Pharmacotherapy with botulinum toxin: harnessing nature's most potent neurotoxin

Coordination of the upper and lower extremities during walking in children with cerebral palsy

BACKGROUND

Children with cerebral palsy indicate poor continuous gait inter-limb coordination compared to typically developing children. Limited research exists in the understanding of the coordinative relationship between the arms and legs of these children and if the phasing relationships between limbs can be improved.

RESEARCH QUESTION

Which motor control factors impact coordination in children with cerebral palsy and can coordination improve with intervention?

METHODS

This literature review provides a comprehensive overview of the current knowledge of continuous coordination in a pediatric, pathologic population with an emphasis on inter-limb coordination. Peer-reviewed research articles related to inter-limb coordination, with a focus on gait, were reviewed to identify relevant research and any gaps in the literature which could inform future study design. Consideration of the most appropriate analysis for evaluation of such movement is also presented.

RESULTS

The coordinative difficulties experienced by children with cerebral palsy may originate from the deficits in motor control, muscle tone, and weakness caused by damage to the central nervous system, which is vital in motor control of inter-limb coordination. Continuous inter-limb coordination in children with cerebral palsy may be improved with enhanced function of the upper extremities through intensive motor-learning based rehabilitation or botulinum toxin injection of the more-affected arm. Importantly, analysis of limb movements should include continuous measures of relative phase, as it provides a more detailed description of coordination compared to discrete measures.

SIGNIFICANCE

Improved upper extremity function may produce a positive change in the phasing relationship between the arms and legs. This type of coordination should be analyzed using relative phase analysis, as this type of analysis can provide more information compared to traditional spatiotemporal parameters. However, more research is required to fully understand the connection between improved upper extremity function and its positive impact on gait coordination in children with cerebral palsy.

Passive Monoclonal and Polyclonal Antibody Therapies

Passive antibody therapies have a long history of use. In the 19th century, antibodies from xenographic sources of polyclonal antibodies were used to treat infections (diphtheria). They were used often as protection from infectious agents and toxins. Complications related to their use involved development of immune complexes and severe allergic reactions. As a result, human source plasma for polyclonal antibodies became the preferential source for antibodies. They are used to treat infection, remove toxins, prevent hemolytic disease of the newborn, modify inflammatory reactions, and control autoimmune diseases. Continued improvements in processing decreased the transfusion/infusion transmission of infections. In the late 20th century (∼1986), monoclonal antibodies were developed. The first monoclonal antibodies were of xenographic source and were wrought with problems of immunogenicity. These forms of antibodies did not gain favor until chimerization took pace in the mid-1990s and in 1998 two monoclonal antibodies were approved one to treat respiratory syncytial virus and the other for breast cancers. Further development of humanized and then fully human monoclonal antibodies has led to an evolution of therapies with these agents. Monoclonal antibodies are being researched or approved to treat a multitude of diseases to include oncologic, inflammatory, autoimmune, cardiovascular, respiratory, neurologic, allergic, benign hematologic, infections, orthopedic, coagulopathy, metabolic and to decrease morbidity of disease (diminution of pain), modify disease progression, and potentially anatomic development. In this chapter, we will review the history of use of these passive antibody therapies, their mechanism of action, pharmacologic-therapeutic classification, particular medical indication, adverse reactions, and potential future use of these medications.

A Retrospective, Single-Center Comparative Cost Analysis of OnabotulinumtoxinA and AbobotulinumtoxinA for Cervical Dystonia Treatment

BACKGROUND

Chemodenervation with botulinum neurotoxin (BoNT) is recommended as first-line treatment for the management of cervical dystonia. The choice of BoNT for treatment is subject to the consideration of several factors, including cost.

OBJECTIVE

To compare the costs incurred by patients and payers for onabotulinumtoxinA (ONA) or abobotulinumtoxinA (ABO) for the treatment of cervical dystonia.

METHODS

We conducted a retrospective, noninterventional closed cohort study of cervical dystonia patients within a single U.S. private neurological practice. Patient and payer incurred costs from medical billing records for patients satisfying inclusion and exclusion criteria treated from November 1, 2009, through January 1, 2013, were de-identified and included in the analysis. Forty-seven patients initially treated with at least 3 consecutive cycles of ONA, followed by at least 3 consecutive cycles of ABO were included, representing 282 injection cycles available for analysis. Patients were required to have had a positive response to treatment with both agents and no concomitant treatment with BoNT for any other condition during the analysis period. The analysis compared the primary endpoint of median overall payer and patient incurred costs reimbursed to the clinic under each treatment regimen. For the purposes of this cost analysis, comparable clinical outcomes on both therapies was assumed.  

RESULTS

Switching from ONA to ABO resulted in an overall incurred reimbursement cost savings for payers and patients. Median costs per injection cycle for ONA were $1,925 ($0-$2,814) compared with $1,214 ($229-$2,899; P  less than  0.0001) for ABO, representing an approximate 37% reduction in incurred reimbursement costs inclusive of toxin and procedure. Overall toxin reimbursement costs, patient out-of-pocket toxin costs, and the cost of unavoidable waste were also lower when patients were treated with ABO. 

CONCLUSIONS

For patients treated for cervical dystonia, switching from ONA to ABO resulted in payer and patient reimbursement cost reductions in a single U.S. private practice with outcomes assumed to be similar.

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.

Association between botulinum toxin injection into the arm and changes in gait in adults after stroke

Botulinum toxin (BTX) is often used to improve arm function in persons with hemiparesis after stroke. Persons injected into the arm sometimes report changes in their gait. The purpose of this open-labeled pilot study was to investigate the association between injecting BTX into the upper limb and ankle and knee range of motion (ROM) and paretic-leg stride-time, defined as the time in seconds required to move the hemiparetic leg from initial contact of the foot to initial contact of the same foot. Gait parameters were recorded before and 4 to 6 weeks after the hemiparetic arm was injected with BTX in 13 adults with hemiparesis secondary to stroke, using a three-dimensional computerized motion analysis system. BTX injection into the paretic arm was associated with a decrease in stride-time of the paretic leg in all participants. Slower striding participants improved knee and ankle ROM in the paretic leg. There was no change in ankle and knee ROM in faster striding participants. Injection of BTX into the upper extremity is associated with a change in hemiparetic leg stride-time and ankle and knee ROM. There is a variability of response, with slow striders improving to a greater extent than fast striders.

Glycosphingolipids-sweets for botulinum neurotoxin

A number of viruses, bacteria, and bacterial toxins can only act on cells that express the appropriate glycosphingolipids (GSLs) on the outer surface of their plasma membranes. An example of this dependency is provided by botulinum neurotoxin (BoNT) which is synthesized by Clostridium botulinum and inhibits neurotransmission at the neuromuscular junction by catalyzing hydrolysis of a SNARE protein, thereby inducing a flaccid paralysis. Haemagglutinin components of progenitor forms of BoNT mediate its adherence to glycosphingolipids (GSLs) on intestinal epithelial cells while the cellular activity of most isolated serotypes requires the presence of certain gangliosides, especially those of the Gg1b family. This review discusses available information about the identity and the roles of GSLs in the activity of BoNT. Observations that serotypes A-F of BoNT require gangliosides for optimum activity (serotype G apparently does not), permits the hypothesis that it should be possible to develop an antagonist of this interaction thereby inhibiting/reducing its effect.

Does training improve writer's cramp? An evaluation of a behavioral treatment approach using kinematic analysis

Patients with writer's cramp (WC) show uncontrollable muscle co-contractions of agonists and antagonists and unusual postures of the upper limb during writing; their handwriting is inefficient and exhausting. Currently the treatment of choice is to inject botulinum toxin in selective hand muscles. However, this treatment has two drawbacks: it is short-lasting and may be associated with adverse side effects. An alternative behavioral treatment, namely, the handwriting training developed by Mai and coworkers, was carried out and evaluated in 50 patients with WC. A digitizing tablet was used to record the handwriting movements before and after training, and then again after a follow-up period. The results indicate the efficacy of the handwriting training. Speed and smoothness of the handwriting increased during the training with effects observed after an extended follow-up period. Handwriting training leads to significant improvements, but does not bring handwriting performance to normal levels. This training should be considered as an alternative or supplement to the traditional treatment with botulinum toxin or other programs based on neuroplasticity.

Novel application of an in vitro technique to the detection and quantification of botulinum neurotoxin antibodies

Detection of Clostridium botulinum neurotoxin (BoNT) neutralising antibodies is currently achieved using the mouse lethality assay (MLA). This technique has provided the majority of the data for vaccine development and, with the increasing use of BoNT as a therapeutic agent, the MLA is the assay of choice to evaluate 'non-responder' antisera. However, the MLA is semi-quantitative and has an animal consumption rate that raises ethical concerns. The development of an alternative is therefore desirable. Here, we describe an in vitro neuronal release assay that may represent such an alternative in terms of both its sensitivity and ability to produce quantitative data. Initially recognised in the course of assessing a novel vaccine candidate, the suitability of this assay has been further explored using an International standard. The results support the conclusion that the detection of neutralising antibodies in human sera should be attempted using this method.

Botulinum toxin A: its expanding role in dermatology and esthetics

The use of botulinum toxin A in cosmetic dermatology has increased in popularity due to the efficacy and relative safety of the treatment. Botulinum toxin A is one of eight exotoxins produced by Clostridium botulinum, a Gram-positive, spore-forming anaerobe. Flaccid paralysis results from the denervation of muscle fibers at the neuromuscular junction after botulinum toxin A administration. While treating blepharospasm, the Carruthers incidentally found that botulinum toxin A improved glabellar frown lines. Dynamic rhytides occur in areas of dynamic motion. These types of lines may be improved with botulinum toxin A. There are two types of botulinum toxin A commercially available (BOTOX and Dysport); only BOTOX is currently available in the US. The efficacy and tolerability of BOTOX was best demonstrated with a multicenter, double-blind, randomized, placebo-controlled study of the efficacy and safety of botulinum toxin type A in the treatment of glabellar lines in 264 patients. There was a significantly greater reduction in glabellar line severity with BOTOX. The effect was maintained for the duration of the study (120 days). There was low occurrence (5.4%) of mostly mild blepharoptosis in the BOTOX group. In another prospective study, it was found that about 1% of BOTOX patients reported severe headache. Botulinum toxin A can provide an alternative treatment of palmar and axillary hyperhidrosis when options such as topical agents (aluminum chloride) and iontophoresis have failed.

Double-blind, placebo-controlled study of the safety and efficacy of botulinum toxin type A for patients with glabellar lines

The objective of this study was to evaluate the efficacy and safety of botulinum toxin type A for the treatment of glabellar lines. Patients with moderate or severe glabellar lines at maximal frown received intramuscular injections of placebo or 20 U of botulinum toxin type A (Botox; Allergan, Inc., Irvine, Calif.) distributed among five injection sites (one in the procerus muscle and two in each corrugator supercilii). Follow-up assessments were performed at 7, 30, 60, 90, and 120 days after injections. Efficacy measures were the physician's rating of glabellar line severity at maximal frown and at rest (none, mild, moderate, or severe) and the patient's global assessment of changes in glabellar lines, from +4 (100 percent better) to -4 (100 percent worse). A total of 273 patients were enrolled (botulinum toxin, 202 patients; placebo, 71 patients). All except five patients (botulinum toxin, two patients; placebo, three patients) completed the study. For the physician's rating at maximal frown, the responder rate (percentage of patients with severity ratings of none or mild in follow-up evaluations) for the botulinum toxin group peaked at 77 percent at day 30 and was significantly greater than that for the placebo group at every follow-up visit (p < 0.001). For the patient's assessment, the responder rate (percentage of patients with scores of +2 or more) for the botulinum toxin group peaked at 89 percent at day 30 and was significantly greater than that for the placebo group at every follow-up visit (p < 0.001). Rates of adverse events were similar for the two groups. The only adverse event with an incidence of >/=5 percent was headache (botulinum toxin, 11 percent; placebo, 20 percent). The incidence of blepharoptosis was 1 percent for the botulinum toxin group. Botulinum toxin type A was remarkably safe and effective in reducing glabellar lines.

Achalasia: a comprehensive review

Achalasia is a rare neurologic deficit of the esophagus, producing a syndrome of impaired relaxation of the lower esophageal sphincter and decreased motility of the esophageal body for which the cause is unknown. The resultant chronic esophageal stasis produces discomforting symptoms that can be managed with medication, chemical paralysis of the lower esophageal sphincter, mechanical dilation, or surgical esophagomyotomy. Chemical paralysis by injection of the esophagus with botulinum toxin and dilation with an inflatable balloon offers good short-term relief of symptoms; however, the best long-term results are produced by surgery, and advancing minimally invasive techniques continually reduce the morbidity of these operations. The type of surgical procedure, the necessity for fundoplication, and the order of treatment continue to be unresolved issues, but prospective evaluation with objective followup should allow us to provide the optimal treatment regimen to our patients.

Hyperhidrosis in social anxiety disorder

PURPOSE

Excessive sweating (hyperhidrosis) is an overlooked and potentially disabling symptom, which is often seen in social anxiety disorder (SAD). We conducted a retrospective review of data acquired in patients with SAD who had participated in placebo-controlled clinical trials of fluoxetine, cognitive behavior therapy, clonazepam and gabapentin. Four specific topics were addressed: (1) overall levels of sweating; (2) characteristics of those with hyperhidrosis; (3) a comparison of active treatments relative to placebo on hyperhidrosis; and (4) an examination of baseline sweating severity as a predictor of treatment outcome.

METHODS

Using the Brief Social Phobia Scale (BSPS) and Social Phobia Inventory (SPIN), we examined the above questions.

RESULTS

Hyperhidrosis was found in 24.8-32.3% of 375 subjects assessed, depending upon the scale used. Hyperhidrosis was associated with higher levels of disability, fear, avoidance, and other physiologic symptoms. While treatment in general was associated with a reduction in the rate of hyperhidrosis from 23.7% to 9.7% (BSPS), and 34.0% to 15.5% (SPIN), only fluoxetine differed significantly from placebo in respect of change in sweating score from baseline to endpoint. In an ANCOVA, gabapentin differed from placebo on the SPIN.

CONCLUSION

We conclude that hyperhidrosis is frequently seen in patients with SAD, and that its response to treatment is variable. Further attention should be paid to the possible importance of this symptom in social anxiety.

Review of the FDA-approved uses of botulinum toxins, including data suggesting efficacy in pain reduction

Botulinum toxin has dramatically improved the treatment of a variety of neurologic disorders. Two botulinum toxin preparations are commercially available in the United States: type A (Botox) and type B (Myobloc). Current indications approved by the United States Food and Drug Administration include cervical dystonia, strabismus, blepharospasm, hemifacial spasm, and glabellar wrinkles for Botox, and cervical dystonia for Myobloc. Botulinum toxin inhibits release of acetylcholine from the neuromuscular junction, resulting in a localized paralysis when minute doses are injected. This mechanism enables botulinum toxin to alleviate symptoms of focal dystonias (which are characterized by excessive muscle contraction), and it may also, along with other theoretical mechanisms, be responsible for pain relief. Studies conducted in patients with cervical dystonia have shown that botulinum toxin effectively reduces pain associated with this disorder, suggesting that this agent may be effective in alleviating other painful syndromes.