Implantable stimulation system dedicated for neural selective stimulation

A functional electrical stimulation system is presented, which is dedicated for the selective neural stimulation of the bladder. The proposed system is composed of an internal stimulator (implant) and an external controller. The system is used to produce low-pressure voiding of the bladder in spinal cord injured patients. The implant is powered and operated by the external controller via radio-frequency electromagnetic coupling. All stimulation parameters are chosen externally using the controller and are sent to the implant, which produces the desired stimuli. These stimuli are applied directly to the S2 nerve which is linked to the sphincter and bladder muscles. A high-frequency signal is used to inhibit the contraction of the sphincter muscle, and low-frequency pulses stimulate the bladder muscle (the detrusor). Dedicated computer software is used by the physician to select the optimal parameters for each patient and to activate the implant through a parallel port interface with built-in transmitter. The parameters are then transferred to a hand-held controller which is used by the technical staff and by the patients themselves. Acute studies have been performed to validate the selective stimulation strategy, and chronic experimentation is currently underway in dogs.