15,136.  Thus over years of treatment, DBS seems to compare favorably on a cost comparison basis.

If you have Parkinson’s, essential tremor or dystonia patients that you think may be candidates for DBS you may contact the St. John’s Clinic Neurology physicians at 417-820-9123.  You may also view a live video of our team placing a DBS at stjohns.com/neuroscience.