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| 번호 | 제목 | 등록일 | 조회수 |
|---|---|---|---|
| 12 | Comparison of Epineural or Intramuscular Nerve Electrodes for Stimulated Graciloplasty [2001년 4월 DCR] | 2011-11-12 | 3212 |
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J. Konsten, M.D., Ph.D., M. J. Rongen, M.D., O. A. Ogunbiyi, M.D., F.R.C.S.,A. Darakhshan, M.D.,I- C. G. M. I. Baeten, M.D., Ph.D.,N. S. Williams, M.S., F.R.C.S.
From the Department of Surgery, University Hospital Maastricht, the Netherlands, and Academic Department of Surgery, The Royal London Hospital, Whitechapel, London, United Kingdom OBJECTIVE: Two different techniques have been developed to stimulate the gracilis muscle when it is used in anal neosphincter reconstruction. These are direct neural stimulation and intramuscular electrode stimulation. The aim of this study was to compare these techniques.
METHODS: Comparison was made of gracilis anal neosphincter reconstruction using neural stimulation (Royal London Hospital in the United Kingdom) with the intramuscular muscular method (University Hospital Maastricht in the Netherlands). The United Kingdom data were obtained from a retrospective database, whereas the Netherlands data were gathered prospectively, RESULTS: A successful outcome was achieved in 46 of 81 patients (57 percent) in London and 148 of 200 cases (74 percent) in the Maastricht study (chisquared = 7.2; P < 0.01). There was no significant differencc
between the two techniques in voltage required for stimulation of the neosphincter muscle during a ten-year period. Reoperative surgery for electrode failure or dislocation was required in 21 (26 percent) patients in the London study, whereas only four (2.7 percent) of the Maastricht cases required such procedures (chi-squared = 37.8; P < 0.05). The high electrode plate failure rate in the London study was related to the source of manufacture. CONCLUSIONS: Both neural and intramuscular nerve techniques provide effective long-term stimulation of the gracilis anal neosphincter.
DISCUSSION
This is a partially retrospective analysis of electrically stimulated gracilis neosphincter reconstruction,
which limits its conclusions. However, it is the largest study (281 patients) reported so far, and the lessons learned will be valuable in the future development and application of this technique. The success rate was better in the patients who had intramuscular nerve stimulation (Maastricht method; 74 percent) as compared with those patients underwent epineural stimulation (London method; 57 percent). However, in the Maastricht group more patients had acquired incontinence (Table 2), which is associated with a better outcome. 12 The intramuscular nerve electrode was stable. Only 4 of 200 patients required electrode replacement. On the other hand, 21 of 81 (26 percent) patients from the epineural stimulation group needed electrode replacement. Nineteen patients had this replacement before the current bipolar electrode was used (Table 7). The new bipolar electrode, which was implanted in 16 patients, was replaced in 1 patient as a result of dislocation. This was an improvement over the Nice® equipment used earlier in the London study. The Maastricht group has gained experience during the past decade with the intramuscular nerve technique, whereas the London group has only recently switched to the currently used bipolar nerve electrode manufactured by" Medtronic®. The conclusions from Rius et at7 and Mavrantonis and Wexner 8 that the success of a graciloplast T is dependent on the method of stimulation cannot be drawn from a small study with limited follow-up. However, in this much larger study derived from two centers, identical results for the Nice® equipment were found. Although the early- results with the Medtronic® bipolar nerve electrodes are encouraging, no definitive statements can as yet be made regarding long-term outcome because of the small numbers and short follow-up. Proper evaluation of the two methods would require a prospective, randomized, controlled trial using identical stimulators and electrodes manufactured by the same company. In London an independent body is currently performing a prospective review of the outcome of neosphincter reconstruction using neural stimulation during a five year period (1997-2002). The voltage required to stimulate the neosphincter was lower in the epineural group as compared with
the intramuscular nerve group in the early phase of stimulation. However, this difference disappeared at one year. Fibrosis around the electrodes probably contributes to this, because an increased threshold of stimulation was noted in both groups on long-term follow-up. Conversion from type II to type I muscle fibers also leads to an increase in the required voltage of stimulation. The epineural stimulation technique has the advantage of a maximal recruitment of all motor units into the neosphincter muscle, whereas the intramuscular nerve stimulation technique stimulates only those peripheral branches in the neighborhood of the electrode. So far this maximal recruitment of a dynamic graciloplasty has not resulted in a better outcome. This may have been because of poor quality of the neural electrodes used by the London group in the first part of the study period. Fixation may be considered to be the main problem for the epineural stimulation technique, because the nerve to the gracilis is quite small. Even if the electrode paddle is fixed to the relatively immobile adductor magnus muscle, dislocation may occur, although this happened in only 1 of the 16 patients with the new Medtronic® electrode. Intramuscular nerve stimulation uses the complete diameter of the graciloplastg, so that dislocation seems tess of a problem. Other factors may explain the observed percentage of success between the epineuraI and intramuscular
stimulation technique. Epineural stimulation requires full mobilization of the vascular pedicle to reach the nerve and fix the electrode paddle. Although the transposed gracilis, which is tethered by its proximally based vessels, can entirely encircle the anal canal pedicle without undue tension, the mobilized vessels may kink, with subsequent ischemic damage to the graciloplasty. Furthermore, it is possible that early stimulation of the neosphincter as used by the London group may negatively affect outcome. This has been demonstrated to be the case in animal experiments. In addition, a stoma was used routinely by the London group. In a recent multicenter study of dynamic graciloplasty using intramuscular nerve electrodes, a protective stoma influenced the outcome negatively. 12 It may be that after stoma closure the patients do not know how to operate their neosphincter, because the rectum has not been subjected to intraluminal filling for a few months. However, because no randomized studies on the use of defunctioning stomas have been reported, it is impossible to make any judgements on their effect on eventual outcome. Constipation is a serious problem after dynamic graciloplasty using both techniques of stimulation.
Additional procedures such as construction of an antegrade colonic conduit or Malone procedure may be necessary to achieve satisfactory evacuation. Some patients have a combination of constipation and incontinence before surgery. An electrically stimulated gracilis neosphincter can cause an outlet obstruction, especially if the sling is placed around the anal verge instead of the anal canal. Furthermore, in patients with an anorectal atresia and those who had extensive anal surgew, there may be scarring around the canal, which makes it impossible to do a high anal canal wrap. In addition, some patients can stretch their gracilis muscle during defecation so that paradoxically it closes the anal canal. Defecography and anorectal physiology were unable to predict which patients would suffer from constipation after an electrostimulated gracilis neosphincter. The difference in anal pressure (Table 1) between the two groups can be explained by the various catheters that have been used. Preoperative rectal sensation in the Maastricht and London studies was similar for patients who experienced success or failure. One might speculate that infection can cause fibrosis and consequently obstruction of the anal canal. The problem of constipation needs prospective evaluation using more sophisticated techniques such as ambulatory manometry and scintigraphy. |
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