Int Urogynecol J DOI 10.1007/s00192-015-2910-7
ORIGINAL ARTICLE
The effect of pelvic organ prolapse repair on vaginal sensation Lior Lowenstein 1,2 & Susana Mustafa-Mikhail 1,2 & Irena Gartman 3 & Ilan Gruenwald 3
Received: 10 September 2015 / Accepted: 20 November 2015 # The International Urogynecological Association 2015
Abstract Introduction and hypothesis The objective was to evaluate vaginal and clitoral sensation before and after robotic sacrocolpopexy for the repair of pelvic organ prolapse. Methods Twenty-two women, mean age 63 years (range 41– 77), were admitted for robotic sacrocolpopexy repair of pelvic organ prolapse; 4 were lost to follow-up. Quantitative sensory thresholds for warm, cold, and vibratory sensations were measured at the vagina (anterior and posterior areas) and clitoris 1 day before and a mean of 12 ± 4 months following surgery. Student’s paired t test was used to compare sensory thresholds before and after surgery. Results For the 18 women who completed follow-up, sensitivity was significantly higher after surgery (sensory threshold decreased) at the clitoral and vaginal regions, to cold and warm stimuli. In contrast, the vaginal and clitoral vibratory sensory thresholds did not change significantly following surgery. Conclusion The repair of pelvic organ prolapse by robotic sacrocolpopexy could potentially play a role in restoring
Lior Lowenstein and Susana Mustafa-Mikhail are co authors * Susana Mustafa-Mikhail
[email protected] 1
Department of Obstetrics & Gynecology, Rambam Health Care Campus, Ruth and Bruce Rappaport Faculty of Medicine Technion, Israel Institute of Technology, Haifa, Israel
2
Department of Urology, Rambam Health Care Campus, Ruth and Bruce Rappaport Faculty of Medicine Technion, Israel Institute of Technology, Haifa, Israel
3
Division of Neurourology, Rambam Health Care Campus, Ruth and Bruce Rappaport Faculty of Medicine Technion-Israel Institute of Technology, Haifa, Israel
clitoral and vaginal wall sensation. The effects of these sensory changes on sexual function and the quality of sexual life need further investigation.
Keywords Genital sensation . Pelvic organ prolapse . Sacrocolpopexy . Robotic surgery . Sexual dysfunction
Introduction The association between pelvic organ prolapse (POP) and sensory functioning of the genital region has not been fully explored. In a previous study it was demonstrated that women with POP are less sensitive to warm and vibratory stimuli that correspond to C fiber and A -δ fibers in the vagina and clitoral region respectively [1]. Data from that study could not determine whether these changes are causative or are a result of the prolapse. Amarenco et al. hypothesized that the changes in neuronal activity of the pelvic floor muscle are due to repeated stretch injury of the diaphragmatic pelvic floor muscles [2]. Electromyography, evoked potentials, and perineal nerve motor latency tests confirmed perineal neurogenic abnormalities in POP [2]. Neural damage may be one of the etiologies for POP, but whether these changes are reversible is still unknown. Minimally invasive endoscopic surgery for the treatment of POP has rapidly evolved, and gained in popularity since it was first presented by Nezhat in 1994 [3]. During the surgical procedure the prolapsed vagina is reduced to its original anatomical site by the introduction of a Y mesh that secures the anterior and posterior vaginal walls to the pre-sacral area. Currently, robotic sacrocolpopexy is considered a safe and effective procedure for the repair of POP [4].
Int Urogynecol J
The present study is aimed at evaluating the sensory changes in the vaginal and clitoral regions following the surgical repair of POP by robotic sacrocolpopexy.
Materials and methods Following IRB approval, all women who were referred to robotic sacrocolpopexy for the repair of POP (≥stage II) were offered to participate in the study. We excluded women with stress urinary incontinence, previous gynecological or pelvic surgery, diabetes, or any neurological pathological condition. Informed consent was obtained from all participants. The following data were collected from the participants’ electronic charts: 1. 2. 3. 4. 5.
Demographics (age, race, and marital or partner status) Medical and surgical history including parity Menopausal and hormonal status Body mass index POP-Q staging [5]
Each participant underwent quantitative sensory testing 1 day before the operation (on a nonmenstrual day), to measure baseline genital sensation at both the anterior and posterior vaginal walls and at the clitoris. The degrees of bother and distress caused by pelvic floor symptoms were evaluated by the validated POPDI-6 questionnaire [6]. Participants were asked to fill the POPDI-6 questionnaire again, at least 6 months after surgery, and the same quantitative sensory testing was repeated.
According to this method, stimulus intensity was linearly increased until the subject indicated by pressing a button, the initial perception of a sensation of temperature (hot or cold) or vibration. The act of pressing the button also reset the probe back to the adaptation temperature or no vibration. The adaptation temperature was 37 °C, and the rate of temperature change was 1 °C/s. The rate of vibratory amplitude increase was 1 μm/s. Four successive stimuli were given in each of the three modalities. A standard deviation of the mean of four thresholds above 0.5 was interpreted as non-optimal performance, probably due to distraction, and was an indication for repeating the stimulatory test. Statistical analysis The software SPSS version 22.0 for Windows (SPSS, Chicago, IL, USA) was used for data management and statistical analysis. Histogram curves were used to evaluate the homogeneity distribution of the data. Student’s paired t test was used to compare sensory thresholds before and after surgery. Pearson correlations were obtained to examine the relationships between independent continuous variables. A 0.05 significance level was used for all statistical tests. No one-sided tests were performed. Power analysis Based on a previous study we estimated that to achieve a difference of 1 °C before and after surgery in the sensation of the anterior vaginal wall, 16 subjects are required to achieve 80 % power to detect the specified difference using a paired Student’s t test with a 0.05 alpha level [9].
Quantitative sensory tests The quantitative sensory tests were performed with a thermal and vibration Genito-Sensory Analyzer (GSA; Medoc, Ramat Yishai, Israel) for the clitoral and vaginal area. The GSA is a computer-controlled diagnostic device for the evaluation of sensory impairment. The GSA generates and records stimuli that are used for sensory threshold measurement by means of repetitive transient temperature stimuli. Cold sensation thresholds are obtained for the sampling of small-caliber A-delta fibers, warm sensation thresholds for C-fibers, and vibratory sensation thresholds for large-caliber A-beta fibers. The thermal probe has a working range of 10–50 °C. The vibration frequency is fixed at 100 Hz, with an amplitude range of 0– 130 μm. Psychophysical methodology We used the method of limits for threshold determination of warm, cold, and vibratory sensations for both the vagina and the clitoris, in this same order, for all the women tested [7, 8].
Results Overall, 22 patients were recruited. The 18 (81 %) who returned for a second visit at a mean time of 12 ± 4 months following surgery were included in our analysis. Two patients could not be reached by phone and two declined to come for a second visit because of their busy schedules. The latter were both satisfied with the results of surgery, as was evaluated by a nonstandardized phone interview. Table 1 presents the baseline characteristics of the study population. At 6 or more months following surgery, for the POP-Q stage median 0 (0–1; Table 2) we found significant improvement in sensitivity to thermal (warm and cold) stimuli at the vaginal and clitoral area. Furthermore, we found a moderate to high correlation between sensitivity to cold and sensitivity to warm stimuli at the anterior and posterior vaginal walls (ρ = −0.66, p < 0.01; ρ = −0.51, p < 0.03 respectively), and a moderate correlation between warm and cold stimuli at the clitoral area (ρ = −05, p < 0.03).
Int Urogynecol J Table 1
Patients’ demographic and clinical characteristics
Characteristic
zData
Age, median (range)
63 (41–77)
Body mass index, median (range)
26 (21–34)
Preoperative POP-Q stage, median (range) Postoperative POP-Q stage, median (range)
3 (2–4) 0 (0–1)
Parity, median (range) Preoperative POPDI-6 score, median (range)
3 (1–7) 28 (16–72)
Postoperative POPDI-6 score, median (range)
16 (0–40)
Concomitant surgery Subtotal hysterectomy
13 (72.2 %)
Salpingo-oophorectomy
13 (72 %)
There were no statistically significant correlations between the delta in sensory changes and the time lapse from surgery. The differences in sensory thresholds to vibratory stimulation that were recorded in both the clitoris and vaginal walls before and after surgery were not statistically significant. Changes in genital sensation following surgery were similar for those who underwent sacrocolpopexy only, and for those who had concomitant hysterectomy and or bilateral salpingo-oophorectomy (p > 0.05).
Discussion To the best of our knowledge this is the first study that demonstrated quantifiable changes in the sensory functioning of the clitoral and anterior vaginal wall region following robotic sacrocolpopexy. Our previous study demonstrated that POP correlates with reduced vaginal and clitoral sensation [1]. We suspect that these differences may be due to anatomical changes that cause damage to the delicate sensory fibers, or that the sensory deficit and neural dysfunction causes poor muscular innervation and decreased muscle tone, resulting in POP. North et al. [10] also evaluated the effect of POP on genital sensation. Their Table 2 Pre- and postoperative threshold values to thermal and vibratory sensation
findings were in concordance with our own, yet the significantly younger age of the controls compared with the study group was a limitation of that investigation. A pilot study carried out by North et al. on a small group of 7 women who underwent vaginal repair of uterovaginal prolapse showed a lack of significant changes in vibratory sensation before and after surgery, concurring with our findings. They stated that their sample was too small to reach meaningful conclusions, and they did not examine changes in warm and cold stimulation before and after surgery. Our study does not explain the mechanism by which sensation to thermal stimuli is improved following the repair of POP. A possible explanation may be derived from the fact that prolapse results in either the stretching or the compression of the small caliber A-delta and C sensory nerve fibers that innervate the vagina and clitoris. Repair of the prolapse relieves the pressure or tension and restores the sensation. Our repeated measures were conducted following a mean time of 12 months after surgery, a sufficient period of time for full recovery of the damaged sensory fibers. Comparison between the sensation values of women without prolapse [1] and the current cohort of patients who had prolapse repair did not demonstrate statistically significant differences in any of the mean threshold values at the anatomical sites examined. Our findings did not demonstrate significant differences in vibratory sensation before and after surgery. When testing the vibration threshold with the GSA, the proximal end of the probe is in close contact with the distal vagina, below the level of the hymen. As was recognized by North et al. [10], this skin area is more densely supplied with vibration-detecting Meissner′s and Pacinian corpuscles, and receives innervation from the ilio-inguinal and genito-femoral nerves in addition to branches of the pudendal nerve. Vibratory sensation, particularly at high amplitudes, is also conducted through tissues (especially bone). It may not, therefore, be possible to specifically focus the vibratory stimuli on the damaged nerve responsible for abnormal sensory function detected by the GSA. Additionally, a high amplitude of the vibratory stimulus is required to elicit a response in women with prolapse.
Sensory modality
Anatomical site
Preoperative group (n = 18)
Postoperative group (n = 18)
p value
Warm (°C)
Anterior vagina Posterior vagina Clitoris Anterior vagina Posterior vagina Vagina Clitoris
42.6 ± 0.8 41.2 ± 1.3 39.5 ± 0.3 29.3 ± 1.3 30.9 ± 0.9 6.9 ± 1.1 3.5 ± 0.8
40.5 ± 0.3 39.8 ± 0.3 38.9 ± 0.2 32.0 ± 0.6 32.1 ± 0.9 8.5 ± 1.8 3.2 ± 0.7
<0.01 <0.03 <0.007 <0.03 <0.05 0.23 0.63
Cold (°C) Vibratory (μm/s)
Data are described as a combination of sensory modality and anatomical site. Thresholds are given as mean ± SEM
Int Urogynecol J
Consequently, thresholds reached via the stimulation of other more distant sensory nerves may not truly reflect genital sensory function. Since the current study evaluated the somatic functioning of the genital region, the findings support the likelihood of the partial recovery of genital sensation following the robotic repair of POP. The clinical significance of the sensory deterioration of both the anterior vaginal wall and the clitoral region is not known. A previous study by our group demonstrated lower levels of sensitivity to vibratory and thermal stimuli in the genital region in women with sexual dysfunction than in women with normal sexual function [11]. In that study, a validated questionnaire revealed a significant correlation between clitoral vibratory sensation (A-β fibers) and orgasmic dysfunction. In the current study, we did not evaluate the correlation between changes in genital sensation and sexual function. To better comprehend the correlation between the changes in genital sensation and sexual function, a more specific validated tool with a larger sample size is needed. A limitation of the study is inherent in its methodology. Comparison with a control group could have improved the scientific level of the study, yet conducting repeated sensory testing, following 6 months without treatment, is problematic for clinicians and for achieving IRB committee approval. In conclusion, after the robotic repair of POP and the repositioning and restoration of the genital organs to their original anatomical location, thermal genital sensation improved in all areas tested.
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Compliance with ethical standards Conflicts of interest None.
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