New Percutaneous Technique of Sacral Nerve Stimulation Has High Initial Success Rate: Preliminary Results
Introduction
Impaired bladder and sphincter function can be altered by various treatment modalities. Electrostimulation is one of the therapeutic options that has been used in urology for many years [1]. The sites where the stimulation is applied have included anal, intravaginal, intravesical, tibial and transcutaneous locations on a body surface [2], [3], [4]. The success rate of those stimulation techniques vary to some degree and this may be the reason why most of the stimulation treatment options did not gain wide acceptance. Thanks to the work of Tanago and Schmidt [5], [6] first and later other urologists, direct chronic stimulation of the sacral nerves became one of the most accepted stimulation treatment modalities in functional urology today.
No other treatment in the area of lower urinary tract dysfunctions has undergone such a wide dissemination in the last few years as the sacral nerve stimulation (SNS). Major hardware developments, published literature with good clinical results [7], [8], [9], FDA approvals and increased knowledge on the physiological mechanisms of action [10], [11], [12], [13] played a major role in the growth of the therapy acceptance.
Many studies have described the advantage of having a test stimulation (often described as PNE) available that allows patient selection through the acute and sub-chronic phase of the test [9], [14], [15]. Use of this acute and sub-chronic test stimulation in candidates for SNS therapy has always been an integral part of the method [16], [17]. However, exception to this approach became obvious when shown that some patients did not have a successful test but still could respond well to the therapy and have sustained clinical benefit after the permanent implantation [18]. This was the turning point where alternatives to test stimulation and thus alternatives to patient selection would start to develop.
Siegel [19] has described the timescales of the SNS technique in detail dividing the process into three main stages.
The basis of this new concept is the development of a minimally invasive method for the placement of the definitive quadripolar lead by means of single-use material that is normally used for the percutaneous positioning during the renal drainage at a pielic level.
By trying and verifying that the permanent lead can be positioned easily and safely through the skin, after the percutaneous placement of a needle is obtained and by monitoring the evoked responses during acute stimulation, we decided to demonstrate the feasibility of this (analogous) approach. The fundamentals of this novel approach include the percutaneous positioning of the definitive quadripolar lead into the foramen without resorting to the surgical opening of the layers over the sacral foramen (as done until now). Various advantages are more than evident: patient is awake because only local anesthesia (conscious sedation) is applied and therefore sensory responses are accessible, operation time is reduced and the incision is minimized. Chances that this lead would migrate are much lower than with the temporary lead so patient can be tested for a longer period of time and if proven successful, only a minor surgical intervention to place the neurostimulator is required.
Section snippets
Description of a percutaneous permanent lead implant technique
The following technique was developed independently, but simultaneously, by a physician in Italy and in the US [20].
The patient is placed in a prone position, as in a standard test stimulation procedure. The bony landmarks are identified and a local anesthetic is applied around the area where the definitive lead will be implanted (posterior to the sacrum). By using local anesthesia only, the physician is able to utilize the patient’s conscious sensory responses to electrical stimulation, which
Results
Evaluation of the results is based on the analysis of voiding diary considering the number of daily incontinent episodes for urge incontinence group, the residual volume in urinary retention group, number of daily voids in urgency frequency group and visual analogue scale in patient suffering from pelvic pain.
Out of the 32 patients who received chronic lead, 4 are currently being screened and 6 patients (19%) reported the improvement lower than 50%, and therefore did not undergo definitive
Discussion
Historically, as the efficacy of a new therapy is being established, the treating physicians focus on the administration of the therapy and later on the development of the less invasive techniques. In January 1997, the use of a staged implant procedure came into practice, in which a chronic lead was used for the test stimulation [18]. Use of a chronic lead for screening was the first step in reducing the invasiveness of the sacral neuromodulation procedure and improving the patient selection by
Conclusion
Experience gained to this date has been promising and shows the feasibility of percutaneous lead placement under local anesthesia with the following advantages:
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use of local anesthesia;
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the possibility of testing the sensitive responses during implant;
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the reduction in operating room time;
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the possibility for more accurate patient selection by using the definitive lead for a longer test period before proceeding with the subcutaneous implant of the neurostimulator (IPG).
The present percutaneous
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