1. Field of the Invention
This invention relates generally to an apparatus that allows for non-direct contact stimulation of the sacral nerves. More specifically, this invention relates to an implantable medical lead having at least one electrode contact wherein the lead is implanted near the sacral nerves for stimulation of a bundle of nerve fibers. Moreover, this invention relates to the method of implantation and anchoring of the medical lead near the sacral nerve to allow for non-direct contact stimulation.
2. Description of Related Art
Pelvic floor disorders such as, urinary incontinence, urinary urge/frequency, urinary retention, pelvic pain, bowel dysfunction (constipation, diarrhea), erectile dysfunction, are bodily functions influenced by the sacral nerves that can be treated using electrical stimulation. Specifically, urinary incontinence is the involuntary control over the bladder that is exhibited in various patients. Electrical stimulation of the sacral nerves can result in partial control over the evacuation function of the bladder and other related functions. Thus, for example, medical leads having discrete electrode contacts have been implanted on and near the sacral nerves of the human body to provide partial control for bladder incontinence. Other methods have been used to control bladder incontinence, for example, vesicostomy or an artificial sphincter implanted around the urethe. These solutions have drawbacks well known to those skilled in the art. In addition, some disease states do not have adequate medical treatments.
In one current method of treatment for incontinence using electrical stimulation, two stimulation systems are implanted and have an implantable lead with discrete electrodes positioned directly on selected sacral nerves for sphincter and bladder stimulation respectively. The leads are connected to a pulse generator wherein an electrical stimulation pulse is transmitted. The sphincter is stimulated to prevent incontinence. When it is desired to evacuate the bladder, the electrical pulse to the sphincter is closed and the electrode connected to the bladder function is stimulated. After a delay, the bladder system stimulation is discontinued and the sphincter is again stimulated. A system and method for inserting an electrical lead within a human for applying electrical stimulation to the sacral nerves for control of incontinence and other related functions is discussed in U.S. Pat. No. 4,771,779 issued to Tanagho et al., and herein is incorporated by reference.
Incontinence is primarily treated through pharmaceuticals and surgery. Many of the pharmaceuticals do not adequately resolve the issue and can cause unwanted side effects and a number of the surgical procedures have a low success rate and are not reversible. Typically, existing leads have four small discrete electrodes built into the distal end of the lead. During implantation, the physician steers the implantable pulse generator outputs to the electrodes to provide the most efficacious therapy.
Unlike other surgical procedures, sacral nerve stimulation using an implantable pulse generator is reversible by merely turning off the pulse generator. The current electrical designs used for sacral nerve stimulation are not optimized for the application. Additionally, due to the small size of the stimulation electrodes, up to 0.060 inches, physicians spend a great deal of time with the patient under a general anesthetic placing the leads. The patient is thereby exposed to the additional dangers associated with extended periods of time under a general anesthetic. The current lead design used for sacral nerve stimulation uses 4 electrodes. Each electrode has a length of 0.030 inches and are spaced by 0.030 inches. Another lead that is currently used has electrodes 0.060 inches spaced by 0.060 inches.
A problem associated with the prior art electrical stimulation to control incontinence is positioning and maintaining the discrete electrode in casual contact or in close proximity to the nerve to provide adequate stimulation of the sacral nerves. Another problem is constant or consistent stimulation. Accordingly, there remains a need in the art for an implantable electrical lead that allows for stimulation of a bundle of nerves and allows for some movement after implantation.