New PercutaneousTechnique of Sacral Nerve Stimulation Has High Initial Success Rate: Preliminary Results

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1 European Urology European Urology 43 (2003) 70±74 New PercutaneousTechnique of Sacral Nerve Stimulation Has High Initial Success Rate: Preliminary Results Michele Spinelli a,*, Gianluca Giardiello b, Andrea Arduini b, Ubi van den Hombergh c a Divisione Urologia Unita Spinale, Ospedale Civile G. Fornaroli, Via Donatori di Sangue 50, I Magenta MI, Italy b Medtronic Italia, Viale Fulvio Testi 280, Milano, Italy c Medtronic, Endepolsdomein 5, P.O. Box 1220, 6201 MP Maastricht, The Netherlands Accepted 17 September 2002 Abstract Objective: We report on the new technique of sacral nerve stimulation in the treatment of voiding dysfunction. This new technique is characterized by percutaneous approach to the sacral nerves resulting in minimally invasiveness of the procedure and the ability to have patient awake during the electrode placement. Methods: Since December 1999, we prospectively evaluated patients who underwent this novel percutaneous technique approach. Thirty-two patients (10 male, 22 female, mean age 43 years) were included and no complications were reported. Average follow-up time was 11 months (range 2±25 months). Main elements of the new technique are also described. The needle is inserted into the sacral foramen to a desired location (usually S3) and metal stylet is then inserted through the needle. With metal stylet only in the foramen, two dilators are successively inserted and the chronic lead is placed through the plastic dilator. Only a very small skin incision is necessary to allow the anchor xation. Results: Out of the 32 patients who underwent the percutaneous lead placement, 22 received the neurostimulator (IPG). Out of the remaining 10 patients, 4 are still in screening and 6 had unsuccessful results (<50% improvement) and therefore did not undergo the second stage (neurostimulator placement). From the 22 implanted patients, 20 reported 90% improvement in their primary voiding symptoms, 1 had an improvement between 50 and 70% and 1 patient was explanted due to IPG damage following magnetic resonance imaging. There were total of four lead displacements, two occurred where the silicone anchoring was used and the other two occurred when no anchoring was done. Conclusion: Success rate of this technique in selecting patients for the permanent implant is signi cantly higher than currently reported in the literature. Very bene cial clinical outcome of the implanted patients con rms better patient selection with no complications. Our experience with this technique shows the feasibility of percutaneous lead placement with major advantages such as: (1) use of local anesthesia and possibility to test sensitive responses during implant, (2) the possibility for more accurate patient selection by using the de nitive lead for a longer test period before proceeding with the neurostimulator (IPG) implant. The presented percutaneous technique requiring fascial lead xation represents a safe and effective method of Sacral Neuromodulation Therapy. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Sacral nerve stimulation; Sacral neuromodulation; Percutaneous technique 1. Introduction * Corresponding author. Present address: Via Vittadini 21, Milano, Italy. Tel ; Fax: address: m.spinelli@iol.it (M. Spinelli). 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±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 /02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII: S (02)

2 M. Spinelli et al. / European Urology 43 (2003) 70±74 71 Tanago and Schmidt [5,6] rst 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±9], FDA approvals and increased knowledge on the physiological mechanisms of action [10±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 bene t 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 de nitive quadripolar lead by means of singleuse 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 de nitive 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. 2. Materials and methods 2.1. 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 identi ed and a local anesthetic is applied around the area where the de nitive 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 is identical to test stimulation procedure. This is of huge importance, since it facilitates placing the de nitive quadripolar lead more accurately to the nerve vicinity and reduces the potential for an inconclusive stimulation response. As soon as the local anesthetic is given and the operation eld sterilized, the procedure can begin. The foramen needle is inserted through one of the sacral foramina, preferably S3 (Fig. 1, Step 1). The needle is hand-guided into the foramen to a desired location. Electrical stimulation is applied to the needle to verify the correct positioning and motor and conscious sensory responses are tested. Fluoroscopy or X-rays are taken to con rm the position of the needle in the S3 foramen. A tiny guide wire is then inserted through the needle (Fig. 1, Step 2). With the guide wire in the selected foramen (position), the needle is removed (Fig. 1, Step 3). The guide wire stays in the foramen and will serve as a guide for the dilator. Fig. 1. Description of percutaneous technique. Step 1: foramen needle insertion. Step 2: stylet insertion in the needle. Step 3: stylet in the foramen. Step 4: insertion of introducer kit. Step 5: introducer kit in place. Step 6: insertion of the lead through the plastic sheath of introducer kit.

3 72 M. Spinelli et al. / European Urology 43 (2003) 70±74 The insertion path is dilated with a metal dilator (8F) to a diameter suf cient for inserting a de nitive lead. L±L uoroscopy is used to ensure that the tip of the dilator stops at the upper edge of sacrum (Fig. 1, Step 4)Ðat the level of the S3 foramen. The metal dilator is then removed and a plastic dilator (8F) is placed, still using the guide wire to guide the insertion, to reach the internal side of the sacrum (Fig. 1, Step 5). As soon as the plastic dilator is placed, the guide wire is removed from the insertion path. When removing the guide wire from the insertion path, care should be taken to avoid displacing the plastic dilator. The de nitive quadripolar lead is inserted through the plastic dilator to the desired location (Fig. 1, Step 6). To verify the lead's position, an electrical signal is applied to the lead to evoke a motor and sensory response by the patient. The position and depth of the lead is easily adjusted in order to obtain the best sensory and motor responses. Typically, uoroscopy is used to con rm and document the placement of the lead. Once positive responses have been achieved, the plastic dilator is removed. When removing the plastic dilator from the insertion path, care should be taken to avoid displacing the lead. The position of the lead is re-veri ed by applying electrical stimulation. Once the plastic dilator is removed and the lead position reveri ed, the lead is xed in place by creating a small skin incision (large enough to allow to reach the fascia layer), anchoring the lead to the fascia layer, and then closing the incision. Adjustable anchors such as the silicone anchor used with the Medtronic 3886 lead or similar adjustable anchors can be used (Figs. 2 and 3). Additional care should be taken to avoid displacing the de nitive lead during anchoring. The use of uoroscopy and external electrical stimulation during the procedure allowed the positioning of the lead at the point where stimulation had the best sensory and appropriate motor responses. Patients were awake and provided not only motor but also sensory responses during stimulation which led to the most appropriate lead placement. The rst practical problem when developing this technique was to study the xation (anchoring) of the lead: initially a fascial silicone xation was used, following a trial period on two patients where no lead xation was used. The nal approach used was a fascial xation by using a twist lock ( Medtronic Inc., Minneapolis, MN) and this turned out to be the best option. The Fig. 3. PNE lead positioning (courtesy of Christer Edlund). average operating time (independently of what kind of xation was used) was around 40 minutes (25±45 minutes) Patient selection Since December 1999, we employed this novel percutaneous technique to implant unilaterally the de nitive quadripolar lead on 32 patients (10 male, 22 female, mean age 43 years). Of those 32 patients, 19 suffered from complete chronic urinary retention, 10 had urge incontinence, 2 patients had urgency frequency disorder and 1 had a long history of pelvic pain. Eight patients had incomplete neurogenic lesions. All patients underwent detailed medical history and urodynamic evaluation before the implant. They were asked to ll out voiding diaries at baseline and during the trial stimulation period, with the de nitive lead. Thirty implants were carried out using local anesthesia with Ropivacaina, two under general anesthesia (the rst two patients implanted with percutaneous technique). Fluoroscopy was used in all cases. The 19 most recent patients underwent implantation of the permanent lead without performing the preliminary test stimulation (PNE). The side of implant was based on the best sensory response to acute stimulation. 3. Results Fig. 2. Twist lock inserted and anchoring suture xed to the fascia. 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 de nitive implantation of the IPG. Twenty-two patients reported more than 90% improvement in their primary voiding symptoms since baseline during the 3±4 weeks of stimulation with the external stimulator. All those patients underwent implantation of neurostimulator (IPG) under local anesthesia.

4 M. Spinelli et al. / European Urology 43 (2003) 70±74 73 Out of those 22 patients implanted with the IPG at an average follow-up of 11 months (range 2±25 months, 20 maintained more than 90% improvement in their primary voiding symptoms, 1 presented an improvement between 50 and 70% and 1 patient was explanted due to IPG damage secondary to magnetic resonance imaging. Three different anchoring systems have been used to xate the electrode. In four patients, the lead was implanted without any xation. In another 20, the twist-lock anchor was used and six patients received the silicon anchor. There were a total of four lead displacements, two occurred where the silicone anchoring was used and the other two occurred where no anchoring was done. Displacements occurred in all cases within 4 weeks from implant of the lead. No early or late infection was reported. 4. Discussion Historically, as the ef cacy 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 rst step in reducing the invasiveness of the sacral neuromodulation procedure and improving the patient selection by reducing the false negative technical failure patients. Speci c advantages include: shorter operating time under local anesthesia for the positioning of the quadripolar electrode that will be connected to the external temporary stimulator; use of local anesthesia will allow patient sensory responses, which is very important in having an optimal lead placement in the sacral foramen and possibly the most appropriate therapeutic outcome; possibility of a longer testing period with the de nitive lead, as opposed to the test stimulation lead; if the test results are good, the same lead is used without any change in its position. So far a positive response to PNE test is the only predictive factor for the long-term ef cacy of SNS therapy. Reported success of the PNE test vary to a great degree and ranges from 40 to 100% [21±23]. As mentioned in the literature, up to 40% of the patients who had bene cial test stimulation with a temporary lead do not continue to have a successful outcome when implanted with the neurostimulator [24]. Success rate in the 22 patients implanted with complete device is signi cantly higher than currently reported in literature. Sometimes the test stimulation ends up in inconclusive results, because temporary electrode would migrate or the site of stimulation is not appropriate. The need for repeated test stimulations as the result of inconclusive outcomes often frustrated and discouraged patients. Evidently, the (or one) way to improve the outcome would be better patient selection, either by nding the predictive factors or by improving the testing technique and by this, reducing false positive responders. A number of physicians were looking into patient selection but nothing was found. A study by Koldewijn et al. [25] was attempted to classify 100 consecutive patients undergoing PNE testing by using a combination of symptom scores, urodynamics and neurourological measurements. No correlation was found and they concluded that better selection using such means was not feasible. Therefore, our attempt is to improve the technique, and by this the therapy outcome should gain even more value as we could prove that the majority of the patients (22/32) who were tested with the de nitive lead had a positive testing result and continued to have a successful outcome with the permanent device on a long-term basis. Edlund et al. [26] in a recent interesting study using a computer model, demonstrated a huge variability of the temporary lead position in the foramen (without correlation to the success score) which con rms earlier cadaver observations of Hasan et al. [27]. This variability could explain the great variability of success rate in PNE. In addition, the duration of the stimulation tests were demonstrated to be insuf cient to guarantee a positive outcome after the permanent implant. The introduction of clinical research regarding new indications for SNS has stimulated investigations towards alternative solutions to PNE. However, published data on these new applications were only related to the use of test stimulation with the temporary electrode and therefore conclusions driven out here have to be taken with some cautions. The temporary leads for the test stimulation (PNE) are different from those used for the de nitive implant, both in terms of structure to the positioning on the sacral nerve. From a neuropsychological standpoint, the depolarization of the nerve depends on precise characteristics in which the position of the source of the electrical stimulation with respect to the nerve (distance, polarity, etc.) is crucial. In addition, the temporary lead can suffer from spontaneous displacement and can shift in response to the movements of the patient. In the last few years, there has been an attempt to introduce instruments such as psychometric testing in order to improve patient selection and preliminary results look were very promising [9]. The objective

5 74 M. Spinelli et al. / European Urology 43 (2003) 70±74 evaluation of the long-term clinical success can also be measured by use of disease-speci c quality of life questionnaire [28]. Use of those tools can contribute to more satisfying patient selection procedures. Or the evaluation of objective results with a scale, which have contributed to satisfying the need for improved selection procedures [9]. Our minimally invasive method includes all the advantages of the Staged Implant proposed by Janknegt et al. [18], and in addition offers the possibility to test the sensory responses to electrical stimulation as well as to perform the de nitive implant under local anesthesia. The percutaneous approach should substitute the PNE test at least by inconclusive PNE, PNE failures and for appropriate patients allowing better patient screening/ selection and therefore an increase in the success rate of the therapy. To our experience the fascial xation by using a twist lock turned out to be the best option. 5. Conclusion Experience gained to this date has been promising and shows the feasibility of percutaneous lead placement under local anesthesia with the following advantages: use of local anesthesia; the possibility of testing the sensitive responses during implant; the reduction in operating room time; the possibility for more accurate patient selection by using the de nitive lead for a longer test period before proceeding with the subcutaneous implant of the neurostimulator (IPG). The present percutaneous procedure (technique), requiring fascial xation of the lead (until standard self-anchoring system is de ned), represents a safe and effective method of Sacral Neuromodulation Therapy. References [1] Caldwell KPS. The electrical control of sphincter incompetence. Lancet 1963;2:174±5. [2] Alexander S, Rowan D, Millar W, et al. Treatment of urinary incontinence by electric pessary. 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