A double-blind, controlled study of botulinum toxin A in chronic myofascial pain

Re-engineering clostridial neurotoxins for the treatment of chronic pain: current status and future prospects

Clostridial neurotoxins from the botulinum neurotoxin (BoNT) family are protein complexes, derived from the bacterium Clostridium botulinum, which potently inhibit acetylcholine release and result in a reversible blockade of the neuromuscular junction. This feature led to the clinical development of BoNT-A for a number of neuromuscular disorders. BoNT-A toxins are commercially available as three different preparations: Dysport/Azzalure, Botox/Vistabel, and Xeomin/Bocouture. Although BoNT-A preparations have not yet been approved for the treatment of pain, a substantial body of preclinical and clinical evidence shows that BoNT-A is effective in treating a number of different types of pain. It is thought to exert an analgesic effect both via muscle-relaxant properties and also directly, via inhibition of nociceptive neuropeptides. This review explores the mechanistic basis of this analgesic effect, summarizing current knowledge of the structure-function relationship of BoNT and discussing effects on both motor and pain neurons. For a complete picture of the analgesic properties of BoNT-A, clinical evidence of efficacy in myofascial pain and neuropathic pain is considered in tandem with a mechanistic rationale for activity. Patients experiencing chronic pain are clear candidates for treatment with a modified clostridial endopeptidase that would provide enduring inhibition of neurotransmitter release. A strong preclinical evidence base underpins the concept that re-engineering of BoNT could be used to enhance the analgesic potential of this neurotoxin, and it is hoped that the first clinical studies examining re-engineered BoNT-A will confirm this potential.

Comparison of miniscalpel-needle release, acupuncture needling, and stretching exercise to trigger point in myofascial pain syndrome

OBJECTIVE

Myofascial pain syndrome (MPS) is one of the most common causes of chronic musculoskeletal pain. Several methods have been recommended for the inactivation of trigger points (TrPs). We carried out this study to investigate the effectiveness of miniscalpel-needle (MSN) release and acupuncture needling and self neck-stretching exercises on myofascial TrPs of the upper trapezius muscle.

METHODS

Eighty-three TrPs in 43 patients with MPS were treated and randomly assigned to 3 groups: group 1 received MSN release in conjunction with self neck-stretching exercises; group 2 received acupuncture needling treatment and performed self neck-stretching exercises; and group 3, the control group, was assigned self neck-stretching exercises only. The therapeutic effectiveness was evaluated using subjective pain intensity (PI) with a visual analog scale, pressure pain threshold (PPT), and contralateral bending range of motion (ROM) of cervical spine at pretreatment, 2 weeks, and 3 months after treatment.

RESULTS

The improvement of PI, PPT, and contralateral bending ROM of cervical spine was significantly greater in group 1 and 2 than that in control group at 2 weeks and 3 months follow-up. Compared with group 2, patients in group 1 had a statistically significant reduction in PI, an increase in PPT, contralateral bending ROM of cervical spine at 3 months follow-up.

DISCUSSION

The effectiveness of MSN release for MPS is superior to that of acupuncture needling treatment or self neck-stretching exercises alone. The MSN release is also safe, without severe side effects in treatment of MPS.

Botulinum neurotoxins in the treatment of refractory pain

The proper management of pain is a critical issue in the practice of medicine. Despite the availability of a large number of analgesic medications, management of pain that is refractory to conventional treatments remains a challenge for both clinicians and surgeons. Botulinum neurotoxin (BoNT) has recently emerged as a potential novel approach to control pain. Animal studies have revealed a number of mechanisms by which BoNTs can influence and alleviate chronic pain, including inhibition of pain peptide release from nerve terminals and sensory ganglia, anti-inflammatory and antiglutaminergic effects, reduction of sympathetic neural discharge, and inhibition of muscle spindle discharge. In humans, prospective, placebo-controlled, double-blind studies have also provided evidence for effectiveness of BoNT therapy in a number of painful disorders. These include cervical dystonia, pelvic pain, low back pain, plantar fasciitis, postsurgical painful spasms, myofascial pain syndromes, migraine, and chronic daily headaches. Long-term studies on cervical dystonia and low back pain have demonstrated safety and sustained efficacy after repeated injections. This Review focuses on the analgesic effects of BoNT and the mechanisms of its pain control as revealed by animal models, and provides evidence-based data on the efficacy of BoNT therapy in various pain syndromes in humans.

Current management of pain associated with multiple sclerosis

While pain is a common problem in patients with multiple sclerosis (MS), it is not frequently mentioned by patients and a more direct approach is required in order to obtain information about pain from patients. Many patients with MS experience more than one pain syndrome; combinations of dysaesthesia, headaches and/or back or muscle and joint pain are frequent. For each pain syndrome a clear diagnosis and therapeutic concept needs to be established. Pain in MS can be classified into four diagnostically and therapeutically relevant categories: (i) neuropathic pain due to MS (pain directly related to MS); (ii) pain indirectly related to MS; (iii) MS treatment-related pain; and (iv) pain unrelated to MS. Painful paroxysmal symptoms such as trigeminal neuralgia (TN), or painful tonic spasms are treated with antiepileptics as first choice, e.g. carbamazepine, oxcarbazepine, lamotrigine, gabapentin, pregabalin, etc. Painful 'burning' dysaesthesias, the most frequent chronic pain syndrome, are treated with TCAs such as amitriptyline, or antiepileptics such as gabapentin, pregabalin, lamotrigine, etc. Combinations of drugs with different modes of action can be particularly useful for reducing adverse effects. While escalation therapy may require opioids, there are encouraging results from studies regarding cannabinoids, but their future role in the treatment of MS-related pain has still to be determined. Pain related to spasticity often improves with adequate physiotherapy. Drug treatment includes antispastic agents such as baclofen or tizanidine and in patients with phasic spasticity, gabapentin or levetiracetam are administered. In patients with severe spasticity, botulinum toxin injections or intrathecal baclofen merit consideration. While physiotherapy may ameliorate malposition-induced joint and muscle pain, additional drug treatment with paracetamol (acetaminophen) or NSAIDs may be useful. Moreover, painful pressure lesions should be avoided by using optimally adjusted aids. Treatment-related pain associated with MS can occur with subcutaneous injections of interferon-beta or glatiramer acetate, and may be reduced by optimizing the injection technique and by local cooling. Systemic (particularly 'flu-like') adverse effects of interferons, e.g. myalgias, can be reduced by administering paracetamol, ibuprofen or naproxen. A potential increase in the frequency of pre-existing headaches after starting treatment with interferons may require optimization of headache attack therapy or even prophylactic treatment. Pain unrelated to MS, such as back pain or headache, is common in patients with MS and may deteriorate as a result of the disease. In summary, a careful analysis of each pain syndrome will allow the design of the appropriate treatment plan using various medical and nonmedical options (multimodal therapy), and will thus help to improve the quality of life (QOL) of the patients.

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 analgesic effect of botulinum-toxin A on postwhiplash neck pain

BACKGROUND

The effectiveness of botulinum neurotoxin type A (BTXA) injections in relieving the neck pain and reduced motion that evolve after whiplash injury (WI) has been controversial.

AIM OF STUDY

To test the long-term efficacy of a tender point injection of BTXA in relieving neck pain in patients with WI.

METHODS

Twenty patients with cervical myofascial pain, 2 to 48 weeks after WI, were randomly assigned to receive either 200 U of BTXA or placebo at 4 tender points and were seen during the follow-ups 3, 6, 9, 12, and 24 weeks after the injections. Outcome measures included the intensity of pain as evaluated by a 10-cm Visual Analog Scale (VAS) and a 5-point Verbal Rating Scale (VRS), quality of life as evaluated by the SF-36 questionnaire, treatment efficacy as per the global assessment of the physician and patient, intensity of pain in response to mechanical pressure, range of cervical motion, and use of other therapies and their adverse effects.

RESULTS

A time-dependent improvement in all the parameters was found in both groups, which was consistently larger in the BTXA-treated group, but mostly not at a significant level. Significant differences between the groups were found only in the percentages of patients who achieved 50% or more of reduction in intensity (VAS and average VRS) at 24 weeks (50% vs. 0%, P>0.05 and 70% vs. 11%, P>0.05, respectively). Systemic adverse effects tended to be more common in the BTXA-treated group (40% vs. 0%, P=0.07).

CONCLUSIONS

Study results suggest that BTXA treatment has some efficacy when administered within 1 year of the WI. However, a large, well-designed clinical trial is needed to draw final conclusions.

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.

Evidence-informed management of chronic low back pain with trigger point injections

The management of chronic low back pain (CLBP) has proven very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing amongst available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to CLBP, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.

Barriers to rehabilitation following surgery for primary breast cancer

Surgery is a mainstay of primary breast cancer therapy. Alterations in surgical technique have reduced normal tissue injury, yet pain and functional compromise continue to occur following treatment. A tenuous evidence base bolstered by considerable expert opinion suggests that early intervention with conventional rehabilitative modalities can reduce surgery-associated pain and dysfunction. Barriers to the timely rehabilitation of functionally morbid sequelae are discussed at length in this article. Barriers arise from a wide range of academic, human, logistic, and financial sources. Despite obstacles, expeditious and effective post-surgical rehabilitation is being regularly delivered to breast cancer patients at many institutions. This experience has given rise to anecdotal information on the management of common sequelae that may undermine function. The epidemiology, pathophysiology, and management of these sequelae are outlined in this article with an emphasis on the caliber of supporting evidence. Myofascial dysfunction, axillary web syndrome, frozen shoulder, lymphostasis, post-mastectomy syndrome, and donor site morbidity following breast reconstruction are addressed. A critical need for more definitive evidence to guide patient management characterizes the current treatment algorithms for surgical sequelae.

A critical review of the use of botulinum toxin in orofacial pain disorders

This article reviews the appropriate use, cautions, and contraindication for botulinum neurotoxin (BoNT) and reviews the peer-reviewed literature that describes its efficacy for treatment of various chronic orofacial pain disorders. The literature has long suggested that BoNT is of value for orofacial hyperactivity and more recently for some orofacial pain disorders; however, the results are not as promising for orofacial pain. The available data from randomized, double-blind, placebo-controlled trials (RBCTs) do not support the use of BoNT as a substantially better therapy than what is being used already. The one exception is that BoNT has reasonable RBCT data to support its use as a migraine prophylaxis therapy. The major caveat is that the use of BoNT in chronic orofacial pain is "off-label".