Neuromodulation
As simple as it may seem at first sight, the accuulation and then emptying of urine is in fact a complex mechanism controlled by the nervous system. The nervous system works like a communication circuit between the different urinary elements and the brain. Therefore the communication allows, for instance, when the bladder is full, to signal that it is time to go to the bathroom.
The information indicating to the urinary sphincter to relax and to the bladder muscle to contract (to be able to urinate) will be transmitted through this communication network. When the bladder is empty, the network sends closure order to the sphincter and relaxation order to the bladder, in order to go back to the accumulation configuration, with no urine leaks.
When this communication network presents abnormalities, the accumulation and emptying of urine does not work normally and the patient will have urinary troubles.
- If the abnormalities are on the accumulation function: the patient will suffer from urgency, frequency and even leaks.
- If the abnormalities are on the emptying function: the patient will not be able to urinate, or will only half empty his bladder: this is urinary retention.
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Some of these abnormalities of the communication network can be corrected by weak electrical impulsions applied to the nerves that control the bladder through the sacral roots neuromodulation.
What is sacral roots neuromodulation ?
Sacral roots neuromodulation uses weak lectrical impulsions to stimulate the neve located in the low back. This nerve belongs to the group of the sacral roots, that control the urinary function. This therapy happens in two steps: first a stimulation test in order to verify the efficacy of neuromodulation on the urinary troubles of the patient. Then if the test if positif, the definitive implant is suggested to the patient.
Who can benefit from neuromodulation?
Patients who present with urinary troubles such as urgency and frequency, incontinence or urinary retention, are usually treated first by medications. Sometimes the treatment is completed by some perineal physiotherapy. For the vast majority, these treatment are enough to restore normal control of the bladder. But some of the patients have persistent troubles despite medications, or medications have to be discontinued because not well tolerated: those patients could benefit from neuromodulation.
How does the stimulation test occur?
The stimulation test consists in placing an electrode (thin metallic thread) near the sacral nerve in the lower back, and to link it to an external stimulator that will deliver electrical impulsions. Implantation of the electrode is a simple procedure realised under local anesthesia that usually lasts less than an hour. The patient feels the stimulation as numbness or a pricking feeling in the anal area.
This sensation should never be painful; this is why the patient can regulate himself the intensity of the stimulation. The test lasts 3 to 7 days with a continuous stimulation. During this period, the patient is asked to go back to his regular activities as normally as possible, and to write down on a every urinary episodes.Other simple exams can also be done during this period.
DAfter this test the electrode is removed and the physician can appreciate the urinary troubles of the patient through the results of the test that the patient has written down. If the urinary troubles are eliminated or significantly improved during the stimulation, then the implantation of the definitive system is suggested.
According to the therapeutic indications the physician can decide to perform the neuromodulation test with the definitive electrode. This is also done under local anesthesia. If positive results are found at the end of the test, the electrode is not removed and will be connected to the implantable stimulator (under local anesthesia as well)
What is a permanent implant ?
The permanent system includes an electrode that will be positonned by percutaneous route, near the sacral nerve. An extension links it to the implatable neurostimulator that is fixed either under the abdominal or lower back skin. It is an easy surgery that lasts around an hour and that is totally reversible. The implantable neurostimulator is a system that functions according to the same principle as the pacemaker (the “heart battery”).
It will continuously deliver electrical implusions to the sacral nerve, in order to restore the bladder control. The physician can regulate the neurostimuator from outside through the machine called N’vision. The patient also has a remote control that allow him to stop or start again his neurostimulator. However, the neurostimulator generally stays permanently activated, even when the patient goes to the bathroom, or when he sleeps …
Like during the stimulation test, the patient might feel some weak electrical impulsions, resembling weak pricking in the anal area. However those sensations should never be painful, and habitually they disappear after some time.
The neurostimulator contains a battery that can deliver the necessary electrical energy: it is going to discharge after a while. The physician can check up the state of the battery through a programation machine.
When it will be completely used, after around 7 years, he will be replacing the neruomodulatot under local anesthesia.
