An update on sacral neuromodulation: where do we stand with this in the management of lower urinary tract dysfunction in 2010?

Chronic pudendal neuromodulation using an implantable microstimulator improves voiding function in diabetic rats

Objective

Few studies have investigated the feasibility of using chronic pudendal neuromodulation for improving voiding function in patients with diabetes who are also experiencing urinary retention. The present study investigated the effects of chronic electrical stimulation (ES) of the sensory branch of the pudendal nerve on voiding function in diabetic rats.

Approach

A custom-made implantable microstimulation system was designed and manufactured for chronic implantation in normal control (NC) and diabetic rats. After three or six weeks of pudendal neuromodulation, the intravesical pressure, external urethral sphincter electromyograms (EUS-EMGs), and urine flow rate (UFR) of all rats were simultaneously recorded to assess the effects of chronic pudendal ES on voiding function. Morphological changes in pudendal axons were assessed through hematoxylin and eosin (H&E) staining.

Significance

This study demonstrated the feasibility of using chronic pudendal neuromodulation for improving voiding function in diabetic rats. These results may facilitate the development of an advanced neural prosthesis for restoring bladder function in clinical settings.

Pharmacologic management of non-neurogenic functional obstruction in women

INTRODUCTION

Impaired bladder emptying in women without neurologic disease may be related to urethral obstruction and/or impaired bladder contractility. Mechanical obstruction generally requires surgical management and options are limited for impaired bladder contractility. However, functional obstruction from voiding dysfunction or primary bladder neck obstruction may present an opportunity for pharmacologic intervention.

AREAS COVERED

In this review, the authors extensively reviewed available literature regarding the use of off-label medications for functional bladder outlet obstruction in women. In addition, side effect profiles and pharmacology of these medications determined from on-label indications are reviewed. Specific medications reviewed include vaginal diazepam, baclofen, urethral botulinum toxin injection, and alpha-adrenergic blockers.

EXPERT OPINION

Alpha-blockers in particular have demonstrated promise in women with demonstrable or suspected bladder outlet obstruction with side effect profiles similar to those observed in men. However, lack of quality data hinders informed decision making with alpha-blockers or any of the other agents studied in women with non-neurogenic functional outlet obstruction. In the absence of well-designed, placebo-controlled multi-institutional trials, those prescribing these medications must be aware of special considerations and side effects associated with relatively unfamiliar treatments in the context of uncertain benefit.

Long-term follow-up of sacral neuromodulation for lower urinary tract dysfunction

OBJECTIVE

To report our long-term experience of sacral neuromodulation (SNM) for various lower urinary tract dysfunctions but with a focus on efficacy, safety, re-interventions and degree of success.

PATIENTS AND METHODS

This is a single tertiary referral centre study that included 217 patients (86% female) who received an implantable pulse generator (IPG) (Interstim™, Medtronic, Minneapolis, USA) between 1996 and 2010. Success was considered if the initial ≥50% improvement in any of primary voiding diary variables persisted compared with baseline, but was further stratified.

RESULTS

The mean duration of follow-up was 46.88 months. Success and cure rates were ≈70% and 20% for urgency incontinence, 68% and 33% for urgency frequency syndrome and 73% and 58% for idiopathic retention. In those patients with an unsuccessful therapy outcome, the mean time to failure was 24.6 months after implantation. There were 88 (41%) patients who had at least one device or treatment related surgical re-intervention. The re-intervention rate was 1.7 per patient with most of them (47%) occurring ≤2 years of follow-up.

CONCLUSIONS

SNM appears effective in the long-term with a success rate after definitive IPG implant of ≈70% and complete cure rates ranging between 20% and 58% depending on indication. Patients with idiopathic retention appear to do best. The re-intervention rate is high with most occurring ≤2 years of implantation. It is likely that with the newer techniques used, efficacy and re-intervention rates will improve.

Neural pathways involved in sacral neuromodulation of reflex bladder activity in cats

This study examined the mechanisms underlying the effects of sacral neuromodulation on reflex bladder activity in chloralose-anesthetized cats. Bladder activity was recorded during cystometrograms (CMGs) or under isovolumetric conditions. An S1-S3 dorsal (DRT) or ventral root (VRT) was electrically stimulated at a range of frequencies (1-30 Hz) and at intensities relative to threshold (0.25-2T) for evoking anal/toe twitches. Stimulation of DRTs but not VRTs at 1T intensity and frequencies of 1-30 Hz inhibited isovolumetric rhythmic bladder contractions. A 5-Hz DRT stimulation during CMGs was optimal for increasing (P < 0.05) bladder capacity (BC), but stimulation at 15 and 30 Hz was ineffective. Stimulation of the S1 DRT was more effective (increases BC to 144% and 164% of control at 1T and 2T, respectively) than S2 DRT stimulation (increases BC to 132% and 150% of control). Bilateral transection of the hypogastric or pudendal nerves did not change the inhibitory effect induced by S1 DRT stimulation. Repeated stimulation of S1 and S2 DRTs during multiple CMGs elicited a significant (P < 0.05) increase in BC (to 155 ± 11% of control) that persisted after termination of the stimulation. These results in cats suggest that the inhibition of reflex bladder activity by sacral neuromodulation occurs primarily in the central nervous system by inhibiting the ascending or descending pathways of the spinobulbospinal micturition reflex.

The treatment of lower urinary tract symptoms in patients with multiple sclerosis: a systematic review

This is a systematic review on the treatment of lower urinary tract symptoms (LUTS) in patients with multiple sclerosis (MS). The heterogeneity of the outcome criteria did not allow a meta-analysis of the published evidence. In the last few decades, the therapeutic options for neurogenic bladder dysfunction have broadened. Despite this, no consensus has been reached as to the management of LUTD and LUTS in patients with MS, and the subject remains controversial. Bladder dysfunction is common in MS, affecting 80 %-100 % of patients during the course of the disease. Several studies have shown that urinary incontinence has a severe effect on patients' quality of life, with 70 % of patients classifying the impact bladder symptoms had on their life as "high" or "moderate." Moreover, the progressive feature of MS makes its treatment complex, since any achieved therapeutic result may be short-lived, with the possibility that symptoms will recur or develop de novo.

[The future of invasive neuromodulation: new techniques and expanded indications]

Due to the increasing popularity of neuromodulation, the number of indications and patient groups to which this technique is offered is also increasing. We evaluated the currently available data concerning neuromodulation in geriatric patients, children and patients with spinal cord injury and potential alternatives regarding neural targets and implantation techniques.The evidence of the use of neuromodulation in these patient groups is low. In geriatric patients, the use of neuromodulation seems to be justified. The few existing results concerning neuromulation in children are positive; however, there are no data about long term effects of neuromodulation on the growing organism. In patients with spinal cord injury, neuromodulation by microsurgical nerve anastomosis does not seem to be successful. According to the preliminary data of a single study, neuromodulation in acute spinal cord injury may prevent development of a neurogenic bladder dysfunction. The laparoscopic implantation of electrodes for neuromodulation unfolds new technical opportunities; however, until today there is no proof of the efficacy of this technique. Pudendal neuromodulation appears to be a meaningful addition to the therapeutic armamentarium for selected indications.The existing studies demonstrate the future opportunities of neuromodulation also in geriatric patients, children and patientens with spinal cord injuries. However, especially in the latter two groups, further studies concerning effectiveness and long term consequences are mandatory prior to offering these techniques to patients in everyday practise.