INSERTION OF A SACRAL NERVE STIMULATOR
What is it?
A device implanted surgically into the buttock with a lead to the sacral nerve to deliver electrical stimulation to the nerves to the bladder or bowel. It is reversible as it can be turned off at any time. You will need to be able to operate the device yourself.
What can it be used for?
- Refractory urge incontinence – urge incontinence that has failed medical therapy.
- Urinary retention – an inability to pass urine or empty the bladder adequately.
- Urgent and frequent need to pass urine.
- Faecal incontinence.
- (Interstitial Cystitis and pelvic pain - there is limited clinical data on the effectiveness of the therapy in these conditions. This therapy is not covered by Medicare or Private Insurance for this indication in Australia.)
How does it work?
We don’t fully understand how this device works. It is thought that it some how resets the normal function and reflexes involved in bladder and bowel function.
What is done?
The device is implanted in 2 stages. The first stage is the test phase where the electrode or wire to the nerve is placed alongside the sacral nerve and then attached to an external stimulator device to see if the treatment works. If it works then stage 2 is performed where the permanent stimulator device (battery) is implanted in the buttock. Usually a single lead is placed.
Stage 1
The electrode is placed to stimulate the sacral nerve – the nerve to the bladder or bowel. The lead is placed via a needle through the skin into the sacrum – just above the tail bone. This is done in an operating theatre under local anaesthetic and with some sedation. You will be lying on your stomach so the needle can be passed into the lower back between the buttocks. By not having a full anaesthetic the feedback you can give may help the surgeon to identify the best position for the electrode. Local anaesthetic will be injected before the needle is passed. When the electrode is in position it will be stimulated and you may be asked what you can feel. Ideally you should be able to feel the stimulation in the region of the anus, labia, vagina, or clitoris in the female and anus, scrotum or penis in the male. The stimulation should be pleasant, felt as a pulling or tingling sensation and not uncomfortable or painful. The surgeon will also look for contraction of the muscle around the anus and movement of the big toe to confirm correct positioning of the needle. X-ray pictures are also taken to assist in positioning the needle electrode. Once a good position is secured the electrode lead is tunnelled under the buttock skin and brought out to be plugged in the external stimulator device to begin the test phase, stage 1.
The Test Phase/Stage1
- The external stimulator is worn on a belt. During the test phase it is important to restrict your activity so the lead doesn’t get dislodged. Ideally you should take a few days off work, don’t drive and don’t shower or bath, (take sponge baths), and not have intercourse to avoid the lead accidentally getting dislodged.
- The trial period is usually 2 weeks. If the treatment is working you can go on to stage 2. Keeping a bladder diary is the best way to determine the effectiveness of the treatment or checking bladder emptying if it is being used for problems with bladder emptying. Generally it is felt there should be at least a 50% reduction in your symptoms for it to be worthwhile to go on to stage 2.
- In the test phase the best settings for the device will be determined. Several adjustments of the settings may be required to get the best response. You will be given instructions on how to operate the external stimulator. You can turn it on and off and you may be instructed to turn it up or down to find the best setting for you.
- If the treatment does not work the lead will be usually be removed under local anaesthetic with some sedation.
Stage 2
- This is again usually perfromed with a combination of local anaesthetic and sedation.
- The external part of the lead is removed and the electrode connected to a stimulator that is inserted under the skin usually in the upper outer part of the buttock. It needs to be somewhere you can reach it to hold the hand held remote operator over the device to adjust the settings as you require.
- It is possible that even though the treatment works in the test phase that is doesn’t when the permanent stimulator is implanted. This is usually due to a technical problem or the lead moving which might be resolved by repositioning the lead.
- At times quick movements may result in you feeling an increase in the level of stimulation. If your device is set to cycle between on and off then there will be times when you will not be able to feel the stimulation. Don’t worry as long as it is controlling your symptoms.
What are the alternatives?
Generally the stimulator treatment is reserved for patients who have already failed alternative treatments such as;
- Pelvic Floor exercises, Bladder Training and Timed Voiding
- Medication like Ditropan, Oxytrol, Detrusitol, Vesicare, Enablex and Betmiga
It is an alternative treatment to;
- Intermittent catheterisation or continuous catheter drainage
- Botox injection into the bladder
- Bladder augmentation
Will it work and for how long?
Success of the treatment does vary for different conditions;
- For urge incontinence about 45% patients were completely dry, 34% had > 50% reduction in number of incontinent episodes and 21% failed the treatment.
- For patients with urgency – frequency about a third return to a normal number of voids per day, a third have the number of voids reduced by 50% or more and a third fail the treatment.
- For urinary retention 61% of patients no longer needed to use a catheter, 16% had to use the catheter less often and 23% failed the treatment.
- Patients with neurological conditions generally have much lower success rates, around 20-30%.
Re-operation rates have been reported as high as 50% in some studies. Patients should accept there is a high likelihood of needing further procedures.
Common reasons for repeat surgery include:
- Repositioning of the lead due to a suspected lead moving or breaking
- The device stops working and needs replacing
- Pain or infection of the device
- The battery reaches the end of its life. (They last about 5-7 years). The battery will eventually run out and the stimulator device, not the lead, will need to be replaced. The programmer can be used to check the status of the battery. If the battery fails the device will stop working and your symptoms will return.
- You develop unwanted effects on bladder or bowel function or sensation.
- You need repositioning of the Implantable Pulse Generator (IPG/battery) due to pain or movement.
- You experience transient electrical shocks from the device.
- For the above problems the device might need to be either replaced or permanently removed.
How do I operate the TEST phase device?
- You will have a remote control to adjust the stimulation to a level where you can feel it and it is still comfortable.
- You should not turn it up so that it is uncomfortable or painful and this will not increase the effectiveness either.
- Your stimulation level and program settings will be visible on a digital display on the remote controller.
- The digital display will also show the battery level and if these need changing.
- You will be shown how to change the batteries if they are flat but this is unlikely as the batteries usually easily last the two weeks of the trial period.
How do I operate the PERMANENT implanted device?
You will be instructed on how to operate the remote control.
Settings can be adjusted within limits set by your surgeon and it can be turned on and off.
What are the other risks and complications?
During the test phase there are problems that could occur such as
- Disconnection of the cable
- Loss of ground pad connection
- Battery failure
- Device malfunction e.g. if dropped
- Lead migration
- Lead fragmentation
- New pain
- Numbness
- Infection at lead site
- Skin irritation
- Adverse change in bladder or bowel function
- Transient electrical shock
- Change in menstrual cycle
- Nerve injury
- Change in sensation which is undesirable
- Foot or leg movement
- Haematoma or seroma – collection of blood or fluid around the device
- Buttock, lumbar or pelvic pain
- Change in sexual function; 1 in 250 patients reported lack of orgasm
It is often not possible to warn patients of every possible risk or potential complication with surgery especially if very rare. Yet it is important that you are aware of what risks are involved, especially the more common ones. This information is not meant to alarm you but allow you to make an informed consent to have surgery. It is very rare but unfortunately some patients can suffer complications and end up worse off as a result of their surgery.
How long does the operation take?
Stage 1 – about an hour.
Stage 2 – about half an hour.
Both stages are usually day surgery but some patients are recommended to stay overnight.
Post-operative follow-up.
You will be given a follow up appointment.
If you experience any of the following problems after discharge you should seek medical attention;
- Severe pain not controlled with pain killers
- Bleeding
- Wound problems – infection or breakdown, redness or swelling.
- Inability to pass a catheter if required
- Or any other significant trouble.
If at any stage your incontinence returns you should arrange a review visit.
IMPORTANT SAFETY INFORMATION
Inform anyone treating you that you can not have any shortwave diathermy, microwave diathermy or therapeutic ultrasound diathermy (as used by physiotherapists) anywhere on your body because it could damage the device or cause you serious injury or even death.
If you have future surgery; surgical diathermy is okay. Bipolar diathermy should be used where possible. The ground pad should be placed away from the device. The minimal amount of energy should be used as is possible. Contact with the device should be avoided.
Turn the test stimulator off or down when you drive or use power tools. This is because brief increases in stimulation due to lead movement could startle you and cause you to lose control of these devices and hurt yourself or others. If in doubt turn it off.
It is not known whether this treatment is safe to use in pregnancy, therefore it is advised that you must have your device turned off if you are planning to start a family or as soon as you know you are pregnant.
Pacemakers, cardiac defibrillators or MRI scans may interfere or damage the device but in life threatening situations they may be required. Ultrasound scanning, lithotripsy or radiotherapy treatments also may damage the device. Sacral nerve neuromodulation devices implanted from August 2021 are MRI compatable.
Walking through security devices can turn your device on or off or you may feel a brief burst of stimulation or jolt. Your ID card may let you bypass the walk through security device. After surgery you will be given a temporary device registration card until the permanent card is sent which takes about 6-8 weeks. Security devices on shops for shop lifting are okay but it is recommended you walk through them quickly and don’t stand between the monitors.
You should carry an ID card in your wallet or wear a Medic Alert bracelet to warn people you have an InterStim device implanted.
Version: V3, July 2017
