Molecular targets of botulinum toxin at the mammalian neuromuscular junction

Is bulbospongiosus muscle botox injection safe and effective in treating lifelong premature ejaculation? Randomized controlled study

PURPOSE

To evaluate the safety and efficacy of botulinum-A toxin injections into the bulbospongiosus muscle for cases of lifelong drug-resistant premature ejaculation (PE).

METHODS

Ninety-eight outpatients diagnosed with lifelong PE were randomly assigned to two groups: the botulinum-A toxin group comprising forty-nine patients and the placebo (saline) group also consisting of forty-nine patients. A 100 U botulinum-A toxin was diluted into 10 cc of saline, with 5 cc injected into one side of the muscle (botulinum-A toxin group) guided by ultrasound to distribute across most muscle fibers. The same technique was applied using the same volume of saline injected into the bulbospongiosus muscle. Intravaginal ejaculatory latency time (IELT), scores from the premature ejaculation profile (PEP), Premature Ejaculation Diagnostic Tool (PEDT), International Index of Erectile Function (IIEF), and recording of any complications were obtained. Follow-ups occurred at 1-, 3-, and 6-month post-procedure.

RESULTS

Cases receiving injections of botulinum-A toxin into the bulbospongiosus muscle showed notably extended intravaginal ejaculatory latency times compared to their initial performance after treatment. In addition, there were enhancements in PEP scores, and notably, no significant complications were reported. Conversely, the bilateral injection of saline into the bulbospongiosus muscle did not demonstrate any impact on ejaculation latencies.

CONCLUSION

Our study demonstrated that the injection of botulinum-A toxin into the bulbospongiosus muscle can serve as a safe and effective option for treating PE. Nonetheless, its clinical application warrants further studies involving larger sample sizes and longer follow-up periods.

Botulinum neurotoxin: A therapeutic powerhouse with broad clinical implications

ABSTRACT

Clostridium botulinum is a Gram-positive bacterium that produces one of the most deadly chemodenervating toxins in the world. To date, six distinct neurotoxins are available for prescription use in the United States. Decades of data across aesthetic therapeutic areas and therapeutic disease states support the safety and efficacy of C. botulinum, providing good symptom management and improved quality of life in appropriately chosen patients. Unfortunately, many clinicians are slow to progress patients to toxin therapy from more conservative measures, and others wrongly interchange the products despite characteristics unique to each. Commensurate with an improved understanding of the complex pharmacology and clinical implications of botulinum neurotoxins is the importance for clinicians to appropriately identify, educate, refer, and/or treat candidate patients. This article provides an overview of the history, mechanism of action, differentiation, indications, and uses for botulinum neurotoxins.

Botulinum Toxin A, a Better Choice for Skeletal Muscle Block in a Comparative Study With Lidocaine in Rats

A positive response to scalene muscle block (SMB) is an important indication for the diagnosis of thoracic outlet syndrome. Lidocaine injection is commonly used in clinical practice in SMB, although there have been some cases of misdiagnosis. Botulinum toxin A (BTX-A) is one of the therapeutic agents in SMB, but whether it is also indicated for SMB diagnosis is controversial. To evaluate the muscle block efficiency of these two drugs, the contraction strength was repeatedly recorded on tibialis anterior muscle in rats. It was found that at a safe dosage, 2% lidocaine performed best at 40 μL, but it still exhibits an unsatisfactory partial blocking efficiency. Moreover, neither lidocaine injection in combination with epinephrine or dexamethasone nor multiple locations injection could improve the blocking efficiency. On the other hand, injections of 3, 6, and 12 U/kg BTX-A all showed almost complete muscle block. Gait analysis showed that antagonistic gastrocnemius muscle, responsible for heel rising, was paralyzed for nonspecific blockage in the 12 U/kg BTX-A group, but not in the 3 U/kg or 6 U/kg BTX-A group. Cleaved synaptosomal associated protein 25 (c-SNAP 25) was stained to test the transportation of BTX-A, and was additionally observed in the peripheral muscles in 6 and 12 U/kg groups. c-SNAP 25, however, was barely detectable in the spinal cord after BTX-A administration. Therefore, our results suggest that low dosage of BTX-A may be a promising option for the diagnostic SMB of thoracic outlet syndrome. SIGNIFICANCE STATEMENT: Muscle block is important for the diagnosis and treatment of thoracic outlet syndrome and commonly performed with lidocaine. However, misdiagnosis was observed sometimes. Here, we found that intramuscular injection of optimal dosage lidocaine only partially blocked the muscle contraction in rats, whereas low-dosage botulinum toxin, barely used in diagnostic block, showed almost complete block without affecting the central nervous system. This study suggests that botulinum toxin might be more suitable for muscle block than lidocaine in clinical practice.

Structure and Function of the Mammalian Neuromuscular Junction

The mammalian neuromuscular junction (NMJ) comprises a presynaptic terminal, a postsynaptic receptor region on the muscle fiber (endplate), and the perisynaptic (terminal) Schwann cell. As with any synapse, the purpose of the NMJ is to transmit signals from the nervous system to muscle fibers. This neural control of muscle fibers is organized as motor units, which display distinct structural and functional phenotypes including differences in pre- and postsynaptic elements of NMJs. Motor units vary considerably in the frequency of their activation (both motor neuron discharge rate and duration/duty cycle), force generation, and susceptibility to fatigue. For earlier and more frequently recruited motor units, the structure and function of the activated NMJs must have high fidelity to ensure consistent activation and continued contractile response to sustain vital motor behaviors (e.g., breathing and postural balance). Similarly, for higher force less frequent behaviors (e.g., coughing and jumping), the structure and function of recruited NMJs must ensure short-term reliable activation but not activation sustained for a prolonged period in which fatigue may occur. The NMJ is highly plastic, changing structurally and functionally throughout the life span from embryonic development to old age. The NMJ also changes under pathological conditions including acute and chronic disease. Such neuroplasticity often varies across motor unit types. © 2022 American Physiological Society. Compr Physiol 12:1-36, 2022.

Long-Term Effects With Potential Clinical Importance of Botulinum Toxin Type-A on Mechanics of Muscles Exposed

Botulinum toxin type-A (BTX-A) is widely used for spasticity management and mechanically aims at reducing passive resistance at the joint and widening joint range of movement. However, recent experiments on acute BTX-A effects showed that the injected rat tibialis anterior (TA) muscle’s passive forces increased, and the length range of active force exertion (l_range) did not change. Additionally, BTX-A was shown to spread into non-injected muscles in the compartment and affect their mechanics. Whether those effects persist in the long term is highly important, but unknown. The aim was to test the following hypotheses with experiments conducted in the anterior crural compartment of the rat: In the long term, BTX-A (1) maintains l_range, (2) increases passive forces of the injected TA muscle, and (3) spreads into non-injected extensor digitorum longus (EDL) and the extensor hallucis longus (EHL) muscles, also affecting their active and passive forces. Male Wistar rats were divided into two groups: BTX-A and Control (0.1 units of BTX-A or only saline was injected into the TA). Isometric forces of the muscles were measured simultaneously 1-month post-injection. The targeted TA was lengthened, whereas the non-targeted EDL and EHL were kept at constant length. Hydroxyproline analysis was done to quantify changes in the collagen content of studied muscles. Two-way ANOVA test (for muscle forces, factors: TA length and animal group) and unpaired t or Mann-Whitney U test (for l_range and collagen content, where appropriate) were used for statistical analyses (P < 0.05). BTX-A caused significant effects. TA: active forces decreased (maximally by 75.2% at short and minimally by 48.3%, at long muscle lengths), l_range decreased (by 22.9%), passive forces increased (by 12.3%), and collagen content increased (approximately threefold). EDL and EHL: active forces decreased (up to 66.8%), passive force increased (minimally by 62.5%), and collagen content increased (approximately twofold). Therefore, hypothesis 1 was rejected and 2 and 3 were confirmed indicating that previously reported acute BTX-A effects persist and advance in the long term. A narrower l_range and an elevated passive resistance of the targeted muscle are unintended mechanical effects, whereas spread of BTX-A into other compartmental muscles indicates the presence of uncontrolled mechanical effects.

Takotsubo-like Myocardial Dysfunction in a Patient with Botulism

Botulinum toxin A (BTXA) can disrupt the neuromuscular and autonomic functions. We herein report a case of autonomic system dysfunction that manifested as Takotsubo-like myocardial dysfunction in a patient with botulism. Takotsubo syndrome results in acute cardiac insufficiency, another fatal complication of botulism in addition to respiratory muscle paralysis, particularly in patients with cardiovascular disease.

Detection of Botulinum Toxin Muscle Effect in Humans Using Magnetic Resonance Imaging: A Qualitative Case Series

BACKGROUND

Although important for dosing and dilution, there are few data describing botulinum toxin (BT) movement in human muscle.

OBJECTIVE

To better understand BT movement within human muscle.

DESIGN

Proof-of-concept study with descriptive case series.

SETTING

Outpatient academic practice.

PARTICIPANTS

Five subjects with stroke who were BT naive with a mean age of 60.4 ± 14 years and time poststroke of 4.6 ± 3.7 years.

METHODS

Three standardized injections were given to the lateral gastrocnemius muscle (LGM): 2 contained 25 units (U) of onabotulinumtoxinA (Botox) in 0.25 mL of saline solution and the third 0.25 mL of saline solution only. The tibialis anterior muscle (TAM) was not injected in any subject. A leg magnetic resonance image was obtained at baseline, 2 months, and 3 months later with a 3.0 Tesla Siemens scanner. Three muscles, the LGM, lateral soleus muscle (LSM), and TAM, were manually outlined on the T2 mapping sequence at each time point. A histogram of T2 relaxation times (T2-RT) for all voxels at baseline was used to calculate a mean and standard deviation (SD) T2-RT for each muscle. Botulinum toxin muscle effect (BTME) at 2 months and 3 months was defined as a subject- and muscle-specific T2-RT voxel threshold ≥3 SD above the baseline mean at or near BT injection sites.

MAIN OUTCOME MEASURES

BTME volume for each leg magnetic resonance imaging slice at 3 time points and 3 muscles for all subjects.

RESULTS

One subject missed the 3-month scan, leaving 18 potential observations of BTME. Little to no BTME effect was seen in the noninjected TAM. A BTME was detected in the LGM in 13 of 18 possible observations, and no effect was detected in 5 observations. Possible BTME effect was seen in the LSM in 3 subjects due to either diffusion through fascia or needle misplacement. Volume of BTME, as defined here, appeared to be substantially greater than the 0.25-mL injection volume.

CONCLUSIONS

This descriptive case series is among the first attempts to quantify BTME within human muscle. Our findings are preliminary and are limited by a few inconsistencies. However, we conclude that use of magnetic resonance imaging to detect the volume of BTME is feasible and may assist researchers in modeling the spread and diffusion of BT within human muscle.

LEVEL OF EVIDENCE

IV.

Botulinum Toxin Injection-Site Selection for a Smooth Shoulder Line: An Anatomical Study

Introduction. This study aimed to improve the accuracy of manual needle placement into the trapezius (TM) for smooth shoulder line. Methods. For macroscopic study 12 TMs and for microscopic study 4 cadavers were detached and then sampled, 1⁎1 cm at the four points from the origin to insertion site (0% at the most lateral point of external occipital protuberance and 100% at the most lateral point of acromion). Results. Most of the nerve endings observed during macroscopic investigations were concentrated in the 60–80% region, and the second most distributed region was the 40–60% region. The microscopic results revealed that the 60–80% region on the reference line had the most dense neuromuscular junction area, while the 40–60% and 80–100% areas were similar in their neuromuscular junction densities. Discussion. These anatomical results will be useful in clinical settings especially for cosmetic surgeons.

[Not Available]

Zusammenfassung. OAB (overactive bladder syndrome) ist zwar ein häufiges Leiden, doch wird es oft nicht diagnostiziert und deshalb nicht behandelt. Die Behandlung erfolgt symptomatisch. Im Praxisalltag muss vorgängig eine Basis-(Ausschluss)-Diagnostik durchgeführt werden. Das Führen eines Blasentagebuchs ist sowohl für die Diagnostik als auch für den Verlauf wichtig. Eine urogynäkologische Abklärung mit Urodynamik empfiehlt sich in unklaren Situationen und beim Vorliegen einer gemischten Symptomatik mit Symptomen einer Belastungsinkontinenz oder bei gleichzeitigem Vorliegen einer Blasenentleerungsstörung. Die Therapie erfolgt Schritt für Schritt. Schon einfache Verhaltensänderungen und ein Blasen- und Beckenbodentraining können die Symptomatik deutlich verbessern. Viele Patientinnen profitieren aber zusätzlich von der medikamentösen Therapie. Jahrzehntelang standen dazu alleinig Anticholinergika zur Verfügung. Doch die Langzeitcompliance ist unter diesen Medikamenten gering. Neu erweitern β3-Adrenorezeptor-Agonisten das therapeutische Spektrum: Bei ähnlicher Wirkung unterscheidet sich das Nebenwirkungsprofil unter anderem durch das Fehlen von Mundtrockenheit. Bei therapierefraktärer OAB steht die intravesikale Injektion von Onabotulinumtoxin A als sehr effektive Therapie zur Verfügung. In seltenen Fällen ist auch eine Neuromodulation indiziert.

Persistence of botulinum neurotoxin a subtypes 1-5 in primary rat spinal cord cells

Botulinum neurotoxins (BoNTs) are the most poisonous substances known and cause the severe disease botulism. BoNTs have also been remarkably effective as therapeutics in treating many neuronal and neuromuscular disorders. One of the hallmarks of BoNTs, particularly serotype A, is its long persistence of 2-6 months in patients at concentrations as low as fM or pM. The mechanisms for this persistence are currently unclear. In this study we determined the persistence of the BoNT/A subtypes 1 through 5 in primary rat spinal neurons. Remarkably, the duration of intracellular enzymatic activity of BoNT/A1, /A2, /A4 and /A5 was shown to be at least 10 months. Conversely, the effects of BoNT/A3 were observed for up to ∼5 months. An intermittent dosing with BoNT/E showed intracellular activity of the shorter acting BoNT/E for 2–3 weeks, followed by reoccurrence and persistence of BoNT/A-induced SNAP-25 cleavage products.

The neural cell adhesion molecule promotes maturation of the presynaptic endocytotic machinery by switching synaptic vesicle recycling from adaptor protein 3 (AP-3)- to AP-2-dependent mechanisms

Newly formed synapses undergo maturation during ontogenetic development via mechanisms that remain poorly understood. We show that maturation of the presynaptic endocytotic machinery in CNS neurons requires substitution of the adaptor protein 3 (AP-3) with AP-2 at the presynaptic plasma membrane. In mature synapses, AP-2 associates with the intracellular domain of the neural cell adhesion molecule (NCAM). NCAM promotes binding of AP-2 over binding of AP-3 to presynaptic membranes, thus favoring the substitution of AP-3 for AP-2 during formation of mature synapses. The presynaptic endocytotic machinery remains immature in adult NCAM-deficient (NCAM-/-) mice accumulating AP-3 instead of AP-2 and its partner protein AP180 in synaptic membranes and vesicles. NCAM deficiency or disruption of the NCAM/AP-2 complex in wild-type (NCAM+/+) neurons by overexpression of AP-2 binding-defective mutant NCAM interferes with efficient retrieval of the synaptic vesicle v-SNARE synaptobrevin 2. Abnormalities in synaptic vesicle endocytosis and recycling may thus contribute to neurological disorders associated with mutations in NCAM.

Botulinum toxin type A in the healing of chronic lesion following bilateral spasticity of gluteus muscle

Use of botulinum toxin is expanding as the clinical studies demonstrate new potential therapeutic applications. In rehabilitation, botulinum toxin is above all used as adjunct therapy for the treatment of spasticity, but it may prove useful for other atypical clinical situations. A 17-year-old man had a sub-arachnoid haemorrhage following the rupture of cerebral aneurism. The patient presented gluteus maximus and medius bilaterally spasticity that produced a chronic lesion in the intergluteal cleft, a flexed wrist and a flexed elbow. As treatment for this spasticity, a total of 100 U botulinum toxin type A were injected into the glutei muscles. This treatment allowed for application of topical medication and subsequently, chronic lesion healing. Botulinum toxin A may be an important therapeutic aid for clinicians faced with treating persistent pathological conditions caused by spasticity.

Treatment of primary axillary hyperhidrosis with botulinum toxin type a: our experience in 50 patients from 2007 to 2010

Background. Local injections of Botulinum toxin type A (BTX-A) are an effective and safe solution for primary bilateral axillary hyperhidrosis. Traditional treatments are often ineffective and difficult to tolerate. This study was performed to assess the efficacy and safety of Botulinum toxin type A in the treatment of these diseases and to evaluate the reliability of patient's subjective rating in the timing of repeat injections. Methods. From 2007 to 2008, we included in the study and treated a total of 50 patients, and we used the Minor's iodine test and the hyperhidrosis diseases severity scale as initial inclusion criteria and also for evaluating the followup, comparing to patient's subjective rating. We used also a specific questionnaire to evaluate the level of pain, the onset of the effect, any eventual adverse effect of the treatment, the onset of compensatory hyperhidrosis, and the global grade of satisfaction. The data were analyzed using standard statistical methods. Results. 88% of patients were totally satisfied and all patients repeated the treatment during all the study. The symptom-free interval was in median 6 months with an average improving of HDSS of 1.5 points. In 86%, there was a complete accordance between the subjective patient's demand of the repetition of the treatment and the positivity to Minor test and HDSS. No major side effects happened. Conclusion. Local injections of Botulinum toxin type A (BTX-A) result in an effective and safe solution for bilateral axillary primary hyperhidrosis for the absence of significant morbidity, side effects, and lack of efficacy or duration. The only defects are the need of repetition of the treatment and relative costs.

[Measurement of botulinum toxin activity: towards a new cellular culture assay?]

The actual gold standard of Botulin A toxin (BoTx A) batches qualification is the mouse lethality assay. With this assay it is nevertheless impossible to set a therapeutic value unit.

AIMS

The goal of this research was to study the effects of BoTx A increasing concentrations on glutamatergic rat neurons.

EXPERIMENTAL PROCEDURE

We studied the glutamate release with increasing concentrations of BoTx A. We also studied the BoTx A target cleavage with a western blot technique.

RESULTS

Our results proved that it is possible to establish a dose-response - like curve of BoTx A effects on glutamate release. Moreover the cleavage of the target protein was visible for the same toxin concentrations that inhibited the glutamate release.

CONCLUSION

This technique could be the first step toward a new way of setting a better pharmaceutical profile for toxin batches.

Efficacy of botulinum toxin type A in the treatment of focal axillary hyperhidrosis

BACKGROUND

Local intradermal injection of botulinum toxin Type A has become a recognized treatment for axillary hyperhidrosis. This study has investigated the efficacy of this method of treatment in terms of symptom-free interval between treatments and patients' satisfaction. We also investigated the reliance on patients' subjective assessment of the recurrence of symptoms in determining the timing of repeat injections.

METHODS

All patients referred to our clinic between May 2001 and December 2005 with a diagnosis of focal primary axillary hyperhidrosis were included in this study. Data were collected prospectively in a standard proforma. Every patient received a questionnaire to complete over a 4-week period. The questionnaire included visual analogue scales for periprocedural pain, degree of dryness, satisfaction, regret, and complications. Final symptom-free interval was recorded when the patient requested a repeat injection. The data were recorded on a spreadsheet and analyzed using standard statistical methods.

RESULTS

A total of 52 consecutive patients and 238 axillary injections were analyzed. The symptom-free interval ranged from 3 to 14 months with a median of 5.97 months. There were no significant complications from this treatment modality. A total of 97% of the patients were highly satisfied with only 1 patient regretting the treatment.

CONCLUSION

Botulinum toxin Type A is an effective and well-tolerated treatment for axillary hyperhidrosis. Timing of repeat injections as determined subjectively by patients is comparable to studies using colorimetric and gravimetric techniques to quantify the severity of sweating prior to the administration of repeat injections. The authors have indicated no significant interest with commercial supporters.

Relationship of botulinum dosage to duration of side effects and normal voice in adductor spasmodic dysphonia

OBJECTIVE

Objective evaluation of botulinum toxin A (BTX-A) dosing by determination of the statistical relationship between injection amount and duration of side effects and normal voice in adductor spasmodic dysphonia (SD) patients. From this information, to provide a rational guide to determine the initial and follow-up BTX-A amounts for injection.

STUDY DESIGN AND SETTING

Private laryngology clinic. Statistical analysis was performed on data obtained from 101 patients with SD.

RESULTS

Significant and predictable positive correlations were found between duration of side effects and duration of normal voice after BTX-A injection in patients with SD. Dose of BTX-A injected also appeared to have a significant positive correlation with duration of side effects, but a negative correlation with duration of normal voice. A trend toward more severe side effects was seen with larger doses of BTX-A injections.

CONCLUSIONS AND SIGNIFICANCE

Increased understanding of the response of the human voice over time after BTX-A injection at various doses suggests new ideas to further increase clinical efficacy with the use of lower BTX-A doses.

Role of two active site Glu residues in the molecular action of botulinum neurotoxin endopeptidase

Botulinum neurotoxin type A (BoNT/A) light chain (LC) is a zinc endopeptidase that causes neuroparalysis by blocking neurotransmitter release at the neuromuscular junctions. The X-ray crystal structure of the toxin reveals that His223 and His227 of the Zn(2+) binding motif HEXXH directly coordinate the active site zinc. Two Glu residues (Glu224 and Glu262) are also part of the active site, with Glu224 coordinating the zinc via a water molecule whereas Glu262 coordinates the zinc directly as the fourth ligand. In the past we have investigated the topographical role of Glu224 by replacing it with Asp thus reducing the side chain length by 1.4 A that reduced the endopeptidase activity dramatically [L. Li, T. Binz, H. Niemann, and B.R. Singh, Probing the role of glutamate residue in the zinc-binding motif of type A botulinum neurotoxin light chain, Biochemistry 39 (2000) 2399-2405]. In this study we have moved the Glu 224 laterally by a residue (HXEXH) to assess its positional influence on the endopeptidase activity, which was completely lost. The functional implication of Glu262 was investigated by replacing this residue with aspartate and glutamine using site-directed mutagenesis. Substitution of Glu262 with Asp resulted in a 3-fold decrease in catalytic efficiency. This mutation did not induce any significant structural alterations in the active site and did not interfere with substrate binding. Substitution of Glu262 with Gln however, dramatically impaired the enzymatic activity and this is accompanied by global alterations in the active site conformation in terms of topography of aromatic amino acid residues, zinc binding, and substrate binding, resulting from the weakened interaction between the active site zinc and Gln. These results suggest a pivotal role of the negatively charged carboxyl group of Glu262 which may play a critical role in enhancing the stability of the active site with strong interaction with zinc. The zinc may thus play structural role in addition to its catalytic role.

The Case for Bladder Botulinum Toxin Application

Botulinum toxin (BoNT) has been shown to be and effective agent in suppressing detrusor overactivity due to neurogenic causes. Recently, BoNT has been extended to patients who have idiopathic detrusor overactivity. This article reviews the use of BoNT to treat disorders of neurogenic detrusor overactivity and establishes BoNT as a therapeutic modality to treat idiopathic bladder overactivity. It is important to remember that the application of BoNT in the lower urinary tract is not approved by the regulatory agencies and caution should be applied until larger randomized clinical studies are completed.

Pharmacology of botulinum toxin: differences between type A preparations

Different types of botulinum neurotoxin (BoNT) block different proteins of the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) protein complex within cholinergic nerve terminals, producing blockade of cholinergic neuromuscular and autonomic synapses. Animal studies indicate the longest duration of action for BoNT type A (BoNTA) followed by types B, F, and E. Diffusion to adjacent and remote muscles may be related to protein composition, dilutions, volume, target muscle selection, and injection technique. A review of head-to-head, randomized, controlled trials of BoNTA preparations (Botox and Dysport) suggests that Dysport tends to have higher efficacy, longer duration, and higher frequency of adverse effects. Conversion factors between the preparations varied, however, and remain controversial. In clinical settings, a Botox:Dysport conversion ratio of 1:3 may be appropriate. Animal studies suggest a conversion ratio of 1:2.5-3. When therapeutic effects between these preparations are attempting to be equalized, Dysport seems to produce more adverse effects. In mice, Botox appears to have a better safety margin than Dysport and BoNTB. In rats, diffusion margins are similar for Botox and Dysport. Jitter derived from stimulation single-fiber EMG of injected and remote muscles show no differences between Botox and Dysport. Atrophy of extrafusal muscle fibers of injected and remote muscles do not differ between the BoNTA preparations.

[Overactive bladder: prospects and limitations of botulinum toxin]

Botulinum toxin is the most potent poison known to man. It is produced by Clostridium botulinum and consists of a heavy chain which is responsible for the internalization of the toxin into the cytosol and a light chain that has the ability to cleave proteins within the nerve terminal. As those proteins are essential for normal vesicular transport and fusion of acetylcholine, botulinum toxins are able to prevent its release at the presynaptic membrane, resulting in a chemodenervation of the detrusor muscle after intravesical injection of the toxin and an impressive reduction of symptoms of overactive bladder. Clinical studies show success rates between 60 and 96% for neurogenic and non-neurogenic detrusor overactivity. Thus, application of botulinum toxin to the lower urinary tract appears to be an efficient, safe and minimally invasive procedure.

Efficacy and safety of repeated doses of botulinum toxin type B in type A resistant and responsive cervical dystonia

Efficacy of botulinum toxin type B (BoNT B) for the treatment of type A-resistant (AR) and non-A-resistant (NAR) cervical dystonia (CD) has been demonstrated in several single injection studies. There is little data available on long-term therapy with repeated injection sessions and it is unknown if AR and NAR patients respond in a similar manner over time. To evaluate the long-term efficacy and safety of BoNT B in AR and NAR CD patients, we carried out a prospective, open-label study examining 10 repeated dosing sessions of BoNT B in 34 patients with CD (15 AR and 19 NAR). Dosing was started at 10,000 units and could be increased to 25,000. Assessments included the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and a patient global assessment at each baseline (injection) and Week 4 (peak effect) visit. Change in TWSTRS total was the primary efficacy end point. Data was analyzed using repeated-measures analysis of variance. BoNT B therapy resulted in an overall significant improvement of CD (P<0.001) and improvement was seen in all 10 individual sessions (2.5 years). The magnitude of response decayed over time (P<0.001). There was no difference between AR and NAR patients with regard to dose, treatment effect, or decay in response. The AR group perceived (patient global) treatment as being less effective (P=0.047). Dry mouth frequency decreased with each session despite increasing doses whereas flu-like syndrome and weakness increased. BoNT B therapy provides long-term benefit for CD patients but the magnitude of response diminishes over time. The cause of this decay is probably multifactorial. AR and NAR CD patients respond in a similar fashion.

Evidence-Based Review of Patient-Reported Outcomes With Botulinum Toxin Type A

This review systematically examines the effects of botulinum toxin type A (BTX-A) on patient-reported outcomes across disorders using evidence-based criteria. The evidence provided by these studies ranged from randomized, controlled trials to case series. The effects of BTX-A on quality of life or global treatment outcomes were assessed in 48 studies across 16 different conditions. All but 7 of these reported benefits of BTX-A over baseline or the comparator condition (placebo or other treatment). The effects of BTX-A on impairment, activities, or participation were assessed in 46 studies across 17 different conditions. All but 4 reported benefits of BTX-A over baseline or the comparison group. The effects of BTX-A on satisfaction or preference were assessed in 14 studies across 11 different conditions, all of which reported high rates of satisfaction with BTX-A or preference over the comparator. These studies provide evidence that BTX-A exerts meaningful benefits on the quality of life of patients treated with this biologic agent.

Botulinum toxin in clinical practice

Botulinum toxin, the most potent biological toxin, has become a powerful therapeutic tool for a growing number of clinical applications. This review draws attention to new findings about the mechanism of action of botulinum toxin and briefly reviews some of its most frequent uses, focusing on evidence based data. Double blind, placebo controlled studies, as well as open label clinical trials, provide evidence that, when appropriate targets and doses are selected, botulinum toxin temporarily ameliorates disorders associated with excessive muscle contraction or autonomic dysfunction. When injected not more often than every three months, the risk of blocking antibodies is slight. Long term experience with this agent suggests that it is an effective and safe treatment not only for approved indications but also for an increasing number of off-label indications.