Botulinum toxin in motor disorders

Hsp104 suppresses polyglutamine-induced degeneration post onset in a drosophila MJD/SCA3 model

There are no effective therapeutics that antagonize or reverse the protein-misfolding events underpinning polyglutamine (PolyQ) disorders, including Spinocerebellar Ataxia Type-3 (SCA3). Here, we augment the proteostasis network of Drosophila SCA3 models with Hsp104, a powerful protein disaggregase from yeast, which is bafflingly absent from metazoa. Hsp104 suppressed eye degeneration caused by a C-terminal ataxin-3 (MJD) fragment containing the pathogenic expanded PolyQ tract, but unexpectedly enhanced aggregation and toxicity of full-length pathogenic MJD. Hsp104 suppressed toxicity of MJD variants lacking a portion of the N-terminal deubiquitylase domain and full-length MJD variants unable to engage polyubiquitin, indicating that MJD-ubiquitin interactions hinder protective Hsp104 modalities. Importantly, in staging experiments, Hsp104 suppressed toxicity of a C-terminal MJD fragment when expressed after the onset of PolyQ-induced degeneration, whereas Hsp70 was ineffective. Thus, we establish the first disaggregase or chaperone treatment administered after the onset of pathogenic protein-induced degeneration that mitigates disease progression.

Botulinum neurotoxins for post-stroke spasticity in adults: a systematic review

The aim of this systematic review was to determine whether botulinum neurotoxin (BoNT) reduce spasticity or improve function in adult patients after stroke. Eleven double-blind randomized placebo-controlled trials met inclusion criteria. They encompassed 782 patients, 767 (98%) of whom received BoNT/A, and 15 (2%) BoNT/B. Most studies used the Ashworth scale as primary outcome measure. Differences between treated and control groups were assessed as categorical or continuous comparisons. The overall effect on upper limb spasticity was in favor of BoNT/A. A significantly higher number of patients had a reduction of upper limb spasticity at 4-week and 8-week evaluations in the treatment group compared with placebo. Mean changes in joint spasticity revealed improvement 3 to 6 weeks and 9 to 12 weeks after treatment. There were insufficient data to establish BoNT/A efficacy on lower limb spasticity or the effect of BoNT/B on the upper and lower limbs. Because of inconsistency and heterogeneity of the available data, it was not possible to perform a meta-analysis on disability and patients' reported outcomes. There was an overlapping safety profile between the treatment and the placebo groups. BoNT/A reduces upper limb spasticity in patients post-stroke, but the improvement in functional ability remains to be established. This gap needs to be filled by new studies to assess the effect of BoNT in the context of multidisciplinary patient management.

Differences in improvement between patients with idiopathic versus neurovascular hemifacial spasm after botulinum toxin treatment

This study was performed to investigate the differences in response to botulinum toxin treatment between patients with idiopathic versus neurovascular hemifacial spasm. A total of 69 patients with hemifacial spasm were investigated prospectively with cranial magnetic resonance imaging and magnetic resonance angiography. Neurovascular contact was found in 23 patients. All patients were assessed with a severity scale and a disease awareness scale. After treatment, the patients with idiopathic hemifacial spasm improved significantly in terms of both severity and awareness scores, but the patients with neurovascular hemifacial spasm improved only in the awareness scores. In conclusion, patients with idiopathic hemifacial spasm experienced a greater improvement after treatment with botulinum toxin than did patients with neurovascular hemifacial spasm.

Selection of treatment modalities in children with spastic cerebral palsy

The purpose of this report was to outline the various options currently used for treatment of spastic cerebral palsy (CP) and to discuss factors involved in selecting the appropriate treatment modalities for the individual child. In a review of the literature and his personal observations, the author presents an outline of treatment options and the criteria for using each. Therapeutic options include the following: physiotherapy; occupational therapy; oral spasmolytic and antidystonic drugs; botulinum toxin injections; orthopedic procedures; continuous infusion of intrathecal baclofen (ITB); selective dorsal rhizotomy (SDR); and selective peripheral neurotomy. The most commonly used neurosurgical procedures are ITB pump placement and SDR, and these are discussed in the most detail. The author's personal schema for assessment of the child to determine the nature of the hypertonia, the impact of the hypertonia, and the appropriate therapeutic intervention is presented. There are factors that help guide the optimal treatment modalities for the child with spastic CP. The treatment of these children is optimized in the setting of a multidisciplinary team.

Injectable neuromuscular blockade in the treatment of spasticity and movement disorders

Neuromuscular blockade via injection of alcohol, phenol, or botulinum toxin reduces the tone of overactive muscles in order to restore the appropriate balance between agonists and antagonists. Such a restoration allows improved stretch and increased resting length and can reduce the likelihood of contracture. Alcohol or phenol, injected onto the motor nerve, denatures proteins and promotes axonal degeneration. The onset of action is within hours, whereas the duration of action is variable, ranging from 2 weeks to 6 months and beyond. The advantages of alcohol or phenol chemodenervation lie in their low cost and lack of antigenicity. The disadvantages include the technical difficulty of the injections and significant risk for pain as a result of treatment. Botulinum toxins, purified forms of Clostridium botulinum exotoxins, are injected directly into muscle, where they cleave one or more vesicle fusion proteins, thus blocking release of acetylcholine at the neuromuscular junction. Three commercial products--two of serotype A and one of B--are available. Each differs in its unit potency, side effects, and duration of action. On average, botulinum toxin has a clinical onset of action approximately 12 to 72 hours after injection, with a peak effect at 1 to 3 weeks. Effects then plateau for 1 to 2 months, with patients often requiring reinjection approximately every 3 months. Side effects may include local discomfort at the site of the injection and excessive weakness of the injected or nearby muscles, although more distant effects may occur. Antibody formation is a significant clinical concern and eventually obviates treatment benefit in approximately 5% of patients. Switching serotypes may be effective, at least temporarily. Consensus dosing guidelines have been developed and are presented within. Numerous studies have suggested that botulinum toxin has a role in the care of children with spasticity or dystonia related to cerebral palsy, and may improve equinus, gait, upper extremity use, comfort, and care. Evidence of functional improvement remains equivocal in the severely impaired child; however, there is evidence for improvement in less impaired children. The optimal candidate for injectable neuromuscular blockade is one who has a limited number of muscles that need treatment, who does not have fixed contracture, and who retains selective motor control. The ultimate goal of treatment for the hypertonic child is to maximize function, comfort, and independence. Hypertonia is only one aspect of the upper motoneuron syndrome, which includes both positive and negative symptoms. The treatment program, in which chemodenervation is only one tool, requires a multidisciplinary evaluation and individualized plan to address the whole patient.

Treatment of spasticity with botulinum toxin

Spasticity is an abnormal increase in muscle contraction often caused by damage to central motor pathways that control voluntary movement. During clinical examination, spasticity manifests as an increase in stretch reflexes, producing tendon jerks and resistance appearing as muscle tone. There are many causes of spasticity, including demyelination from multiple sclerosis, congenital damage from diseases such as cerebral palsy, trauma to the brain or spinal cord, hemorrhage or infarction, and other pathologic conditions that interrupt neural pathways. Effects of spasticity range from mild muscle stiffness to severe, painful muscle contractures and repetitive spasms that reduce mobility and substantially impede normal activities of daily living. Botulinum toxin therapy reduces spasticity and pain associated with several disorders. Local treatment with botulinum toxins can be used as adjunctive therapy, along with oral antispasticity medications, or alone to provide localized decrease in symptoms of spasticity and pain. Botulinum toxin therapy may be particularly useful for patients with spasticity due to stroke, whose treatment can be tailored based on recovery of function over time. In addition, botulinum toxin therapy is safe for pediatric patients, including children with cerebral palsy, who may not be able to tolerate the cognitive side effects of oral medications. Results of studies evaluating botulinum toxin for the treatment of spasticity due to various causes are presented here.

Adenoviral retrograde gene transfer in motoneurons is greatly enhanced by prior intramuscular inoculation with botulinum toxin

Retrograde axonal transport of recombinant adenoviral vectors has been used successfully to deliver genes to motoneurons in rodents after injection of the vectors into muscles. However, only a small proportion of motoneurons take up and retrogradely transport adenoviral particles, limiting the value of this gene delivery method for the treatment of motor neuron diseases (MNDs). Here we validate a new pharmacological approach for enhancing motoneuronal gene transfer after intramuscular injection of recombinant adenoviruses. We injected botulinum neurotoxin A (BoNT) into muscles of normal C57BL/6 mice and transgenic mice expressing the G93A mutation in the superoxide dismutase 1 gene (SOD1-G93A mutation, a model of amyotrophic lateral sclerosis) several days before inoculation with adenoviruses. Treatment with BoNT significantly enhanced gene transfer to motoneurons innervating the injected muscles. Modifications in motoneuron transduction appear to be a consequence of toxin-induced nerve sprouting at the end plates. These findings have major implications for devising protocols for preclinical and clinical studies using intramuscular injection of retrogradely transported gene vectors.