IMPLANTABLE STIMULATION SYSTEM DEDICATED FOR NEURAL SELECTIVE STIMULATION

A functional electrical stimulation system is presented, which is dedi cated for the selective neural stimulation of the bladder. The propose d system is composed of an internal stimulator (implant) and an extern al controller. The system is used to produce low-pressure voiding of t he bladder in spinal cord injured patients. The implant is powered and operated by the external controller via radio-frequency electromagnet ic coupling. All stimulation parameters are chosen externally using th e controller and are sent to the implant, which produces the desired s timuli. These stimuli are applied directly to the S-2 nerve which is l inked to the sphincter and bladder muscles. A high-frequency signal is used to inhibit the contraction of the sphincter muscle, and low-freq uency pulses stimulate the bladder muscle (the detrusor). Dedicated co mputer software is used by the physician to select the optimal paramet ers for each patient and to activate the implant through a parallel po rt interface with built-in transmitter. The parameters are then transf erred to a hand-held controller which is used by the technical staff a nd by the patients themselves. Acute studies have been performed to va lidate the selective stimulation strategy, and chronic experimentation is currently underway in dogs.