Abstract: The aim of our study is to investigate the effects of chronic sacral neuromodulation on Nitric Oxide (NO) metabolism in the rat bladder. 26 female Sprangue-Dawley rats were considered: group I, normal control rats; group II, a sham treatment, in whom catheters for electrical stimulation were placed in the S1 foramen bilaterally and left in place for 21 days, without performing neuromodulation; group III in whom electrical sacral neuromodulation was performed for 21 days. Finally a cystectomy was performed and the bladder biopsy specimens were sent for immunostaining with n-NOS and i-NOS. Morphological and immunohistochemical analysis was carried out, and evaluated in urothelial cells, endothelial cells and muscle fibers of the muscularis propria. Differences between the 3 groups were analyzed by Student Newman-Keuls test. We could observe that urothelial and endothelial i-NOS (37.00+/-4.69 and 59.00+/-7.42 respectively) and urothelial n-NOS (36.80+/-7.85) expression are significantly increased in neuromodulated rats, compared to groups 1 and 2 (p<0.005). In conclusion, the increase of i-NOS expression on endothelial cells after sacral neuromodulation could be in some way related to angiogenetic responses in the microvascular structures; the increase of n-NOS and i-NOS expression on urothelial cells can suggest that NO is able to influence the plasticity of bladder response, inducing the release of messengers within the urothelium. This study can therefore improve our understanding of the mechanisms of sacral neuromodulation on chronic bladder dysfunction; further studies will need to better demonstrate the role of angiogenesis in the bladder after sacral neuromodulation and to investigate the effects of neuromodulation in rats with chronically induced bladder dysfunction.
Abstract: AIMS: The aim of this study is to present the normative data of direct and reflex motor anal sphincter responses, simultaneously evoked by S3 surface electrical stimulation. By this method, it is possible to test the functional integrity of the nervous pathways activated during sacral neuromodulation (SNM). METHODS: Twenty healthy subjects were studied. Motor-evoked potentials (MEPs) were recorded by concentric needle electrode from external anal sphincter (EAS). Electrical stimulation was applied by means of a bipolar surface electrode over the S3 right or left sacral foramina. RESULTS: Direct (R1) and reflex responses (R2 and R3) were found at latencies of 6.98, 25.12, and 50.31 msec, respectively. The two first responses were recorded in all the cases; the last response is steadily recorded in 17 out of 20 subjects. CONCLUSIONS: Our data can serve as reference values for future study in patients with pelvic floor dysfunction. EAS responses following S3 percutaneous electrical stimulation can represent a useful aid in the selection of candidates to SNM.
Abstract: PURPOSE: Sacral neuromodulation is a new treatment for refractory voiding disorders such as urge incontinence, urinary retention, frequency-urgency syndromes and faecal incontinence. The current approach to sacral nerve stimulation consists of a two-stage procedure.The first is a PNE test (Percutaneous Nerve Evaluation) by a provisional electrically stimulated spinal needle, placed percutaneously in the S3 foramina for four to ten days. If successful, the second stage, permanent implantation, is carried out. The PNE test is performed under fluoroscopic control using the palpable bony sacral foramina as referral points. This technique can show some limitations, such as operator Rx exposure, poor visualization of sacral foramina because of bowel gas artefacts or sacral malformation. In order to reduce these inconveniences and to improve efficiency of the test we tried an alternative technique. The purpose of our study was to test the use of CT as an alternative technique in order to evaluate its advantages and possible routine use. MATERIALS AND METHODS: We tested 30 patients with the PNE test under CT guidance (16 males and 14 females) suffering from serious pelvic disorders and not responding to the normal therapeutic regime. Twenty-seven patients showed relative anatomical integrity of the pelvis and the sacrum, the remaining 3 patients presented morphological anomalies of the sacral foramina. With the patient in the prone position the sacral foramina were identified with CT volumetric scanning using a spiral CT scanner equipped with a second console for the three-dimensional reconstructions. Having identified the location of the S3 foramina, a sterile field was prepared and the spinal needle introduced checking correct positioning with a CT control scan. An electrode was then inserted after having checked correct muscular contractile response and the precise position with a further CT scan. RESULTS: Thirty patients were subjected to PNE under CT guidance for a total of 38 centerings. Eight patients underwent the PNE procedure on both the S3 foramina.The sacral foramen was centred at the first attempt in 36 out of 38 cases. Two cases required several attempts to centre correctly the foramen. In 4 patients out of 30 a second electrode was implanted. In one patient who had a nonconsolidated sacral fracture, CT guidance enabled insertion of the electrode inside the only practicable foramen, a manoeuvre that would have been impossible with fluoroscopical guidance.Only once was the electrode placed in a wrong location but promptly repositioned after a CT control.During the whole trial period we had a positive response to the PNE test in 18 out of 30 patients (60%), a partial response in 4 out of 30 patients and a negative response in the remaining 8 patients. None of the patients who underwent the PNE test had infectious complications and the procedure was well tolerated by all. The procedure lasted about 45 minutes.
