Electrical nerve stimulators, also known as neuromodulators, send mild electrical pulses to nerves in the lower back and help manage urinary function or offer relief of chronic pain.
Some neuromodulators are worn externally. Others are
surgically implanted devices. Most implanted neuromdoulators work by sending mild electrical pulses to nerves located in the lower back. These nerves, called sacral nerves, influence the bladder and surrounding muscles that manage urinary function. Before surgically placing under the skin, typically in the lower back, a test stimulation procedure is performed. Only patients who respond positively to the test stimulator are considered for the permanent implants.
Eon Mini (www.poweroveryourpain.com): Advanced Neuromodulation Systems (ANS), a division of St. Jude Medical, Inc., makes the Eon Mini, the world's smallest, longest-lasting rechargeable neurostimulator to treat chronic pain of the trunk or limbs and pain from failed back surgery. The Eon Mini has the longest-lasting battery life of any rechargeable spinal cord stimulation (SCS) device in its class. It is the only small rechargeable neurostimulator to receive a 10-year battery longevity approval by the FDA. While not approved specifically for interstitial cystitis, neuromodulation devices such as this have been tried and tested in people with IC with varying degrees of success.
Urgent PC (www.uroplasty.com): The Urgent PC Neuromodulation System, also called percutaneous tibial nerve neuromodulation (PTNS), is a combination of a stimulator and a lead set. This system is designed to treat urinary urgency, urinary frequency and urge incontinence. The stimulator generates a specific kind of electrical impulse that is delivered to the patient through the lead set. Using a needle electrode placed near the ankle as an entry point, the stimulator’s impulses travel along the tibial nerve to the nerves in the spine that control pelvic floor function. The needle electrode is connected to a battery-powered stimulator. After turning on the stimulator, your physician will observe your body’s response to determine the ideal strength of the impulses.
Each of your treatments will last approximately 30 minutes. You will receive an initial series of 12 treatments, typically scheduled a week apart. After the initial 12 treatments, your physician will discuss your response to the treatments and determine how often you will need future treatments to maintain your results. For most patients it takes at least 6 treatments to see changes in symptoms. However, continue receiving treatments for the recommended 12 treatments before you and your physician evaluate whether this therapy is an appropriate treatment for your symptoms.
The most common side-effects include transient mild pain or skin inflammation at or near the stimulation site. Urgent PC is not recommended for patients with pacemakers or implantable defibrillators, patients prone to excessive bleeding, atients with nerve damage that could impact either percutaneous tibial nerve or pelvic floor function, or patients who are pregnant or planning to become pregnant during the duration of the treatment.
InterStim Therapy for Urinary Control (www.interstim.com): This device is FDA approved for urinary urge incontinence, nonobstructive urinary retention, and significant symptoms of urgency-frequency in patients who have failed to respond to, or could not tolerate, more conservative treatments. Some IC patients report that InterStim also helps to relieve their pain, as well as symptoms of urinary frequency and urgency. However, the FDA has not approved it for pain management.
Patients interested in the implant surgery are initially evaluated with a complete history, physical examination, voiding diaries, and a bladder function study. If they qualify, they undergo test stimulation, conducted by a urologist or urogynecologist, which typically takes less than one hour, and is considered a "same day" procedure. The test stimulation involves the placement of a needle into the lower back in a location where nerves travel to the bladder. Typically, a local anesthetic is used during the test stimulation. A small wire (lead) is left in place and transmits electrical impulses to these nerves. The patient returns home with the test stimulator in place for 3 to 7 days, and keeps a voiding diary. The wire is then removed by the surgeon. Some patients report the test stimulation to be painful, while others do not. If you are concerned about this, please discuss pain management options with your physician.
If the test stimulation is successful, and improvement is noted within five to seven days, then the permanent system can be surgically implanted under general anesthesia. This generally requires an overnight stay in the hospital. The patient is given a small device that can be used to turn on/off and modulate the level of stimulation to nerves. InterStim® can only be implanted by a urologist or urogynecologist who has been specifically trained to perform the procedure.
As with any surgical procedure, there are risks involved. The system components include a lead (wire), a neurostimulator, and an extension that connects the lead to the neurostimulator. The therapy is conducted in two stages: 1) test stimulation lead placement, and 2) the neurostimulator implant. Other risks associated with this implant include infection, lead/wire migration that could necessitate a revision procedure, and post-operative pain in the area of the implant. Adverse events related to the therapy, device, or procedure can include: pain at the implant sites; lead migration which necessitates additional surgery to reposition the leads; infection or skin irritation; technical or device problems; transient electric shock; adverse change in bowel or voiding function; numbness; nerve injury; seroma (cyst-like structure filled with fluid) at the neurostimulator site; change in menstrual cycle; and undesirable stimulation or sensations. To date, there have been no reports of permanent nerve injury occurring with the use of InterStim. Since this is a new treatment for IC that is not FDA-approved, it is possible that other adverse events could occur that are as yet unreported. Due to lead migration, pain, and infection, there may be a need for reoperation (of the permanent implant) 15-30 percent of the time.
InterStim is not intended for patients with mechanical obstructions such as benign prostatic hypertrophy, cancer, or urethral strictures. InterStim has not been studied in pregnant patients, children, patients with diabetes, or patients with multiple sclerosis. Patients are contraindicated for the implant if they have not demonstrated an appropriate response to test stimulation or are unable to operate the neurostimulator. Also, diathermy (e.g., short wave diathermy, microwave diathermy or therapeutic ultrasound diathermy) is contraindicated because diathermy's energy can be transferred through the implanted system (or any of the separate implanted components), which can cause tissue damage and can result in severe injury or death.
For specific InterStimtherapy related questions, call the Medtronic Patient Services Department at 800-510-6735. If you would like a contact list of other IC patients who have tried InterStim® Therapy, please call the ICA at 800-Help-ICA.
Interstim FAQs by Robert Evans, MD, ICA Medical Advisory Board member
- Will InterStim help with the pain of IC?
With InterStim, you are really affecting the nerves that cause increased urinary frequency. You should not expect that it will have an effect on your pain. Further research is needed to assess this device's effects on the pain of IC.
- Will I get immediate relief of my symptoms?
Some patients may experience immediate relief. Others may require reprogramming of the permanent implant, up to several times, in order to achieve optimal results.
- How long can the test stimulator be left in place?
It can be left in place for about a week. After that length of time, the wires move themselves out, the tape tends to peel off, and effectiveness is lost.
- Will my insurance cover InterStim?
Medtronic has been very helpful in getting the stimulators pre-approved. My policy is that we do not do a test stimulation until we get approval to test and pre-approval to use the permanent implant. We are very close to having a Medicare ruling on a code for the implant. Once this happens, the other insurance carriers tend to adopt the same procedure.
- What kinds of physical activity can you do after InterStim implantation?
For the first week or so, the patient needs to keep the area dry. After about 3 weeks, when the incision is fully healed, there is no limitation of activity.
- How long does the InterStim battery last?
Right now it is felt that the neuromodulator should work for seven to ten years. They make a nearly identical pulse generator for pacemakers. When the battery needs to be replaced, your physician can make a small incision and put a new battery in. This procedure takes approximately 15-20 minutes.
- Is InterStim implanted under general anesthesia?
Yes. The permanent device is implanted under general anesthesia. However, for the test implant, the patient has to be awake so that they can let their doctor know if their bladder symptoms are responding to the test stimulator.
Revised November 27, 2008