Advances in electronics have enabled the development of implantable medical devices that are both biocompatible and have the ability to function in the human body for many years without requiring replacement.  Once implanted, these devices have the ability to sense bioprocesses and stimulate functions to correct certain medical conditions.  Devices that use electrical signaling have established a place in the biomedical market.  

Cardiac pacemakers are implanted in patients when they have a slow or irregular heart beat.  To keep the heart beating regularly, a pacemaker is used to send a small electric current to the heart and stimulate the heart beat.  Improvements in the design of the pacemaker have included sensors to provide feedback so that the heart is stimulated to the appropriate rate.  During physical exertion, the pacemaker can detect the increased need and respond by increasing the heart rate.

The cochlear implant is an electronic device that when surgically placed, can restore partial hearing to people who had been profoundly deaf.  The cochlear implant functions by conducting sound directly to the auditory nerve, bypassing the damaged hair cells that are a normal part of sound transmission.  The electronic signal from the implant is transmitted to the auditory nerve then travels to the brain and is registered as sound.

Bions, or bionic neurons, are electrical devices used to stimulate muscles and nerves.  These tiny, electronic devices can be implanted without surgery, via a hypodermic needle, and are powered and controlled by radio waves generated by a small device worn by the patient.  BIons are being used to strengthen muscles that have atrophied as a result of stroke and to treat urinary incontinence.   

Diseases that require drug therapy have also been affected by device technology.  Implantable medical devices have been used as efficient drug delivery systems.   Glucose-monitoring sensors combined with an insulin infusion pump provide for a greater degree of control over blood glucose levels in people with diabetes.  Clinical studies have shown that individuals with blood glucose levels that are close to normal are at significantly lower risk for serious complications associated with the disease.  Automated glucose monitoring and the titration and delivery of insulin removes this time consuming and often unpleasant burden from the patient and places the patient at lower risk for retinopathy, nephropathy, and neuropathy.

The need in the medical marketplace that is not yet being filled is for diseases 
that require treatment by a combination of electrical stimulation and targeted drug delivery.  This device could be used to treat a broader range of diseases than could be effectively treated by either electrical stimulation or drug delivery alone.

NeuroSystec is developing technologies to fill this void in the marketplace.  Tinnitus, a disease related to irregularities in the outer hair cells located in the cochlea portion of the ear, is our first disease target.  Tinnitus is the perception of sound when no source of sound is present.  Tinnitus is a symptom associated with hearing loss of various origins.  As many as 50 million people are estimated to suffer from some form of the disease with almost 12 million having a condition serious enough for them to seek medical assistance.

Most frequently, tinnitus is associated with noise-induced hearing loss, age-related hearing loss, and Meniere’s Disease.  Tinnitus may also result from exposure to ototoxic drugs (high-dose loop diuretics, nonsteroidal anti-inflammatory agents, aminoglycoside antibiotics, and certain types of chemotherapy), ischemia, autoimmune disease, trauma, or infectious disease.

Individuals with a cochlear implant often experience a reduction of tinnitus.
Research suggests that tinnitus is caused by excessive and spontaneous firing in the auditory nerve.  Since the cochlear implant acts by electrical stimulation to increase firing of the auditory nerve, the implant does not treat the underlying cause of the tinnitus although it can have an effect on the symptoms.  

Neurotransmitters are chemical agents that act to transmit signals from the ear and auditory nerve to the brain.  With excessive neuronal firing, excessive amounts of neurotransmitters are released and signal the brain.  This signaling is perceived as sound and results in the person experiencing tinnitus.  Decreasing the amount of neurotransmitters released or blocking the uptake of these chemical agents would be an approach for treating the underlying cause of the disease.

At NeuroSystec, we believe that electrical stimulation minimizes the symptoms of tinnitus without treating the cause of the disease.  Drug therapy targeted specifically to this area is required.   We are employing the cochlear implant to serve two functions:  to treat hearing deficit as well as acting as a delivery system so that drugs can reach the target area and treat the underlying disease, tinnitus.

Links to Associated Web Sites
 

Advanced Bionics	www.advancedbionics.com
Alfred E. Mann Foundation	www.aemf.org
Alfred E. Mann Institute at University of  Southern California	ami.usc.edu
American Tinnitus Association	www.ATA.org
Brain Research Institute at University of  California at Los Angeles	www.bri.ucla.edu
Center For Disease Control	www.cdc.gov
National Institute on Deafness and Other  Communication Disorders at the NIH	www.nidcd.gov