Presynaptic effects of botulinum toxin type A on the neuronally evoked response of albino and pigmented rabbit iris sphincter and dilator muscles

Intradermal injection of Botulinum toxin type A alleviates infraorbital nerve constriction-induced thermal hyperalgesia in an operant assay

Recent studies have shown that infraorbital nerve constriction (IoNC)-induced mechanical allodynia has been attenuated by administration of highly purified 150-kDa Botulinum neurotoxin type A (BoNT/A). Here, we extend these studies to determine whether BoNT/A could attenuate IoNC-induced symptoms of thermal hyperalgesia. Instead of testing head withdrawal thresholds, a thermal operant assay was used to evaluate cortical processing of sensory input following IoNC. In this assay, a fasted rat's desire to obtain a food reward (sweetened condensed milk) is coupled to its ability to tolerate facial contact with a warm (45 °C) thermode. Bilateral IoNC decreased the ratio of thermode contact duration/event, which is an indicative of thermal hyperalgesia. BoNT/A injection intradermally in the area of infraorbital nerve (IoN) innervation 7 days after IoNC resulted in decreased number of facial contacts and increased the ratio of contact duration/event (measured at 14 days after IoNC). The BoNT/A (2-200 pg) effects were dose dependent and statistically significant at 100 and 200 pg (P < 0·05). Complete reversal of thermal hyperalgesia symptoms was obtained with a 200-pg dose, without affecting sham rat behaviour. Off-site (neck) injection of BoNT/A did not relieve thermal hyperalgesia, while co-injection of BoNT/A with a neutralising antibody in the area of IoN innervation prevented relief of thermal hyperalgesia. Neither IoNC nor BoNT/A injection affected operant assay parameters with a 24 °C thermode, indicating selectivity of thermal hyperalgesia measurements. These results strongly suggest that intradermal injection of BoNT/A in the area of IoN innervation alleviates IoNC-induced thermal hyperalgesia in an operant assay.

Botulinum Toxin: Non-cosmetic Indications and Possible Mechanisms of Action

Botulinum toxin (BTX) has gained a great interest in cosmetic dermatology for its effects on hyperkinetic facial lines. Understanding the basic research and analysis of effects of this potent drug can lead to other possible indications of interest for dermatologists. The use of BTX in focal hyperhidrosis is well established, but BTX has also effects on pain perception, itch and inflammation as discussed in this review.

[Botulinum toxin and painful peripheral neuropathies: what should be expected?]

Botulinum toxin type A (BTX-A) is a potent neurotoxin that blocks acetylcholine release from presynaptic nerve terminals by cleaving the SNARE complex. BTX-A has been reported to have analgesic effects independent of its action on muscle tone. The most robust results have been observed in patients with neuropathic pain. Neuropathic pain due to peripheral lesions has been the most widely studied. BTX-A has shown its efficacy on pain and allodynia in various animal models of inflammatory neuropathic pain. The only randomized, double-blind, placebo-controlled trial in patients with focal painful neuropathies due to nerve trauma or postherpetic neuralgia demonstrated significant effects on average pain intensity from 2 weeks after the injections to 14 weeks. Most patients reported pain during the injections, but there were no further local or systemic side effects. The efficacy of BTX-A in painful peripheral neuropathies has been more recently studied. Results were positive in the only study in an animal model of peripheral neuropathy. One study in patients with diabetic painful peripheral neuropathy demonstrated a significant decrease in Visual Analog Scale. In conclusion, one session of multiple intradermal injection of BTX-A produces long-lasting analgesic effects in patients with focal painful neuropathies and diabetic neuropathic pain, and is particularly well tolerated. The findings are consistent with a reduction of peripheral sensitisation, the place of a possible central effect remaining to define. Further studies are needed to assess some important issues, i.e. BTX-A efficacy in patients with small fiber neuropathies and the relevance of early and repeated injections. Future studies could also provide valuable insights into pathophysiology of neuropathic pain.

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 neurotoxin type A counteracts neuropathic pain and facilitates functional recovery after peripheral nerve injury in animal models

A growing interest was recently focused on the use of Botulinum neurotoxin serotype A (BoNT/A) for fighting pain. The aim of this study was to investigate the effects of BoNT/A on neuropathic pain. It was observed that BoNT/A is able to counteract neuropathic pain induced by chronic constriction injury (CCI) to the sciatic nerve both in mice and in rats. This effect is already present after a single intraplantar (i.pl.) or intrathecal (i.t.) neurotoxin administration that significantly reduces the sciatic nerve ligation-induced mechanical allodynia in mice and rats and thermal hyperalgesia in rats. This effect was evident starting 24 h after the administration of BoNT/A and it was long-lasting, being present 81 or 25 days after i.pl. injection of the higher dose in mice (15 pg/paw) and rats (75 pg/paw), respectively, and 35 days after i.t. injection in rats (75 pg/rat). Moreover, BoNT/A-injected mice showed a quicker recovery of the walking pattern and weight bearing compared to control groups. The behavioral improvement was accompanied by structural modifications, as revealed by the expression of cell division cycle 2 (Cdc2) and growth associated protein 43 (GAP-43) regeneration associated proteins, investigated by immunofluorescence and Western blotting in the sciatic nerve, and by the immunofluorescence expression of S100β and glial fibrillary acidic protein (GFAP) Schwann cells proteins. In conclusion, the present research demonstrate long-lasting anti-allodynic and anti-hyperalgesic effects of BoNT/A in animal models of neuropathic pain together with an acceleration of regenerative processes in the injured nerve, as evidenced by both behavioral and immunohistochemistry/blotting analysis. These results may have important implications in the therapy of neuropathic pain.

Comparison between botulinum toxin and corticosteroid injection in the treatment of acute and subacute tennis elbow: a prospective, randomized, double-blind, active drug-controlled pilot study

OBJECTIVE

To compare botulinum toxin type A injection with corticosteroid injection in the treatment of tennis elbow.

DESIGN

In this prospective, randomized, double-blind, drug-controlled trial,19 affected elbows of 16 patients were randomly assigned to receive injection with botulinum toxin type A (Botox group) or triamcinolone acetonide (steroid group). We used the Visual Analog Scale, pain-free grip strength, and World Health Organization Quality of Life Brief Questionnaire to assess the perception of pain, grip strength, and quality of life, respectively. Measures were performed before and at 4, 8, and 12 wks after the treatment.

RESULTS

Four weeks after the treatment, the Botox group had smaller decrease in pain (P = 0.02) but greater decrease in grip strength (P = 0.01). The difference in grip strength remained significant at 8 wks (P = 0.03). No significant differences in quality of life were observed throughout the study period.

CONCLUSIONS

Corticosteroid is superior to botulinum toxin type A in relieving pain in tennis elbow at 4 wks after injection. Because botulinum toxin injection did not relieve pain significantly but is associated with weakness, the muscle weakness caused by botulinum toxin is unlikely to be the sole mechanism of the pain relief observed in previous studies.

Efficacy of intra-articular botulinum toxin type A in painful knee osteoarthritis: a pilot study

OBJECTIVE

To evaluate the efficacy and safety of botulinum toxin type A (BoNT-A) injected intra-articularly in 60 subjects with moderate pain and functional impairment secondary to knee osteoarthritis. The study investigators hypothesized that intra-articular BoNT-A would result in statistically significant improvements in pain and function at 8 weeks.

DESIGN

Double-blind, randomized, single tertiary care academic medical center trial with 6-month follow-up.

PATIENTS

Sixty patients aged 40 years or older with painful osteoarthritis of the knee who had failed physical therapy, medications, and/or injection therapy presenting to the musculoskeletal or orthopedic outpatient clinics at a large tertiary care medical institution. All 60 patients completed 8-week follow-up, but only 32 patients completed the 26-week follow-up.

METHODS

Subjects were randomized to receive a single injection of corticosteroid, low-dose BoNT-A (100 units), or high-dose BoNT-A (200 units). Outcome measures were compared at baseline, 4, 8, 12, and 26 weeks after injection.

MAIN OUTCOME MEASUREMENTS

The primary outcome measure was pain visual analog scale (VAS) at 8 weeks. Secondary outcome measures included Western Ontario McMaster Arthritis Index, Short Form-36 scores, patient global assessment, 40-meter timed walk, and adverse effects.

RESULTS

The primary end point was pain VAS score at 8 weeks, which decreased within each group but only reached statistical significance in the low-dose BoNT-A group. In the intra-articular corticosteroid group, VAS decreased from 6.4 +/- 1.8 to 5.4 +/- 2.3 (P = .15); for low-dose BoNT-A, from 6.6. +/- 1.9 to 4.5 +/- 2.2 (P = .01); and for high-dose BoNT-A, from 6.6 +/- 1.4 to 5.9 +/- 2.4 (P = .15). All groups showed statistically significant improvements in Western Ontario McMaster Arthritis Index scores (pain, stiffness, function) at 8 weeks. No serious adverse events were noted in any group.

CONCLUSIONS

This pilot study supports a possible role for BoNT-A as a treatment option for symptomatic knee osteoarthritis; however, larger double-blind randomized studies are needed to determine whether BoNT-A is more effective than placebo in this patient population.

Injection of botulinum toxin type A (BOTOX) into trigger zone of trigeminal neuralgia as a means to control pain

This article illustrates a case of persistent trigeminal neuralgia in a medically compromised 65-year-old female who did not respond to pharmacotherapy. She had undergone several peripheral neurectomies as well as a failed right posterior fossa exploration that resulted in a cerebrospinal fluid leak. Persistent pain over the right external nasal area and right mental region was relieved for several hours after daily injections of bupivacaine. A trial of a single dose of 100 units of botulinum toxin type A (BOTOX) diluted in 2.5 mL saline was injected into the external nasal trigger zone (60 units) and to the mental nerve region (40 units). She achieved complete pain relief in the external nasal region for 5 months. Pain recurred and the site was again injected with 100 units of botulinum toxin type A (BOTOX). Pain relief at the mental region was partial. This was finally controlled with peripheral neurectomy. The patient was pain free with a maintenance dose of 200 mg carbamazepine daily for about 1 year, after which she elected to undergo stereotactic gamma knife radiosurgery when pain recurred at the external nasal region.

What are melanocytes really doing all day long...?

Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research.

CENTRAL EFFECT OF BOTULINUM TOXIN TYPE A IN HUMANS

This study investigated the changes in the cortical excitability with a paired-pulse transcranial magnetic stimulation (TMS) model after a botulinum toxin type A (BTA) injection in normal humans. Ten healthy subjects were enrolled in the study, which involved applying paired TMS to the motor cortex and recording the motor evoked potentials (MEP) before and after the BTA injection. BTA (2.5 mouse units) was injected into the right extensor digitorum brevis muscle. The amplitudes of MEP during rest and the cortical silent period (CSP) for the period of the tonic muscle contraction were measured at an interstimulus interval (ISI) of 3 ms and 20 ms. One month and three months after BTA injection, the level of intracortical inhibition increased significantly at an ISI of 3 ms and the intracortical facilitation decreased at an ISI of 20 ms. The duration of CSP shortened significantly at an ISI of 3 ms 1 month after BTA injection, which was also shortened significantly at an ISI of 20 ms. These findings were maintained until 3 months after the injection. It was concluded that cortical excitability could be modified by BTA injection in normal humans.

Botulinum toxin type A reduces histamine-induced itch and vasomotor responses in human skin

BACKGROUND

Clinical evidence has revealed the antipruritic effect of botulinum toxin type A (BoNT/A). BoNT/A is believed to be effective against itch as it inhibits the release of acetylcholine as well as some other substances that may be involved in itch.

OBJECTIVES

To investigate the effect of subcutaneous administration of BoNT/A on experimentally histamine-induced itch in human skin.

METHODS

In this double-blind, placebo-controlled study, 14 healthy men (mean +/- SD age 26.3 +/- 2.6 years) received BoNT/A (Botox; Allergan, Irvine, CA, U.S.A.; 5 U) and isotonic saline on the volar surface of either forearm. Histamine prick tests were performed four times at the treatment sites (before treatment, and days 1, 3 and 7 after treatment). The itch intensity (as rated on a 0-10 visual analogue scale), itch area, neurogenic inflammation (visible flare area), blood flow (laser Doppler) and cutaneous temperature (thermographic images) were measured over the course of the trials.

RESULTS

BoNT/A reduced the histamine-induced itch intensity (F(1,39) = 30.2, P < 0.001) and itch area (F(1,39) = 8.8, P = 0.011) compared with saline at all time points after treatment. The duration of itch was also shorter for BoNT/A-treated areas (F(1,39) = 19.4, P < 0.001), with a peak effect at day 7. The flare area was smaller in the BoNT/A-treated arm compared with the saline-treated arm at all time points after treatment (F(1,39) = 15.4, P = 0.002). Findings from blood flow (F(1,26) = 177.3, P < 0.001) and temperature measurements (F(1,26) = 27.6, P < 0.001) clearly showed the suppressive effect of BoNT/A on vasomotor reactions, with the maximal effect on days 3 and 7.

CONCLUSIONS

BoNT/A reduced the itch intensity, blood flow and neurogenic inflammation in response to the histamine prick test in human skin. The findings could be applicable in the treatment of some pruritic conditions that can be difficult to treat with conventional treatments.

Is botulinum toxin useful in treating headache? No

The discrepancy between the widespread use of botulinum neurotoxin (BoNT) in managing headache and the supporting clinical evidence is unprecedented. No substance seems to have inspired more physicians and patients to undertake spirited treatment attempts. Tremendous treatment success in small, uncontrolled clinical trials has been repeatedly reported, but no substance that has been studied to an equal extent has so utterly failed to provide proof of effect in controlled clinical trials. Nevertheless, even though most randomized, controlled clinical trials have not met their defined primary outcome criterion, BoNT is still considered a promising treatment alternative for primary headache disorders. Experimental approaches to the pathophysiologic impact of BoNT on the perception of pain have been equally unsuccessful. Although most studies have been unable to find a direct antinociceptive effect in humans, some researchers continue to seek specific injection sites or injection techniques that may promise more successful results. Others look for a positive effect by narrowing the indications for BoNT to more homogenous symptoms or special patient subgroups. The results of randomized, controlled studies involving a total of 3552 patients indicate that BoNT injection is probably ineffective for patients with migraine and chronic tension-type headache regardless of injection site, dosage, or injection regimen, and there is insufficient evidence to draw a conclusion about its effectiveness for the treatment of chronic daily headache or subforms. The lack of direct experimental or clinical trial evidence that BoNT has a direct antinociceptive effect in humans must be addressed before more trials are conducted, involving even more patients. Additional pathophysiologically oriented research is also needed to unravel the mechanisms of action of BoNT in human pain perception or, alternatively, to bring it all down to the placebo effect.

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.

Subcutaneous Botulinum toxin type A reduces capsaicin-induced trigeminal pain and vasomotor reactions in human skin

The present human study aimed at investigating the effect of subcutaneous administration of Botulinum toxin type A (BoNT/A) on capsaicin-induced trigeminal pain, neurogenic inflammation and experimentally induced cutaneous pain modalities. Fourteen healthy males (26.3+/-2.6 years) were included in this double-blind and placebo-controlled trial. The subjects received subcutaneous BoNT/A (22.5U) and isotonic saline in the mirror sides of their forehead. Pain and neurogenic inflammation was induced by four intradermal injections of capsaicin (100mug/muL) (before, and days 1, 3 and 7 after treatments). The capsaicin-induced pain intensity, pain area, the area of secondary hyperalgesia, the area of visible flare and vasomotor reactions were recorded together with cutaneous heat, electrical and pressure pain thresholds. BoNT/A reduced the capsaicin-induced trigeminal pain intensity compared to saline (F=37.9, P<0.001). The perceived pain area was smaller for the BoNT/A-treated side compared to saline (F=7.8, P<0.05). BoNT/A reduced the capsaicin-induced secondary hyperalgesia (F=5.3, P<0.05) and flare area (F=10.3, P<0.01) compared to saline. BoNT/A reduced blood flow (F(1,26)=109.5, P<0.001) and skin temperature (F(1,26)=63.1, P<0.001) at the capsaicin injection sites compared to saline and its suppressive effect was maximal at days 3 and 7 (P<0.05, post hoc test). BoNT/A elevated cutaneous heat pain thresholds (F=17.1, P<0.001) compared to saline; however, no alteration was recorded for electrical or pressure pain thresholds (P>0.05). Findings from the present study suggest that BoNT/A appears to preferentially target Cfibers and probably TRPV1-receptors, block neurotransmitter release and subsequently reduce pain, neurogenic inflammation and cutaneous heat pain threshold.

Evidence for the use of botulinum toxin in the chronic pain setting--a review of the literature

A significant proportion of chronic pain is of musculoskeletal origin. Botulinum toxin (BTX) has been successfully used in the treatment of spasmodic torticollis, limb dystonia, and spasticity. Investigators have, thus, become interested in its potential use in treating many chronic pain conditions. Practitioners have used BTX, outside the product license, in the treatment of refractory myofascial pain syndrome and neck and low back pain (LBP). This article reviews the current evidence relating to chronic pain practice. There is evidence supporting the use of both BTX type A and type B in the treatment of cervical dystonias. The weight of evidence is in favor of BTX type A as a treatment in: pelvic pain, plantar fasciitis, temporomandibular joint dysfunction associated facial pain, chronic LBP, carpal tunnel syndrome, joint pain, and in complex regional pain syndrome and selected neuropathic pain syndromes. The weight of evidence is also in favor of BTX type A and type B in piriformis syndrome. There is conflicting evidence relating to the use of BTX in the treatment whiplash, myofascial pain, and myogenous jaw pain. It does appear that BTX is useful in selected patients, and its duration of action may exceed that of conventional treatments. This seems a promising treatment that must be further evaluated.

The effects of botulinum toxin type A on muscle blood perfusion and metabolism

BACKGROUND

Botulinum toxin type A is approved by the U.S. Food and Drug Administration for the treatment of facial rhytides. However, the complete spectrum of action of botulinum toxin A has not yet been completely defined. Little is known about the metabolism of muscle after botulinum toxin A injection. This information may give insight into the additional effects botulinum toxin A may have on muscle. The authors assessed the influence of botulinum toxin A on the metabolism of muscle using dynamic investigative techniques.

METHODS

Twenty New Zealand White rabbits were divided into control, paralysis, and sham groups. Masseter muscle paralysis was achieved with botulinum toxin A. Dynamic computed tomographic and positron emission tomographic scans were obtained. Masseter muscle blood flow, blood volume, permeability surface, and mean transit time and glucose uptake were measured.

RESULTS

Eighteen animals completed the study. Masseter blood perfusion showed consistent results across all parameters. Blood flow, blood volume, and permeability surface were significantly increased at weeks 4 and 8 on the paralyzed side. Mean transit time at week 4 was decreased on the paralyzed side. Positron emission tomographic scans showed that injected muscles in the botulinum toxin A group tended to have increased glucose uptake compared with untreated muscles.

CONCLUSIONS

Botulinum toxin A injection increases muscle blood perfusion parameters and glucose uptake for a transient period. This increase is similar in duration to the known interval of botulinum toxin A-induced paralysis. These changes have been identified in a dynamic fashion and may represent changes in calcitonin gene-related peptide release.

Botulinum toxin for pain

Botulinum toxin (BTX) injection is being increasingly used 'off label' in the management of chronic pain. Data support the hypothesis of a direct analgesic effect of BTX, different to that exerted on muscle. Although the pain-reducing effect of BTX is mainly due to its ability to block acetylcholine release at the synapse, other effects on the nervous system are also thought to be involved. BTX affects cholinergic transmission in both the somatic and the autonomic nervous systems. Proposed mechanisms of action of BTX for pain relief of trigger points, muscular spasms, fibromyalgia and myofascial pain include direct action on muscle and indirect effects via action at the neuromuscular junction. Invitro and invivo data have shown that BTX has specific antinociceptive activity relating to its effects on inflammation, axonal transport, ganglion inhibition, and spinal and suprasegmental level inhibition. Our review of the mechanisms of action, efficacy, administration techniques and therapeutic dosage of BTX for the management of chronic pain in a variety of conditions shows that although muscular tone and movement disorders remain the most important therapeutic applications for BTX, research suggests that BTX can also provide benefits related to effects on cholinergic control of the vascular system, autonomic function, and cholinergic control of nociceptive and antinociceptive systems. Furthermore, it appears that BTX may influence the peripheral and central nervous systems. The therapeutic potential of BTX depends mainly on the ability to deliver the toxin to the target structures, cholinergic or otherwise. Evidence suggests that BTX can be administered at standard dosages in pain disorders, where the objective is alteration of muscle tone. For conditions requiring an analgesic effect, the optimal therapeutic dosage of BTX remains to be defined.

Future aspects of botulinum neurotoxins

The future of botulinum neurotoxin (BoNT) development is expected to proceed along two lines: the development of novel indications and the development of novel products. New indications will likely be based on the neuromuscular mode of action of BoNTs, as well as action on primary sensory fibers and other neuronal types. Novel BoNT products may be designed for increased specificity or enhanced duration. As new products enter the market, it will be important for each to demonstrate efficacy and safety. Unfortunately, the future of BoNTs will also likely include attempts to obtain and distribute unlicensed and illegal BoNT products that may pose substantial risks to patients.

Botulinum toxin type a in the prophylactic treatment of transformed migraine in Taiwanese patients: a review of 30 consecutive cases

BACKGROUND

Botulinum toxin type A (BoNT-A) for the treatment of patients with various forms of migraine has been studied, but there is a paucity of data regarding the use of BoNT-A in Asian headache patients. Our study was designed to evaluate the efficacy of BoNT-A in the treatment of transformed migraine (TM) in a population of Taiwanese patients.

METHODS

We retrospectively analyzed 30 patients who underwent BoNT-A treatment for TM from July 2003 to May 2004. Of 30 patients, 14 had palpable muscle tenderness (or tender points) in the pericranial region and 16 did not. All patients received injections into the corrugator, procerus, frontalis, and temporalis muscles (a total of 30 U), while a subset of TM patients with tender points (6 of 14 patients) also received injections to additional muscles based on a follow-the-tenderness approach (mean dose, 45 U).

RESULTS

Twenty-seven of the 30 patients (90%) surveyed reported effective relief of their symptoms with BoNT-A treatment (at least a 50% reduction in the number of headache days or in headache intensity). The greatest reduction in headache days per month and headache intensity was found in TM patients with tender points who received a mean dose of 45 U compared to those who received fixed-site dosing of 30 U.

CONCLUSION

Our results suggest that BoNT-A may be an effective prophylactic treatment for TM in Taiwanese patients. Interestingly, similar efficacy was demonstrated in TM patients with tender points compared to those without tender points when an additional dose of BoNT-A was injected into the tender muscles in the former.

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.

Evidence based medicine on the use of botulinum toxin for headache disorders

Botulinum toxin blocks the release of acetylcholine from motor nerve terminals and other cholinergic synapses. In animal studies botulinum toxin also reduces the release of neuropeptides involved in pain perception. The implications of these observations are not clear. Based on the personal experiences of headache therapists, botulinum toxin injections have been studied in patients with primary headaches, namely tension-type headache (TTH), chronic migraine (CM) and chronic daily headache (CDH). So far, the results of randomized, double-blind, placebo controlled trials on botulinum toxin in a total of 1117 patients with CDH, 1495 patients with CM, and 533 patients with TTH have been published. Botulinum toxin and placebo injections have been equally effective in these studies. In some of the studies, the magnitude of this effect was similar to that of established oral pharmacotherapy. This finding may help to explain the enthusiasm that followed the first open-label use of botulinum toxin in patients with headache. However, research is continuing to determine the efficacy of botulinum toxin in certain subgroups of patients with CM or CDH.

Treatment of chronic low back pain with botulinum neurotoxins

In a double-blind, randomized, placebo-controlled study, administration of botulinum toxin A (Botox; Allergan Inc., Irvine, CA) into paraspinal muscles using a novel technique produced significant pain relief in 60% of patients with chronic, refractory low back pain. A similar yield of 53% was noted in a prospective, randomized, open-label study of 75 patients, with 14 months of follow-up. In this study, an early response predicted later responsiveness, with 91% of the responders continuing to respond to repeat injections. The technique of treatment for both studies included covering the whole length of the lumbar erector spinae with one injection given at each lumbar level regardless of pain, tenderness, or trigger point location(s). The dose per injection site was 50 U (Botox), with the total dose per session not to exceed 500 U. Side effects were uncommon and consisted of a transient, mild flu-like reaction in 5% of the patients. Botulinum treatment of paraspinal muscles can reduce pain in a substantial number of patients with refractory chronic low back pain and is safe in the recommended doses.

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

The effect of botulinum toxin type A (BTX-A) on rat pyloric myoelectrical activity in vivo and the content and distribution of substance P (SP) in pylorus were investigated, respectively, with electromyography, radioimmunoassay, and immunohistochemistry. A pair of electrodes for recording pyloric myoelectrical activity and a guide cannula for drug injection were implanted into the pylorus. The changes of pyloric myoelectrical activity were recorded followed vehicle, 10, 20, and 40 U/kg body mass of BTX-A injection. Pyloric tissues were dissected for radioimmunoassay and immunohistochemistry after recording. The 3 dosages of BTX-A injections caused the reduction of slow wave of pyloric myoelectrical activity in amplitude but not in frequency and the diminishment of spike activity in amplitude and spike burst. The inhibitory effect of 20 U/kg BTX-A was significantly different from that of 10 U/kg (p<0.05), but not from the effect of 40 U/kg administration (p>0.05). After BTX-A intrasphincteric injection, SP content was reduced in the pylorus, and cell number of SP-immunoreactivity was decreased more in myenteric nerve plexus of circular muscle and in mucosa of pylori. In conclusion, BTX-A inhibits pyloric myoelectrical slow activity in amplitude and spike activity and weakens pyloric smooth muscle contractility depending on threshold of dose or concentration. BTX-A-induced inhibition of pyloric myoelectrical activity implies a mechanism of inhibiting SP release from the autonomic and enteric nervous terminals in the pylorus.

Botulinum toxin A does not alter capsaicin-induced pain perception in human skin

A genuine peripheral antinociceptive and anti-inflammatory effect of Botulinum neurotoxin type A (BoNT/A) has been proposed but could not be demonstrated in humans so far. Therefore, 100 mouse units of Botulinum toxin A (Dysport) and placebo were injected in a double blind paradigm in defined skin areas of 50 subjects. At baseline and after 4 and 8 weeks allodynia was induced in the skin areas with capsaicin ointment. Heat and cold pain threshold temperatures were measured with quantitative sensory testing, and threshold intensities upon electrical stimulation with a pain specific surface electrode were determined. No BoNT/A related differences in pain perception were found at any quality. There is neither a direct peripheral antinociceptive effect nor a significant effect against neurogenic inflammation of BoNT/A in humans.

Low-Dose Botulinum Toxin Type A for the Treatment of Refractory Piriformis Syndrome

STUDY OBJECTIVES

To evaluate the efficacy of a single, low-dose injection of botulinum toxin type A in relieving pain in Korean patients with piriformis syndrome resistant to conventional therapy, and to assess the drug's influence on these patients' quality of life.

DESIGN

Prospective, single-site, open-label trial.

SETTING

Rehabilitation medicine clinic in Seoul, Korea.

PATIENTS

Twenty-nine patients with a confirmed diagnosis of chronic piriformis syndrome and 82 age- and sex-matched healthy subjects were enrolled from April 1, 2003-February 28, 2004. Intervention. In 20 of the patients, botulinum toxin type A 150 U was injected using computed tomographic guidance into the affected unilateral piriformis muscle. The other nine patients served as active controls and received an injection of dexamethasone 5 mg and 1% lidocaine. The healthy subjects did not receive any injection.

MEASUREMENTS AND MAIN RESULTS

The patients' pain at baseline and at 4, 8, and 12 weeks after treatment was rated by using a numeric rating scale. Health-related quality of life was assessed by using the validated Korean version of the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) at baseline and at 4 weeks of treatment. Healthy subjects also completed the SF-36 at baseline. Pain intensity scores were significantly lower at 4, 8, and 12 weeks after treatment than at baseline (p<0.0001). Baseline scores from the SF-36 subscales, including those for physical functioning (p<0.0001), role physical (p<0.0001), bodily pain (p<0.0001), general health (p<0.0001), vitality (p<0.0001), and social functioning (p<0.002), were significantly lower in the patients than in the healthy subjects. Four weeks after treatment, physical functioning (p=0.003), role physical (p=0.021), bodily pain (p=0.016), general health (p=0.013), vitality (p=0.031) and social functioning (p=0.035) improved significantly from baseline in the patients. However, at 4 weeks, patients in the active control group were withdrawn from the study because their pain did not improve, and continuation without further medical care was considered unethical.

CONCLUSION

A low dose of botulinum toxin type A relieved pain and improved quality of life in patients with refractory piriformis syndrome.

Botulinum toxin therapy in the ovalbumin-sensitized rat

OBJECTIVE

The aim of this study was to determine whether intranasal administration of botulinum toxin type A (BTX-A) could relieve the typical symptoms of allergic rhinitis (AR) and alter substance P (SP)- and vasoactive intestinal peptide (VIP)-immunoreactive (IR) expression in nasal mucosa of AR animals sensitized with ovalbumin (OVA).

METHODS

AR was induced by intraperitoneal injection of OVA followed by its repeated intranasal instillation in female Wistar rats. Some AR animals were intranasally treated with a cotton strip containing BTX-A (10 U per nostril) for 1 h. After BTX-A treatment, OVA was repeatedly instilled in AR and AR + BTX-A groups every 2 days for 10 days. Subsequently, nasal symptoms were evaluated, and nasal secretions collected. Finally, the nasal mucosae of all animals were prepared for histological and immunohistochemical assessment.

RESULTS

BTX-A administration alleviated typical AR symptoms including rhinorrhea, nasal itching and sneezing, and subsequent intranasal repeated challenge with OVA did not trigger AR symptoms. After BTX-A treatment, inflammatory histological characteristics within the nasal mucosa of AR animals were absent, but atrophy of serous glands was observed. BTX-A decreased dense SP-IR and VIP-IR cells and fibers within and beneath the epithelium, around blood vessels and close to serous glands in AR animals.

CONCLUSION

Local BTX-A treatment is an effective method to reduce AR symptoms. BTX-A decreased the excessive SP-IR and VIP-IR expression induced by OVA. Therefore, BTX-A may affect the nasal mucosa via the suppression of neuropeptides, playing a major role in autonomous mucosal innervation in the pathophysiology of AR.

Dyshidrosis: Epidemiology, Clinical Characteristics, and Therapy

Dyshidrosis is a common chronic dermatitis of the hands and feet that may cause significant physical discomfort, psychological distress, and occupational impairment. Topics reviewed in this article include epidemiology, clinical findings, quality of life, and therapeutic considerations. Dyshidrosis is often difficult to manage; therefore, extra attention is given in this review article to current treatment options.

Efficacy and safety of a single botulinum type A toxin complex treatment (Dysport®) for the relief of upper back myofascial pain syndrome: Results from a randomized double-blind placebo-controlled multicentre study

Botulinum type A toxin (BoNT-A) has antinociceptive and muscle-relaxant properties and may help relieve the symptoms of myofascial pain syndrome. In this study we evaluated the efficacy and tolerability of BoNT-A (Dysport) in patients with myofascial pain syndrome of the upper back. We conducted a prospective, randomized, double-blind, placebo-controlled, 12-week, multicentre study. Patients with moderate-to-severe myofascial pain syndrome affecting cervical and/or shoulder muscles (10 trigger points, disease duration 6-24 months) were randomized to Dysport or saline. Injections were made into the 10 most tender trigger points (40 units per site). The primary outcome was the proportion of patients with mild or no pain at week 5. Secondary outcomes included changes in pain intensity and the number of pain-free days per week. Tolerability and safety were also assessed. At week 5, significantly more patients in the Dysport group reported mild or no pain (51%), compared with the patients in the placebo group (26%; p=0.002). Compared with placebo, Dysport resulted in a significantly greater change from baseline in pain intensity during weeks 5-8 (p<0.05), and significantly fewer days per week without pain between weeks 5 and 12 (p=0.036). Treatment was well tolerated, with most side effects resolving within 8 weeks. In conclusion, in patients with upper back myofascial pain syndrome, injections of 400 Ipsen units of Dysport at 10 individualised trigger points significantly improved pain levels 4-6 weeks after treatment. Injections were well tolerated.

Shaping the pupil’s response to light in the hooded rat

The contribution of iris muscle steady state and dynamic response characteristics to the shaping of the pupil response to light in the hooded rat were studied using electrical stimulation of the parasympathetic fibers in the III nerve. The waveforms of pupillary contractions to single or brief trains of electrical impulses applied to the III nerve were virtually identical to those elicited with short duration light flashes. Individual contractions could be resolved at stimulation rates of 2 Hz and below, and the size of the contractions increased with the decrease in frequency. The pupil responded to long trains of stimuli above 2 Hz with smooth tonic contractions. Steady state contraction amplitude was linearly related to log stimulation frequency. The mean time constant of pupil constriction to stimulus trains was 1.41 s (SD +/- 0.71 s) and the shortest mean latency was 292 ms (SD +/- 30 ms). The fastest mean latency of pupil constriction to the brightest light flash used was 295 ms. In contrast, the time constant of pupillary dilation was 7 s (SD +/- 1.4 s) and the shortest latency was 485 ms (SD +/- 74 ms). Therefore, the sluggish dynamic properties of the iris musculature are responsible for the asymmetries in pupil contraction, dilation, and latencies as well as low flicker fusion frequency and constriction amplitude characteristics of pupil responses to light.

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.

Pharmakologische Aspekte therapeutischer Botulinum-Toxin-Präparationen

Therapeutic preparations of botulinum toxin (BT) consist of botulinum neurotoxin (BNT), complexing proteins, and excipients. Depending on the target tissue, BNT can block cholinergic neuromuscular innervation of intra- and extrafusal muscle fibres or cholinergic autonomic innervation of sweat, lacrimal, and salival glands and smooth muscles. Indirect CNS effects are numerous; direct ones have not been reported after intramuscular application. Botulinum toxin type A is distributed as Botox, Dysport, Xeomin, Hengli/CBTX-A, and Neuronox and BT type B as NeuroBloc/Myobloc. Differences in potency labelling of therapeutic BT preparations can be corrected by introduction of a conversion factor of 1:3 between Botox and Dysport, of 1:1 between Botox and Xeomin, and of 1:40 between Botox and NeuroBloc/Myobloc. Acute adverse effects of BT can be obligate, local or systemic. Adverse effect profiles of the different preparations are similar. However, BT type B frequently produces additional autonomic systemic adverse effects. Long-term application does not produce additional adverse effects. BNT can be partially or completely blocked by antibodies. Risk factors include the amount of BNT applied at each injection series, the interval between injection series, and the specific biological potency (SBP) of the BT preparation used. The SBP is 5 equivalent mouse units/ng BNT for NeuroBloc, 60 for Botox, 100 for Dysport, and 167 for Xeomin. Xeomin should therefore have a particularly low antigenicity. Clinical confirmation of this predicition, however, is lacking.

The effects of Botulinum Toxin type A on capsaicin-evoked pain, flare, and secondary hyperalgesia in an experimental human model of trigeminal sensitization

The trigeminovascular system is involved in migraine. Efficacy of Botulinum Toxin type A (BoNT-A) in migraine has been investigated in clinical studies but the mechanism of action remains unexplored. It is hypothesized that BoNT-A inhibits peripheral sensitization of nociceptive fibers and indirectly reduces central sensitization. We examined the effect of intramuscular injection of BoNT-A on an experimental human model of trigeminal sensitization induced by intradermal capsaicin injection to the forehead. BoNT-A (BOTOX) or saline was injected intramuscularly in precranial, neck and shoulder muscles to 32 healthy male volunteers in a double blind-randomized manner. Intradermally capsaicin-induced pain, flare and secondary hyperalgesia were obtained before and 1, 4 and 8 weeks after the above treatments. A significant suppressive effect of BoNT-A on pain, flare and hyperalgesia area was observed. The pain intensity area was significantly smaller in BoNT-A group (9.16+/-0.83 cm x s) compared to saline group (15.41+/-0.83cm x s) (P=0.011). The flare area was also reduced significantly in BoNT-A group (29.81+/-0.69 cm2) compared to saline group (39.71+/-0.69 cm2) (P<0.001). Similarly, the mean area of secondary hyperalgesia was significantly smaller in BoNT-A group (4.25+/-0.91 cm2) compared to saline group (7.03+/-0.91 cm2) (P=0.040). Post hoc analysis showed significant differences across the trials with a remarkable suppression effect of BoNT-A on capsaicin-induced sensory and vasomotor reactions as early as week1 (P<0.001). BoNT-A presented suppressive effects on the trigeminal/cervical nociceptive system activated by intradermal injection of capsaicin to the forehead. The effects are suggested to be caused by a local peripheral effect of BoNT-A on cutaneous nociceptors.

Treatment of Refractory, Chronic Low Back Pain with Botulinum Neurotoxin A: An Open-Label, Pilot Study

OBJECTIVE

To study the short- and long-term effects of botulinum neurotoxin A (BoNT-A, Botox, Allergan Inc.) on refractory chronic low back pain.

DESIGN

The effect of botulinum neurotoxin A on chronic low back pain was prospectively studied in 75 patients with repeated treatments over a period of 14 months. Pain intensity (visual analog scale [VAS]), pain frequency (pain days), and perceived functional status (Oswestry scale) were assessed at baseline, 3 weeks, and at 2, 4, 6, 8, 10, 12, and 14 months. BoNT-A was injected into para-spinal muscles at 4-5 levels (between L1 and S1) unilaterally or bilaterally. The dose per site varied from 40 to 50 units. The total dose per session ranged from 200 to 500 units. Reinjections were performed at 4 months only when pain returned.

RESULTS

At 3 weeks, 40 patients (53%) and at 2 months, 39 patients (52%) reported significant pain relief. The change in VAS, Oswestry score, and pain days was significant compared with baseline at 2 months after each injection period (P < 0.005) and remained so over subsequent treatments. Among initial responders, 91% continued responsiveness over the length of the study. Three patients (4%), after the first treatment, had a mild flulike reaction that lasted 2-5 days.

CONCLUSION

Botulinum neurotoxin A may be beneficial in patients with chronic low back pain. A favorable initial response predicts subsequent responsiveness. The treatment is well tolerated, and side effects are mild and transient.

Botulinum toxin type A (Botox) in the treatment of migraine and other headaches

Botulinum toxin type A (Botox) is increasingly used in the management of migraine and tension-type headaches. The results from small placebo-controlled trials and extensive open-label experience has suggested a significant role for this neurotoxin in the management of refractory headache. Several large placebo-controlled trials of episodic and chronic migraine are currently underway.

Botulinum neurotoxins and formalin-induced pain: central vs. peripheral effects in mice

Neurotoxins affecting neuroexocytosis can represent an innovative pharmacological approach to the investigation of neural mechanisms of pain. Our interest has been focused on the use of botulinum neurotoxins (BoNTs), whose peripheral effects are extensively documented, while the effects on the central nervous system are much less clear. We have investigated both peripheral (sc into the hindpaw) and central (icv) effects of two BoNTs isoforms, BoNT/A and BoNT/B, on inflammatory pain. BoNT/A (sc: 0.937-15; icv: 0.937-3.75 pgtox/mouse) and BoNT/B (sc: 3.75, 7.5; icv: 1.875, 3.75 pgtox/mouse) were injected in CD1 mice and tested in the formalin test 3 days later. Licking response, as index of pain, and behavioral parameters, such as general activity and grooming, were recorded for 40 min during the test. BoNT/A partially affects the licking response in the second phase of formalin test in a similar magnitude of attenuation whether peripherally or centrally administered. BoNT/A does not significantly affect licking behavior during the first phase of the test. Peripheral administration of BoNT/B attenuates the licking response during the first phase not modifying the second phase, while the icv administration has hyperalgesic effect on the interphase of the formalin test. General activity and grooming behavior are not affected either by peripheral or by central administration of BoNTs. Our results show for the first time a central effect of BoNTs that differently modulate inflammatory pain depending both on serotype and on route of administration. Such data suggest BoNTs as a useful tool in the studies aimed at the comprehension of the mechanisms of inflammatory pain.

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 in dermatology - beyond wrinkles and sweat

Botulinum toxin (BTX) types A and B have been used with success in cosmetic dermatology and hyperhidrosis treatment. The present review focuses on other uses of BTX in dermatology. Discussed in particular are the available data on BTX in inflammatory diseases, proctology, and some other indications. From studies in various types of eczema, it seems that BTX-A not only acts as a potent inhibitor of acetylcholine but also as an inhibitor of substance P and of glutamate as well. By those mechanisms, BTX-A may be antipruritic, which may help explain the benefits of BTX-A in lichen simplex and dyshidrotic hand eczema. In Hailey-Hailey disease, facial eccrine hidrocystomas, salivary fistulas, and intrinsic rhinitis, BTX-A blocks the secretion of sweat/saliva/mucus. BTX-A has important applications in proctology where it has become the most powerful nonsurgical therapy for anal fissures. In proctalgia fugax and after hemorrhoidectomy, BTX-A is analgesic. Current treatment applications of BTX-A and its limitations are reviewed in this paper.

Improvement of wound healing after hemorrhoidectomy: a double-blind, randomized study of botulinum toxin injection

PURPOSE

Hemorrhoidectomy is usually associated with significant pain during the postoperative period. The spasm of the internal sphincter seems to play an important role in the origin of pain. This study was designed to evaluate the effectiveness of intrasphincter injection of botulinum toxin after hemorrhoidectomy in reducing the maximum resting pressure of the anal canal, accelerating wound healing, and decreasing postoperative pain when resting and during defecation.

METHODS

Thirty patients with hemorrhoids of third and fourth degree were included in the study and randomized in two groups. Anorectal manometry was performed preoperatively and 5 and 30 days afterward in all patients undergoing Milligan-Morgan hemorrhoidectomy. One group received an injection of 0.4 ml of saline into the internal anal sphincter, the other group were injected with 0.4 ml of solution containing 20 units of botulinum toxin.

RESULTS

After five days from hemorrhoidectomy, maximum resting pressure decreased in the group injected with botulinum toxin and increased in the placebo group. The time of healing and postoperative pain when resting and during defecation significantly decreased in the group treated with an injection of botulinum toxin.

CONCLUSIONS

Botulinum toxin injection into internal anal sphincter after hemorrhoidectomy is effective in reducing maximum resting pressure, time of healing, and postoperative pain both on resting and during defecation in absence of complications or side effects.

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.

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.