For patients left paralyzed and unable to speak from a spinal cord injury or stroke, communication is a constant challenge that threatens independence, emotional well being and health.
Roy E. Bakay, M.D., a neurosurgeon at Emory University and neuroscience colleague Phillip R. Kennedy, M.D., have developed a neurotrophic electrode that can be placed in the brain to help these patients communicate through a computer. The electrodes have been successfully implanted into the brains of two patients at Emory University Hospital, one with amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease) and one with brainstem stroke.
Drs. Bakay and Kennedy present this research at the Society for Neuroscience meeting in Los Angeles this week.
"A person can interact with the world if they can use a computer," Dr. Bakay said. "This development will open up a tremendous amount of opportunity for patients who have lost the ability to move and talk because of stroke, spinal cord injury or diseases like Lou Gehrig's disease."
The neurotrophic electrode is implanted into the motor cortex of the brain using a tiny glass encasing. Neurotrophic factors are implanted into the glass, and the cortical cells grow into the neurotrophic electrode and form contacts. It takes several weeks for the cortical tissue to grow into the electrode.
The neurons in the brain transmit an electronic signal when they "fire." Recording wires are placed inside the glass cone to pick up the neural signals from the ingrown brain tissue and transmit then through the skin to a receiver and amplifier outside of the scalp. The system is powered by an induction coil placed over the scalp. There are no wires going through the skin. Neural signals are used to drive the computer cursor in the same way a computer mouse is moved back and forth. The recorded neural signals are connected to the computer and are used as a substitute for the mouse cursor.
"The trick is teaching the patient to control the strength and pattern of the electric impulses being produced in the brain," Dr. Bakay said. "After some training, they are able to "will" a cursor to move and then stop on a specific point on the computer screen. If you can move the cursor, you can stop on certain icons, send email, turn on or off a light and interact with the environment.
"Our present patient, who is at the Atlanta Veterans Affairs Medical Center, is paralyzed except for his face due to brainstem stroke following a heart attack, is dependent on a ventilator and cannot speak, yet he is fully alert and intelligent," Dr. Bakay said. "This patient, who was implanted five months ago with the electrode, can move the cursor from icon to icon in a horizontal direction. As each icon is encountered, a phrase is spoken by the computer. The patient's favorite is, "See you later. Nice talking with you."
"Our work with this patient is very successful, and we will be continuing with this research," Dr. Bakay said. "Our hope is that soon we will be able to get to the point that we can connect the neural signals to a muscle stimulator in the patient's paralyzed limb and have them move that limb using the same principle that they use to move the cursor."
Results from implanting the electrode in the first patient were published in the June 1998 issue of NeuroReport. The patient was able to control computer signals in an on/off manner for 76 days before she died from her terminal ALS condition.
More than 700,000 Americans suffer from stroke each year and tens of thousands more suffer spinal cord injuries or from diseases like Lou Gehrig's that threaten their ability to communicate. Stroke is currently the leading cause of permanent adult disability in the United States.
The neurotrophic electrode technology was developed and patented by Dr. Kennedy while at the Georgia Institute of Technology. Its testing and development in animals over the past 12 years has been a collaboration between Emory University and Georgia Tech. The research has been supported by the Emory/Georgia Tech Biomedical Research Consortium, the American Paralysis Association and the Department of Veterans Affairs. The National Institutes of Health (NIH) has recently awarded funding to continue the Phase I research in at least one more patient.