The natural course of idiopathic cervical dystonia.

Idiopathic cervical dystonia (ICD) is by far the largest subgroup of dystonia. Still, its natural course is largely unknown. We studied the natural course of 100 ICD patients from our botulinum toxin clinics (age at ICD onset 45.8 ± 13.5 years, female/male ratio 2.0) over a period of 17.5 ± 11.5 years with follow-ups during botulinum toxin therapy and with semi-structured interviews. Two courses of ICD could be distinguished by symptom development of more or less than 6 months. ICD-type 2 was less frequent (19% vs 81%, p < 0.001), had a more rapid onset (8.7 ± 8.0 weeks vs 3.8 ± 3.5 years), a higher remission rate (92% vs 5%, p < 0.001) and a higher prevalence of excessive psychological stress preceding ICD (63% vs 1%, p < 0.001). In both ICD-types, the plateau phase was non-progressive. Significant differences in patient age at ICD onset, latency and extent of remission, female/male ratio and prevalence of family history of dystonia could not be detected. ICD is a non-progressive disorder. ICD-type 1 represents the standard course. ICD-type 2 features rapid onset, preceding excessive psychological stress and a high remission rate. These findings will improve prognosis, treatment strategies and understanding of underlying disease mechanisms. They contradict the widespread fear of patients of a constant and continued decline of their condition. Excessive psychological stress may be an epigenetic factor triggering the manifestation of genetically predetermined dystonia.

Consensus guidelines for botulinum toxin therapy: general algorithms and dosing tables for dystonia and spasticity.

Botulinum toxin (BT) therapy is a complex and highly individualised therapy defined by treatment algorithms and injection schemes describing its target muscles and their dosing. Various consensus guidelines have tried to standardise and to improve BT therapy. We wanted to update and improve consensus guidelines by: (1) Acknowledging recent advances of treatment algorithms. (2) Basing dosing tables on statistical analyses of real-life treatment data of 1831 BT injections in 36 different target muscles in 420 dystonia patients and 1593 BT injections in 31 different target muscles in 240 spasticity patients. (3) Providing more detailed dosing data including typical doses, dose variabilities, and dosing limits. (4) Including total doses and target muscle selections for typical clinical entities thus adapting dosing to different aetiologies and pathophysiologies. (5) In addition, providing a brief and concise review of the clinical entity treated together with general principles of its BT therapy. For this, we collaborated with IAB-Interdisciplinary Working Group for Movement Disorders which invited an international panel of experts for the support.

Defining spasticity: a new approach considering current movement disorders terminology and botulinum toxin therapy.

Spasticity is a symptom occurring in many neurological conditions including stroke, multiple sclerosis, hypoxic brain damage, traumatic brain injury, tumours and heredodegenerative diseases. It affects large numbers of patients and may cause major disability. So far, spasticity has merely been described as part of the upper motor neurone syndrome or defined in a narrowed neurophysiological sense. This consensus organised by IAB-Interdisciplinary Working Group Movement Disorders wants to provide a brief and practical new definition of spasticity-for the first time-based on its various forms of muscle hyperactivity as described in the current movement disorders terminology. We propose the following new definition system: Spasticity describes involuntary muscle hyperactivity in the presence of central paresis. The involuntary muscle hyperactivity can consist of various forms of muscle hyperactivity: spasticity sensu strictu describes involuntary muscle hyperactivity triggered by rapid passive joint movements, rigidity involuntary muscle hyperactivity triggered by slow passive joint movements, dystonia spontaneous involuntary muscle hyperactivity and spasms complex involuntary movements usually triggered by sensory or acoustic stimuli. Spasticity can be described by a documentation system grouped along clinical picture (axis 1), aetiology (axis 2), localisation (axis 3) and additional central nervous system deficits (axis 4). Our new definition allows distinction of spasticity components accessible to BT therapy and those inaccessible. The documentation sheet presented provides essential information for planning of BT therapy.

Safety of botulinum toxin short interval therapy using incobotulinumtoxin A.

The therapeutic efficacy of botulinum toxin (BT) can be completely blocked by formation of BT antibodies (BTAB), thus producing antibody-induced therapy failure (ABTF). One of the risk factors for this is the interval between two subsequent injection series. To prevent BTAB formation it is universally recommended not to use interinjection intervals of less than 12 weeks. However, BT's therapeutic efficacy may be considerably shorter than this interval, thus causing substantial reduction of quality of life. We wanted to study whether BT therapy with interinjection intervals of less than 12 weeks (short interval therapy, SIT) would be immunologically and otherwise safe. To minimise the risk of BTAB formation we used incobotulinumtoxin A which has a particularly low antigenicity. Altogether 30 patients (age 59.2 ± 13.5 years. 19 females, 11 males) with different dystonias were included in this study. They received SIT with incobotulinumtoxinA (Xeomin®, Merz Pharmaceuticals, Frankfurt/M, Germany) at interinjection intervals of 69.0 ± 8.1 days (equal 9.9 weeks or 2.2 months, min 48.9 ± 2.4 days) for 14.3 ± 2.9 injection series (equal 906 ± 169 days or 2.5 ± 0.5 years) in a dose of 259 ± 159 MU (max 670 ± 144.4 MU). None of the patients showed signs of ABTF, unusual BT effects or increased adverse effects. Information provided by this study confirms safety of SIT. With a considerable percentage of patients hitherto undertreated for prolonged periods of time with BT therapy applying 12 weeks intervals, SIT may substantially improve the quality of life for those patients. Whether SIT is also safe with other BT drugs needs to be tested.

Botulinum toxin therapy for treatment of spasticity in multiple sclerosis: review and recommendations of the IAB-Interdisciplinary Working Group for Movement Disorders task force.

Botulinum toxin (BT) therapy is an established treatment of spasticity due to stroke. For multiple sclerosis (MS) spasticity this is not the case. IAB-Interdisciplinary Working Group for Movement Disorders formed a task force to explore the use of BT therapy for treatment of MS spasticity. A formalised PubMed literature search produced 55 publications (3 randomised controlled trials, 3 interventional studies, 11 observational studies, 2 case studies, 35 reviews, 1 guideline) all unanimously favouring the use of BT therapy for MS spasticity. There is no reason to believe that BT should be less effective and safe in MS spasticity than it is in stroke spasticity. Recommendations include an update of the current prevalence of MS spasticity and its clinical features according to classifications used in movement disorders. Immunological data on MS patients already treated should be analysed with respect to frequencies of MS relapses and BT antibody formation. Registration authorities should expand registration of BT therapy for spasticity regardless of its aetiology. MS specialists should consider BT therapy for symptomatic treatment of spasticity.

Strategies for treatment of dystonia.

Treatment of dystonias is generally symptomatic. To produce sufficient therapy effects, therefore, frequently a multimodal and interdisciplinary therapeutic approach becomes necessary, combining botulinum toxin therapy, deep brain stimulation, oral antidystonic drugs, adjuvant drugs and rehabilitation therapy including physiotherapy, occupational therapy, re-training, speech therapy, psychotherapy and sociotherapy. This review presents the recommendations of the IAB-Interdisciplinary Working Group for Movement Disorders Special Task Force on Interdisciplinary Treatment of Dystonia. It reviews the different therapeutic modalities and outlines a strategy to adapt them to the dystonia localisation and severity of the individual patient. Hints to emerging and future therapies will be given.

Botulinum toxin therapy of cervical dystonia: duration of therapeutic effects.

We sought to explore the therapeutic effect of botulinum toxin (BT) therapy by analysing the time between the BT application and the onset of its decrease (treatment duration, TD), the inter-injection interval (II), and the excess time (ET, ET = II-TD). For this we studied 59 patients (37 females, 22 males, age 52.6 ± 10.9 years) with cervical dystonia (CD, Tsui score 9.0 ± 4.1) and BT therapy with Botox(®) and/or Xeomin(®) sequentially. Altogether 1,289 treatment cycles were evaluated. On average 21.8 ± 14.0 (4-66) treatment cycles were recorded for each patient. TD was 11.8 ± 2.7 weeks (7.8 ± 1.4 to 21.0 ± 3.9 weeks), II 15.4 ± 3.4 weeks (11.3 ± 1.3 to 27.8 ± 11.6 weeks) and ET 3.5 ± 2.4 weeks (23% of II). TD and II were stable throughout the treatment course. In 36% of the patients we found TD ≤10 weeks, in 83% TD ≤12 weeks. In 17% of the patients we saw treatment delays due to appointment difficulties, due to the patient's attempts to explore TD or his actual CD severity, from fear of adverse effects or due to psychiatric comorbidity. 19% of the patients showed prolonged treatment effects probably due to CD fluctuations. 0.38% of the injection series produced singular unexplained therapy failure (SUTF). Antibody-induced therapy failure did not occur. TD and II are stable on long-term monitoring. SUTF, treatment delays, and CD fluctuations can occur. 23% of the time patients are treated suboptimally. Our data suggest to reduce II. If II is to be reduced to ≤12 weeks, use of low antigenicity BT drugs might be useful.

Safety aspects of incobotulinumtoxinA high-dose therapy.

Botulinum toxin (BT) used for dystonia and spasticity is dosed according to the number of target muscles and the severity of their muscle hyperactivities. With this no other drug is used in a broader dose range than BT. The upper end of this range, however, still needs to be explored. We wanted to do this by a prospective non-interventional study comparing a randomly selected group of dystonia and spasticity patients receiving incobotulinumtoxinA (Xeomin(®)) high-dose therapy (HD group, n = 100, single dose ≥400 MU) to a control group receiving incobotulinumtoxinA regular-dose therapy (RD group, n = 30, single dose ≤200 MU). At the measurement point all patients were evaluated for systemic BT toxicity, i.e. systemic motor impairment or systemic autonomic dysfunction. HD group patients (56.1 ± 13.8 years, 46 dystonia, 54 spasticity) were treated with Xeomin(®) 570.1 ± 158.9 (min 400, max 1,200) MU during 10.2 ± 7.0 (min 4, max 37) injection series. In dystonia patients the number of target muscles was 46 and the dose per target muscle 56.4 ± 19.1 MU, in spasticity patients 35 and 114.9 ± 67.1 MU. HD and RD group patients reported 58 occurrences of items on the systemic toxicity questionnaire. Generalised weakness, being bedridden, feeling of residual urine and constipation were caused by the underlying tetra- or paraparesis, blurred vision by presbyopia. Dysphagia and dryness of eye were local BT adverse effects. Neurologic examination, serum chemistry and full blood count did not indicate any systemic adverse effects. Elevated serum levels for creatine kinase/MB, creatine kinase and lactate dehydrogenase were most likely iatrogenic artefacts. None of the patients developed antibody-induced therapy failure. Xeomin(®) can be used safely in doses ≥400 MU and up to 1,200 MU without detectable systemic toxicity. This allows expanding the use of BT therapy to patients with more widespread and more severe muscle hyperactivity conditions. Further studies-carefully designed and rigorously monitored-are necessary to explore the threshold dose for clinically detectable systemic toxicity.

Botulinum toxin: mechanisms of action.

This review describes therapeutically relevant mechanisms of action of botulinum toxin (BT). BT's molecular mode of action includes extracellular binding to glycoproteine structures on cholinergic nerve terminals and intracellular blockade of the acetylcholine secretion. BT affects the spinal stretch reflex by blockade of intrafusal muscle fibres with consecutive reduction of Ia/II afferent signals and muscle tone without affecting muscle strength (reflex inhibition). This mechanism allows for antidystonic effects not only caused by target muscle paresis. BT also blocks efferent autonomic fibres to smooth muscles and to exocrine glands. Direct central nervous system effects are not observed, since BT does not cross the blood-brain-barrier and since it is inactivated during its retrograde axonal transport. Indirect central nervous system effects include reflex inhibition, normalisation of reciprocal inhibition, intracortical inhibition and somatosensory evoked potentials. Reduction of formalin-induced pain suggests direct analgesic BT effects possibly mediated through blockade of substance P, glutamate and calcitonin gene related peptide.

Botulinum toxin: mechanisms of action

O propósito deste artigo é uma revisão dos mecanismos de ação da toxina botulínica (TB) relevantes para a compreensão do seu uso terapêutico. A ação da TB a nível molecular consiste na sua ligação extracelular a estruturas glicoprotéicas em terminais nervosos colinérgicos e no bloqueio intracelular da secreção de acetilcolina. A TB interfere no reflexo espinal de estiramento através do bloqueio de fibras musculares intrafusais causando redução da sinalização aferente veiculada por fibras Ia e II e do tono muscular. Portanto, o efeito da TB pode estar relacionado não somente à paresia muscular mas também à inibição reflexa espinal. A TB promove ainda o bloqueio de fibras autonômicas para músculos lisos e glândulas exócrinas. Apesar de ocorrer alguma difusão sistêmica após a aplicação intramuscular a TB não atinge o sistema nervoso central (SNC) devido ao seu peso molecular (não atravessa a barreira hematoencefálica) e à lentidão do seu transporte axonal retrógrado que permite a sua inativação. Os efeitos indiretos sobre o SNC são: inibição reflexa, reversão das alterações da inibição recíproca, da inibição intracortical e de potenciais evocados somatosensoriais. A redução da dor induzida por formalina sugere que a TB tenha efeito analgésico direto possivelmente mediado por bloqueio da substância P, do glutamato e do peptídeo relacionado ao gene da calcitonina.