The Botulinum Treatment of Neurogenic Detrusor Overactivity: The Double-Face of the Neurotoxin

Effects of repetitive functional magnetic stimulation in the sacral nerve in patients with neurogenic detrusor overactivity after suprasacral spinal cord injury: a study protocol for a randomized controlled trial

BACKGROUND

Neurogenic detrusor overactivity (NDO) is a serious and common complication after spinal cord injury, affecting patients' quality of life seriously. Therefore, we developed this research protocol to evaluate the efficacy of repetitive functional magnetic stimulation (rFMS) in the sacral nerve in patients with neurogenic detrusor overactivity (NDO) after suprasacral spinal cord injury (SCI) and provide more options for rFMS in treating NDO after suprasacral SCI.

METHODS

This study is a single-center, randomized, parallel-group clinical trial. We will recruit the patients with NDO after suprasacral SCI in the Rehabilitation Department of the Affiliated Hospital of Southwest Medical University from September 2022 to August 2023. They will be assigned to the rFMS group and the sham stimulation group randomly. The sample size is 66, with 33 patients in each group. The rFMS group will receive real rFMS treatment of the sacral nerve (100% stimulation intensity, 5 Hz, 20 min each time, five times a week), and the sham group will receive sham stimulation. Both groups will receive similar treatment strategies, including medication, standard urine management, acupuncture treatment, and health education. The bladder compliance (bladder capacity/detrusor pressure) and pudendal nerve electromyography will be evaluated at baseline, 8th week of treatment. The residual volume of the bladder and bladder diary will be recorded once a week during 8 weeks of treatments. SCI-QOL and NBSS will be evaluated at baseline, the 4th and 8th week of treatment. In addition, the above assessments will be followed up at 8 weeks after the end of treatment.

DISCUSSION

It is expected that the bladder function, symptoms, and quality of life might be significantly improved after rFMS of the sacral nerve.

TRIAL REGISTRATION

The China Clinical Trials Registry has approved this study, registration number: ChiCTR2100045148. Registered on April 7, 2021.

Molecular Mechanism Operating in Animal Models of Neurogenic Detrusor Overactivity: A Systematic Review Focusing on Bladder Dysfunction of Neurogenic Origin

Neurogenic detrusor overactivity (NDO) is a severe lower urinary tract disorder, characterized by urinary urgency, retention, and incontinence, as a result of a neurologic lesion that results in damage in neuronal pathways controlling micturition. The purpose of this review is to provide a comprehensive framework of the currently used animal models for the investigation of this disorder, focusing on the molecular mechanisms of NDO. An electronic search was performed with PubMed and Scopus for literature describing animal models of NDO used in the last 10 years. The search retrieved 648 articles, of which reviews and non-original articles were excluded. After careful selection, 51 studies were included for analysis. Spinal cord injury (SCI) was the most frequently used model to study NDO, followed by animal models of neurodegenerative disorders, meningomyelocele, and stroke. Rats were the most commonly used animal, particularly females. Most studies evaluated bladder function through urodynamic methods, with awake cystometry being particularly preferred. Several molecular mechanisms have been identified, including changes in inflammatory processes, regulation of cell survival, and neuronal receptors. In the NDO bladder, inflammatory markers, apoptosis-related factors, and ischemia- and fibrosis-related molecules were found to be upregulated. Purinergic, cholinergic, and adrenergic receptors were downregulated, as most neuronal markers. In neuronal tissue, neurotrophic factors, apoptosis-related factors, and ischemia-associated molecules are increased, as well as markers of microglial and astrocytes at lesion sites. Animal models of NDO have been crucial for understanding the pathophysiology of lower urinary tract (LUT) dysfunction. Despite the heterogeneity of animal models for NDO onset, most studies rely on traumatic SCI models rather than other NDO-driven pathologies, which may result in some issues when translating pre-clinical observations to clinical settings other than SCI.

Neurogenic bladder in patients with paraplegia: a two-center study of the real-life experience of the patients' journey

INTRODUCTION

Several patterns of urological dysfunctions have been described following spinal cord injury (SCI), depending on the level and the completeness of the injury. A better understanding of the natural history of neurogenic bladder in patients with SCI, and the description of their successive therapeutic lines based on their clinical and urodynamic pattern is needed to improve their management. This study aimed to describe the real-life successive therapeutic lines in patients with neurogenic lower urinary tract dysfunction (NLUTD) following SCI.

METHODS

We conducted a two-center retrospective review of medical files of patients with SCI followed in two French specialized departments of Physical Medicine and Rehabilitation between January 2000 and January 2018. All patients with SCI with a level of lesion bellow T3 and older than 18 years old were eligible. The primary outcome was the description of the natural journey of neurogenic bladder in this population, from the awakening bladder contraction to the last therapeutic line. Survival curves were calculated with a 95-confidence interval using the Kaplan-Meier method.

RESULTS

One hundred and five patients were included in this study. Most of the patients were young men with a complete SCI lesion. The median time of treatment introduction was 1 and 9 years for anticholinergics and intradetrusor injection of BoNT/A, respectively. Median duration of effect of treatments was 4 and 6 years post-introduction of anticholinergics and BoNT/A, respectively.

CONCLUSION

This study describes NLUTD journey of patients with SCI demonstrating the mid-term efficacy of the two first therapeutic lines of NDO management. An improvement of non-surgical therapeutics is needed.

BoNT/A1 Secondary Failure for the Treatment of Neurogenic Detrusor Overactivity: An Ex Vivo Functional Study

Management of neurogenic detrusor overactivity (NDO) remains a clinical priority to improve patients’ quality of life and prevent dramatic urological complications. Intradetrusor injection of onabotulinumtoxinA (BoNT/A1, botulinum neurotoxin A1) is approved as second therapeutic line in these patients, demonstrating a good efficacy. However, a loss of its efficacy over time has been described, with no clear understanding of the underlying mechanisms. This paper aims at shedding new light on BoNT/A1 secondary failure in NDO through functional and structural analysis. Three groups of patients (either non-NDO, NDO with no toxin history or toxin secondary failure) were investigated using an ex vivo bladder strip assay. Detrusor strips were tensed in organ baths and submitted to electrical field stimulation to generate contractions. Recombinant BoNT/A1 was then added at various concentrations and contractions recorded for 4 h. Histology exploring BoNT/A1 targets, fibrosis and neuronal markers was also used. Detrusor strips from patients with BoNT/A1 secondary failure displayed a smaller sensitivity to toxin ex vivo at 3 nM compared to the other groups. Histological evaluation demonstrated the presence of cleaved Synaptosomal-Associated Protein, 25 kDa (c-SNAP25) in the detrusor from the toxin-secondary failure population, indicating some remaining in vivo sensitivity to BoNT/A1 despite the therapeutic escape. Moreover, residual c-SNAP25 did not affect parasympathetic-driven contractions observed ex vivo. This study confirms the slightly lower efficacy of BoNT/A1 in the BoNT/A1 secondary failure NDO group, suggesting that the escape from BoNT/A1 efficacy in NDO occurs at least at the parasympathetic level and could imply compensatory mechanisms for detrusor contraction.

Botulinum Toxin: From Poison to Possible Treatment for Spasticity in Spinal Cord Injury

Botulism has been known for about three centuries, and since its discovery, botulinum toxin has been considered one of the most powerful toxins. However, throughout the 20th century, several medical applications have been discovered, among which the treatment of spasticity stands out. Botulinum toxin is the only pharmacological treatment recommended for spasticity of strokes and cerebral palsy. Although its use as an adjuvant treatment against spasticity in spinal cord injuries is not even approved, botulinum toxin is being used against such injuries. This article describes the advances that have been made throughout history leading to the therapeutic use of botulinum toxin and, in particular, its application to the treatment of spasticity in spinal cord injury.

Development of an alternative approach for detecting botulinum neurotoxin type A in honey: Analysis of non-toxic peptides with a reference labelled protein via liquid chromatography-tandem mass spectrometry

In this study, we developed a reference labelled protein containing the partial amino acid sequence of botulinum neurotoxin type A (BoNTA). We also applied it as an internal standard to detect specific and non-toxic peptides originated from BoNTA in honey with the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS). Original proteins in the honey sample were collected through a two-step process that included solubilisation and trichloroacetic acid (TCA) precipitation. Solubilisation by adding water enabled processing of proteins in honey. TCA precipitation collected proteins without specific binding. The combination of protein alkylation and an appropriate enzyme-to-protein ratio ensured feasibility of tryptic digestion. A desalting process eliminated a large amount of salts and other tryptic peptides in the honey sample. The use of the reference labelled protein enabled compensation for tryptic digestion efficiency and electrospray ionisation efficiency based on LC-MS/MS measurement. After the peptide selection and protein BlastP analysis, five unique peptides were chosen. The non-toxic peptides originating from BoNTA were reliably detected using LC-MS/MS based on a multiple-reaction monitoring mode. Detection of several peptides ensured screening of BoNTA in honey samples. Based on the responses, the proteotypic peptide LYGIAINPNR was selected as the quantitative peptide. Due to maintaining the relative ion ratios, the selective transition completely identified the non-toxic peptides. The intensity of the transitions established a detection limit of BoNTA estimated to be 9.4 ng mL^-1. Although extraction efficiency was not evaluated using the BoNTA standard, the results suggested this method may be used for quantification of BoNTA in honey. The method was applied to 19 honey samples purchased in Tokyo; none of them was found to contain the target toxin. Overall, the method is expected to accelerate BoNTA monitoring for food safety.

Are 200 units of onabotulinumtoxin A sufficient for the suppression of neurogenic detrusor overactivity in individuals with established 300-unit botulinum toxin treatment? A retrospective cohort study

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To investigate the effects of 200-unit onabotulinumtoxin A detrusor injections on neurogenic detrusor overactivity (NDO) in patients who have previously been treated with 300-unit injections.

SETTING

Tertiary urologic referral center in Switzerland.

METHODS

The patient database was screened for patients with NDO as a result of chronic (≥ 12 months) spinal cord injury (SCI), who had been treated with 300- followed by 200-unit onabotulinumtoxin A detrusor injections. Patient characteristics, bladder management data and concurrent bladder medication as well as urodynamic data were collected. The percent changes in the urodynamic parameters from the 300- to the 200-unit treatment phase were calculated to test for non-inferiority of the 200-unit treatment.

RESULTS

The data of 61 individuals with a mean age of 44 ± 15 years (range 18-73 years) and a mean 13.2 ± 9.5 years (range 2-43 years) since SCI were analyzed. The 200-unit treatment was not inferior regarding the urodynamic parameters compared to the 300-unit treatment. Furthermore, the proportion of patients with urinary incontinence was similar for both doses. There was no significant difference in the number of daily bladder evacuations (p = 0.13) or used incontinence pads (p = 0.43) between the two dosage phases. Moreover, there was no significant (p = 0.19) increase in the use of concurrent NDO medication (antimuscarinics or mirabegron) during the 200-unit treatment.

CONCLUSIONS

The treatment of NDO with 200 units of onabotulinumtoxin A was not inferior to a 300-unit treatment regarding urodynamic parameters in patients with chronic SCI.

Effect of Botulinum Toxin A on Bladder Pain-Molecular Evidence and Animal Studies

Botulinum toxin A (BTX-A) is a powerful neurotoxin with long-lasting activity that blocks muscle contractions. In addition to effects on neuromuscular junctions, BTX-A also plays a role in sensory feedback loops, suggesting the potentiality for pain relief. Although the only approved indications for BTX-A in the bladder are neurogenic detrusor overactivity and refractory overactive bladder, BTX-A injections to treat bladder pain refractory to conventional therapies are also recommended. The mechanism of BTX-A activity in bladder pain is complex, with several hypotheses proposed in recent studies. Here we comprehensively reviewed properties of BTX-A in peripheral afferent and efferent nerves, the inhibition of nociceptive neurotransmitter release, the reduction of stretch-related visceral pain, and its anti-inflammatory effects on the bladder urothelium. Studies have also revealed possible effects of BTX-A in the human brain. However, further basic and clinical studies are warranted to provide solid evidence-based support in using BTX-A to treat bladder pain.