Sacral neuromodulation (SNM) is a medical electrical stimulation minimally invasive procedure that is used to treat urinary incontinence. The procedure involves the implantation of a programmable stimulator subcutaneously, which delivers low amplitude electrical stimulation via a lead to the sacral nerve (plexus nerve that provides sensory to the posterior thigh), mostly accessed via S3 frames.
This sacral neuromodulation procedure is an option for the management of patients with an overactive bladder, a condition characterised by involuntary contraction of the muscles in the wall of the urinary bladder that causes a sudden urge to urinate.
Indications of SNM Procedure
Symptoms that may lead to the need for sacral neuromodulation include:
- Sudden urge to urinate
- Frequent urination
- Involuntary loss of urine
- Urinary incontinence (leakage of urine)
- Non-obstructive urinary retention
Sacral Neuromodulation Procedure
During the sacral neuromodulation procedure, a neurotransmitter is implanted under the skin of the upper buttock region. A mild electrical current is then transmitted through the lead wires to stimulate the lead nerves. Through this, the functioning of the bladder and muscles is regulated.
It is important to note that sacral nerve stimulation is not a cure for an overactive bladder, though the procedure may help reduce the frequency of voids or wetting episodes associated with an overactive bladder or urinary incontinence.
This procedure normally involves two stages, which include:
Stage 1: Here, a stimulation lead is implanted in a subcutaneous pocket in the upper outer quadrant of the buttock for about one to two weeks purposely to evaluate the patient’s response to the stimulation and to check if stimulation improves the overactive bladder symptoms.
This stage of the procedure is performed on an outpatient basis and normally takes about 30-45 minutes.
Stage 2: This second phase of sacral neuromodulation is normally done after the successful completion of the first phase. The neurotransmitter device is permanently implanted during this stage.
This phase is performed under local anaesthesia and usually takes about 15 minutes.
The surgeon makes a small incision on the skin over the upper buttock region, then a neurotransmitter is implanted under the skin of the upper buttock region. The surgeon then makes another small incision across the lower back to implant a long-term electrode that provides moderate electrical impulses to the sacral nerves that control the bladder, sphincters, and pelvic floor muscles through a lead.
Precautions After SNM Procedure
- It is advisable that patients with an implanted neurostimulator device should avoid MRI scans, x-rays, and radiation therapy since this may affect the functioning of the device.
- Since the neurostimulator battery life depends on individual settings and frequency of use per day, the neurostimulator needs to be replaced every 3 to 5 years.
- For any additional tests, an individual should always consult with the doctor first.
Risk Factors of Sacral Neuromodulation
There are minimal risks associated with sacral neuromodulation therapy, however, risks may be caused by problems related to the device or the implantation procedure requiring programming of the device. The risks could include:
- Technical problems
- Pain at the implant
- Shifting of the lead
- Undesirable changes in stimulation
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