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Permanent Sacral nerve Stimulation SNS

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What is sacral nerve stimulation (SNS)?

This is a procedure in which stimulation of the nerves from the sacrum (lower part of the backbone) is undertaken to help alleviate symptoms of faecal incontinence.

When is SNS performed?

The most common reason for performing sacral nerve stimulation is to try and improve symptoms of incontinence. Patients most likely to benefit are those whose pelvic floor and sphincter muscles are intact but do not work very well; sometimes patients with damaged muscles benefit. It is becoming more widely used for some other symptoms and is occasionally used for patients with constipation.

What other tests are necessary?

Most patients having SNS will need studies on their anal sphincter to look at its structure and function (anorectal physiology and ultrasound) and a proctogram. These tests will look for damage to the sphincter muscle and more importantly rule out other causes e.g., an internal rectal prolapse. SNS only works in about 30% of patients with prolapse.  These patients do better with a laparoscopic ventral mesh rectopexy.

It is not clear how sacral nerve stimulation works. In part this may explain why some patients, despite appearing suitable on the basis of these investigations, do not benefit from the procedure. A “test” or “temporary” wire is therefore inserted in patients before the permanent implant is undertaken.

Temporary Sacral Nerve Stimulation

What does the temporary wire involve? Patients who are considered likely to benefit from SNS are first given a temporary or test wire. This is inserted with you awake after numbing the skin over the lower spine just above the buttocks. It usually takes about 30 minutes to insert these temporary wires. The other end of the wire is attached to a little stimulator (battery box) like an iPOD, worn on a belt.

The wire and stimulator connectors are all covered up with dressings. You should not bath or shower during the temporary test period as it is important that the dressings, the wire and stimulator stay dry and do not get dislodged. You will be shown how to disconnect the wire from the stimulator and we would recommend that you do this when driving.This test period usually lasts two to three weeks and then the temporary wire is removed. Removal of the wire is straightforward and does not even require a local anaesthetic.

You will be given a diary to fill in so that your surgeon can assess how beneficial the temporary stimulator has been. About three quarters of patients improve with the temporary wire and are then offered a permanent implant.  It is important to be objective about any positive effect.  There is no point in having an implant if the test result is only marginal.


Permanent Sacral Nerve Stimulation

When is this performed?

All patients having a permanent implant will first have had a temporary test wire. Those benefiting from this will be offered a permanent stimulator.

What does the permanent implant involve?

The permanent stimulator is inserted under a general anaesthetic. A wire is inserted as for the temporary stimulator but this time, the other end of the wire is tunneled under the skin and attached to a small stimulator (about the size of a watch) buried within the fat of the buttock. Apart from the small scars, there are no external wires or equipment after permanent implantation. Recovery is rapid and the patient will usually be allowed home on the same day.

What happens after insertion of the permanent implant?

You will be given full instructions before you are discharged home and contact details if you have any questions. You will be supplied with a wireless handset that communicates with the implanted stimulator, enabling you to turn it on and off and change the settings.  When the wounds have healed, you can shower and bath as usual. You can drive with the permanent implant as usual.

We will keep you under regular review to ensure that you are continuing to benefit from the stimulator.


What happens if I get back or leg pain?

If you have problems with pains in your legs, then again, you might try and see if switching off the stimulator stops the problem. Leg pains are, however, more likely related to the stimulator and we can make adjustments that should be able to overcome this 

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