COLUMBIA, Md. -- The Pharaohs of ancient Egypt stood in water next to electric eels to relieve pain. Now scientists have developed an electronic nerve stimulator that is implanted beneath the skin to do the same thing.
The new device, called 'a tremendous advance' over cumbersome external pain killers of the past decade, can be adjusted by radio command from outside the body to provide millions of different patterns of electrical stimulation to nerve centers.
The stimulator also can report via radio on its own condition to an inquiring physician.
Although it is not known for sure how electrical stimulation of nerve tissue deadens pain, one theory is that it causes the body to produce a brain chemical that quells pain. Another is that stimulators block the pain message transmitted via nerve fibers from the ache to the brain.
The implantable stimulator also has been used successfully to arrest involuntary movements of nervous system disorders.
The new pain killer is about the size of a deck of cards and uses a special battery that can be recharged merely by holding a special magnetic field generator above the skin for a few minutes daily.
It was unveiled Thursday at Johns Hopkins University's Applied Physics Laboratory, which played a role in its development along with space agency engineers and Pacesetter Systems, Inc., of Sylmar, Calif., the maker of the units.
Dr. Irving Cooper of the Westchester County (N.Y.) Medical Center implanted the first of the new devices in February in a woman with severe involuntary shaking associated with multiple sclerosis.
Electrodes from the stimulator were applied to part of the brain and as soon as the device was turned on, the woman's tremors vanished and she was able to guide a cup of coffee to her lips for the first time since the ailment began.
Dr. Donlin Long, chairman of neurological surgery at Johns Hopkins, implanted the second stimulator in March beneath the left arm pit of Larry Herrington, 34, who had been suffering from excruciating pain in his arm from a rare condition resulting from a wrist injury.
The stimulator is connected by wires to a group of nerves in his neck that link the spinal cord with his injured arm. Herrington said the device eliminates about 80 percent of the nerve pain.
Long said extensive testing will be required before this type of device will be available for general use in controlling chronic pain.
'This represents a tremendous advance,' Long said. 'But these things are not a panacea for pain. They are for the worst kinds of problems when no simpler thing will solve the situation.'
The devices use micro-miniature circuitry, command and telemetry systems, battery design and quality control techniques developed by the National Aeronautics and Space Administration for spacecraft.
When produced in large numbers, it was estimated each device would cost a few thousand dollars.
