Surgical therapy of neurogenic detrusor overactivity (hyperreflexia) in paraplegic patients by sacral deafferentation and implant driven micturition by sacral anterior root stimulation: methods, indications, results, complications, and future prospects

[Invasive neurostimulation in neuro-urology: state of the art]

Modulation or stimulation of the nerves supplying the lower urinary tract is a possible treatment option for dysfunction of the lower urinary tract, pelvic floor and rectum if conservative or minimally invasive treatment approaches fail. This overview shows the possibilities and limitations of sacral neuromodulation, sacral deafferentation with sacral anterior root stimulation and conus deafferentation.Sacral neuromodulation (SNM) is a procedure for the treatment of refractory pelvic floor dysfunction of various origins (idiopathic, neurogenic or post-operative), such as overactive bladder, non-obstructive retention and faecal incontinence. A particular advantage of SNM is the possibility of prior test stimulation with a high prognostic value. The procedure is minimally invasive, reversible and associated with relatively low morbidity rates.Following the introduction of MRI-compatible SNM systems, there has been renewed interest in the treatment of neurogenic bladder dysfunction. A recent meta-analysis reports similar success rates as in the idiopathic patient population.Sacral deafferentation with implantation of a sacral anterior root stimulator (SARS/SDAF) is an excellent therapeutic option for patients with spinal cord injury, which can significantly improve the quality of life of those affected and, in addition to treating neurogenic lower urinary tract dysfunction, can also have a positive effect on neurogenic bowel dysfunction, neurogenic sexual dysfunction or autonomic dysreflexia. If conservative or minimally invasive treatment fails, it is crucial for the success of this procedure to consider SDAF/SARS at an early stage in order to avoid irreversible organic damage.Conus deafferentation (KDAF) is a less invasive surgical treatment option for patients with spinal cord injury for whom sacral deafferentation would be indicated but who would not benefit from the simultaneous implantation of a sacral anterior root stimulator. In principle, these patients also have the option of being subsequently treated with an extradural implant and thus utilising the advantages of anterior root stimulation. Indications for KDAF are autonomic dysreflexia, therapy-refractory detrusor overactivity, recurrent urinary tract infections, urinary incontinence and spasticity triggered by detrusor overactivity. With KDAF, we have a safe and efficient procedure with great potential for improving the spectrum of paraplegiological and neuro-urological treatment.

The past, present, and future of traumatic spinal cord injury therapies: a review

This review provides a concise outline of the advances made in the care of patients and to the quality of life after a traumatic spinal cord injury (SCI) over the last century. Despite these improvements reversal of the neurological injury is not yet possible. Instead, current treatment is limited to providing symptomatic relief, avoiding secondary insults and preventing additional sequelae. However, with an ever-advancing technology and deeper understanding of the damaged spinal cord, this appears increasingly conceivable. A brief synopsis of the most prominent challenges facing both clinicians and research scientists in developing functional treatments for a progressively complex injury are presented. Moreover, the multiple mechanisms by which damage propagates many months after the original injury requires a multifaceted approach to ameliorate the human spinal cord. We discuss potential methods to protect the spinal cord from damage, and to manipulate the inherent inhibition of the spinal cord to regeneration and repair. Although acute and chronic SCI share common final pathways resulting in cell death and neurological deficits, the underlying putative mechanisms of chronic SCI and the treatments are not covered in this review.

Therapeutic effects of electrical stimulation on overactive bladder: a meta-analysis

Background

To systematically evaluate the therapeutic effect of electrical stimulation (ES) on overactive bladder (OB).

Method

We retrieved information by searching databases from PubMed, CBM-disc, The Cochrane Library, ScienceDirect (from Elsevier publishers) and Springer publishers up to March 2016. We looked for randomized controlled trials that studied ES in OB treatment with subject headings and keywords using literature searches and manual retrieval. References of included studies were reviewed. Literature was screened independently by two investigators according to inclusion and exclusion criteria. After extracting data and evaluating their quality, meta-analysis was undertaken with RevMan v5.2.

Results

Ten randomized controlled trials involving 719 patients were included. Meta-analysis results demonstrated ES to have better effects for improving bladder compliance, reducing residual urine, and decreasing the frequency of enuresis in OB patients compared with the control group. ES elicited significantly better effects for diminishing the maximum detrusor pressure in children than in controls, but there was no significant difference in the maximum detrusor pressure between adults and controls. The therapeutic effect of ES combined with other therapies for increasing the maximum bladder capacity was better compared with other therapies alone. No significant difference was noted between ES alone and other therapies alone.

Conclusions

Based on current evidence, ES has certain effects on OBs. Severe adverse reactions are not observed. ES is safe, efficacious, and worthy of clinical use.

Neurostimulation for neurogenic bowel dysfunction

Background. Loss of normal bowel function caused by nerve injury, neurological disease or congenital defects of the nervous system is termed neurogenic bowel dysfunction (NBD). It usually includes combinations of fecal incontinence, constipation, abdominal pain and bloating. When standard treatment of NBD fails surgical procedures are often needed. Neurostimulation has also been investigated, but no consensus exists about efficacy or clinical use. Methods. A systematic literature search of NBD treated by sacral anterior root stimulation (SARS), sacral nerve stimulation (SNS), peripheral nerve stimulation, magnetic stimulation, and nerve re-routing was made in Pubmed, Embase, Scopus, and the Cochrane Library. Results. SARS improves bowel function in some patients with complete spinal cord injury (SCI). Nerve re-routing is claimed to facilitate defecation through mechanical stimulation of dermatomes in patients with complete or incomplete SCI or myelomeningocele. SNS can reduce NBD in selected patients with a variety of incomplete neurological lesions. Peripheral stimulation using electrical stimulation or magnetic stimulation may represent non-invasive alternatives. Conclusion. Numerous methods of neurostimulation to treat NBD have been investigated in pilot studies or retrospective studies. Therefore, larger controlled trials with well-defined inclusion criteria and endpoints are recommended before widespread clinical use of neurostimulation against NBD.

Is there a direct antimicrobial effect of botulinum neurotoxin type A?

Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Several studies describe a reduction of symptomatic urinary tract infections in patients with neurogenic detrusor overactivity after intradetrusor injections of botulinum neurotoxin A (BoNT/A). It was, however, unclear if a direct antibacterial effect of BoNT/A plays a role in this clinical observation. This is the first study to investigate a potential antibacterial effect of two frequently used BoNT/A formulations (i.e. Botox® and Dysport®), providing evidence that BoNT/A does not exert an antibacterial effect on lower urinary tract pathogens.

OBJECTIVE

• To determine a potential direct antimicrobial effect of botulinum neurotoxin type A (BoNT/A).

MATERIALS AND METHODS

• A prospective study was carried out using onabotulinumtoxin A (Botox®) and abobotulinumtoxin A (Dypsort®) in agar diffusion and broth microdilution assays with various clinical urinary tract isolates (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, Acinetobacter baumannii, Citrobacter freundii, Klebsiella oxytoca and Bacillus subtilis). • Inhibition zones (mm) of bacteria around a disc containing 20 µL saline with 4 IU of Botox® were measured in the agar diffusion assay. • Minimal inhibitory concentrations (MICs, IU/mL) of both toxins for all bacteria were determined in the broth microdilution assay after overnight incubation at 35 °C.

RESULTS

• There was no inhibition zone in the agar diffusion assays with any bacterial strain. • The microdilution test using Botox® and Dysport® showed bacterial growth in all dilutions, i.e. MICs > 20 and >100 IU/mL for Botox® and Dysport®, respectively.

CONCLUSIONS

• BoNT/A has no direct antimicrobial effect. • The reduced frequency of symptomatic urinary tract infections (sUTIs) in patients with neurogenic detrusor overactivity (NDO) after BoNT/A intradetrusor injections seems to be caused by different indirect mechanisms, which are still not completely understood.

Toward a fully integrated neurostimulator with inductive power recovery front-end

In order to investigate new neurostimulation strategies for micturition recovery in spinal cord injured patients, custom implantable stimulators are required to carry-on chronic animal experiments. However, higher integration of the neurostimulator becomes increasingly necessary for miniaturization purposes, power consumption reduction, and for increasing the number of stimulation channels. As a first step towards total integration, we present in this paper the design of a highly-integrated neurostimulator that can be assembled on a 21-mm diameter printed circuit board. The prototype is based on three custom integrated circuits fabricated in High-Voltage (HV) CMOS technology, and a low-power small-scale commercially available FPGA. Using a step-down approach where the inductive voltage is left free up to 20 V, the inductive power and data recovery front-end is fully integrated. In particular, the front-end includes a bridge rectifier, a 20-V voltage limiter, an adjustable series regulator (5 to 12 V), a switched-capacitor step-down DC/DC converter (1:3, 1:2, or 2:3 ratio), as well as data recovery. Measurements show that the DC/DC converter achieves more than 86% power efficiency while providing around 3.9-V from a 12-V input at 1-mA load, 1:3 conversion ratio, and 50-kHz switching frequency. With such efficiency, the proposed step-down inductive power recovery topology is more advantageous than its conventional step-up counterpart. Experimental results confirm good overall functionality of the system.

[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.

Cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in conscious rats

The response to myocardial ischemia is complex and involves the cardio-cardiac sympathetic reflex. Specifically, cardiac spinal (sympathetic) afferents are excited by ischemic metabolites and elicit an excitatory sympathetic reflex, which plays a major role in the genesis of ventricular arrhythmias. For example, brief myocardial ischemia leads to ATP release, which activates cardiac spinal afferents through stimulation of P2 receptors. Clinical work with patients and preclinical work with animals document that disruption of this reflex protects against ischemia-induced ventricular arrhythmias. However, the role of afferent signals in the initiation of sustained ventricular tachycardia has not been investigated. Therefore, we tested the hypothesis that cardiac spinal deafferentation reduces the susceptibility to sustained ventricular tachycardia in adult (12-15 wk of age), conscious, male Sprague-Dawley rats. To test this hypothesis, the susceptibility to ventricular tachyarrhythmias produced by occlusion of the left main coronary artery was determined in two groups of conscious rats: 1) deafferentation (bilateral excision of the T1-T5 dorsal root ganglia) and 2) control (sham deafferentation). The ventricular arrhythmia threshold (VAT) was defined as the time from coronary occlusion to sustained ventricular tachycardia resulting in a reduction in arterial pressure. Results document a significantly higher VAT in the deafferentation group (7.0 ± 0.7 min) relative to control (4.3 ± 0.3 min) rats. The decreased susceptibility to tachyarrhythmias with deafferentation was associated with a reduced cardiac metabolic demand (lower rate-pressure product and ST segment elevation) during ischemia.

[Neurogenic urinary incontinence. Value of surgical management]

Damage to the CNS, the cauda equina, and the pelvic nerval structures causes neurogenic bladder dysfunction with neurogenic urinary incontinence (NUI). The definitive diagnosis of NUI is made with urodynamic examination methods. The most frequent cause of NUI is neurogenic detrusor overactivity (NDO). The treatment concept must take into account the physical and emotional restrictions. The treatment of NUI due to NDO is a domain of conservative therapy, i.e., mostly antimuscarinics and intermittent catheterization (IC). In about 30%, there is a good chance for therapy failures. An advancement in therapy is the injection of BTX-A into the detrusor. The missing drug approval is a disadvantage.Operative treatments are considered if conservative and minimally invasive therapies are unsuccessful. Sacral deafferentation (SDAF) and sacral anterior root stimulator implantation (SARSI) are available as organ-preserving techniques only for paraplegics with NDO and reflex urinary incontinence and neuromodulation for the other forms of NDO provided that a successful percutaneous nerve evaluation (PNE) test has previously taken place. Augmentation cystoplasty is indicated if SDAF and neuromodulation cannot be used and the bladder wall is damaged irreversibly by fibrosis. Kidney function of at least 25% and acceptance of IC are prerequisites. Myectomy (autoaugmentation) has an indication similar to augmentation cystoplasty but there must not be any fibrosis. Bladder neck insufficiency (BNI) caused by paralysis or iatrogenically can be treated by the implantation of an alloplastic sphincter high at the bladder neck. A stable reservoir function is required. If not all methods are possible, the ileum conduit or the suprapubic bladder fistula can be the last resort.