Permanent Sacral nerve Stimulation SNS
What is sacral nerve stimulation
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
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
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
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
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
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