When pain is more of an issue, Dr. Bukkapatnam will consider a different experimental approach, called a caudal implant. He worked with Larissa Rodriguez, MD, at UCLA, who researched the technique. It involves stimulating, not just the S3 nerve root, but three sacral nerve roots—S2, S3, and S4—and feeding the stimulator leads to those nerve roots through the space at the end of the sacrum and parallel to the spine. “You capture a larger area of the pelvis with this neuromodulation technique,” he explained. This helps reduce the chance that the leads will move from where they were originally placed (termed “lead migration”), which is one of the reasons that stimulation may stop working after a time. The multiple leads are then connected to a Synergy device.  The approach still needs research, and Dr. Bukkapatnam doesn’t offer this as a first-line neuromodulation therapy. But he will try it when everything else he has tried doesn’t work.

Implanting of the Long-term Lead for the Test and Testing for a Longer Time

With the InterStim, a lead is placed perpendicular to the spine through the third hole in the sacral bone to stimulate third sacral nerve root (S3) on one side. Before a patient has the stimulator implanted, she or he goes through a “trial run.” The trial stimulation has been done using a temporary lead placed through the skin in the surgeon’s office and left there, attached to an external pulse generator, for four days to a week. If the test turns out well, the surgeon implants a sturdier, long-term lead and the internal InterStim pulse generator.

But now, many surgeons are implanting the long-term lead for the test and testing for a longer time—a minimum of two weeks and up to a month. Recent research has shown that this improves success rates for neurostimulation. Charles Butrick, MD, Director of the Urogynecology Center in Overland Park, Kansas, and Raviender Bukkapatnam, MD, of Tampa Urology in Tampa, Florida, explained why.

“The percutaneous leads are so delicate that they may not really get a good test,” said Dr. Bukkapatnam. He may test for as long as four weeks to be sure stimulation works, which can’t be done with the “floppy” leads, which are usually left in place only for one to four days and can fall out.

“A problem with percutaneous leads is that 20 percent of the time, you do not necessarily get the permanent lead in the exact same spot as that percutaneous wire you placed two or three weeks earlier,” added Dr. Butrick. “That wire is already gone, so if you happen to put your permanent lead in a different spot, it might not work. If the permanent lead works in the test phase, there’s no guessing about it. It’s going to work once you hook it up to the permanent pulse generator.”

Urologist Judy Siegel, of A Family Urology Practice in Hastings-on-Hudson, New York, however, will still perform the in-office test because it’s less intrusive, which can make the process less daunting than going to the operating room. The potential to miss the right spot is still a downside, though, she agreed.

Longer test phases and patience with finding the optimal programming aren’t the only keys to success with sacral neuromodulation. It needs to be the right approach for you. Dr. Butrick never relies on this alone as a treatment. He also thinks that patients who have obvious pelvic floor muscle dysfunction and voiding dysfunction do best with InterStim. Also, if patients have pain worse on one side of the body, he will be sure to implant the lead on that side.

Dr. Bukkapatnam thinks IC patients who have frequency and urgency as their predominant symptoms, rather than pain, do best. When symptoms are very severe, for example, voiding every 15 minutes with pain and urgency, he’ll considering using a new approach—implanting leads to stimulate both the left and right S3 nerve roots. When he does this type of implant, he will use Medtronic’s Synergy device, a pulse generator that allows two leads to be attached. The device is a little thicker than InterStim.

Dr. Butrick considers bilateral stimulation when unilateral sacral neuromodulation has been successful but then stops working after a time (even though the battery is functioning), which he said happens in about 10 percent of patients. The options are to take the InterStim pulse generator out, substitute the Synergy device, and connect both leads to it or to implant a second InterStim pulse generator on the other side.

Upside Down Approach

Daniel Brookoff, MD, PhD, at Presbyterian-St. Luke’s Hospital in Denver, Colorado, takes a different approach to stimulating multiple sacral nerve roots. It’s “upside down” Instead of threading the leads up from the end of the sacrum, the leads are inserted through a small incision in the lumbar area and are threaded down to the S2, S3, and S4 nerve roots on the left and right sides. The technique, he noted, was developed by Claudio Feller, MD, at the University of Tennessee in Memphis. Dr. Feller found the method to be successful for patients with severe bladder and pelvic pain, some of whom had not had success with the more typical sacral neurostimulation with a lead placed through the hole in the sacrum at S3.

The leads can be either wires placed through the skin or paddle electrodes placed surgically through a tiny hole in a vertebral bone. Although surgery is required to place paddle electrodes, the risk is only marginally greater than with the wires, and these electrodes have better contact with nerves and use less power, which prolongs the life of the stimulator battery or reduces the need for recharging, said Dr. Brookoff.

There is a test period, usually five to seven days. If stimulation works, a pulse generator is then implanted. Much higher frequencies can be used with these systems than with the InterStim device, Dr. Brookoff said, giving patients more stimulation options, which translate to better pain control. He added that there is less risk of lead migration, too, than with the common sacral neuromodulation technique. He noted that the technique has eased bladder pain for some of his IC patients who would otherwise have had their bladders removed. The neurostimulation systems are made by various companies, including Medtronic, Boston Scientific, and Advanced Neuromodulation Systems.

Going Downstream

New approaches to neuromodulation also involve stimulating peripheral nerves. These nerves are “downstream” from the spinal cord, and their impulses lead back to sacral nerve roots. Kenneth Peters, MD, at William Beaumont Hospital in Royal Oak, Michigan, is pioneering stimulation of the pudendal nerve. He used InterStim technology to compare sacral nerve stimulation with pudendal nerve stimulation and found that patients had greater reductions in symptoms with the latter approach and that patients preferred pudendal nerve stimulation. Dr. Peters told the ICA Update that he hopes to expand his initial clinical trial further, but he has done more than 70 implants this way. “I clearly feel the pudendal is a better lead,” he said.

Dr. Peters was one of the researchers studying another approach to pudendal nerve stimulation, the bion neurostimulator. The matchstick-sized device that had no internal battery. Instead, patients sat on a charging mat. The study was stopped, and the device won’t go to market in its current form, noted Dr. Peters. Boston Scientific, which purchased the bion portion of the previous manufacturer, Advanced Bionics, is likely redesigning a small, rechargeable device that may go back to testing in the near future.

Dr. Siegel uses another kind of peripheral nerve stimulation, tibial nerve stimulation. Impulses from the tibial nerve run back to the same network of nerves in the pelvis and t sacral nerve roots as the bladder and pudendal nerves. She has long been enthusiastic about tibial nerve stimulation for bladder symptoms—ever since the developer of the first device, Marshall Stoller, MD, spoke at her residency program. In fact, before a device was commercially available, she had one made. Later, the first commercial device, called SANS (Stoller Afferent Nerve Stimulation), was approved for marketing by the FDA for urgency and frequency, but it wasn’t easily available. In 2006, however, Uroplasty, Inc. acquired the device, updated it, and began to market it. Many more physicians and physical therapists have the Urgent PC, as it is now called, and can offer the treatment, and the numbers are growing quickly.

Called PTNS for “percutaneous tibial nerve stimulation,” the treatment is noninvasive. Nothing is implanted. “Any patient who is reluctant to have a surgical procedure or an implant can try PTNS,” noted Dr. Siegel, who is featured in a video clip on the company’s website. The treatment involves inserting a needle, similar to an acupuncture needle, through the skin at the ankle. “It doesn’t hurt,” she emphasized. In fact, when a patient is concerned, she just pulls out the needs and pops it into her own ankle. “I’ve never had a patient who couldn’t tolerate the procedure.”

The lead goes to a hand-held, battery-operated electrical stimulator, a device about as big as a pack and a half of cards. The healthcare professional who administers the treatment will check to see what level of current you can feel, which is something like a tingling and may make your toes move, explained Nancy Kolb, who is Vice President of Global Marketing at Uroplasty. Then, usually, the stimulation is set a bit lower so there’s no intrusive sensation, the treatment program is set for 30 minutes, and you sit comfortably in a chair, where you can read, nap, or chat with others. Sometimes, Kolb explained, therapists will increase the setting after 10 or 15 minutes because the nerve accommodates to the stimulation, in other words, gets used to it.

The standard treatment is 30 minutes administered once a week for 12 weeks. Then, the interval between the treatments is determined by how soon symptoms return, explained Kolb. Some patients go two weeks or a month between treatments, and some never need to come back, said Dr. Siegel. If patients need to come back frequently, she talks to them about InterStim or some other implantable stimulator “because you’ve shown that neuromodulation works, and you’ve shown that they kind of need a top-up all the time.”

“PTNS is more intermittent, so it takes a little longer to become effective. It’s not as potent as central nerve stimulation, but it works,” said Dr. Siegel. She noted that, even though the device is approved for urgency and frequency, many of her patients find it helps ease pain. She said she has had patients whose vulvar pain was eased with the therapy as well.

How much the treatment costs depends on your insurance, but generally, the treatment does get insurance reimbursement, she said. A typical charge is about $250 for a treatment, so the 12 treatments before insurance reimbursement might cost about $3,000, much less than an implantable stimulator. Kolb added that Medicare does reimburse on a case-by-case basis across the country.

Revised December 9, 2008