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World J Urol (1992) 10:120-126
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"Prepubien" section: a new surgical treatment of frequency, nocturia and urge incontinence?
J. Beco ( * ), V. Jossa (**), and R. Lambotte (*)
* Université de Liege, CHR La citadelle, Service de Gynecologie-obstétrique, Boulevard du 12eme de Ligne, B-4000 Liege, Belgium
** Clinique de L'Esperance, Service anatomo-pathologie, Rue Saint Nicolas 447, B-4420 Montegnée, Belgium
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Summary:
The use of transvaginal ultrasound (7.5 MHz, linear array) during urethral instability enabled us to describe three movements that were seen during the urethral pressure drops: a shortening of the urethra (relaxation of the striated sphincter), an increase in the distance between the probe and the symphysis pubis (relaxation of the levator ani muscles) and a forward displacement of the "prepubien". During ultrasound examinations (endovaginal and vulvar), the prepubien and its movements are easily visible in the space located between the external urethral meatus and the clitoris. The drop in urethral pressure is sometimes associated with an urgent need to urinate. In 75% of the patients, finger compression of the prepubien on the symphysis inhibited urethral instability and urgency. After all classic treatments for pollakiuria, nocturia and urge incontinence had failed, we tried to cut the prepubien in patients who were under general anesthesia. This operation was carried out in 19 women, of whom 13 were cured (68%), 5 showed improvement and 1 was a failure. Only two short-term side effects were observed: a sexual disability that lasted for 2 months and a labial haematoma.
Introduction:
Pollakiuria, nycturia, mictional urgency and urge incontinence are classic features of bladder instability. Certain authors, including ourselves, think that urethral instability most probably plays a role at least as important as that of bladder instability in these urinary problems. Urethral instability is a recently discovered phenomenon that has hardly been explored. Controversy exists as to its definition, its role in urinary physiopathology and its incidence in the population. According to the International Continence Society (ICS), terms such as "unstable urethra" await further data and precise definition [1].
Since 1986 we have studied urethral instability by associating endovaginal ultrasound examination with classic urodynamic exploration [5]. This approach enabled u to describe the different movements characteristic of ure thral instability and to propose a new surgical treatment for pollakiuria and urge incontinence. A detailed description of this new surgical treatment, called "prepubien" section, requires a summary of the ultrasonography study of urethral instability.
Urethral instability as determined using endovaginal and vulvar ultrasound
1. Endovaginal ultrasound.
During transurethral bladder filling (50 ml/min, normal saline solution at room temperature), an endovaginal ultrasound examination is per formed with the patient placed in the gynecological position (feet at the same level as the bottom). We use a Siemens linear probe operating at 7.5 MHz and attached to a Sonoline 8000 apparatus from the same company This probe is horizontally positioned in the vagina suet that the urethra is not compressed. A simultaneous, manometric study is carried out using a continuous-floe Bohler catheter (diameter, 2.5 mm), which enables the simultaneous measurement of bladder and urethral pressures. The flow rate of the catheter perfusion is 2 ml/min.
Urethral instability is defined as the occurrence of urethral pressure drops of > 15 cm H20 that are independent of the arterial pulse [14, 18]. Among the different classifications proposed in the literature, we used that described by Kramer and Venema [14]. Among the three types of urethral instability proposed by these authors, only the fast-variation and long-lasting sudden types provoke mictional urgency in certain patients, and only these two types of rapid variation can be explored using ultrasound. The slow-variation type is asymptomatic and difficult to investigate by ultrasonography. During the pressure drops that characterize rapid urethral instability, three types of movements are observed: a shortening of the sphincter zone, an increase in the distance measured on the ultrasound image between the anterior vaginal wall and the symphysis pubica (in the absence of an abdominal push), and a prepubien contraction.
The shortening of the sphincter zone is associated with the relaxation of the para-urethral striated sphincter. In effect, the electromyographic (EMG) activity (needle placed in the para-urethral sphincter under ultrasound control) decreases when the sphincter zone shortens. The longitudinal orientation of the smooth fibers and the elastic fibers [10] explains this shortening. It is generally brief and provokes a fast-variation type of urethral instability. Dorschner and Hofner [8] also describe a "musculus dilatator urethrae", which is inserted at the inferior symphysis lip and at the bulbus vestibuli level; this muscle could shorten the urethra and open the smooth and elastic sphincter.
The second observable movement is an increase in the distance between the anterior vaginal wall and the symphysis pubica It is associated with relaxation of the levator ani muscles. This movement is more frequent both during the sudden long-lasting type of drop in urethral pressure and when a bladder contraction follows the urethral pressure drop.
The third activity, the prepubien contraction, was discovered using endovaginal ultrasound [5]. The prepubien is a small, mobile structure that is easily visible on endovaginal ultrasound images under the symphysis in the space between the clitoris and the urethral meatus. It is modestly hypoechogenic and its average width is 6 mm. It can be made conspicuous outside of urethral instability by contraction of the levator ani muscles, whereby the prepubien displaces itself backwards and presents a scissor movement in relation to the pubic symphysis that clearly shows the independence of the two structures (sliding organ sign). Its denomination derives from its location in front of the symphysis from the viewpoint of the examining physician, as its exact nature had not been defined at the time of its discovery using ultrasound. During certain rapid urethral pressure drops, this structure moves towards the clitoris, exerting traction on the antero-distal part of the sphincter zone (Fig. 1). This traction movement, called prepubien contraction, is sometimes transmitted up to the anterior side of the bladder neck, inducing a more pronounced pressure drop. Instability associated with prepubien movement is especially of the fast-variation type.
An evaluation of the last 46 episodes of rapid urethral instability (fast-variation or sudden long-lasting type) observed in our patients enabled us to study the incidence of the different movements described above (Fig. 2). The prepubien contraction occurs in 80% of cases, and the movements are frequently associated with one another. These movements were also noted during the initiation of micturition: sphincter shortening, in 59% of cases; levator relaxation, in 39% of cases; and prepubien contraction, in 36% of cases [4].
2.Vulvar ultrasound.
More recently, we began conducting vulvar ultrasound examinations in several patients using the same probe. Among the different sections used, the transverse images provide the most important information: the prepubien presents an inverted Y form. It divides itself into two parts in front of the urethral meatus and becomes deeper towards the posterior of the vulva. In the oblique para-sagittal left and right sections, the two inferior branches are easily observed lying lengthwise. They first lie under the mucous membrane and are then located under the bulbus vestibuli, which becomes increasingly thicker posteriorly. A forward movement of these branches occurs at the time of a urethral pressure drop.
3. Inhibition tests.
The prepubien contraction is associated with a drop in urethral pressure and, sometimes, with mictional urgency. What is the actual role of this activity in the initiation of the need to urinate? Two tests provide several replies to this question:
1. The compression test consists of preventing the prepubien from moving by vigorously compressing it against the symphysis with a finger. This can be done under ultrasound control, but the structure and its movements are often easily palpated by finger. The test is considered to be positive if the urethral instability and/or the mictional urgency presented by the patient disappears during the compression, only to reappear at the end of the compression (Fig. 3). The compression test was positive in 75% of cases in which the prepubien was involved in the instability (n = 33).
2. The lidocaine test consists of injecting 2-3 ml 1% lidocaine at a point located 1 cm behind the clitoris. The test is considered to be positive if the symptoms presented by the patient disappear during several hours. Among six attempts, four tests were positive.
Prepubien section
Due to the good results we obtained using the compression test and to the unsuitability of classic treatments for the therapy of certain patients presenting with extremely disabling urinary problems, we decided to propose a prepubien section to these subjects [3]. The initial indication for this operation is the existence of urge incontinence, embarrassing pollakiuria or nycturia. Urethral instability or urethro-vesical instability associated with prepubien activity is observed, and the compression test is positive. No organic cause is evident, nor is urinary infection. Conservative modes of treatment (anticholinergics, alphamimetics, spasmolytics and physiotherapy) have failed or have been poorly tolerated by the patient. The subject is duly informed of the experimental nature of the operation.
Patients and methods
The population study included 19 women who underwent surgery between 1987 and 1990. The average age of our patients was 44.7 (range, 25-66) years, and 37070 of them were menopausal. The average parity was 2.7 (range, 0-9). They experienced nycturia an average of 1.8 (range, 0-6) times/night, and the average interval between two episodes of micturition was 54 (range, 15-180) min.
The symptoms indicating prepubien section are shown in Fig. 4 (before). The all 12 patients presenting with a stress urinary incontinence (SUI) association also underwent treatment for SUI using 3 different methods: Burch, 5 cases; Mouchel, 6 cases [15]; and Bologna, 1 case [6]. From a presurgical urodynamic point of view, 10 patients exhibited isolated urethral instability of the fast-variation type, 6 displayed bladder instability associated with urethral instability of the sudden long-lasting type, and 2 showed no instability; the latter 2 subjects reported an embarrassing urge incontinence. The first need to urinate was felt following bladder filling to a volume of 160 ml (range, 50-400 ml), the maximal bladder capacity averaged 356 ml (range, 150-700 ml), and the average compliance was 53 ml/cm H20 (range, 16-116 ml/cm H20)' In all, 18 of the 19 patients underwent a postoperative urodynamic followup evaluation.
The operation was performed with the patient under general (or epidural) anaesthesia. First, a short U-shaped incision was made in the vestibular vulvar mucous membrane at a point located 1 cm in front of the urethral meatus. The mucous membrane was then separated from the underlying surface. The prepubien was found by finger palpation and was progressively isolated on a fine O'Shaugnessy forceps such that the symphysis could be scraped (Fig. 5). It was sectioned between two ties, with the intermediate fragment being left as long as possible for anatomo-pathological analysis. The mucous membrane was then closed with a fine resorbable suture. For our procedure, we do not place a urinary catheter. Patients can leave at 24-48 h after surgery, provided that they have undergone only the prepubien operation. In practice, the prepubien section is often simple and brief (average duration, 20 min). Sometimes the prepubien is difficult to locate and the haemostasis of this rather vascular area is delicate.
Results
The results were analysed according to the subjective information provided by the patients and according to the objective data obtained during the urodynamic follow-up evaluation. Wilcoxon's non-parametric test was used for statistical analysis of the results.
Subjective results
The average follow-up period was 8 (range, 1-36) months. Patients reported a significant improvement in pollakiuria (average increase of 105 min in the interval between episodes of micturition; P = 0.0015), in nycturia (average decrease of 1.1 time/night; P = 0.0076) and in urge incontinence (average decrease of 80%). The subjective improvements are presented in Fig. 4. For these symptoms, there was no significant difference between the results obtained in the presence vs the absence of associated SUI treatment. A study of the degree of satisfaction expressed by our patients revealed that 13 subjects (68%) considered themselves to be cured, 5 experienced a sufficient improvement in their symptoms and 1 felt that the treatment had failed. The results were better in subjects whose treatment was associated with SUI therapy (rate of cure, 75%) as compared with those who underwent prepubien section alone (57%), but the population was too small to enable statistical analysis. Three patients who were questioned as to their urinary needs reported an alteration in the area of need, which changed from the retroclitoral area (presurgery) to the lower abdomen (postsurgery).
Objective results
The average follow-up period was 5 (range, 1-26) months. We observed a significant rise in the value at which the first need to urinate was experienced (+77 ml; P = 0.024) and in the compliance (+ 17.4 ml/cm H20; P = 0.041). The increase observed in the strong need to urinate was not significant. For these parameters, there was no significant difference between the results obtained in the presence vs the absence of associated SUI treatment. Of the ten cases of urethral instability that were diagnosed preoperatively, four persisted, but these subjects exhibited an improvement in their filling level and were often asymptomatic. Two of seven cases of bladder instability persisted, two developed into cases of urethral instability, two subjects were completely cured and one patient did not return for her urodynamic follow-up evaluation. The two patients who showed no preoperative instability remained normal postoperatively. The postoperative endovaginal ultrasound examination quite often revealed a prepubien persistence. Finally, the only two secondary effects encountered were of short duration: one patient experienced sexual problems during the first 2 months following the operation, and another exhibited a haematoma of the labium majus pudendi that was spontaneously resorbed.
Anatomo pathological results
Four types of results were found: two aspecific fibrous tissues, ten ligaments, one striated muscle and six ligament-striated muscle associations. Elastic fibers were observed in all of the samples, and cavernous tissue was found in one specimen. It should be emphasised that the structure was located with the assistance of an ultrasound-guided harpoon in two cases (one ligament and one striated muscle). The anatomo-pathological results did not seem to influence the clinical outcome.
Discussion
For years, even the existence of urethral instability was denied. Several authors have shown that this phenomenon exists and is accessible by means of investigation other than simple simultaneous urethro-cystomanometry. Thus, during rapid drops in urethral pressure, a diminution of the electromyographic (EMG) activity of the urethral sphincter [18] and an increase in electrical conductance at the bladder neck level [9] are frequently observed. In addition, the use of several urethral sensors on the same catheter has enabled the confirmation of a synchronous decrease in pressure along the full length of the urethra, thus excluding the possibility of an artefact due to catheter displacement [14]. Endovaginal ultrasound renders visible the soft-tissue movements that occur during episodes of urethral instability as well as involuntary bladder contractions [4].
Some authors have described urethral instability as a physiological phenomenon due to its frequent occurrence in a control population. It would be more logical to speak of symptomatic or asymptomatic urethral instability. In fact, not all drops in urethral pressure provoke a need to urinate [18]. The amplitude of the pressure drop, its speed, the degree of urethral sensitiveness and probably other factors explain the differences in the expression of the symptomatology. It is equally possible that the urethral or bladder instability might not occur under the conditions of a urodynamic evaluation, which is not always a faithful reflection of the changes that are observed during the patient's normal activities. The three movements described in the ultrasound study of urethral instability enable a better comprehension of this pathology. These movements were rediscovered by Jacquetin et al. [12], who used a sectorial probe operating at 7.5 MHz posed at the vaginal entrance (introital ultrasound). Ultrasound examination enables the confirmation of urethral instability and specifies as to whether the muscle relaxation involves the levators (increase in the distance between the symphysis and the anterior vaginal wall) and/or the para-urethral sphincter (longitudinal contraction of the sphincter).
The prepubien contraction was discovered using endovaginal ultrasound. This activity is clearly visualized during certain urethral pressure drops. The details in the literature concerning the anatomy of the interclitorideanmeatal space are not very precise. According to these, four structures could correspond to the prepubien: (1) the anterior pubo-urethral ligament described by Zacharin [19], (2) the deep part of the bulbocavernosus muscles, (3) the intermediate mass, and (4) the anterior extremity of the musculus dilator urethrae [8].
According to our anatomical findings (sections of foetus and of fresh cadavers), the prepubien part situated between the clitoris and the urethral meatus corresponds to a group of tissues comprising dense, rather fibrous tissue that is surrounded from place to place by a fine prolongation of the vestibular bulbus and, especially, by the anterior extremities of the bulbocavernosus muscles. These are inserted in the angle formed by the two cavernous bodies. At the urethral meatus level, the bulbocavernosus separates and extends under the vestibular bulbus. A link seems to exist between the bulbocavernosus and the anterior part of the urethral sphincter.
From a theoretical point of view, the prepubien contraction observed using ultrasound may correspond to two precise situations. The prepubien movement towards the front of the patient corresponds either to an active movement of the bulbocavernosus (relaxation or contraction?) or to a passive movement associated for example, with a relaxation of the levators. Three elements favour the latter hypothesis. First, preoperatively a total absence of effect of the electric stimulation of the bulbocavernosus on the urethral pressure is observed in spite of a tetanization of the muscle. Second, the prepubien frequently exhibits a purely ligamentous structure and is thus not contractile. Finally, in several patients a brief effort to retain provoked a backward movement of the prepubien without causing a decrease in the distance separating the probe from the symphysis. This inverted movement of the prepubien occurred in the absence of a significant shortening of the levators and thus must be related to their isometric contraction. It is quite conceivable that an isometric levator relaxation could produce a forward movement of the prepubien without causing an increase in the distance between the symphysis and the ultrasound probe as seen on the ultrasound image (a relaxation associated with an increase in the length of the levators manifests itself through an increase in the distance between the ultrasound probe and the symphysis). According to this hypothesis, the prepubien (and the entire vulva) behaves like an extended elastic band. During isometric relaxation of the levators, the elastic band, which is fixed at its anterior end, shortens in exerting traction forwards to the sphincter zone. This traction provokes in one way or another a urethral pressure drop and the subsequent need to urinate (Fig. 6).
The efficiency of the compression test is an element that favours the role of the prepubien in urethral instability and the need to urinate. However, this pressure can act either in a purely mechanical manner by stopping the prepubien from moving or by way of reflex in increasing the degree of vigilance at the perineal level (with an increase in levator tonus). The work of Aranda and LetztRibinik [2] confirms the importance of the degree of vigilance to urethral instability. Thus, simply the mental alertness or a trial test of this type can make urethral instability disappear and increase levator tonus [2]. The mechanical hypothesis (the blockage of movement) is equally plausible; as the prepubien movement remains palpable by finger during application of the pressure, prevention of prepubien displacement requires a concentrated effort to stop the movement. In the case of an inhibition reflex, this movement should theoretically be abolished.
The lidocaine test also enables a disappearing of the symptomatology in a high percentage of cases. The reasons for this involve several hypotheses: either the interclitoridean-meatal space harbours the receptors that are responsible for the need to urinate (perhaps stimulated by the prepubien movement) or lidocaine infiltrates the entire length of the urethra and is assimilated into a para-urethral absorption, whose effectiveness is known [17]. A study of the different receptors occurring at this level should provide a partial reply to this question.
However, these results demonstrate the probable role of the inter-clitoridean-mental area in the need to urinate. These clinical observations and urodynamic findings are confirmed by the observation of women presenting with mictional urgency, who instinctively compress the area so as to diminish the need. In addition, a personal study (unpublished) carried out using questionnaires in a population of 122 unselected patients (hospital personnel; average age, 36 years) revealed that the need to urinate is felt exclusively in the retro-clitorial area (interclitorideanmeatal space) in 10% of cases, in the lower abdomen and the retro-clitorial area in 45% of cases and in the lower abdomen alone in 45% of cases. The incidence of urge incontinence was significantly higher in subjects exhibiting
exclusively retro-clitorial needs (33% vs only 15% for those whose need was perceived in the lower abdomen
alone).
The actual efficacy of the prepubien section is an important issue. If the clinical results seem very encouraging, the possible role of a placebo effect or of an associated operation should not be ignored, especially as the
prepubien sometimes remains visible at the time of the postoperative ultrasound examination. The psyche of patients presenting with pollakiuria, nycturia and urge in continence is often disturbed. A considerable placebo effect of the operation on such a sensitive population should not be absolutely excluded. According to Zeegers
et al. [20], the subjective efficacy of a placebo in this type of problem is estimated to be 41 %. It is not inconceivable
that the placebo effect of a surgical operation could be even more important. The only way in which the actual
efficacy of the operation could be determined would involve the composition of a control group of patients who
would be anaesthetized under the same conditions but would not undergo structural section. This type of approach is difficult to accept from an ethical point of view.
The role of stress urinary incontinence (SUI) treatment in association with certain prepubien sections can not be ignored. In the case of isolated SUI treatment, urge incontinence and bladder instability disappear in 50%-90% of cases [7, 13]. Sand et al. [16] have even described the disappearance of all cases of urethral instability (n = 4) following anterior colposuspension. In our
population and during the same period, 11 patients presenting with urge incontinence associated with SUI underwent anterior colposuspension according to Burch in the absence of prepubien section. The urge incontinence disappeared in 36% of cases (vs 80% in subjects who underwent prepubien section associated with SUI treatment) and the instability disappeared in 16% of cases (vs 55% in those who underwent prepubien section). The prepubien section thus seems to improve the recovery rate. However, such a definitive conclusion would require a random prospective study comparing the effect of colposuspension on urge incontinence and instability as carried out in the presence vs the absence of prepubien section.
If it is not considered to involve a placebo effect, the prepubien section can theoretically act through two different methods: the denervation of the distal urethra or a suppression of traction. Denervation of the distal urethra may play the determining role in the operation. In fact, the lidocaine test, causes a transient improvement in the symptomatology of two-thirds of the patients tested.
Moreover, Ingelman-Sundberg [11] reported that denervation of the proximal urethra seemed to be quite effective against urethral instability [11]. However, in prepubien samples taken after surgical section, the nervous fibers are few and small. The best hypothesis would be that the prepubien section interrupts the connection between the bulbocavernosus muscles and the sphincter zone and thus suppresses the traction exerted on the sphincter, regardless of whether it is induced by levator relaxation.
In conclusion, the use of endovaginal ultrasound enables a new approach to the management of urethral instability. The discovery of the movement of the prepubien led to the application of a new operation for the treatment of pollakiuria, nycturia and urge incontinence. The actual effectiveness of prepubien section in the long term has not yet been definitively established. However, as the initial results have been encouraging and because the operation is simple and non-aggressive (no long-term side effects), we think that it should be attempted by other teams to define its true place in the therapeutic armamentarium, which is expected to lie between the different conservative modes of therapy and the major surgical procedures used to treat urge incontinence.
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