Botulinum toxins in pain management

Neuropeptide Y nerve paracrine regulation of prostate cancer oncogenesis and therapy resistance

BACKGROUND

Nerves are key factors in prostate cancer (PCa) progression. Here, we propose that neuropeptide Y (NPY) nerves are key regulators of cancer-nerve interaction.

METHODS

We used in vitro models for NPY inhibition studies and subsequent metabolomics, apoptotic and migration assays, and nuclear transcription factor-κB (NF-κB) translocation studies. Human naïve and radiated PCa tissues were used for NPY nerve density biomarker studies. Tissues derived from a Botox denervation clinical trial were used to corroborate metabolomic changes in humans.

RESULTS

Cancer cells increase NPY positive nerves in vitro and in preneoplastic human tissues. NPY-specific inhibition resulted in increased cancer apoptosis, decreased motility, and energetic metabolic pathway changes. A comparison of metabolomic response in NPY-inhibited cells with the transcriptome response in human PCa patients treated with Botox showed shared 13 pathways, including the tricarboxylic acid cycle. We identified that NF-κB is a potential NPY downstream mediator. Using in vitro models and tissues derived from a previous human chemical denervation study, we show that Botox specifically, but not exclusively, inhibits NPY in cancer. Quantification of NPY nerves is independently predictive of PCa-specific death. Finally, NPY nerves might be involved in radiation therapy (RT) resistance, as radiation-induced apoptosis is reduced when PCa cells are cocultured with dorsal root ganglia/nerves and NPY positive nerves are increased in prostates of patients that failed RT.

CONCLUSION

These data suggest that targeting the NPY neural microenvironment may represent a therapeutic approach for the treatment of PCa and resistance through the regulation of multiple oncogenic mechanisms.

Effect of Acupuncture on Chronic Pelvic Pain Secondary to Abdominal Myofascial Syndrome Not Responsive to Local Anesthetic Block: A Pilot Study

Objective: Strong evidence shows that 85% of women with chronic pelvic pain (CPP) have musculoskeletal disorders, such as abdominal myofascial pain syndrome (AMPS). The aim of this research was to assess the efficacy of local acupuncture treatment for women with CPP secondary to AMPS unresponsive to treatment with trigger-point injection. Materials and Methods: This pilot study involved 17 women with moderate-to-severe AMPS-related CPP. Acupuncture treatments were given at abdominal-wall trigger points once per week for 10 consecutive weeks. Pain relief was assessed with a visual analogue scale (VAS), the McGill questionnaire, and pressure dynamometer. Quality of life and psychosocial function (risk for anxiety and depression) were evaluated using the Short-Form-36 questionnaire and the Hospital Anxiety and Depression scale. Assessments were performed at baseline and after 1, 3, and 6 months of treatment. Results: Both the VAS and McGill pain questionnaire showed significantly decreased pain intensity (VAS, P < 0.001; and McGill, P 0.049), and the effects were sustained even at 6 months after treatment. Conclusions: Acupuncture treatment was effective for the women who participated in this study, and the current authors believe that these preliminary results suffice to recommend performing randomized controlled trials.

Infection, Pain, and Itch

Pain and itch are unpleasant sensations that often accompany infections caused by viral, bacterial, parasitic, and fungal pathogens. Recent studies show that sensory neurons are able to directly detect pathogens to mediate pain and itch. Nociceptor and pruriceptor neurons respond to pathogen-associated molecular patterns, including Toll-like receptor ligands, N-formyl peptides, and bacterial toxins. Other pathogens are able to silence neuronal activity to produce analgesia during infection. Pain and itch could lead to neuronal modulation of the immune system or behavioral avoidance of future pathogen exposure. Conversely, pathogens could modulate neuronal signaling to potentiate their pathogenesis and facilitate their spread to other hosts. Defining how pathogens modulate pain and itch has critical implications for sensory neurobiology and our understanding of host-microbe interactions.

Drugs obtained by biotechnology processing

In recent years, the number of drugs of biotechnological origin available for many different diseases has increased exponentially, including different types of cancer, diabetes mellitus, infectious diseases (e.g. AIDS Virus / HIV) as well as cardiovascular, neurological, respiratory, and autoimmune diseases, among others. The pharmaceutical industry has used different technologies to obtain new and promising active ingredients, as exemplified by the fermentation technique, recombinant DNA technique and the hybridoma technique. The expiry of the patents of the first drugs of biotechnological origin and the consequent emergence of biosimilar products, have posed various questions to health authorities worldwide regarding the definition, framework, and requirements for authorization to market such products.

Botulinum neurotoxin — from laboratory to bedside

Botulinum neurotoxin (BoNT) has been used clinically since 1980, with an ever-increasing range of clinical applications. This has coincided with a period of massively expanded interest in the underlying biology of the neurotoxin. Tremendous advances have taken place in the scientific understanding of neurotoxin structure and function since the description of their endopeptidase activity in 1992. These developments have led to an increased understanding of the mechanisms underpinning the clinical use of the neurotoxins and also in the technologies available to support their clinical use. The expanding range of clinical applications, and use in increasing doses, has also generated challenges for the clinicians and manufacturers of BoNT preparations to ensure continuing efficacy and safety margins for these new clinical settings. To date the increased clinical use of BoNTs has occurred largely empirically, and not by application of the recent insights into neurotoxin structure and function. With the increased knowledge regarding the biology of the neurotoxins, however, there is the opportunity to select preferred forms of the toxin for particular clinical applications and even to consider engineering the neurotoxins to produce modified products more suited to specific clinical applications. These developments and opportunities that have arisen, particularly over the last decade, emphasise the increasing need to maintain an active two way dialogue between clinicians and basic scientists to ensure that the advances in the laboratory are translated into clinical benefit and that the clinical developments in use of neurotoxin are supported by the scientific research activity. This article is based upon presentations given in a workshop at the 5th International Conference on Basic and Therapeutic Aspects of Botulinum and Tetanus Toxin in Denver in June, 2005 seeking to address issues relating to the laboratory/clinic interface.

Treatment of phantom limb pain with botulinum toxin type A

INTRODUCTION

Phantom limb pain and sensations are common in amputees. The pathophysiology remains unclear and the treatment difficult and often unsuccessful. Opioids are frequently used when non-narcotics have failed, but are not effective in many cases. We report on three phantom and stump pain patients, refractive to previous treatments, who were successfully treated with botulinum toxin A (BoNT-A).

METHODS

Three patients who had previously undergone amputation of their leg due to accident (N = 2) or injury by a landmine (N = 1) were treated with BoNT-A (Dysport). We injected a total dose of up to 500 units (U) BoNT-A under EMG-control. Global clinical improvement was based on a 0-3 scale (0 = no effect; 3 = marked improvement) and on a questionnaire rating pain intensity (based on the visual analog scale), intake of pain medication and phantom limb sensations.

RESULTS

All three patients evaluated the clinical global improvement with 3 (marked improvement). The pain intensity and pain medication was reduced significantly in all three cases. No side effects were reported. The duration of response lasted up to 11 weeks.

DISCUSSION

These three successfully treated phantom and stump pain patients show that therapy with BoNT-A may be worth studying as an effective and safe treatment option for this kind of pain.

The role of botulinum toxin type A in the radiation fibrosis syndrome: a preliminary report

OBJECTIVE

To describe the use of botulinum toxin type A (BTX-A) in radiation fibrosis syndrome (RFS).

DESIGN

Retrospective case series.

SETTING

A large tertiary care cancer center.

PARTICIPANTS

Twenty-three consecutive patients treated for sequelae of RFS with BTX-A.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

A description of the components of RFS thought to benefit from BTX-A injections and the patient's self-report of benefit from those injections.

RESULTS

The sequelae of RFS for which BTX-A injection was thought to be indicated include radiation-induced cervical dystonia in 18 (78%), trigeminal nerve or cervical plexus neuralgia in 10 (43%), trismus in 7 (30%), migraine in 3 (13%), and thoracic pain in 1 (4%) patient. Most (87%) patients self-reported benefit from the injections.

CONCLUSIONS

Initial clinical experience with the use of BTX-A as adjunctive treatment for select neuromuscular and musculoskeletal complications of RFS in a variety of cancer patients has been encouraging. Well-designed prospective studies are needed to clarify the potential beneficial role of BTX-A in specific sequelae of RFS.

Therapeutic use of botulinum toxin type A in treating neck and upper-back pain of myofascial origin: a pilot study

OBJECTIVE

To determine the efficacy of botulinum toxin type A (BTX-A) in treating neck and upper-back pain of myofascial origin.

DESIGN

A randomized, double-blind, placebo-controlled pilot study.

SETTING

Outpatient physical medicine and rehabilitation clinic of a university-affiliated tertiary hospital.

PARTICIPANTS

A total of 29 subjects enrolled from among 45 screened patients. No subject withdrawal due to serious adverse events occurred.

INTERVENTION

Subjects were evaluated at baseline, received a 1-time injection of either BTX-A (treatment group) or saline (control group), and were followed up at 2 weeks and at months 1, 2, 3, 4, and 6.

MAIN OUTCOME MEASURES

Visual analog scale (VAS) for pain, the Neck Disability Index (NDI), and the Medical Outcome Study 36-Item Short-Form Health Survey (SF-36).

RESULTS

Improvements in the VAS and NDI scores were seen in the treatment group but were not significant when compared with the controls. Statistically significant improvements for the treatment group were seen in the SF-36 bodily pain (at months 2 and 4) and mental health (at month 1) scales but not in the other scales, nor in the summary measures. No serious adverse events were reported.

CONCLUSIONS

Trends toward improvements in VAS and NDI scores of the BTX-A group are encouraging, but they were possibly due to a placebo effect and were not statistically significant. The BTX-A subjects, at certain time points, showed statistically significant improvements in the bodily pain and mental health scales of the SF-36 compared with controls. Our study had limited power and population base, but the results could be used to properly power follow-up studies to further investigate this topic.

Intramuscular botulinum toxin-A reduces hemiplegic shoulder pain: a randomized, double-blind, comparative study versus intraarticular triamcinolone acetonide

BACKGROUND AND PURPOSE

Shoulder pain is frequent after stroke and interferes with the rehabilitative process and outcome. However, treatments used for hemiplegic shoulder pain are limited and largely ineffective. This prospective, randomized, double-blind controlled study was conducted to compare the efficacies of botulinum toxin type A (BoNT-A) and triamcinolone acetonide (TA) on hemiplegic shoulder pain and their effects on arm function in patients with stroke.

METHODS

Twenty-nine hemiplegic stroke patients with shoulder pain (duration <or=24 months, pain on numeric rating scale >or=6/10) were randomized into 2 groups. One group received intramuscular injections of BoNT-A (BOTOX 100 U total) during one session to the infraspinatus, pectoralis and subscapularis muscles in conjunction with an intraarticular injection of normal saline to painful shoulder joint, whereas the other group received an intraarticular injection of TA (40 mg) and an intramuscular injection of normal saline to the same muscles. Outcome measures were pain (measured using a numeric rating scale), physician's global rating scale, shoulder range of motion (ROM) in 4 directions, arm function measured using Fugl-Meyer score, and spasticity measured using the modified Ashworth scale. Measurements were made at baseline and 2, 6, and 12 weeks after injection.

RESULTS

At 12 weeks after treatment mean decrease in pain was 4.2 in the BoNT-A-treated group versus 2.5 in the TA-treated group (P=0.051), and improvements in overall ROM were 82.9 degrees versus 51.8 degrees in these groups (P=0.059), showing a strong trend toward there being less pain and better ROM among those treated with BoNT-A than with TA. However, no significant differences were observed between the 2 groups in terms of improvement in physician global rating, Fugl-Meyer score or modified Ashworth scales. No adverse effect was observed in either group.

CONCLUSIONS

Results from this study suggest that injection of BoNT-A into selected muscles of the shoulder girdle might provide more pain relief and ROM improvement than intraarticular steroid in patients with hemiplegic shoulder pain. A larger clinical trial needs to be undertaken to confirm the benefits of this approach.

The analgesic potential of clostridial neurotoxin derivatives

Botulinum neurotoxins are the most potent acute lethal toxins known, and yet for the last two decades they, and in particular serotype A, have found increasing use in the clinical treatment of diseases or conditions involving neuromuscular or autonomic neuronal transmission. The neurotoxins work by inhibiting the release of acetylcholine from peripheral cholinergic nerve terminals. More recently, the effects on non-cholinergic pathways have been identified, and this has led to an increase in the diseases and syndromes for which botulinum neurotoxins have been found to have clinical utility. In particular, botulinum neurotoxins have been demonstrated to potentially benefit a range of chronic pain syndromes. With the description in the last decade of the biochemical basis of neurotoxin action and the tertiary structure of the toxin molecule, the possibility of designing novel agents utilising selected aspects of toxin function has arisen. This possibility has been pursued in the context of pain relief with the description of a novel hybrid protein derived from botulinum neurotoxin type A, LH(N)/A-ECL, able to selectively target nociceptive afferent neurons and inhibit the release of neurotransmitters involved in pain transmission. This novel derivative of botulinum neurotoxin type A demonstrates prolonged analgesic activity in vivo. This review will consider the evidence for the analgesic properties of the botulinum neurotoxins and their suitability as the basis for novel therapeutic proteins. The general concept of deriving novel therapeutic molecules from the neurotoxins will also be considered.

Botulinum toxin A versus bupivacaine trigger point injections for the treatment of myofascial pain syndrome: a randomised double blind crossover study

The treatment of myofascial pain syndrome (MPS) is diverse and includes trigger point injections of various substances including local anesthetics, steroids and Botulinum toxin A (BTX A). The purpose of this study was to compare the effectiveness of trigger point injections using BTX A versus bupivacaine, both in combination with a home-based rehabilitation program. To be enrolled, subjects first had to demonstrate responsiveness to bupivacaine trigger point injection. In this single center, double blind, randomized, cross-over trial, 18 patients with MPS received trigger point injections of either 25 units Botulinum toxin A or 0.5 ml of 0.5% bupivacaine per trigger point. A maximum of eight trigger points were injected per subject. Subjects were followed until their pain returned to 75% or more of their pre-injection pain for two consecutive weeks, after which there was a 2 week wash-out period. The subjects then crossed over and had the same trigger points injected with the other agent. All subjects participated in a home exercise program involving static stretches of the affected muscles. Both treatments were effective in reducing pain when compared to baseline (P=0.0067). There was, however, no significant difference between the BTX A and 0.5% bupivacaine groups in duration or magnitude of pain relief, function, satisfaction or cost of care (cost of injectate excluded). Considering the high cost of BTX A, bupivacaine is deemed a more cost-effective injectate for MPS.

A new wrinkle on pain relief: re-engineering clostridial neurotoxins for analgesics

Botulinum neurotoxins are used to treat of a range of chronic neuromuscular conditions and, increasingly, conditions involving non-neuromuscular transmission, both cholinergic and non-cholinergic, including chronic pain. However, their clinical use is limited by the potential for adverse effects related to the neuromuscular activity, which results from the selectivity of the toxin for the neuromuscular junction. The elucidation of the structure of the botulinum toxin molecule and its relationship to neurotoxin function has enabled the design of novel molecules incorporating selected aspects of toxin function. This review considers the suitability of engineered neurotoxins as the basis for novel therapeutic proteins and the opportunity of developing analgesics based on these neurotoxins.

Botulinum Toxin a Injection of the Obturator Internus Muscle for Chronic Perineal Pain

Chronic perineal pain is often a difficult condition to manage. Current treatments include pudendal nerve injections and pudendal nerve release surgery. The obturator internus muscle has a close relationship to the pudendal nerve and might be a potential target for therapeutic intervention.

PERSPECTIVE

A case is presented of refractory perineal pain that was successfully treated by injecting the obturator internus muscle with botulinum toxin A.

Practical considerations in the assessment and treatment of pain in adults with physical disabilities

Adults aging with physical disabilities experience a variety of pain disorders that affect their functionality and QOL. It is important that clinicians caring for this population be knowledgeable about this common symptom and be able to perform a thorough history and physical examination. In addition, it is imperative to have a good working knowledge of the strengths and limitations of the treatments available.