HHS NEWS

P97-24                        FOOD AND DRUG ADMINISTRATION
FOR IMMEDIATE RELEASE         Sharon Snider:    (301) 443-3285
August 4, 1997                
                              Consumer Hotline: (800) 532-4440 

                               
    FDA APPROVES IMPLANTED BRAIN STIMULATOR TO CONTROL TREMORS

     The Food and Drug Administration has approved a brain
implant device to help control tremors in people with essential
tremor or Parkinson's disease.
     The device, a deep brain stimulator made by Medtronics Corp.
of Minneapolis, Minn., controls hand and arm shaking on one side
of the body enough to enable many patients--particularly those
with essential tremor--to once again eat, drink, write and
perform other daily living activities.
     "Deep brain stimulation systems can significantly decrease
tremors in  many people with these debilitating diseases,"  said
FDA Lead Deputy Commissioner Michael J. Friedman, M.D.  "They 
will enable patients with essential tremor to once again perform
daily living activities unaided, and may improve these activities
somewhat in people with Parkinson's disease."
     About 2 million Americans have essential tremor, a little-
understood neurological disorder that often runs in families.  In
severe cases, it causes violent shaking but has few other
symptoms.  The new device may help the small fraction of people
disabled by their tremors.  Currently, tremors are treated with
drugs or surgery.
     An estimated 1.5 million Americans have Parkinson's disease,
which results in tremors, rigidity, slowness, difficulty moving
and, in some people, intellectual deterioration.  The new device
helps tremors but does not treat the other symptoms of
Parkinson's disease.
      The new device was approved for implantation in one side of
the brain, to help control tremors in the hand and arm on the
opposite side of the body--usually the dominant arm.  Studies of
implantation in both sides of the brain are underway, but results
will not be available for several months.  
     The brain stimulator, called the Activa Tremor Control
System, consists of an electrode implanted into the thalamus, a
structure deep in the brain, and connected by lead wire under the
skin to a pulse generator implanted in the chest.   When
activated, the device sends a constant stream of tiny electrical
pulses to the brain, blocking tremors.  To turn the stimulator on
or off, the patient touches a hand held magnet over the pulse
generator.  The generator must be replaced every three to five
years, the life of the battery.
     FDA's approval of the product was based on a review of
clinical studies on safety and effectiveness submitted by the 
manufacturer and on the recommendation of the Neurological
Devices Panel of FDA's Medical Devices Advisory Committee.

     The brain stimulator was implanted in 113 people with 
Parkinson's and 83 people with essential tremor at approximately 
20 medical centers in the United States and Europe.  All of the
patients had severe tremors, making daily living activities
almost impossible.  These activities included the ability to
handle personal hygiene, cut food, dress and write.
      Almost all people implanted with the device experienced a
reduction in tremors.  Only a few showed little or no
improvement.  In the U.S. study, tremors were significantly
reduced in 58 percent of essential tremor patients and 67 percent
of Parkinson's patients--i.e., on a scale of 0 to 4, their
tremors decreased at least two levels.  The remaining  patients
had a one level decrease in tremors.  The European study showed
similar results.
     For patients with essential tremor, reduction in tremors
translated into an improvement in daily living activities.  Most
Parkinson's patients continued to have problems with daily living
activities.  A few experienced a worsening of their overall
condition, with increased tremors, increased problems with
movement, and depression. 
     About one-third of all patients experienced a tingling
sensation in the head and hands.  This was controlled by the
doctor, however, by changing the stimulation setting on the
device.
     FDA is requiring the company to do additional studies to
determine the overall, long term safety and effectiveness of the
device and the effect on patients when it is necessary to replace 
lead wires. Lead wires broke in a number of patients during the
study.  The agency has also asked the company to conduct a study
on the long term effect of electrical stimulation on brain
tissue.
                               ####