Botulinum toxin type A inhibits rat pyloric myoelectrical activity and substance P release in vivo

Treating neuropathic pain and comorbid affective disorders: Preclinical and clinical evidence

INTRODUCTION

Neuropathic pain (NP) significantly impacts quality of life and often coexists with affective disorders such as anxiety and depression. Addressing both NP and its psychiatric manifestations requires a comprehensive understanding of therapeutic options. This study aimed to review the main pharmacological and non-pharmacological treatments for NP and comorbid affective disorders to describe their mechanisms of action and how they are commonly used in clinical practice.

METHODS

A review was conducted across five electronic databases, focusing on pharmacological and non-pharmacological treatments for NP and its associated affective disorders. The following combination of MeSH and title/abstract keywords were used: "neuropathic pain," "affective disorders," "depression," "anxiety," "treatment," and "therapy." Both animal and human studies were included to discuss the underlying therapeutic mechanisms of these interventions.

RESULTS

Pharmacological interventions, including antidepressants, anticonvulsants, and opioids, modulate neural synaptic transmission to alleviate NP. Topical agents, such as capsaicin, lidocaine patches, and botulinum toxin A, offer localized relief by desensitizing pain pathways. Some of these drugs, especially antidepressants, also treat comorbid affective disorders. Non-pharmacological techniques, including repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and photobiomodulation therapy, modulate cortical activity and have shown promise for NP and mood disorders.

CONCLUSIONS

The interconnection between NP and comorbid affective disorders necessitates holistic therapeutic strategies. Some pharmacological treatments can be used for both conditions, and non-pharmacological interventions have emerged as promising complementary approaches. Future research should explore novel molecular pathways to enhance treatment options for these interrelated conditions.

Gastroparesis: An Evidence-Based Review for the Bariatric and Foregut Surgeon

Gastroparesis is a gastric motility disorder characterized by delayed gastric emptying. It is a rare disease and difficult to treat effectively; management is a dilemma for gastroenterologists and surgeons alike. We conducted a systematic review of the literature to evaluate current diagnostic tools as well as treatment options. We describe key elements in the pathophysiology of the disease, in addition to current evidence on treatment alternatives, including nutritional considerations, medical and surgical options, and related outcomes.

Dramatic Effect of Botulinum Toxin Type A on Hypertrophic Scar: A Promising Therapeutic Drug and Its Mechanism Through the SP-NK1R Pathway in Cutaneous Neurogenic Inflammation

Background

Hypertrophic scar formation may be related to cutaneous neurogenic inflammation (CNI) through the substance P-neurokinin 1 receptor (SP-NK1R) signaling pathway. As a widely used drug in aesthetic clinical work, botulinum toxin type A (BTX-A) has a therapeutic effect on scars, but the actual mechanism remains unclear. This study aimed to clarify the potential mechanism by which BTX-A inhibits CNI in hypertrophic scars both in vitro and in vivo.

Methods

Tissue samples were obtained from surgical excisions. Immunohistological analysis was used to locate SP in human hypertrophic scars and normal skin. RT-PCR and western blot analysis were used to evaluate the expression of collagens after SP/BTX-A treatment. A rabbit ear scar model was used to explore the in vivo effect of BTX-A on scar treatment.

Results

SP and NK-1R were overexpressed in hypertrophic scars compared to normal skin tissues. Collagen secretion of hypertrophic scar-derived fibroblasts increased with increasing doses of SP. However, BTX-A may downregulate collagen expression through SP-NK1R pathway with or without the presence of SP inducing agent capsaicin. Meanwhile, SP inhibited the expression of NK-1R, and this inhibition was blocked by pretreatment with BTX-A. In vivo, intralesional BTX-A injection can also reduce the volume of scars and inhibit collagen secretion. Capsaicin may cause more severe scar manifestations, while the therapeutic effect of BTX-A remains.

Conclusion

Our research confirms that CNI stimulates fibroblasts during scar formation, while BTX-A can reduce collagen secretion by inhibiting the SP-NK1R signaling pathway, thus identifying a novel therapeutic target for this benign solid skin tumor.

The Effect of Botulinum Toxin in Experimental Hypertrophic Pyloric Stenosis

Purpose: Infantile hypertrophic pyloric stenosis is the most common cause of gastric outlet obstruction in the first month of life. Botulinum toxin (BT) is a neurotoxin produced by clostridium botulinum, which causes paralysis in skeletal muscles. We aimed to evaluate the effectiveness of BT in the experimental pyloric stenosis model. Methods: The study protocol was approved by the Selcuk University Medical Faculty Ethics Committee (2017/20). We performed an experimental study using 32 Wistar-Albino newborn rats. Rats were divided randomly into four groups with six rats in both control (C), and L-nitro-arginine methyl ester hydrochloride group, and 10 rats in each sham (S), and BT group. 100 mg/kg per day L-NAME was applied to all groups intraperitoneally for 14 days from birth except control group. 0.2 mL saline and 20 U/kg BT was injected by surgery to S and BT groups, respectively, at 21 days from birth. After 35 days all rats were sacrificed and biopsies were performed from pyloric muscle for histopathological examination. The results were evaluated with the "one-way ANOVA" test. Results: Total and circular muscle thickness of the groups were compared. The total muscle thickness of the L-NAME group was significantly higher than the control group (P = .031). Comparing the circular muscle thickness of botox group (BTG) with control group (CG) and L-NAME GROUP (LNG), muscle thickness was significantly smaller (P < .001, P < .001). The total muscle thickness of BTG was significantly different between LNG (P < .001). Conclusions: Hypertrophy of pylor in an experimental model was reduced by BT injection in this study. We think that Botox injection through endoscopic or interventional radiological methods may be an alternative method for surgery.

Comparative Effectiveness of Injection Therapies for Hemiplegic Shoulder Pain in Stroke: A Systematic Review and Network Meta-Analysis

Hemiplegic shoulder pain (HSP) hampers post-stroke functional recovery and is not well managed with conservative treatments. This systematic review aimed to examine the various injection therapies for HSP and investigate their effectiveness at different time points. The protocol of this meta-analysis was registered on INPLASY with a registration number of INPLASY202180010. PubMed, EMBASE, and Scopus were searched from their inception to 4 August 2021 for the clinical studies investigating comparative effectiveness of different injection regimens for treating hemiplegic shoulder pain in patients with stroke. The primary outcome was the weighted mean difference (WMD) on the visual analog scale (VAS) of pain reduction in the fourth-week and between the fourth and twenty-fourth weeks. Ranking probabilities of the WMD for each treatment were obtained using simulations. Seventeen studies with 595 participants were included. The network meta-analysis showed that at the fourth-week, intra-muscular botulinum toxin (BoNT) injections and suprascapular nerve blocks (SSNB) were superior to a placebo, with WMDs of 1.55 (95% CI, 0.09 to 3.01) and 1.44 (95% CI, 0.07 to 2.80), respectively. SSNB possessed the highest probability (53.3%) and appeared to be the best treatment in the fourth-week, followed by intra-muscular BoNT injections (42.6%). Intramuscular BoNT injections were better than the placebo, with a WMD of 1.57 (95% CI, 0.30 to 2.84) between the 4th and 24th weeks. Intramuscular BoNT injections had the highest probability (79.8%) as the best treatment between the 4th and 24th weeks. SSNB was likely to rank first in relieving HSP at the fourth post-treatment week, whereas intra-muscular BoNT injections had the highest probability to achieve the best treatment effectiveness in the post-injection period between the fourth and twenty-fourth weeks. However, as some of the included studies used a non-randomized controlled design, more randomized controlled trials are needed in the future to validate and better understand the short- and long-term efficacy of different injection therapies for management of HSP.

Efficacy of Intra-Articular Botulinum Toxin in Osteoarticular Joint Pain: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This study was conducted with the aim of evaluating the efficacy of intra-articular injections of botulinum toxin type A (BT-A) into the painful joint diseases through a systematic review of the literature and a meta-analysis of controlled randomized trials. Intra-articular therapies (corticosteroids, hyaluronic acid) have limited efficacy and run a risk of toxicity in patients with joint pain. New therapeutic options are needed to treat painful osteoarticular disease.

METHODS

We searched via Pubmed, American College of Rheumatology, and European League Against Rheumatism congresses, and gray literature for the studies reported until June 2016 and addressing the issue of BT intra-articular injections in patients with refractory joint pain. Randomized trials were included. For the meta-analysis, we compared a numeric rating scale (NRS) from 0 to 10 before treatment and at 1 or 2 months and 6 months after in the BT-A and the control groups for each study. We also compared separately low dose and high dose of BT at 1 or 2 months' evaluation.

RESULTS

In a total of 269 selected articles, 8 were analyzed and 6 studies were included in the meta-analysis involving a total of 382 patients. On comparing the NRS rating for 5 trials, at 1 or 2 months irrespective of the dose of BT, 4 trials showed a positive effect of BT compared with the control on the NRS and 1 found no effect; the overall weighted mean difference [95% confidence interval (CI)] was -1.10 (-1.62, -0.58) (P<0.0001, I=63%). Among the 4 trials with a low dose of BT (100 U), comparing NRS at 1 or 2 months, 3 trials showed significant results with a positive effect of BT-A injection compared with the control on the NRS; the fourth study failed to find any effect. The overall weighted mean difference (95% CI) was -0.95 (-0.02, -1.88) (P=0.05, I=67%). In the 2 trials using a high dose of BT (200 U) comparing NRS at 1 or 2 months, there was an almost zero effect of BT, with an overall weighted mean difference (95% CI) of 0.13 (-0.55, 0.81) (P=0.71, I=0%). In the 3 trials comparing NRS at 6 months there was an overall weighted mean difference (95% CI) of -0.57 (-1.98, 0.83) (P=0.42, I=73%).

CONCLUSIONS

BT-A intra-articular injections have short-term benefits with a statistically significant decrease in the NRS pain score of around 1 point in patients with refractory joint pain. A decrease in the pain score was also observed at 6 months but with a nonsignificant result.

OnabotulinumtoxinA in the treatment of refractory chronic cluster headache

BACKGROUND

Cluster headache (CH) is a clinically well-defined primary headache disorder, approximately 20% of cluster headache sufferers experience recurrent attacks without periods of significant remission. For the treatment of chronic cluster headache (CCH) only limited therapeutic options are available.

METHODS

A potential refractory CCH patient group was identified according to the clinical definition of rCCH based on the consensus statement of the European Headache Federation (EHF). Treatment with OnabotulinumtoxinA (BoNT-A; Botox®, 150 Allergan IU) was done according to the PREEMPT study protocol. A standardized headache diary was used for recording frequency, duration of attacks and pain intensity. To assess personal burden the HIT-6 and the Hospital Anxiety and Depression scale was used. Primary outcome measure was a > 50% reduction in headache minutes.

RESULTS

Seventeen male patients suffering from rCCH, aged 32 ± 11 (mean ± SD) years, presenting a mean disease duration of 6.6 years completed the study of 28 weeks. The cut-off point of > 50% reduction in headache minutes as positive result was reached in 58.8%, 29.4% experienced an improvement of 30-50%. Mean frequency of headache days dropped from 28.2 to 11.8 days at week 24 (p = 0.0001; 95% CI -21.33 to - 11.61;). Intensity of remaining attacks was also reduced significantly. Headache disability scores showed a trend to improvement after BoNT-A.

CONCLUSIONS

Encouraging results for the treatment with BoNT-A in rCCH patients were observed in our study population.

Botulinum toxin: A review of the mode of action in migraine

Botulinum toxin serotype A (BoNT/A) was originally used in neurology for the treatment of dystonia and blepharospasms, but is now clinically used worldwide for the treatment of chronic migraine. Still, the possible mode of action of BoNT/A in migraine is not fully known. However, the mode of action of BoNT/A has been investigated in experimental pain as well as migraine models, which may elucidate the underlying mechanisms in migraine. The aim of this study was to review studies on the possible mode of action of BoNT/A in relation to chronic migraine treatment. Observations suggest that the mode of action of BoNT/A may not be limited to the injection site, but also includes anatomically connected sites due to axonal transport. The mechanisms behind the effect of BoNT/A in chronic migraine may also include modulation of neurotransmitter release, changes in surface expression of receptors and cytokines as well as enhancement of opioidergic transmission. Clinical and experimental studies with botulinum toxin in the last decade have advanced our understanding of headache and other pain states. More research into botulinum toxin as treatment for headache is warranted as it can be an attractive alternative for patients who do not respond positively to other drugs.

The Inhibitory Effect of Botulinum Toxin Type A on Rat Pyloric Smooth Muscle Contractile Response to Substance P In Vitro

A decrease in pyloric myoelectrical activity and pyloric substance P (SP) content following intrasphincteric injection of botulinum toxin type A (BTX-A) in free move rats have been demonstrated in our previous studies. The aim of the present study was to investigate the inhibitory effect of BTX-A on rat pyloric muscle contractile response to SP in vitro and the distributions of SP and neurokinin 1 receptor (NK1R) immunoreactive (IR) cells and fibers within pylorus. After treatment with atropine, BTX-A (10 U/mL), similar to [D-Arg¹, D-Phe⁵, D-Trp^7,9, Leu¹¹]-SP (APTL-SP, 1 μmol/L) which is an NK1R antagonist, decreased electric field stimulation (EFS)-induced contractile tension and frequency, whereas, subsequent administration of APTL-SP did not act on contractility. Incubation with BTX-A at 4 and 10 U/mL for 4 h respectively decreased SP (1 μmol/L)-induced contractions by 26.64% ± 5.12% and 74.92% ± 3.62%. SP-IR fibers and NK1R-IR cells both located within pylorus including mucosa and circular muscle layer. However, fewer SP-fibers were observed in pylorus treated with BTX-A (10 U/mL). In conclusion, BTX-A inhibits SP release from enteric terminals in pylorus and EFS-induced contractile responses when muscarinic cholinergic receptors are blocked by atropine. In addition, BTX-A concentration- and time-dependently directly inhibits SP-induced pyloric smooth muscle contractility.

Endoscopic treatment of gastroparesis

Gastroparesis has traditionally been a largely medically managed disease with refractory symptoms typically falling under the umbrella of the surgical domain. Surgical options include, but are not limited to, gastrostomy, jejunostomy, pyloromyotomy, or pyloroplasty, and the Food and Drug Administration approved gastric electrical stimulation implantation. Endoscopic management of gastroparesis most commonly involves intrapyloric botulinum toxin injection; however, there exists a variety of endoscopic approaches on the horizon that have the potential to radically shift standard of care. Endoscopic management of gastroparesis seeks to treat delayed gastric emptying with a less invasive approach compared to the surgical approach. This review will serve to highlight such innovative and potentially transformative, endoscopic interventions available to gastroenterologists in the management of gastroparesis.

Substance P is essential for maintaining gut muscle contractility: a novel role for coneurotransmission revealed by botulinum toxin

Substance P (SP) is commonly coexpressed with ACh in enteric motor neurons, and, according to the classical paradigm, both these neurotransmitters excite smooth muscle via parallel pathways. We hypothesized that, in addition, SP was responsible for maintaining the muscular responsiveness to ACh. We tested this hypothesis by using botulinum toxin (BoNT/A), a known blocker of vesicular release of neurotransmitters including ACh and neuropeptides. BoNT/A was injected into rat pyloric sphincter in different doses; as control we used boiled BoNT/A. At the desired time point, pylorus was dissected out and pyloric contractility was measured ex vivo in an organ bath and by measuring phosphorylation of myosin light chain 20 (MLC20). BoNT/A (10 IU) significantly reduced the response of pyloric muscle to exogenous ACh, an effect that was accompanied by reduced MLC20 phosphorylation in the muscle. Both effects were reversed by exogenous SP. CP-96345, a NK1 receptor antagonist, blocked the ability of exogenous SP to reverse the cholinergic hyporesponsiveness as well as the reduction in MLC20 phosphorylation induced by BoNT/A. In conclusion, we have identified a novel role for SP as a coneurotransmitter that appears to be important for the maintenance of muscular responsiveness to the principal excitatory neurotransmitter, ACh. These results also provide new insight into the effects of botulinum toxin on the enteric nervous system and gastrointestinal smooth muscle.

Botulinum toxin type a therapy in migraine: preclinical and clinical trials

BACKGROUND

Botulinum toxin type A (BTX-A) has been reported to be effective for the therapy for migraine. The purpose of this study was to investigate the effect of BTX-A on the immunoreactive levels of calcitonin gene-related peptide (CGRP) and substance P (SP) in the jugular plasma and medulla oblongata of migraine in rats induced by nitroglycerin (NTG), and then to evaluate and compare the effectiveness of fixed (muscle)-sites and acupoint-sites injection of BTX-A for migraine therapy of patients in a randomly controlled trial extending over four months.

MATERIALS AND METHODS

Rats with NTG-induced migraine were subcutaneously injected with vehicle or BTX-A (5 U/kg or 10 U/kg bodyweight). CGRP- and SP-like immunoreactivity (CGRP-LI and SP-LI) were determined by radioimmunoassay. In clinical trials, sixty patients respectively received BTX-A (2.5 U each site, 25 U per patient) at fixed-sites (group F, n = 30) including occipitofrontalis, corrugator supercili, temporalis and trapezius or at acupoint-sites (group A, n = 30) including EX-HN3, EX-HN5, GV20, GB8, GB20 and BL10.

RESULTS

Local BTX-A injection suppressed NTG-induced CGRP-LI and SP-LI levels in jugular plasma and oblongata. BTX-A injection for both groups with migraine significantly reduced the attack frequency, intensity, duration and associated symptoms. The efficacy of BTX-A for migraine in group A (93% improvement) was more significant than that in group F (83% improvement) (P < 0.01).

CONCLUSIONS

The evidence that BTX-A decreases NTG-induced CGRP-LI and SP-LI levels in trigeminovascular system suggests that BTX-A attenuates migraine by suppression of neuropeptide release. BTX-A injections for migraine at acupoint-sites and fixed-sites are effective. Acupoint-sites BTX-A administration shows more efficacy for migraine than fixed-sites application.

Emerging opportunities for serotypes of botulinum neurotoxins

Background: Two decades ago, botulinum neurotoxin (BoNT) type A was introduced to the commercial market. Subsequently, the toxin was approved by the FDA to address several neurological syndromes, involving muscle, nerve, and gland hyperactivity. These syndromes have typically been associated with abnormalities in cholinergic transmission. Despite the multiplicity of botulinal serotypes (designated as types A through G), therapeutic preparations are currently only available for BoNT types A and B. However, other BoNT serotypes are under study for possible clinical use and new clinical indications; Objective: To review the current research on botulinum neurotoxin serotypes A-G, and to analyze potential applications within basic science and clinical settings; Conclusions: The increasing understanding of botulinal neurotoxin pathophysiology, including the neurotoxin’s effects on specific neuronal populations, will help us in tailoring treatments for specific diagnoses, symptoms and patients. Scientists and clinicians should be aware of the full range of available data involving neurotoxin subtypes A-G.

Preferential entry of botulinum neurotoxin A Hc domain through intestinal crypt cells and targeting to cholinergic neurons of the mouse intestine

Botulism, characterized by flaccid paralysis, commonly results from botulinum neurotoxin (BoNT) absorption across the epithelial barrier from the digestive tract and then dissemination through the blood circulation to target autonomic and motor nerve terminals. The trafficking pathway of BoNT/A passage through the intestinal barrier is not yet fully understood. We report that intralumenal administration of purified BoNT/A into mouse ileum segment impaired spontaneous muscle contractions and abolished the smooth muscle contractions evoked by electric field stimulation. Entry of BoNT/A into the mouse upper small intestine was monitored with fluorescent HcA (half C-terminal domain of heavy chain) which interacts with cell surface receptor(s). We show that HcA preferentially recognizes a subset of neuroendocrine intestinal crypt cells, which probably represent the entry site of the toxin through the intestinal barrier, then targets specific neurons in the submucosa and later (90–120 min) in the musculosa. HcA mainly binds to certain cholinergic neurons of both submucosal and myenteric plexuses, but also recognizes, although to a lower extent, other neuronal cells including glutamatergic and serotoninergic neurons in the submucosa. Intestinal cholinergic neuron targeting by HcA could account for the inhibition of intestinal peristaltism and secretion observed in botulism, but the consequences of the targeting to non-cholinergic neurons remains to be determined.

Botulism is a severe and often fatal disease in man and animals characterized by flaccid paralysis. Clostridium botulinum produces a potent neurotoxin (botulinum neurotoxin) responsible for all the symptoms of botulism. Botulism is most often acquired by ingesting preformed botulinum neurotoxin in contaminated food or after intestinal colonization by C. botulinum under certain circumstances, such as in infant botulism, and toxin production in the intestine. The first step of the disease consists in the passage of the botulinum neurotoxin through the intestinal barrier, which is still poorly understood. We investigated the trafficking of the botulinum neurotoxin in a mouse intestinal loop model, using fluorescent HcA (half C-terminal domain of the heavy chain). We observed that HcA preferentially recognizes neuroendocrine intestinal crypt cells, which likely represent the entry site of the toxin through the intestinal barrier, then targets specific neurons, mainly cholinergic neurons, in the submucosa, and later (90–120 min) in the musculosa leading to local paralytic effects such as inhibition of intestinal peristaltism. These results represent an important advance in the understanding of the initial steps of botulism intoxication and can be the basis for the development of new specific countermeasures against botulism.

Botulinum neurotoxin A enhances the analgesic effects on inflammatory pain and antagonizes tolerance induced by morphine in mice

Over the recent years compelling evidence has accumulated indicating that botulinum neurotoxin serotype A (BoNT/A) results in analgesic effects on neuropathic as well as inflammatory pain, both in humans and in animal models. In the present study, the pharmacological interaction of BoNT/A with morphine in fighting inflammatory pain was investigated in mice using the formalin test. Moreover, the effects of BoNT/A on the tolerance-induced by chronic administration of morphine were tested and the behavioral effects were correlated with immunofluorescence staining of glial fibrillary acidic protein, the specific marker of astrocytes, at the spinal cord level. An ineffective dose of BoNT/A (2 pg/paw) combined with an ineffective dose of morphine (1 mg/kg) exerted a significant analgesic action both during the early and the late phases of formalin test. A single intraplantar injection of BoNT/A (15 pg/paw; i.pl.), administered the day before the beginning of chronic morphine treatment (7 days of s.c. injections of 20 mg/kg), was able to counteract the occurrence of tolerance to morphine. Moreover, BoNT/A reduces the enhancement of the expression of astrocytes induced by inflammatory formalin pain. Side effects of opiates, including the development of tolerance during repeated use, may limit their therapeutic use, the possibility of using BoNT/A for lowering the effective dose of morphine and preventing the development of opioid tolerance would have relevant implications in terms of potential therapeutic perspectives.

Botulinum toxin type-A effect as a preemptive treatment in a model of acute trigeminal pain: a pre-clinical double-blind and placebo-controlled study

The purpose of this study was to investigate if botulinum neurotoxin type-A (BoNT/A) had a preemptive antinociceptive effect in a formalin-induced orofacial pain model (FT). To test this hypothesis, male Rattus norvegicus were injected with isotonic saline solution 0.9% or BoNT/A administered as a 40 μl bolus, lateral to their nose, at 24 hours, 8, 15, 22, 29 or 36 days pre-FT. The procedures were repeated 42 days later. Influence on motor activity was assessed through the open-field test. Pain scores corresponded to the time spent rubbing and flicking the injected area. Animals pre-treated with BoNT/A at the first protocol (8 days subgroup) showed reduced inflammatory scores (p=0.011). For the other groups no significant results were observed at any phase. Motor activity was similar in both groups. BoNT/A showed to be effective preventing inflammatory pain up to eight days after the first treatment, an effect not reproduced on the second dose administration.

Botulinum neurotoxin for pain management: insights from animal models

The action of botulinum neurotoxins (BoNTs) at the neuromuscular junction has been extensively investigated and knowledge gained in this field laid the foundation for the use of BoNTs in human pathologies characterized by excessive muscle contractions. Although much more is known about the action of BoNTs on the peripheral system, growing evidence has demonstrated several effects also at the central level. Pain conditions, with special regard to neuropathic and intractable pain, are some of the pathological states that have been recently treated with BoNTs with beneficial effects. The knowledge of the action and potentiality of BoNTs utilization against pain, with emphasis for its possible use in modulation and alleviation of chronic pain, still represents an outstanding challenge for experimental research. This review highlights recent findings on the effects of BoNTs in animal pain models.

Botulinum toxin A for treatment of allodynia of complex regional pain syndrome: a pilot study

OBJECTIVE

To investigate the efficacy and tolerability of Botulinum toxin A (BoNT-A) in allodynia of patients with complex regional pain syndrome.

DESIGN

A total of 14 patients were studied. Eight patients were participants of a randomized, prospective, double-blind, placebo-controlled protocol. Six patients were studied prospectively in an open-label protocol. Patients were rated at baseline and at 3 weeks and 2 months after BoNT-A administration. Ratings included brief pain inventory, McGill pain questionnaire, clinical pain impact questionnaire, quantitative skin sensory test, sleep satisfaction scale, and patient global satisfaction scale. BoNT-A was injected intradermally and subcutaneously, five units/site into the allodynic area (total dose 40-200 units).

RESULTS

None of the patients with allodynia showed a significant response after treatment. The treatment was painful and poorly tolerated.

CONCLUSION

Intrademal and subcutaneous administration of BoNT-A into the allodynic skin of the patients with complex regional pain syndrome (CRPS) failed to improve pain and was poorly tolerated.

Orbicularis oculi myo-osseous fixation: a new treatment for benign essential blepharospasm and blepharospasm associated with diffuse facial dystonia (meige syndrome)

BACKGROUND AND OBJECTIVE

This article describes a novel surgical procedure, myo-osseous fixation, as an adjunct therapy for patients with reduced or poor response to repeated botulinum toxin injections for essential blepharospasm and Meige syndrome.

PATIENTS AND METHODS

The small-incision, rapidly healing, rapidly performed technique uses self-drilling titanium screws tightly engaged with a compression wrench. The screws fixate the periorbital orbicularis oculi muscle to bone, creating mechanical resistance to outer portions of the orbicularis muscle involved in debilitating involuntary contractions.

RESULTS

Eleven of the treated 12 patients experienced immediate improvement in function. Each responding patient noted enhanced effect of subsequent botulinum toxin injections at previously ineffective doses. The benefit was substantial and sustained for 6 months in 9 of 12 patients. Decreased brow depression during forced closure, forced frown, and brow elevation at rest was apparent in all patients postoperatively. Although the brow elevation effect was reduced after 6 months, reduced brow depression during forced closure still was easily demonstrated in most patients. Complications included a nodular bump over the brow, more commonly found when large titanium screws were used, transient headache, and easily removed dislodged screw.

CONCLUSION

Initial data suggest that this procedure appears safe, well tolerated, and useful in the treatment of patients with essential blepharospasm and Meige syndrome responding poorly to botulinum toxin therapy.

Factors associated with symptom response to pyloric injection of botulinum toxin in a large series of gastroparesis patients

Case series report symptom reductions after pyloric botulinum toxin injection in gastroparesis, but small controlled trials show no benefit. Factors that enhance response to therapy are undefined. A retrospective analysis of 179 gastroparetics undergoing pyloric botulinum toxin injection from 2001 to 2007 assessed responses relating to drug dosing, demographic factors, comorbidities, and gastric function. Overall, there was a decrease in gastroparetic symptoms 1-4 months after pyloric botulinum toxin injection in 92 patients (51.4%). Increasing the botulinum toxin dose significantly improved clinical responses of patients who provided information on symptoms after therapy (100 units: 54.2%; 200 units: 76.7%; P=0.02). Other factors that improved response to botulinum toxin included female gender, age <50 years, and nondiabetic nonpostsurgical etiology (all P<0.05). Eighty-seven patients received 307 follow-up injections. A clinical response to a second injection was observed in 73.4% of evaluable patients. In conclusion, responses to pyloric botulinum toxin depended on dose and were maintained on repeat injection. Subgroup analyses defined subgroups likely to benefit. These findings provide the foundation for large, controlled trials of high-dose botulinum toxin in selected gastroparesis subsets.

Botulinum neurotoxin-A for treatment of refractory neck pain: a randomized, double-blind study

OBJECTIVE

To investigate the efficacy and tolerability of Botulinum neurotoxin-A (BoNT-A) in the patients with refractory neck pain.

BACKGROUND

An analgesic effect is suggested for BoNT-A by a number of animal studies. Two blinded studies suggested efficacy of BoNT-A in a chronic neck pain.

METHODS

Forty-seven subjects were enrolled in a prospective, double-blind, placebo-controlled study. A total of 150 to 300 units of BoNT-A were injected into the neck and shoulder muscles based on pain localization. Subjects completed the visual analog scale (VAS), Pain Frequency Questionnaire and the Modified Oswestry Pain Questionnaire (MOPQ) at baseline, 3 and 8 weeks after the treatment. The primary outcomes consisted of: 1) > or =50% improvement on the VAS; and 2) > or =30% reduction in pain day frequency. The secondary outcome was an improvement of ADL in MOPQ. Excellent responders (ERs) were those who met all three outcomes.

RESULTS

At 2 months, a significant reduction in the mean VAS (pain intensity) was noted in the BoNT-A group compared with the placebo (P = 0.0018, CI 95% from 2.51 to 7.89). At 2 months, there were six ERs in the BoNT-A group and one ER in the placebo group (P = 0.0152).

CONCLUSION

Administration of BoNT-A into the neck and shoulder muscles for treatment of chronic refractory neck pain met one of the two primary outcomes: reduction in pain intensity. More ERs were noted in the Botox group.