The effects of purified botulinum neurotoxin type A on cholinergic, adrenergic and non-adrenergic, atropine-resistant autonomic neuromuscular transmission

Chapitre C-l C - Traitement pharmacologique de l’hyperactivité détrusorienne neurologique : injections intra-détrusoriennes de toxine botulique A

Botulinum toxins are among the most powerful of all natural poisons. They are responsible for human botulism and constitute potential chemical weapons, but are nevertheless used as therapeutic agents in an increasing number of indications and medical specialties. Botulinum toxins were used for the first time in urology by intrasphincteric injection by Dykstra in 1988 to treat detrusor-sphincter dyssynergia in spinal cord injury patients. Schurch performed the first intradetrusor injections in 2000 to treat incontinence due to overactive bladder in adult spinal cord injury or multiple sclerosis patients. This review of the literature presents the results and level of proof for the use of botulinum toxin intradetrusor injection to treat neurogenic voiding disorders. Botulinum toxin A intradetrusor injections constitute a safe, conservative, reversible and short-term effective (6-12 months) alternative after failure of anticholinergic therapy for overactive bladder and its clinical consequences in adult spinal cord injury or multiple sclerosis patients (level 1b) and in children with neural tube defects (level 4). The efficacy of the first injection appears to be maintained at subsequent injections (up to 10 cycles) (level 4). Convergent and longer-term data are necessary to document and more clearly define the medium- and long-term efficacy profile of this approach, currently considered to be a major progress in neurourology.

The structure and mode of action of different botulinum toxins

The seven serotypes (A-G) of botulinum neurotoxin (BoNT) are proteins produced by Clostridium botulinum and have multifunctional abilities: (i) they target cholinergic nerve endings via binding to ecto-acceptors (ii) they undergo endocytosis/translocation and (iii) their light chains act intraneuronally to block acetylcholine release. The fundamental process of quantal transmitter release occurs by Ca2+-regulated exocytosis involving sensitive factor attachment protein-25 (SNAP-25), syntaxin and synaptobrevin. Proteolytic cleavage by BoNT-A of nine amino acids from the C-terminal of SNAP-25 disables its function, causing prolonged muscle weakness. This unique combination of activities underlies the effectiveness of BoNT-A haemagglutinin complex in treating human conditions resulting from hyperactivity at peripheral cholinergic nerve endings. In vivo imaging and immunomicroscopy of murine muscles injected with type A toxin revealed that the extended duration of action results from the longevity of its protease, persistence of the cleaved SNAP-25 and a protracted time course for the remodelling of treated nerve-muscle synapses. In addition, an application in pain management has been indicated by the ability of BoNT to inhibit neuropeptide release from nociceptors, thereby blocking central and peripheral pain sensitization processes. The widespread cellular distribution of SNAP-25 and the diversity of the toxin's neuronal acceptors are being exploited for other therapeutic applications.

Botulinum Toxin Type A Injections Into the Trigone to Treat Idiopathic Overactive Bladder do Not Induce Vesicoureteral Reflux

PURPOSE

We assessed the generation of vesicoureteral reflux before and after injection of botulinum toxin A into the trigone of patients with nonneurogenic overactive bladder, and evaluated its short-term efficacy.

MATERIALS AND METHODS

Adults with nonneurogenic overactive bladder resistant to behavioral treatments, pelvic floor exercises, medication and neuromodulation were included in the study. The initial evaluation (history, physical examination, 3-day urinary diary, V8 score, flowmetry and post-void residual) was repeated 6 weeks after botulinum toxin A injection. Videourodynamic study was performed 1 hour before injection and 6 weeks later. Botulinum toxin A (200 units) was injected into the detrusor in 10 sites over the bladder base including the trigone. The primary outcome was the presence or absence of vesicoureteral reflux before and 6 weeks after botulinum toxin A injection. The secondary outcomes were clinical and urodynamic parameter changes. Values were compared using the Wilcoxon test.

RESULTS

A total of 12 women were enrolled in the study (median age 76 years). The duration of symptoms was 7.5 years. One patient was excluded from analysis because of a urinary tract infection. There were 10 women with no vesicoureteral reflux at baseline and 1 had bilateral vesicoureteral reflux (grade 2 right, grade 1 left). At 6 weeks there was no induced vesicoureteral reflux and the patient with vesicoureteral reflux at baseline showed no change in vesicoureteral reflux grade. No local or systemic side effects related to botulinum toxin A were reported. In terms of efficacy, at direct questioning 6 weeks after treatment 4 of 11 patients reported an improvement that made them ask for another injection.

CONCLUSIONS

Botulinum toxin A injection into the trigone does not induce de novo vesicoureteral reflux in patients with nonneurogenic overactive bladder. The therapeutic value of this approach remains to be confirmed and compared to other injection designs.

Pannexin: to gap or not to gap, is that a question?

Vertebrates express two families of gap junction proteins: the well characterized connexins and the recently discovered pannexins. The latter are related to invertebrate innexins. Here we present the hypothesis that pannexins, rather than providing a redundant system to gap junctions formed by connexins, exert a physiological role as nonjunctional membrane channels. Specifically, we propose that pannexins can serve as ATP release channels. This function presumptively is also performed by innexins in invertebrates, in addition to their traditional gap junction role.

The application of botulinum toxin in the prostate

PURPOSE

Botulinum neurotoxin is the most potent naturally occurring toxin known to inhibit various neurotransmitters. Injection of botulinum neurotoxin into the bladder and urethral sphincter has been used to treat bladder hyperactivity and sphincter dyssynergia. Recently botulinum neurotoxin application was extended to prostate disorders. Why would a urologist want to target the prostate?

MATERIALS AND METHODS

We reviewed the literature on the mechanisms of action and clinical efficacy of botulinum neurotoxin treatment of the prostate. In addition to our personal clinical experience and basic research, information was gathered from MEDLINE and published abstracts from international meetings. We also present basic research and discuss the potential mechanism of action of botulinum neurotoxin on the prostate.

RESULTS

There are 8 current peer reviewed publications on the injection of botulinum neurotoxin in the prostate. Cystoscopic transurethral or transperineal/transrectal ultrasound guided techniques have been used. Outcome improvement reported includes decreases in prostate size, prostate specific antigen and residual urine volume, and improvement in the flow rate and symptom score lasting 6 months or longer.

CONCLUSIONS

Botulinum toxin has demonstrated exciting and promising preliminary results for male lower urinary tract symptoms. Translational research suggests novel mechanism of action of botulinum toxin in the prostate for benign prostatic hyperplasia and chronic nonbacterial prostatitis. It may even be considered as adjuvant treatment for prostate cancer. The use of botulinum neurotoxin in the prostate is currently Food and Drug Administration off label and in support of evidence based medicine practices caution should be applied until larger, randomized clinical studies are completed. More basic research is needed to identify the mechanisms by which botulinum toxin affects the prostate.

Effectiveness of repeated treatment with botulinum toxin type A across different conditions

This review assessed the overall effectiveness of repeated treatments with botulinum toxin type A (BoNTA) across different conditions, as documented in the published literature. Forty-four original research articles reporting on 16 different conditions were identified that included data on the duration or efficacy of multiple treatments with BoNTA. All of the 44 studies found sustained or enhanced improvement in efficacy and/or duration over the follow-up period, which ranged from a few treatments to more than 10 years. Dosages did not change over time in 22 of the studies, increased in 4 studies, were not reported over time in 17 studies, and tended to increase then decrease in one study. Seven studies reported a statistically significant increase in the efficacy or duration of BoNTA over time. Results suggest that continued benefit with repeated BoNTA treatment is widely reported in the literature.

Botulinum a toxin for the treatment of benign prostatic hyperplasia/lower urinary tract symptoms

Botulinum neurotoxin (BoNT) has been called the most poisonous poison and a potential bioterrorism weapon, and yet modern medicine has been able to harvest the elegant and specific activity of this toxin to treat a variety of medical conditions. BoNT application recently has been extended to prostate disorders, and this article reviews the literature on the mechanisms of action and clinical efficacy of BoNT treatment in the prostate. BoNT has demonstrated promising preliminary results for male lower urinary tract symptoms, and translational research suggests novel mechanism of action of BoNT in the prostate. It is important to remember that the application of BoNT in the prostate is not approved by the regulatory agencies and caution should be applied until larger randomized clinical studies are completed.

Intraprostatic injection of botulinum toxin type-A relieves bladder outlet obstruction in human and induces prostate apoptosis in dogs

BACKGROUND

With the increasing interest with botulinum toxin--A (BTX-A) application in the lower urinary tract, we investigated the BTX-A effects on the canine prostate and also in men with bladder outlet obstruction (BOO) due to benign prostatic hyperplasia (BPH).

METHODS

Transperineal injection into the prostate using transrectal ultrasound (TRUS) was performed throughout the study. Saline with or without 100 U of BTX-A was injected into mongrel dogs prostate. One or 3 months later, the prostate was harvested for morphologic and apoptotic study. In addition, eight BPH patients refractory to alpha-blockers were treated with ultrasound guided intraprostatic injection of 200 U of BTX-A.

RESULTS

In the BTX-A treated dogs, atrophy and diffuse apoptosis was observed with H&E stain and TUNEL stain at 1 and 3 months. Clinically, the mean prostate volume, symptom score, and quality of life index were significantly reduced by 18.8%, 73.1%, and 61.5% respectively. Maximal flow rate significantly increased by 72.0%.

CONCLUSION

Intraprostatic BTX-A injection induces prostate apotosis in dogs and relieves BOO in humans. It is therefore a promising alternative treatment for refractory BOO due to BPH.

Botulinum Toxin for the Management of Bladder Dysfunction

This review highlights a recent innovation in the medical treatment of detrusor overactivity (DO). Anticholinergics are usually the gold standard to treat bladder overactivity. Adverse effects and lack of efficacy are the two main causes for considering alternative treatments. Until recently, invasive surgery (mainly bladder augmentation) was the only available treatment option for patients with intractable DO. This article considers botulinum toxin type A (BTX-A) injection as an alternative treatment to surgery in patients with DO who do not respond to anticholinergic therapy. To identify papers for inclusion in this review, we searched PubMed with the keywords 'botulinum toxin', 'overactive bladder', 'urinary incontinence' and 'neurogenic bladder' for the years 2000-5. Review articles were not included. Abstracts were cited only if they contained important new information. Experimental animal studies and articles or book chapters related to the use of botulinum toxin for other indications (such as achalasia and cervical dystonia) were analysed with regard to the mechanisms of action of botulinum toxin. From this review, it appears that BTX-A injection into the detrusor muscle is a very effective method for treating urinary incontinence secondary to neurogenic detrusor overactivity (NDO), as well as urinary incontinence due to idiopathic overactive bladder (IDO). In both conditions, the duration of effect seems to be at least 6 months. Overall success rates seem to be similar in both patient populations. For NDO, only one evidence-based medicine level 1 study is available, whereas for IDO, only evidence-based medicine level 3 or 4 studies have been published. Particularly in this latter indication, injection technique and outcome parameters vary from study to study and need to be standardised. Without randomised controlled studies aimed at comparing different techniques and dosages, it remains difficult to decide what technique is optimal for treating patients with IDO who are not willing to perform clean intermittent self-catheterisation (CISC). Therefore, studies that compare different dosages and techniques with the risk of needing CISC in regard to the duration of the effect are mandatory. As more studies of repeated injections have been published, it appears that, at least at medium follow-up, the toxin remains as effective as after the first injection, and there is no evidence of change in bladder compliance or detrusor fibrosis. However, long-term observational studies are necessary to assess these last points. Finally, the commonly reported dose appears to be well tolerated, since few adverse effects have been reported.

Nicotinamide adenine dinucleotide is released from sympathetic nerve terminals via a botulinum neurotoxin A-mediated mechanism in canine mesenteric artery

Using high-performance liquid chromatography techniques with fluorescence and electrochemical detection, we found that beta-nicotinamide adenine dinucleotide (beta-NAD) is released in response to electrical field stimulation (4-16 Hz, 0.3 ms, 15 V, 120 s) along with ATP and norepinephrine (NE) in the canine isolated mesenteric arteries. The release of beta-NAD increases with number of pulses/stimulation frequencies. Immunohistochemistry analysis showed dense distribution of tyrosine hydroxylase-like immunoreactivity (TH-LI) and sparse distribution of TH-LI-negative nerve processes, suggesting that these blood vessels are primarily under sympathetic nervous system control with some contribution of other (e.g., sensory) neurons. Exogenous NE (3 micromol/l), alpha,beta-methylene ATP (1 micromol/l), neuropeptide Y (NPY, 0.1 micromol/l), CGRP (0.1 micromol/l), vasoactive intestinal peptide (VIP, 0.1 micromol/l), and substance P (SP, 0.1 micromol/l) had no effect on the basal release of beta-NAD, suggesting that the overflow of beta-NAD is evoked by neither the sympathetic neurotransmitters NE, ATP, and NPY, nor the neuropeptides CGRP, VIP, and SP. Botulinum neurotoxin A (BoNTA, 0.1 micromol/l) abolished the evoked release of NE, ATP, and beta-NAD at 4 Hz, suggesting that at low levels of neural activity, release of these neurotransmitters results from N-ethylmaleimide-sensitive factor attachment protein receptor/synaptosomal-associated protein of 25 kDa-mediated exocytosis. At 16 Hz, however, the evoked release of NE, ATP, and beta-NAD was reduced by BoNTA by approximately 90, 60, and 80%, respectively, suggesting that at higher levels of neural activity, beta-NAD is likely to be released from different populations of synaptic vesicles or different populations of nerve terminals (i.e., sympathetic and sensory terminals).

Botulinum toxin injections for paediatric incontinence

PURPOSE OF REVIEW

This review highlights a recent innovation in the medical treatment of children with neurogenic detrusor overactivity. Anticholinergics are usually the main way to treat bladder overactivity. Side effects and lack of efficacy are the two main causes for considering alternative treatment. Up to recently, invasive surgery, mainly bladder augmentation, was the only available treatment for these intractable bladders. Here, we report on botulinum A toxin injection as an alternative to surgery in children with neurogenic detrusor overactivity.

RECENT FINDINGS

There are only four published articles on the use of botulinum A toxin in children with neurogenic detrusor overactivity. However, an increasing number of reports indicate clinical benefit and a good safety profile of botulinum A toxin in neurogenic and idiopathic detrusor overactivity. Extrapolation of the data published in adults treated with botulinum A toxin injections and understanding the mechanism of action on the detrusor muscle are worthwhile to encourage paediatric physicians to propose this option to their patients. Furthermore, the literature does not seem to warn against drug resistance or ultrastructural changes of the detrusor after repeated injection.

SUMMARY

Botulinum A toxin appears to be a reasonable alternative to surgery in the management of intractable overactive bladder in children. However, studies of the delivery method, site of injection, dose and long-term follow-up are required to confirm the good safety profile/clinical benefit of this new, minimally invasive approach.

Botulinum toxin for the treatment of lower urinary tract symptoms: A review

AIMS

To review the available literature on the application of botulinum toxin in the urinary tract, with particular reference to its use in treating detrusor overactivity (DO).

METHODS

Botulinum toxin, overactive bladder (OAB), detrusor instability, DO, detrusor sphincter dyssynergia (DSD), and lower urinary tract dysfunction were used on Medline Services as a source of articles for the review process.

RESULTS

DO poses a significant burden on patients and their quality of life. Traditionally patients have been treated with anti-cholinergic drugs if symptomatic, however, a significant number find this treatment either ineffective or intolerable due to side effects. Recent developments in this field have instigated new treatment options, including botulinum toxin, for patients' refractory to first line medication. Botulinum toxin, one of the most poisonous substances known to man, is a neurotoxin produced by the bacterium Clostridium botulinum. Botulinum toxin injections into the external urethral sphincter to treat detrusor sphincter dyssynergia has been successfully used for some years but recently its use has expanded to include voiding dysfunction. Intradetrusal injections of botulinum toxin into patients with detrusor overactivity and symptoms of the overactive bladder have resulted in significant increases in mean maximum cystometric capacity and detrusor compliance with a reduction in mean maximum detrusor pressures. Subjective and objective assessments in these patients has shown significant improvements that last for 9-12 months. Repeated injections have had the same sustained benefits.

CONCLUSIONS

Application of botulinum toxin in the lower urinary tract has produced promising results in treating lower urinary tract dysfunction, which needs further evaluation with randomised, placebo-controlled trials.

Treating chronic anal fissure with botulinum neurotoxin

Recent reports confirm that the management of chronic anal fissure has undergone extensive re-evaluation during the past few years. This rejuvenation of interest is attributable to the application of neurochemical treatment, which has contributed to the tendency to treat the disease on an outpatient basis. The use of botulinum neurotoxin seems to be a promising and safe approach for the treatment of chronic anal fissure, particularly in patients at high risk for incontinence. Indeed, botulinum neurotoxin has been successfully used selectively to weaken the internal anal sphincter as a treatment for chronic anal fissure. It is also more efficacious than nitrate therapy, and is not related to the patient's willingness to complete treatment.

Emerging role of botulinum toxin in the management of voiding dysfunction

PURPOSE

In recent years there has been tremendous excitement over the use of botulinum neurotoxin (BTX) to treat various urethral and bladder dysfunctions. BTX is the most potent, naturally occurring toxin known to mankind. Why, then, would a urologist want to use this agent to poison the bladder or urethral sphincter?

MATERIALS AND METHODS

We reviewed the recent literature on the mechanisms underlying the effects of BTX treatment and discuss current use of this agent within the urological community, as well as provide perspective on future targets of BTX. The information was gathered from MEDLINE, abstracts from recent urological meetings and personal experience.

RESULTS

Injection of BTX appears to have a positive therapeutic effect in multiple urological conditions, including detrusor hyperreflexia and detrusor external sphincter dyssynergia, and nonneurogenic conditions such as pelvic floor spasticity, refractory overactive bladder and, possibly, benign prostatic hyperplasia. Interstitial cystitis may even be potentially helped with bladder BTX injection.

CONCLUSIONS

Botulinum toxin is a novel and promising treatment for a variety of lower urinary tract dysfunctions. The basic science behind its mechanism of action and physiology, and published clinical results are impressive. However, since application of BTX in the lower urinary tract has not been approved by the Food and Drug Administration, caution should be used until future properly designed, multicenter randomized studies are completed to assess the safety and efficacy of BTX in urological diseases.

Treatment with botulinum neurotoxin of gastrointestinal smooth muscles and sphincters spasms

Local injections of botulinum neurotoxin are now considered an efficacious treatment for neurological and non-neurological conditions. One of the most recent achievements in the field is the observation that botulinum neurotoxin provides benefit in diseases of the gastrointestinal tract. Botulinum neurotoxin inhibits contraction of gastrointestinal smooth muscles and sphincters; it has also been shown that the neurotoxin blocks cholinergic nerve endings in the autonomic nervous system, but it does not block nonadrenergic responses mediated by nitric oxide. This aspect has further promoted the interest to use botulinum neurotoxin as a treatment for overactive smooth muscles, such as the anal sphincters to treat anal fissure and outlet-type constipation, or the lower esophageal sphincter to treat esophageal achalasia. Knowledge of the anatomical and functional organization of innervation of the gastrointestinal tract is a prerequisite to understanding many features of botulinum neurotoxin action on the gut and the effects of injections placed into specific sphincters. This review presents current data on the use of botulinum neurotoxin to treat diseases of the gastrointestinal tract and summarizes recent knowledge on the pathogenesis of disorders of the gut due to a dysfunction of the enteric nervous system.

Differential distribution and regulation of expression of synaptosomal-associated protein of 25 kDa isoforms in the Xenopus pituitary gland and brain

Synaptosomal-associated protein of 25 kDa (SNAP-25) regulates various membrane fusion processes including exocytosis by endocrine and neural cells. To increase our understanding of the occurrence and regulation of SNAP-25 isoforms, we identified and characterized SNAP-25a and SNAP-25b mRNAs in the pituitary gland and brain of the amphibian Xenopus laevis. The proteins are strongly conserved and are resistant to botulinum neurotoxin A but not to botulinum neurotoxin E, as shown by Western blotting. The spatial distribution of the two SNAP-25 isoforms was assessed with in situ hybridization. Both SNAP-25a mRNA and SNAP-25b mRNA reside in cells in the pituitary distal lobe and, particularly, in the endocrine melanotrope cells in the pituitary intermediate lobe. The melanotrope cells are involved in the background adaptation process of the skin by releasing alpha-melanophore-stimulating hormone. Quantitation of the respective in situ hybridization signals in the Xenopus pars intermedia indicated a differential response, SNAP-25b mRNA being more highly expressed in black-adapted animals than SNAP-25a mRNA, and more than in white-adapted toads. This differential upregulation was also studied by real-time reverse transcriptase polymerase chain reaction, showing that in the intermediate pituitary lobe, both isoforms are physiologically controlled by the background light intensity stimulus, but with different intensities; in black-adapted animals SNAP-25b mRNA is upregulated by 3.33 times compared with white-adapted animals, but SNAP-25a only by 1.96 times. As to neural tissue, in situ hybridization showed that both isoforms coexist throughout the brain, sometimes with similar strengths, but in various areas either SNAP-25a mRNA or SNAP-25b mRNA expression is prevalent. It is speculated that each of the SNAP-25 isoforms in the Xenopus pituitary and brain has a distinct function in cellular fusion processes including secretion, and that their occurrence and regulation depend on the type of secreted neurotransmitter/hormone and/or the activity state of the cell.

Botulinum toxin in the management of bowel and bladder function in spinal cord injury and other neurologic disorders

Botulinum toxin inhibits release of acetylcholine and other neurotransmitters. It has been used successfully to treat pain and abnormal skeletal and smooth muscle activity in patients. This article discusses its use in patients with bladder and bowel disorders.

Mechanism of action of botulinum toxin on the internal anal sphincter

Background

Botulinum toxin is an effective treatment for anal fissure. Manometric studies support an apparent action of botulinum toxin on the internal anal sphincter (IAS). This aim of this study was to establish the underlying mechanism.

Methods

Porcine IAS strips were suspended in a superfusion organ bath and allowed to equilibrate. Electrical field stimulation (EFS) was applied with parameters that induced nitrergic relaxation followed by noradrenaline-mediated contraction. These responses were compared before and after addition of botulinum toxin.

Results

All strips developed myogenic tone, which was slightly increased following the addition of botulinum toxin. EFS-induced nitrergic relaxation was unaffected by toxin treatment. However, EFS-induced contraction was significantly reduced by toxin treatment. 1,1-Dimethyl-4-phenylpiperazinium iodide (DMPP), a nicotinic agonist, caused muscle strip contraction, which was blocked by guanethidine, implying the presence of sympathetic ganglia within the IAS. Botulinum toxin significantly attenuated DMPP-induced contraction.

Conclusion

In the treatment of anal fissure the major effect of botulinum toxin on the IAS is blockade of sympathetic (noradrenaline mediated) neural output. This is probably a postganglionic action, involving a reduction in noradrenaline release at the neuromuscular junction. Botulinum toxin has no significant effect on nitrergic transmission, which is probably not vesicular in nature.

Botulinum toxin injection inhibits myogenic tone and sympathetic nerve function in the porcine internal anal sphincter

OBJECTIVE

Botulinum toxin is an effective treatment for anal fissure, though there is a lack of agreement over the optimal site for its injection. This reflects our current ignorance of its mechanism, and whether it has any action on the nerves of the internal anal sphincter (IAS). This study set out to resolve this issue through use of a pig model.

MATERIALS AND METHODS

Eight pigs were studied in pairs: one of each pair received a botulinum toxin injection into the anal sphincter, whilst the other acted as its control. Manometry was performed every two weeks under anaesthesia. Pigs were slaughtered at between four and six weeks after injection and the properties of the IAS compared in vitro.

RESULTS

Whilst maximum anal resting pressure (MARP) increased slowly in control pigs during the experimental period, reflecting weight gain, a fall was observed in treated pigs. In vitro, IAS strips from control pigs generated 400 mg of spontaneous tone per gram of tissue (+/- 45; standard error), compared to 250 (+/- 25) mg/g tissue from treated pigs (P < 0.01). Electric Field Stimulation at 50 Hz produced 150 (+/- 22) mg contraction/gram tissue in IAS strips from control pigs compared to 53 (+/- 13) mg/g tissue in treated pigs (P < 0.0005). This contractile response was blocked by guanethidine.

CONCLUSION

Botulinum toxin has a significant action on the IAS. It reduces myogenic tone and contractile responses of this tissue to sympathetic nerve stimulation. Further studies are required to clarify its mechanism of action more precisely.

Inhibitory effects of botulinum toxin on pyloric and antral smooth muscle

Botulinum toxin injection into the pylorus is reported to improve gastric emptying in gastroparesis. Classically, botulinum toxin inhibits ACh release from cholinergic nerves in skeletal muscle. The aim of this study was to determine the effects of botulinum toxin on pyloric smooth muscle. Guinea pig pyloric muscle strips were studied in vitro. Botulinum toxin type A was added; electric field stimulation (EFS) was performed every 30 min for 6 h. ACh (100 microM)-induced contractile responses were determined before and after 6 h. Botulinum toxin caused a concentration-dependent decrease of pyloric contractions to EFS. At a low concentration (2 U/ml), botulinum toxin decreased pyloric contractions to EFS by 43 +/- 9% without affecting ACh-induced contractions. At higher concentrations (10 U/ml), botulinum toxin decreased pyloric contraction to EFS by 75 +/- 7% and decreased ACh-induced contraction by 79 +/- 9%. In conclusion, botulinum toxin inhibits pyloric smooth muscle contractility. At a low concentration, botulinum toxin decreases EFS-induced contractile responses without affecting ACh-induced contractions suggesting inhibition of ACh release from cholinergic nerves. At higher concentrations, botulinum toxin directly inhibits smooth muscle contractility as evidenced by the decreased contractile response to ACh.

Botulinum toxin as a new therapy option for voiding disorders: current state of the art

Botulinum toxin is a presynaptic neuromuscular blocking agent inducing selective and reversible muscle weakness up to several months when injected intramuscularly in minute quantities. Different medical disciplines have discovered the toxin to treat mainly muscular hypercontraction. In urology, indications for botulinum-A toxin have been neurogenic detrusor overactivity, detrusor-sphincter dyssynergia, motor and sensory urge and, more recently, chronic prostatic pain. The available literature was reviewed using Medline Services. The keywords "botulinum-A toxin", "detrusor-sphincter dyssynergia", "neurogenic bladder", "spinal cord injury", "denervation", "chronic prostatic pain", "chronic urinary retention" were used to obtain references. A toxin injection is effective to treat detrusor-sphincter dyssynergia when injected either transurethrally or transperineally. After treatment, external urethral sphincter pressure, voiding pressure and post-void residual volume decreased. The effect lasts between 2 to 9 months depending on the number of injections. Best indications seem to be multiple sclerosis and incomplete spinal cord injury patients suffering from neurogenic detrusor overactivity and detrusor-sphincter dyssynergia. According to the previous results, the use of botulinum-A toxin injections into the external urethral sphincter has been extended to a variety of bladder obstructions and to decrease outlet resistance in patients with acontractile detrusor. In cases of successful treatment, spontaneous voiding re-occurs and catheterization can be resumed. Injections of the toxin into the external urethral sphincter also seem to have a beneficial effect on chronic prostatic pain, presumably by reducing hypertonicity and hyperactivity of the external urethral sphincter. Injections of botulinum-A toxin into the detrusor muscle has first been tested to treat neurogenic detrusor activity in spinal cord injured patients and in myelomeningocele children. Long lasting (mean 9 months) detrusor relaxation occurs after injection of usually 300 units of Botox). Continence is restored in about 95% of the patients and anticholinergic drugs can be markedly reduced or even stopped. Excellent results of botulinum-A toxin injections into the detrusor in neurogenic detrusor overactivity have lead to an expansion of this treatment to incontinence due to idiopathic detrusor overactivity. Although preliminary results are promising, adequate dosage of the toxin required for this indication is not yet known. In conclusion, it appears that botulinum toxin injection into either the external urethral sphincter or the detrusor offers new promising treatment options for many different urological dysfunctions. However, large controlled trials are absolutely required to establish the role of botulinum-A toxin injections in the fields of urology and neurourology on evidence based medicine.

Effect of stimulation intensity and botulinum toxin isoform on rat bladder strip contractions

The present experiments compared the inhibitory effects of botulinum toxin A (BoNT-A) and botulinum toxin D (BoNT-D) on neurally evoked contractions of rat bladder strips. We examined the effect of fatigue (trains of 100 shocks at 20Hz every 20s for 10min) followed by non-fatigue stimulation (trains of 100 shocks at 20Hz every 100s for 20min) on the onset of effect and potency of the two toxins. For non-fatigue experiments, strips were untreated (n=4); or incubated with 1.36nM BoNT-A (n=4). During fatigue experiments, strips were untreated (n=5); or treated with either 1.36nM BoNT-A (n=6) or 0.8nM BoNT-D (n=6). In non-fatigue experiments, BoNT-A produced significant decreases in contractile area after 1h of stimulation compared to untreated strips (P<0.05). After three series of fatigue stimulation, differences in recovery amplitude and area between untreated versus BoNT-A, and untreated versus BoNT-D bladder strips, were statistically significant (P<0.05). The onset of inhibitory effect was quicker in BoNT-D-treated strips, as a significant reduction (P<0.05) in recovery of contractile area was observed after 1h of stimulation compared to both untreated and BoNT-A-treated preparations. In addition, treated (BoNT-A and BoNT-D) and untreated bladder strips responded similarly to atropine, suggesting that the effects of BoNT result from inhibition of both acetylcholine and ATP release. Our results demonstrate that BoNT-D may be a more effective agent to inhibit transmitter release from autonomic nerves of the rat lower urinary tract. Moreover, in our hands, non-fatigue stimulation is as effective as fatigue stimulation in inhibiting bladder strip contractions.

[Efficacy of botulinum toxin A for the treatment of detrusor hyperreflexia]

OBJECTIVE

To determinate the efficacy of botulinum toxin to treat refractory urinary incontinence due to bladder hyperreflexia.

METHOD

The international medical literature was reviewed from the Medline and Pubmed database.

DISCUSSION

The usual first line treatment of detrusor hyperreflexia is parasympathicolytic drugs and self cathterization. In case of lack of efficacy or severe side effects, a surgical procedure (enterocystoplasty) can be performed. 300 units of Botox injected into the detrusor permit a significant increase of bladder capacity and a significant decrease of maximal detrusor pressure for at last 6 months. But we did not find any double blind controlled studies in this indication and no fundamental studies focused on the mechanism of action of botulinum toxin on the bladder muscle. It is now impossible to conclude on the long term efficacy and toxicity.

CONCLUSION

Botulinum toxin injected into the detrusor muscle seems to be an efficient treatment of bladder hyperreflexia for 6 months in patients resistant to parasympathicolytic drugs. Long term efficacy and mechanism of action is actually not known.

Review article: botulinum toxin in the therapy of gastrointestinal motility disorders

Since 1980, botulinum toxin has been employed for the treatment of various voluntary muscle spastic disorders in the fields of neurology and ophthalmology. More recently, botulinum toxin has been proved to be effective in the therapy of dyskinetic smooth muscle disorders of the gastrointestinal tract. Achalasia and anal fissure are the gastrointestinal disorders in which botulinum toxin therapy has been most extensively investigated. Botulinum toxin is the best treatment option for achalasia in patients whose condition makes them unfit for pneumatic dilation or surgery. In anal fissure, botulinum toxin is highly effective and may become the treatment of choice. In the future, botulinum toxin application in the gastrointestinal tract will be extended to many other gastrointestinal disorders, such as non-achalasic motor disorders of the oesophagus, dysfunction of Oddi's sphincter, achalasia of the internal anal sphincter and others. This article describes the mechanism of action, rationale of employment, indications and side-effects of botulinum toxin application in smooth muscle disorders of the gastrointestinal tract, and compares the results of different techniques of botulinum toxin therapeutic application.

[Mode of action of botulinum neurotoxin: pathological, cellular and molecular aspect]

Several bacteria of the Clostridium genus (C. botulinum) produce 150 kDa di-chainal protein toxins referred as botulinum neurotoxins or BoNTs. They associate with non-toxic companion proteins and form a complex termed botulinum toxin or BoTx. The latter is used in clinic for therapeutic purpose. BoNTs affect cholinergic nerve terminals in periphery where they block acetylcholine release, thereby causing dysautonomia and motorparalysis (i.e. botulism). The cellular action of BoNTs can be depicted according to a three steps model: binding, internalisation and intraneuronal action. The toxins heavy chain mediates binding to specific receptors followed by endocytotic internalisation of BoNT/receptor complex. BoNT receptors may comprise gangliosides and synaptic vesicle-associated proteins as synaptotagmins. Vesicle recycling induces BoNT internalisation. Upon acidification of vesicles, the light chain of the neurotoxin is translocated into the cytosol. Here, this zinc-endopeptidase cleaves one or two among three synaptic proteins (VAMP-synaptobrevin, SNAP25, and syntaxin). As the three protein targets of BoNT play major role in fusion of synaptic vesicles at the release sites, their cleavage is followed by blockage of neurotransmitter exocytosis. The duration of the paralytic effect of the BoNTs is determined by 1) the turnover of their protein target; 2) the time-life of the toxin light chain in the cytosol, and 3) the sprouting of new nerve-endings that are retracted when the poisoned nerve terminal had recovered its full functionality.

Effect of botulinum toxin A on the autonomic nervous system of the rat lower urinary tract

PURPOSE

The magnitude and duration of the effects of botulinum toxin A on acetylcholine (ACh) and norepinephrine release from the bladder and urethra of rats were measured using a radiochemical method.

MATERIALS AND METHODS

Saline (sham treatment) or botulinum toxin A was injected into the bladder (50 microl.) or urethra (30 microl.) in separate groups of animals. The release of 3H-norepinephrine or 14C-choline was measured at 2 time points after injection (5 or 30 days).

RESULTS

The fractional release of ACh in botulinum toxin A treated animals was significantly inhibited at higher frequencies of electrical field stimulation (20 Hz.) but not at lower frequencies (2 Hz.) 5 days after injection. However, ACh release recovered to sham injected values 30 days after toxin injection. No significant differences in the fractional release of norepinephrine from sham injected or botulinum toxin A bladders were observed. In contrast, norepinephrine release from the urethra was inhibited by botulinum toxin A for at least 30 days after injection. Similar to its effect on transmitter release in the bladder, botulinum toxin A inhibited norepinephrine release in the urethra at high (20 Hz.) but not at low (4 Hz.) electrical stimulation frequencies.

CONCLUSIONS

These data indicate that the clinical effects of botulinum toxin A on the lower urinary tract may vary depending on the site of injection and level of nerve activity.

Emerging role of botulinum toxin in the treatment of neurogenic and non-neurogenic voiding dysfunction

Botulinum toxin (BTX) is the most lethal naturally occurring toxin known to mankind. Why, then, would an urologist want to use this agent to poison the bladder or urethral sphincter? This article reviews the mechanisms underlying the effects of BTX treatment, summarizes the current usage of this agent within the urologic community, and provides perspectives on future targets of this therapy.

Achalasia: a review of therapeutic options and outcomes

Advances in achalasia has led to the development of new therapeutic options. This review will focus on methodology and outcomes of two established techniques; pneumatic dilation and surgical myotomy; and one new technique, LES injection of botulinum A toxin.

Botulinum neurotoxin and other treatments for fissure-in-ano and pelvic floor disorders

BACKGROUND

The management of disorders of the lower gastrointestinal tract, such as chronic anal fissure and pelvic floor dysfunction, has undergone re-evaluation recently. To a large extent this is due to the advent of neurochemical treatments, such as botulinum neurotoxin injections and topical nitrate ointment.

METHODS AND RESULTS

This review presents, inter alia, current data on the use of botulinum neurotoxin to treat lower gastrointestinal tract diseases, such as chronic anal fissure for which it promotes healing and symptom relief in up to 70 per cent of cases. This agent has also been used selectively to weaken the external anal sphincter and puborectalis muscle in constipation and in Parkinson's disease. Symptomatic improvement can also be induced in anterior rectocele by botulinum neurotoxin injections.

CONCLUSION

Botulinum neurotoxin appears to be a safe therapy for anal fissure. It is more efficacious than nitrate application and does not require patient compliance to complete treatment. While it may also be a promising approach for the treatment of chronic constipation due to pelvic floor dysfunction, further investigation of its efficacy and safety in this role is needed before general usage can be advocated.

Treatment of achalasia with botulinum A toxin

Achalasia is an idiopathic neuromuscular disorder of the esophagus which is associated with absence of esophageal peristalsis and incomplete relaxation of a normal or raised lower esophageal sphincter (LES). Dysphagia is the most commonly associated symptom. Conventional therapeutic approaches are directed to reducing LES pressure and include orally-administered smooth muscle relaxants, forceful sphincter dilation with balloon dilators, and open or laparoscopic-assisted myotomy of the LES. Pharmacologic therapies have a low success rate. Forceful dilation has a perforation complication rate of 2% to 5%, and myotomies may precipitate significant gastroesophageal reflux, a complication minimized when a partial fundal wrap is employed simultaneously. In recent years, botulinum toxin, utilized widely as a striated muscle relaxant in managing blepharospasm, anal sphincter spasm, and muscle spasm complicating CVAs, and in smoothening facial wrinkles, has been extended to the management of achalasia on the basis that it impairs smooth muscle responsiveness to acetylcholine. Eighty units of Botox (botulinum toxin) are injected directly into the endoscopically (endoscopic ultrasound techniques may facilitate localization) located LES region (20 units into each of 4 quadrants). Symptom relief lasting 6 months on average is experienced in more than 65% of treated patients, and the complication rate is negligible. This therapeutic option is reserved for patients too ill to undergo any surgical procedure and is most effective when the lower esophageal region is hypertonic.

Effectiveness of higher doses of botulinum toxin to induce healing in patients with chronic anal fissures

BACKGROUND

Botulinum toxin induces healing in patients with idiopathic anal fissures.

METHODS

One hundred-fifty patients with posterior anal fissures were treated with botulinum toxin injected in the internal anal sphincter on each side of the anterior midline. Subjects were randomized into 2 treatment groups based on the number of units of botulinum toxin injected. Patients in group I were treated with 20 units of botulinum toxin and, if the fissure persisted, were retreated with 30 units. Patients in group II were treated with 30 units and retreated with 50 units, if the fissure persisted.

RESULTS

The 2 groups were comparable in age, gender distribution, duration of symptoms, resting pressure, and maximum voluntary pressure at anorectal manometry. One month after the injection, examinations revealed complete healing in 55 patients (73%) from group I and 65 patients (87%) from group II (P =.04). Five patients from group II reported a mild incontinence of flatus that lasted 2 weeks after the treatment and disappeared spontaneously. The values of the resting anal pressure (P=.3) and the maximum voluntary pressure (P =.2) did not differ between the 2 groups. At 2 months' evaluation, a healing scar was found in 67 patients (89%) from group I and 72 patients (96%) from group II. A relapse of the fissure was observed in 6 patients (8%) from group I who had a healing scar at 1 month, and 2 other patients never healed. A persistent fissure was present in 3 patients from group II who had no other symptoms.

CONCLUSIONS

Botulinum toxin injected into the internal anal sphincter is effective in managing anal fissures and avoiding permanent complications. All patients were treated with the active drug and healed after 1 or 2 successive treatments. The results also confirm that higher doses account for a higher success rate, with little increase in complications or side effects, which is probably related to the diffusion of the toxin to the external sphincter.

Differential inhibition by botulinum neurotoxin A of cotransmitters released from autonomic vasodilator neurons

The role of the soluble NSF attachment protein receptor (SNARE) protein complex in release of multiple cotransmitters from autonomic vasodilator neurons was examined in isolated segments of guinea pig uterine arteries treated with botulinum neurotoxin A (BoNTA; 50 nM). Western blotting of protein extracts from uterine arteries demonstrated partial cleavage of synaptosomal-associated protein of 25 kDa (SNAP-25) to a NH2-terminal fragment of approximately 24 kDa by BoNTA. BoNTA reduced the amplitude (by 70-80%) of isometric contractions of arteries in response to repeated electrical stimulation of sympathetic axons at 1 or 10 Hz. The amplitude of neurogenic relaxations mediated by neuronal nitric oxide (NO) was not affected by BoNTA, whereas the duration of peptide-mediated neurogenic relaxations to stimulation at 10 Hz was reduced (67% reduction in integrated responses). In contrast, presynaptic cholinergic inhibition of neurogenic relaxations was abolished by BoNTA. These results demonstrate that the SNARE complex has differential involvement in release of cotransmitters from the same autonomic neurons: NO release is not dependent on synaptic vesicle exocytosis, acetylcholine release from small vesicles is highly dependent on the SNARE complex, and neuropeptide release from large vesicles involves SNARE proteins that may interact differently with regulatory factors such as calcium.

The pharmacology of the internal anal sphincter and new treatments of ano-rectal disorders

Surgical options for faecal incontinence in the presence of intact sphincters are limited. Furthermore, in patients with fissures, lateral sphincterotomy reduces anal sphincter hypertonia but there has been concern about complications. A greater understanding of the basic pharmacology of the internal anal sphincter has led to the development of novel treatments for both these disorders. A Medline review was undertaken for internal anal sphincter pharmacology, anal fissures and faecal incontinence. This review is based on these articles and those found by further cross-referencing. Nitric oxide released from non-adrenergic non-cholinergic nerves is the main inhibitory agent in the internal anal sphincter. Relaxations are also mediated through beta-adrenoceptors and muscarinic receptors. Stimulation of alpha-receptors results in contraction. Calcium and its entry through L-type calcium channels is important for the maintenance of tone. Nitric oxide donors produce reductions in resting anal tone and heal fissures but are associated with side-effects. Muscarinic agents and calcium channel antagonists show promise as low side-effect alternatives. Botulinum toxin appears more efficacious than other agents in healing fissures. To date, alpha-receptor agonists have been disappointing at improving incontinence. Further understanding of the pharmacology of the internal anal sphincter may permit the development of new agents to selectively target the tissue with greater efficacy and fewer side-effects.

Indications and efficacy of botulinum toxin in disorders of the gastrointestinal tract

In recent years, botulinum toxin type A (BT) has been found to be effective in the treatment of various spastic disorders of smooth muscle in the upper and lower gastrointestinal tract. The short-term efficacy of intrasphincteric injection of BT in achalasia is now well established, however, because of the chronic nature of the disease, patients will require repeated injections at regular intervals. In contrast, after a single injection into the anal sphincter, BT has impressively high healing rate with minimal side effects. BT remains a novel therapeutic approach in a range of other gastrointestinal motility disorders including diffuse oesophageal spasm, sphincter of Oddi dysfunction and anismus, and the list of its indications is increasing. BT seems to be safe but as its long-term effects remain unestablished, it should be used with caution in younger patients. In this review we discuss the mechanism of action, indications, efficacy and side-effects of BT with its use in various areas of gastrointestinal tract.

Different levels of immunoreactivity for synaptosomal-associated protein of 25 kDa in vasoconstrictor and vasodilator axons of guinea-pigs

Immunoreactivity (IR) for synaptosomal-associated protein of 25 kDa (SNAP-25) was examined in axons of autonomic vasoconstrictor and vasodilator neurons innervating the lingual and uterine arteries of guinea-pigs. Polyacrylamide gel electrophoresis and immunoblotting of protein extracts demonstrated a SNAP-25-IR band at 25 kDa in both arteries. Quantitative confocal microscopy demonstrated significantly higher levels of SNAP-25-IR in varicosities with IR for vasoactive intestinal peptide (VIP) than in adjacent axons with IR for tyrosine hydroxylase (TH). Levels of SNAP-25-IR in TH-IR axons, relative to adjacent VIP-IR axons, were significantly higher in the lingual artery than the uterine artery. These differences in IR for SNAP-25, a protein considered essential for calcium-dependent exocytosis of neurotransmitters, raise the possibility that mechanisms of transmitter release may vary between different classes of autonomic neurons.

Influence of botulinum toxin site of injections on healing rate in patients with chronic anal fissure

BACKGROUND

Botulinum toxin induces healing in patients with idiopathic anal fissure.

METHODS

Fifty patients affected by posterior anal fissure were treated with 20 units of botulinum toxin, injection in the internal anal sphincter on each side of the posterior midline (group I) or on each side of the anterior midline (group II).

RESULTS

At 2 months evaluation, a healing scar was observed in 15 patients of group I and in 22 patients of group II(P = 0.025). Resting anal pressure was significantly different from the baseline values at 1-month as well as at 2-month check-ups in both groups, but the values were significantly lower in patients of group II.

CONCLUSIONS

The intersite comparison revealed that anterior injection of the internal anal sphincter resulted in improved lowering of resting anal pressure and produced an earlier healing scar.

The association of Clostridium botulinum type C with equine grass sickness: a toxicoinfection?

The cause of grass sickness, an equine dysautonomia, is unknown. The disease usually results in death. Gastrointestinal (GI) dysfunction is a common clinical manifestation in all forms of the disease. It is generally thought that equine grass sickness (EGS) is caused by an ingested or enterically produced neurotoxin which is absorbed through the GI tract. Clostridium botulinum was first implicated as a causative agent when it was isolated from the GI tract of a horse with EGS in 1919. The aim of the present study was to investigate the hypothesis that EGS results from toxicoinfection with C. botulinum type C: growth of the bacterium in the GI tract with production of toxin (BoNT/C). Ileum contents and faeces from horses with EGS were investigated for BoNT/C, and indirectly for the presence of C. botulinum type C, and compared with control samples from horses without EGS. BoNT/C was detected directly by ELISA in the ileum of 45% (13/29) of horses with EGS compared to 4% (1/28) of controls, and in the faeces of 44% (20/45) of horses with EGS compared to 4% (3/77) of controls. Levels of up to 10 Mlg toxin/g wet weight of gut contents were observed. The one control horse with detectable toxin in the ileum had been clinically diagnosed as having acute EGS, but this was not confirmed by histopathology. The organism was detected indirectly by assaying for BoNT/C by ELISA after enrichment in culture medium. C. botulinum type C was shown to be present in 48% (14/29) of ileum samples and 44% (20/45) of faecal samples from horses with EGS, compared with 7% (2/27) of ileum samples and 8% (6/72) of faecal samples from controls. These results support the hypothesis that EGS results from a C. botulinum type C toxicoinfection.

Identification of anti-endothelial cell antibodies in patients with chronic anal fissure

BACKGROUND

Recent studies demonstrate that chronic anal fissure can be the consequence of a local ischemic process. Thus hypothesizing that at the perianal level the interaction of immune component with endothelium could constitute a mechanism determining ischemia and hypertonia, the presence or absence of circulating anti-endothelial cell antibodies (AECAs) was determined in the serum of patients with anal fissure.

METHODS

The study was carried out on 30 patients: 10 with posterior chronic anal fissure (group 1), 10 with grades III and IV hemorrhoids (group 2), and 10 without previous or active anorectal disease, or both (group 3). An indirect immunofluorescence assay on sections of rat kidney tissue was used to identify AECA in the peripheral blood.

RESULTS

The assay result was positive for AECAs in 12 patients, all with anorectal disease when compared to the control group (P = .001). The basal anal tone was higher in the AECA-positive patients than in the AECA-negative patients (P = .001).

CONCLUSIONS

Only the patients with anal fissure or hemorrhoids were AECA positive. All healthy controls tested negative for AECA. Although the number of subjects studied is small, the presence of auto-antibodies directed against the endothelial cells in the serum of these patients supports the hypothesis that the endothelium is involved in the anal disease.

Neuronal nitric oxide synthase in the neural pathways of the urinary bladder

Nitric oxide (NO) is a unique biological messenger molecule. It serves, in part, as a neurotransmitter in the central and peripheral nervous systems. Neurons containing NO have been identified histochemically by the presence of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) reactivity or immunohistochemically by the antibody for neuronal NO synthase (n-NOS). Previous histochemical or pharmacological studies have raised the possibility that NO may play an important role in the neural pathways of the lower urinary tract. There is also considerable evidence to suggest that n-NOS is plastic and could be upregulated following certain lesions in the lower urinary tract. The present review summarises the distribution of n-NOS containing neurons innervating the urinary bladder and the changes of the enzyme expression in some experimentally induced pathological conditions.

Botox-induced prostatic involution

BACKGROUND

A simple approach to induced prostatic atrophy was explored. Surgical denervation is known to produce profound atrophy of the rat prostate. Because Botulinum toxin type A (Botox) produces a long-term chemical denervation, the potential to induce atrophy of the rat prostate was explored.

METHODS

Thirty rat prostates were injected with varying doses of Botox. Single and serial injections were used, and rats were subsequently sacrificed after either 1 or 4 weeks, respectively. The prostate glands were harvested, weighed, and histologically studied for morphologic and apoptotic changes.

RESULTS

The total prostate volume and weight were found to be reduced in all Botox-injected animals. Histologically, a generalized atrophy of the glands was observed with the H&E stain. There was also diffuse glandular apoptosis evident with the Tunel stain. There were no significant complications (e.g., urinary retention, weight loss, or hind/limb weakness).

CONCLUSIONS

Botulinum toxin type A injection into the prostate gland induces selective denervation and subsequent atrophy of the prostate. Apoptosis was seen diffusely throughout the gland. It may be possible that in the future, this long-acting neurotoxin could be used for the treatment of common pathologies of the human prostate.

Use of botulinum toxin in the treatment of achalasia

Achalasia is a chronic esophageal motor disorder characterized by failure of the lower esophageal sphincter (LES) to relax during swallowing, aperistalsis of the esophageal body, and, often, an elevated resting LES pressure. Pneumatic dilation and Heller cardiomyotomy have been the time-honored, accepted treatments, but each may carry significant morbidity. Recently, intrasphincteric injection of botulinum toxin has been shown to be an effective treatment for achalasia, probably by reducing the excitatory cholinergic tone of the LES. Subjective and objective improvement have been reported in many patients with few reported adverse reactions. Clinical improvement generally lasts 2-6 months with patients often requiring repeat treatment. Although studies directly comparing botulinum toxin injection with pneumatic dilation and surgical myotomy are needed, botulinum toxin injection has rapidly become another therapeutic option in the treatment of achalasia.

Sialorrhea in amyotrophic lateral sclerosis: a hypothesis of a new treatment--botulinum toxin A injections of the parotid glands

The inhibitory action of botulinum toxin is not confined to the neuromuscular junction. The toxin has long been known to block all the autonomic cholinergic fibers, including the major secretomotor parasympathetic fibers to salivary glands. The parotids are the largest of the salivary glands and their selective chemodenervation with botulinum toxin A is likely to result in substantial reduction of saliva production. Injection of the parotid glands with botulinum toxin is proposed as an new treatment for sialorrhea in patients with amyotrophic lateral sclerosis and other neurological diseases.