Evidence-based review and assessment of botulinum neurotoxin for the treatment of movement disorders

Botulinum Toxin Therapy: A Comprehensive Review on Clinical and Pharmacological Insights

Background: Botulinum toxin (BoNT), produced by Clostridium botulinum, has transitioned from being a lethal neurotoxin to a versatile therapeutic agent. Its ability to inhibit neurotransmitter release by targeting Soluble N-ethylmaleimide-sensitive factor Attachment Protein Receptor (SNARE) proteins underpins its applications in treating conditions such as spasticity, dystonia, chronic pain, and overactive bladder. The clinical and pharmacological properties of BoNT have been extensively studied, with significant advancements in its therapeutic use, safety profile, and understanding of associated adverse effects. Objective: This comprehensive review aims to consolidate historical developments, molecular mechanisms, clinical applications, and challenges associated with BoNT, with a focus on expanding its therapeutic scope while ensuring safety and efficacy. Method: A narrative approach was used to analyze and synthesize insights from 155 references spanning experimental studies, clinical trials, and reviews. Key topics included BoNT's historical milestones, mechanisms of action, therapeutic applications, and adverse events. Findings: BoNT demonstrates remarkable efficacy in a wide range of medical and cosmetic applications. In movement disorders such as dystonia and spasticity, it reduces muscle overactivity and improves functional outcomes. In chronic pain management, including migraines and neuropathic pain, BoNT significantly alleviates symptoms by modulating neurotransmitter activity. Cosmetic use for conditions like glabellar lines and hyperhidrosis highlights its precision and safety when administered appropriately. For conditions like strabismus and blepharospasm, BoNT effectively restores muscle control, reducing involuntary contractions. In urological applications, BoNT has proven to be an effective therapy for overactive bladder, offering significant symptom relief in refractory cases. However, concerns about long-distance effects, where the toxin may spread beyond the injection site to affect distant muscles or systems, have been reported in certain high-dose or sensitive populations. These findings emphasize the importance of dose optimization and patient-specific approaches. Adverse effects such as localized pain, hematoma, dysphagia, and systemic effects, particularly in high-risk groups, underscore the need for careful monitoring. The development of immunogenicity, leading to neutralizing antibodies, remains a challenge that impacts long-term therapeutic efficacy. Emerging research on novel serotypes, including BoNT/X, and innovations in delivery mechanisms, offer promising avenues to address current limitations. Advances in optimizing dosing regimens and refining injection techniques have also contributed to minimizing complications and improving outcomes across diverse patient populations. Conclusions: BoNT remains a cornerstone in neurology and cosmetic medicine, with its therapeutic potential still expanding. The balance between efficacy and safety, driven by innovations in formulation and application, underscores the importance of continued research. Future directions should focus on minimizing adverse effects, reducing immunogenicity, and exploring novel indications to further enhance its clinical utility.

Excitation-contraction coupling inhibitors potentiate the actions of botulinum neurotoxin type A at the neuromuscular junction

BACKGROUND AND PURPOSE

Botulinum neurotoxin type A1 (BoNT/A) is one of the most potent neurotoxins known. At the same time, it is also one of the safest therapeutic agents used for the treatment of several human disorders and in aesthetic medicine. Notwithstanding great effectiveness, strategies to accelerate the onset and prolong BoNT/A action would significantly ameliorate its pharmacological effects with beneficial outcomes for clinical use.

EXPERIMENTAL APPROACH

Here, we combined BoNT/A with two fast-acting inhibitors of excitation-contraction coupling inhibitors (ECCI), either the μ-conotoxin CnIIIC or dantrolene, and tested the effect of their co-injection on a model of hind-limb paralysis in rodents using behavioural, biochemical, imaging and electrophysiological assays.

KEY RESULTS

The BoNT/A-ECCI combinations accelerated the onset of muscle relaxation. Surprisingly, they also potentiated the peak effect and extended the duration of the three BoNT/A commercial preparations OnabotulinumtoxinA, AbobotulinumtoxinA and IncobotulinumtoxinA. ECCI co-injection increased the number of BoNT/A molecules entering motoneuron terminals, which induced a faster and greater cleavage of SNAP-25 during the onset and peak phases, and prolonged the attenuation of nerve-muscle neurotransmission during the recovery phase. We estimate that ECCI co-injection yields a threefold potentiation in BoNT/A pharmacological activity.

CONCLUSIONS AND IMPLICATIONS

Overall, our results show that the pharmacological activity of BoNT/A can be combined and synergized with other bioactive molecules and uncover a novel strategy to enhance the neuromuscular effects of BoNT/A without altering the neurotoxin moiety or intrinsic activity, thus maintaining its exceptional safety profile.

Botulinum toxin treatment for hemifacial spasm: harmonising neurological and aesthetic outcomes

Hemifacial spasm (HFS) represents a challenging cranial movement disorder primarily affecting the facial nerve innervated muscles, with significant prevalence among Asians. Botulinum toxin type A (BoNT/A) injections, established as a primary therapeutic intervention since FDA approval, offer considerable effectiveness in alleviating spasms, albeit accompanied by challenges such as temporary effects and potential adverse events including facial asymmetry. This comprehensive review underscores the crucial need for harmonising neurological benefits and aesthetic outcomes in HFS management. The discussion delves into the interplay between facial aesthetics and neurological objectives in BoNT/A injections, emphasising precise techniques, dosages, and site considerations. Distinct aspects in neurological and aesthetic domains are also examined, including detailing the targeted muscles and injection methodologies for optimal therapeutic and aesthetic results. Importantly, evidence regarding various BoNT/A formulations, recommendations, and reconstitution guidelines in both neurology and aesthetics contexts are provided, along with a schematic approach outlining the stepwise process for BoNT/A injection in HFS treatment, addressing critical areas such as orbicularis oculi muscle sites, eyebrow correction strategies, mid- and lower-face considerations, contralateral injection sites, and post-injection follow-up and complication management. By highlighting the culmination of neurological efficacy and facial esthetics in BoNT/A treatment for HFS patients, this review proposes a holistic paradigm to achieve balanced symptomatic relief and natural aesthetic expression, ultimately enhancing quality of life for individuals grappling with HFS.

Stable Convergent Polyneuronal Innervation and Altered Synapse Elimination in Orbicularis oculi Muscles from Patients with Blepharospasm Responding Poorly to Recurrent Botulinum Type-A Neurotoxin Injections

Botulinum neurotoxin type-A (BoNT/A), which blocks quantal acetylcholine (ACh) release at the neuromuscular junction (NMJ), has demonstrated its efficacy in the symptomatic treatment of blepharospasm. In 3.89% of patients treated for blepharospasm at Tenon Hospital, BoNT/A was no longer effective in relieving the patient's symptoms, and a partial upper myectomy of the Orbicularis oculi muscle was performed. We used surgical waste samples from 14 patients treated with repeated injections of either abobotulinumtoxinA (Dysport®) or incobotulinumtoxinA (Xeomin®). These muscle fragments were compared to others from 4 normal subjects, naïve of BoNT/A. The morphological study was performed blinded to the BoNT/A treatment and between treated and control samples. Neuromuscular specimens analyzed by confocal laser scanning microscopy, using fluorescent staining and immune-labeling of presynaptic proteins, revealed that the pattern of innervation (e.g., polyneuronal and convergent innervation), the muscle nicotinic ACh receptors (nAChRs), and the NMJs exhibited marked differences in BoNT/A-treated muscles (regardless of the toxin clinically used), with respect to controls. BoNT/A-treated junctions exhibited profuse polyneuronal innervation in which 2-6 axons innervated 74.84% of single muscle fibers, while 99.47% of control junctions were mono-innervated. Another new finding was the stable convergent innervation, in which several motor axons end onto the same endplate. Morphological signs of synapse elimination included the presence of retraction bulbs in axons and nerve terminals and a reduced extension of postsynaptic nAChRs. These outcomes suggest that synapse elimination is altered and raise questions on the origin and factors contributing to the plasticity changes observed and the functioning of NMJs.

Therapy with botulinum neurotoxin for Parkinson's disease

Botulinum neurotoxin (BoNT) has been in use since the 1970's. Its effect is reached mainly by inhibiting the release of acetylcholine in the synaptic gap of motor neurons or at the motor end plate and the parasympathetic ganglia. In the case of Parkinson's disease, it is used to treat several motor and non-motor symptoms. Within recent years increasingly numerous possible fields of application of BoNT have been found for the treatment of Parkinson's disease, and for some specific symptoms it has in fact become the therapy of choice, while for others it is but one of the therapeutic options that come into consideration when others are not sufficiently effective. In the following, we intend to outline the indications, the possible side effects and also the approvals for therapies with botulinum toxin in the primary and secondary symptoms of Parkinson's disease.

Therapeutic Uses and Efficacy of Botulinum Toxin in Orofacial Medicine: A Dental Perspective

Botulinum neurotoxin (BoNT) is the exotoxin of Clostridium botulinum, a Gram-positive, spore-forming bacterium [...].

Experimental study on the effect and mechanism of adipose stem cell-derived exosomes combined with botulinum toxin A on skin trauma in rats

BACKGROUND

Adipose stem cell-derived exosomes (ADSC-EXO) and botulinum toxin type A (BTX-A) individually showed a therapeutic effect on skin wound repair.

AIMS

This study investigated their synergistic effect on promoting skin wound healing in vitro and in vivo and the underlying molecular events.

METHODS

ADSCs were isolated from Sprague-Dawley (SD) rats to obtain ADSC-EXO by ultrafiltration and ultracentrifugation and were confirmed using nanoparticle tracking analysis and transmission electron microscopy. Human skin fibroblasts (HSF) were cultured and treated with or without ADSC-EXO, BTX-A, or their combination. Changes in cell phenotypes and protein expression were analyzed using different in vitro assays, and a rat skin wound model was used to assess their in vivo effects.

RESULTS

The isolated ADSC-EXO from primarily cultured ADSCs had a circular vesicle shape with a 30-180 nm diameter. Treatment of HSF with ADSC-EXO and/or BTX-A significantly accelerated HSF migration in vitro and skin wound healing in a rat model. Moreover, ADSC-EXO plus BTX-A treatment dramatically induced VEGFA expression but reduced COL III and COL I levels in vivo. ADSC-EXO and/or BTX-A treatment significantly upregulated TGF-β3 expression on Day 16 after surgery but downregulated TGF-β1 expression, suggesting that ADSC-EXO plus BTX-A promoted skin wound healing and reduced inflammatory cell infiltration.

CONCLUSIONS

The ADSC-EXO plus BTX-A treatment demonstrated a synergistic effect on skin wound healing through upregulation of VEGF expression and the TGF-β3/TGF-β1 and COL III/COL I ratio.

Basis of movement control in dystonia and why botulinum toxin should influence it?

Dystonia is a network disorder involving multiple brain regions, such as the motor cortex, sensory cortex, basal ganglia, and cerebellum. Botulinum toxin (BoNT) is the first-line therapy for treating focal dystonia and is a potent molecule that blocks the release of acetylcholine at the peripheral neuromuscular junction. However, the clinical benefits of BoNT are not solely related to peripheral muscle relaxation or modulation of afferent input from the muscle spindle. An increasing body of evidence, albeit in smaller cohorts, has shown that BoNT leads to distant modulation of the pathological brain substrates implicated in dystonia. A single treatment session of BoNT has been observed to reduce excessive motor excitability and improve sensory processing. Furthermore, owing to plasticity effects that are induced by botulinum, neural reorganization of pathological networks occurs, presumably leading to defective motor programs of dystonia replaced with normal movement patterns. However, longitudinal studies investigating the effects of multiple treatment sessions in large, well-characterized homogenous cohorts of dystonia will provide further compelling evidence supporting central botulinum mechanisms.

Improvement in Quality-of-Life-Related Outcomes Following Treatment with IncobotulinumtoxinA in Adults with Limb Spasticity: A Pooled Analysis

A strong correlation has been reported between patient-reported quality of life (QoL) and the investigator-rated Disability Assessment Scale (DAS) in patients with spasticity. The current analysis evaluates the effect of incobotulinumtoxinA on QoL-related outcomes (limb position abnormality, as well as dressing- and hygiene-related disability, measured with the DAS) in adults with upper limb spasticity, using pooled data from six studies. Separate analyses for each DAS domain were performed using data from patients with disabilities for that domain (DAS score ≥1). Results showed that a significantly greater proportion of incobotulinumtoxinA-treated compared with placebo-treated patients achieved a ≥1-point reduction from baseline in each of the DAS domains (improvement) 4 weeks after the first injection. The benefits of incobotulinumtoxinA were observed regardless of the baseline severity of DAS impairment and of the time elapsed since stroke. The effects of incobotulinumtoxinA 4 weeks after injection were maintained or enhanced over multiple injection cycles for all three DAS domains, supporting the use of repeated injection cycles to provide sustained QoL benefit. IncobotulinumtoxinA represents an important treatment option to achieve better QoL-related outcomes for patients with upper limb spasticity, irrespective of the duration of their condition.

Mechanism and clinical use of botulinum neurotoxin in head and facial region

PURPOSE

Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region.

STUDY SELECTION

MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles.

RESULTS

The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia.

CONCLUSIONS

BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Effectiveness of Botulinum Toxin on Hand Tremor Intensity and Upper Limb Function in Patients with Parkinson's Disease: Results of a Systematic Review

Background

Hand tremor is a common symptom of Parkinson's disease (PD). Tremors may be resistant to drug treatments. Therefore, Botulinum toxin (BoNT) could be a good alternative. This study aimed to review and analyze studies on the efficacy and safety of BoNT injection in hand tremor intensity and upper limb function in patients with idiopathic PD.

Methods

A comprehensive search was conducted for studies on the effect of local BoNT injections on tremors in PD patients from 1990 to December 2021. Electronic databases such as Cochrane Central Control Records, PubMed, Scopus, Web of Science, EMBASE, Google Scholar, Clinicaltrial.gov, ProQuest, Science Direct, CINAHL, and Psychoinfo were searched systematically.

Results

Ten studies, comprising one double-blinded randomized clinical trial and nine pilot open-labeled studies with 131 participants, met eligibility criteria. The reported tremor intensity ranged from 1 to 3, and the average tremor duration of 5.93 ± 2.08 years. The injectable dose was 68-100 units of onabotulinum-toxin-A in each upper limb muscle, mostly wrist flexors. The results showed a decrease in unified Parkinson's disease rating scale (UPDRS)_20 and UPDRS_21 indices by 1.22 ± 1.1 and 1.20 ± 0.9, respectively, without causing severe side effects. The BoNT relative effectiveness in the forearm and arm muscles was reported 6-16 weeks after injection.

Discussion

The kinematic, electromyography-guided, and electrical stimulation evaluations allow for accurate muscle localization and minimize the possibility of BoNT diffusion and antibody formation. More extensive randomized clinical trials with uniform measurement criteria are recommended to reduce bias and provide more accurate conclusions.

Highlight

Tremor treatment in Parkinson's-disease (PD) is challenging. Drugs effect is temporary, and surgery is critical management. This study reviews the Botulinum-toxin injection efficacy in hand tremor intensity and upper limb function. The results showed a decrease in unified Parkinson's disease rating scale (UPDRS)_20 and UPDRS_21 by 1.22 ± 1.1 and 1.20 ± 0.9, respectively, 6-16 weeks after injection.

Treatment of strabismus and blepharospasm with Botox (onabotulinumtoxinA): Development, insights, and impact

Strabismus, deviation of the ocular alignment, can adversely affect quality of life and activities of daily living. Surgery was the prior standard of care for strabismus, but up to 40% of patients required additional surgeries. This need for more effective and less invasive treatment, along with the convergence of other events such as the development of electromyography, purification of botulinum toxin A, and the finding that injection of botulinum toxin type A could paralyze the hind limbs of chicks, led Dr. Alan Scott to investigate injection of his formulation for strabismus. The positive results of initial trials in monkeys segued to human trials with observations of alignment improvements and few adverse events. The success of botulinum toxin type A in the treatment of strabismus led to interest in its use to treat other skeletal muscles, particularly in blepharospasm, a type of focal dystonia involving eyelid spasms and involuntary eye closure that lacked an effective pharmacological treatment. Patient groups helped to increase awareness of this novel treatment, and results from clinical trials confirmed its effectiveness. Dr. Scott's formulation, then known as Oculinum, received its first Food and Drug Administration approvals in 1989 for strabismus and blepharospasm. Allergan acquired Oculinum in 1991, renaming it Botox. These initial uses led to its application in a myriad of other indications as outlined in other articles of this supplement.

Treatment of cervical dystonia with Botox (onabotulinumtoxinA): Development, insights, and impact

Cervical dystonia (CD), the most common focal dystonia encountered in neurologic practice, is a chronic disorder in which the muscles of the neck involuntarily contract and cause abnormal postures and movements of the head, neck, and shoulders. Treatment of CD prior to botulinum toxin was unsatisfactory, as existing therapies often did not improve symptoms. The use of botulinum toxin for CD grew out of its success in treating blepharospasm, another type of focal dystonia. On the basis of results from a double-blind, placebo-controlled trial, onabotulinumtoxinA was approved in 2000 in the US for the treatment of CD in adults in order to alleviate abnormal head position and neck pain. A subsequent large observational trial further demonstrated the effectiveness of onabotulinumtoxinA for CD, showing improvements in various rating scales, physician-reported measures, and profound positive effects on patient quality of life, including in amelioration of pain and improvements in work productivity. In addition, onabotulinumtoxinA treatment also reduced the complications of CD, as patients no longer develop contractures (permanent muscle and tendon shortening from prolonged untreated dystonia), which markedly limited the range of neck motion. The onset of onabotulinumtoxinA treatment also accompanied advances in understanding the functional anatomy of neck muscles, basal ganglia physiology, and video and other recording technology. Following the success of onabotulinumtoxinA in the treatment of CD, its use has been expanded into numerous other therapeutic indications, and these advances stimulated educational and training programs by various neurologic and other medical societies.

Pooled Safety Analysis of IncobotulinumtoxinA in the Treatment of Neurological Disorders in Adults

The pooled incidences of treatment-emergent adverse events (TEAEs) were examined by indication using the integrated clinical database of Merz-sponsored, placebo-controlled, or repeat-dose studies of incobotulinumtoxinA in adults with cervical dystonia, blepharospasm, limb spasticity, sialorrhea, or essential tremor of the upper limb. Overall incidences of TEAEs, serious TEAEs, TEAEs leading to discontinuation, fatal TEAEs, TEAEs of special interest (TEAESIs; indicating possible toxin spread), and treatment-related (TR) events were determined for incobotulinumtoxinA and placebo after a single injection and for repeated dose cycles of incobotulinumtoxinA. The most frequent events after a single dose of incobotulinumtoxinA are summarized. After a single cycle, incidences of overall TEAEs were similar between incobotulinumtoxinA and the placebo in most indications, although between-indication differences were observed. Few TEAEs led to incobotulinumtoxinA discontinuation; there were no fatal TEAEs with incobotulinumtoxinA. In general, repeated cycles did not increase the incidence of any event. The most frequent TR-TEAEs were indication-dependent, including dysphagia for indications affecting the head or neck. The TR-TEAESIs across all indications were most commonly muscular weakness, dysphagia and dry mouth. Overall, the results of this pooled analysis support and extend the favorable safety and tolerability profile of incobotulinumtoxinA for the treatment of adult neurological disorders established by individual clinical studies.

Physiology of Dystonia: Animal Studies

Dystonia is currently ranked as the third most prevalent motor disorder. It is typically characterized by involuntary muscle over- or co-contractions that can cause painful abnormal postures and jerky movements. Dystonia is a heterogenous disorder-across patients, dystonic symptoms vary in their severity, body distribution, temporal pattern, onset, and progression. There are also a growing number of genes that are associated with hereditary dystonia. In addition, multiple brain regions are associated with dystonic symptoms in both genetic and sporadic forms of the disease. The heterogeneity of dystonia has made it difficult to fully understand its underlying pathophysiology. However, the use of animal models has been used to uncover the complex circuit mechanisms that lead to dystonic behaviors. Here, we summarize findings from animal models harboring mutations in dystonia-associated genes and phenotypic animal models with overt dystonic motor signs resulting from spontaneous mutations, neural circuit perturbations, or pharmacological manipulations. Taken together, an emerging picture depicts dystonia as a result of brain-wide network dysfunction driven by basal ganglia and cerebellar dysfunction. In the basal ganglia, changes in dopaminergic, serotonergic, noradrenergic, and cholinergic signaling are found across different animal models. In the cerebellum, abnormal burst firing activity is observed in multiple dystonia models. We are now beginning to unveil the extent to which these structures mechanistically interact with each other. Such mechanisms inspire the use of pre-clinical animal models that will be used to design new therapies including drug treatments and brain stimulation.

Mental health and quality of life in patients with craniofacial movement disorders: A cross-sectional study

Background

Facial appearance and expressions influence social interaction. Hemifacial spasm (HFS), blepharospasm (BPS), and blepharospasm-oromandibular dystonia (BOD) are common forms of craniofacial movement disorders. Few studies have focused on the mental burden and quality of life (QoL) in patients with craniofacial movement disorders. Therefore, this study investigated mental health and QoL in these patients.

Methods

This cross-sectional study included 90 patients with craniofacial movement disorders (HFS, BPS, and BOD; 30 patients per group) and 30 healthy individuals without craniofacial movement disorders (control group) recruited from October 2019 to November 2020. All participants underwent QoL and mental health evaluations for depression, anxiety, and stigma using the 36-item Short Form Health Survey (SF-36), Hamilton Anxiety Rating Scale (HAMA), Hamilton Rating Scale for Depression-24 (HAMD-24) and a questionnaire related to stigma.

Results

Depression was diagnosed in 37 (41.11%) patients, whereas 30 patients (33.33%) had anxiety. HAMA scores were significantly higher in the BPS and BOD groups than in the control group. Nineteen patients (21.11%) experienced stigma and SF-36 scores were lower in various dimensions in the movement disorders groups compared to healthy controls. The role-physical and social function scores were significantly lower in the movement disorders groups than in the control group all p < 0.05. The vitality scores of the BPS group and mental health scores of the BPS and BOD groups were significantly lower than those of the control group. Correlation analysis showed that the eight dimensions of SF-36 correlated with education level, disease duration, HAMD score, and HAMA score (all p < 0.05). Regression analysis demonstrated that the HAMD score correlated with general health, vitality, social function, role-emotional, and mental health (all p < 0.05). The HAMA score correlated with body pain after adjusting for education level and disease duration.

Conclusion

This study highlights the significant frequency of mental symptoms, including depression, anxiety, and stigma, which lower QoL in patients with craniofacial movement disorders.

Botulinum Injection Into the Proximal Intestinal Wall of Diet-Induced Obese Mice Leads to Weight Loss and Improves Glucose and Fat Tolerance

Botulinum neurotoxin (available commercially as BOTOX) has been used successfully for treatment of several neuromuscular disorders, including blepharospasm, dystonia, spasticity, and cerebral palsy in children. Our data demonstrate that injection of Botox into the proximal intestinal wall of diet-induced obese (DIO) mice induces weight loss and reduces food intake. This was associated with amelioration of hyperglycemia, hyperlipidemia, and significant improvement of glucose tolerance without alteration of energy expenditure. We also observed accelerated gastrointestinal transit and significant reductions in glucose and lipid absorption, which may account, at least in part, for the observed weight loss and robust metabolic benefits, although possible systemic effects occurring as a consequence of central and/or peripheral signaling cannot be ignored. The observed metabolic benefits were found to be largely independent of weight loss, as demonstrated by pair-feeding experiments. Effects lasted ∼8 weeks, for as long as the half-life of Botox as reported in prior rodent studies. These results have valuable clinical implications. If the observed effects are translatable in humans, this approach could lay the foundation for therapeutic approaches geared toward robust and sustained weight loss, mimicking some of the benefits of bariatric operations without its cost and complications.

Clinical Features and Evolution of Blepharospasm: A Multicenter International Cohort and Systematic Literature Review

Objective:

Blepharospasm is a type of dystonia where the diagnosis is often delayed because its varied clinical manifestations are not well recognized. The purpose of this study was to provide a comprehensive picture of its clinical features including presenting features, motor features, and non-motor features.

Methods:

This was a two-part study. The first part involved a systematic literature review that summarized clinical features for 10,324 cases taken from 41 prior reports. The second part involved a summary of clinical features for 884 cases enrolled in a large multicenter cohort collected by the Dystonia Coalition investigators, along with an analysis of the factors that contribute to the spread of dystonia beyond the periocular region.

Results:

For cases in the literature and the Dystonia Coalition, blepharospasm emerged in the 50s and was more frequent in women. Many presented with non-specific motor symptoms such as increased blinking (51.9%) or non-motor sensory features such as eye soreness or pain (38.7%), photophobia (35.5%), or dry eyes (10.7%). Non-motor psychiatric features were also common including anxiety disorders (34–40%) and depression (21–24%). Among cases presenting with blepharospasm in the Dystonia Coalition cohort, 61% experienced spread of dystonia to other regions, most commonly the oromandibular region and neck. Features associated with spread included severity of blepharospasm, family history of dystonia, depression, and anxiety.

Conclusions:

This study provides a comprehensive summary of motor and non-motor features of blepharospasm, along with novel insights into factors that may be responsible for its poor diagnostic recognition and natural history.

Botulinum Toxin Therapy for Oromandibular Dystonia and Other Movement Disorders in the Stomatognathic System

Various movement disorders, such as oromandibular dystonia, oral dyskinesia, bruxism, functional (psychogenic) movement disorder, and tremors, exist in the stomatognathic system. Most patients experiencing involuntary movements due to these disorders visit dentists or oral surgeons, who may be the first healthcare providers. However, differential diagnoses require neurological and dental knowledge. This study aimed to review scientific advances in botulinum toxin therapy for these conditions. The results indicated that botulinum toxin injection is effective and safe, with few side effects in most cases when properly administered by an experienced clinician. The diagnosis and treatment of movement disorders in the stomatognathic system require both neurological and dental or oral surgical knowledge and skills, and well-designed multicenter trials with a multidisciplinary team approach must be necessary to ensure accurate diagnosis and proper treatment.

Longitudinal follow up of mood in cervical dystonia and influence on age at onset

Background

Anxiety and depression are highly prevalent conditions in cervical dystonia and considered intrinsic to the disease mechanism. Psychiatric symptoms do not appear to be influenced by botulinum toxin therapy. Studies focusing on changes in mood disorder during the course of the disease are limited in this chronic, lifelong disorder.

Objective

To assess the longitudinal prevalence of mood disorder, pain, and quality of life in patients with cervical dystonia attending a botulinum toxin clinic.

Methods

Patients involved in phase I of our study were invited to be involved in reassessment using the Beck Depression Inventory, Second Revision; Beck Anxiety Index; Cervical Dystonia Impact Profile-58 (CDIP-58); and the Toronto Western Spasmodic Torticollis Rating Scale-2 Pain Scale (TWSTRS2-Pain).

Results

A total of 53 participants took part after a mean study interval duration of 24 months. There were no significant differences between the 2 study time points in the prevalence of anxiety (P = 0.2919) and depressive symptoms (P = 0.5). Self-reported quality of life by CDIP-58 (P = 0.96) and pain by TWSTRS2-Pain (P = 0.9321) were unchanged. Men and women with significant symptoms of mood disorder had an earlier age of onset of cervical dystonia (P = 0.008).

Conclusion

Anxiety and depressive symptoms persist in cervical dystonia, seem to be unrelated to pain severity, and need to be specifically targeted to improve quality of life. The relationship between mood disorder and age of onset suggest that mood disorder may be part of the disease pathophysiology.

Toxicology and pharmacology of botulinum and tetanus neurotoxins: an update

Tetanus and botulinum neurotoxins cause the neuroparalytic syndromes of tetanus and botulism, respectively, by delivering inside different types of neurons, metalloproteases specifically cleaving the SNARE proteins that are essential for the release of neurotransmitters. Research on their mechanism of action is intensively carried out in order to devise improved therapies based on antibodies and chemical drugs. Recently, major results have been obtained with human monoclonal antibodies and with single chain antibodies that have allowed one to neutralize the metalloprotease activity of botulinum neurotoxin type A1 inside neurons. In addition, a method has been devised to induce a rapid molecular evolution of the metalloprotease domain of botulinum neurotoxin followed by selection driven to re-target the metalloprotease activity versus novel targets with respect to the SNARE proteins. At the same time, an intense and wide spectrum clinical research on novel therapeutics based on botulinum neurotoxins is carried out, which are also reviewed here.

Time to onset and duration of botulinum toxin efficacy in movement disorders

Background

Botulinum toxin (BoNT) is a valuable treatment in movement disorders; however, time to onset and duration of efficacy may widely differ among patients. We aimed to clarify the impact of main demographic and clinical features on time to onset and duration of BoNT efficacy.

Methods

We analyzed time-to-onset and duration of BoNT efficacy in 186 consecutive patients treated with BoNT for blepharospasm, cervical dystonia, facial hemispasm, oromandibular dystonia, limb dystonia, and sialorrhea due to Parkinsonism. The following factors were considered as potential efficacy predictors: doses and types of toxin, sex, age, years of treatment, and clinical condition. Kruskall–Wallis, Spearman correlation, and multivariate linear regression were used for statistical analysis.

Results

The average time to onset was 6.7 ± 5 days and duration of BONT efficacy 78.5 ± 28.4 days. Both time to onset and duration of efficacy were correlated with BoNT doses (p: 0.007 and p: 0.02). The multiple regression analysis showed that sex, age, years of BoNT treatment, doses, type of toxin, and clinical condition significantly predicted time to onset (F(11, 171) = 2.146, p: 0.020) with age being the strongest predictor (p: 0.004).

The same model explained 20.1% of the variance of duration of BoNT efficacy, showing a significant prediction of the outcome (F(11, 164) = 3.754, p < 0.001), with doses (p < 0.001), type of toxin (p: 0.017), and clinical condition (p < 0.001) being the strongest predictors.

Conclusion

Our findings suggest that age, type of toxin, clinical condition and especially doses may account for the variability of BoNT efficacy in terms of time to onset and duration.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-10995-2.

Patient selection and injection techniques for botulinum neurotoxin in oromandibular dystonia

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Botulinum toxin is considered as the first-line therapy in oromandibular dystonia (OMD) by most experts and evidence-based literature.

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Oromandibular dystonia (OMD) can be classified into several subtypes so primary muscle involvements can be identified for botulinum toxin (BoNT) injections.

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This review article aims to provide a framework for practical clinical approaches in patients with OMD for BoNT injections.

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Careful stepwise planning is recommended to identify primary muscles responsible and employ a conservative approach to dosing titration.

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Treating physicians should be diligent to observe for adverse events as muscles involved in OMD are small, delicate and situated in close proximity.

Oromandibular dystonia (OMD) is a form of focal dystonia that involves the masticatory, lower facial, labial, and lingual musculature. It is a disabling disorder which had limited treatment options until the recent introduction of botulinum toxin (BoNT) as the recommended first-line therapy by most experts and evidence-based literature. Owing to the complex relationship between the muscles of mastication and surrounding muscles, there is a wide variety of dynamic clinical presentations, making clinical recognition and the corresponding approach to BoNT injection therapy difficult. In this review, the authors provide a framework for practical clinical approaches, beginning with the recognition of clinical subtypes of OMD (jaw-opening, jaw-closing, jaw-deviating, lingual, peri-oral, and/or pharyngeal dystonias), followed by patient selection and clinical evaluation to determine function interferences, with injection techniques illustrated for each subtype. Careful stepwise planning is recommended to identify the muscles that are primarily responsible and employ a conservative approach to dosing titration. Treating physicians should be diligent in checking for adverse events, especially for the first few injection cycles, as muscles involved in OMD are small, delicate, and situated in close proximity. It is recommended that future studies should aim to establish the clinical efficacy of each subtype, incorporating muscle targeting techniques and patient-centred outcome measures that are related to disturbed daily functions.

European clinical guidelines for Tourette syndrome and other tic disorders-version 2.0. Part III: pharmacological treatment

In 2011, the European Society for the Study of Tourette Syndrome (ESSTS) published the first European guidelines for Tourette Syndrome (TS). We now present an update of the part on pharmacological treatment, based on a review of new literature with special attention to other evidence-based guidelines, meta-analyses, and randomized double-blinded studies. Moreover, our revision took into consideration results of a recent survey on treatment preferences conducted among ESSTS experts. The first preference should be given to psychoeducation and to behavioral approaches, as it strengthens the patients' self-regulatory control and thus his/her autonomy. Because behavioral approaches are not effective, available, or feasible in all patients, in a substantial number of patients pharmacological treatment is indicated, alone or in combination with behavioral therapy. The largest amount of evidence supports the use of dopamine blocking agents, preferably aripiprazole because of a more favorable profile of adverse events than first- and second-generation antipsychotics. Other agents that can be considered include tiapride, risperidone, and especially in case of co-existing attention deficit hyperactivity disorder (ADHD), clonidine and guanfacine. This view is supported by the results of our survey on medication preference among members of ESSTS, in which aripiprazole was indicated as the drug of first choice both in children and adults. In treatment resistant cases, treatment with agents with either a limited evidence base or risk of extrapyramidal adverse effects might be considered, including pimozide, haloperidol, topiramate, cannabis-based agents, and botulinum toxin injections. Overall, treatment of TS should be individualized, and decisions based on the patient's needs and preferences, presence of co-existing conditions, latest scientific findings as well as on the physician's preferences, experience, and local regulatory requirements.

Botulinum Toxin for the Treatment of Hemifacial Spasm: An Update on Clinical Studies

Hemifacial spasm (HFS) is a movement disorder characterized by involuntary contractions of the facial muscles innervated by the seventh cranial nerve. Generally, it is associated with a poor quality of life due to social embarrassment and can lead to functional blindness. Moreover, it is a chronic condition, and spontaneous recovery is rare. Intramuscular injections of Botulinum Toxin (BoNT) are routinely used as HFS treatment.

METHODS

We reviewed published articles between 1991 and 2021 regarding the effectiveness and safety of BoNT in HFS as well as any reported differences among BoNT formulations.

RESULTS

The efficacy of BoNT for HFS treatment ranged from 73% to 98.4%. The mean duration of the effect was around 12 weeks. Effectiveness did not decrease over time. Adverse effects were usually mild and transient. The efficacy and tolerability of the different preparations appeared to be similar. Among the studies, dosage, injected muscles, intervals of treatment, and rating scales were variable, thus leading to challenges in comparing the results.

CONCLUSIONS

BoNT was the treatment of choice for HFS due to its efficacy and safety profile. Further studies are needed to investigate the factors that influence the outcome, including the optimal timing of treatment, injection techniques, dosage, and the best selection criteria for formulations.

Chemodenervation for Oromandibular Dystonia Utilizing Botulinum Toxins

Oromandibular dystonia (OMD) is a chronic focal dystonia that involves the mouth, jaw, and tongue. It may cause repetitive or sustained dystonic movements, which can be very disabling for patients. It is usually a life-long disorder with numerous treatment options that are, most often, partially curative. In our experience, the best modality to treat OMD is botulinum toxin (BoNT) injections, which not only provide long-term relief but also have fewer adverse effects compared to other medications. Although multiple small- and large-scale studies support this fact, there is still a need for evidence from large randomized clinical trials. Jaw-closing dystonia responds very well to BoNT injections compared to other subtypes of OMD. This review discusses in detail the evidence, injection technique, and typical starting doses for botulinum injection.

Effects of Botulinum Toxin Type A on Pain among Trigeminal Neuralgia, Myofascial Temporomandibular Disorders, and Oromandibular Dystonia

The differences in analgesic effects of botulinum toxin type A were compared in 28 patients with trigeminal neuralgia, 53 patients with myofascial temporomandibular disorders, and 89 patients with the jaw closing oromandibular dystonia. The patients were treated by injection of botulinum toxin type A into the masseter, temporalis, medial pterygoid, and other muscles based on the symptoms of each patient. The pain severity was evaluated using the visual analog scale, pain frequency, and pain scale of the oromandibular dystonia rating scale. Botulinum toxin injection was performed 1068 times in all patients without significant adverse effects. The visual analog, pain frequency, and pain scales at baseline were reduced (p < 0.001) after two, four, eight, and 12 weeks after the first botulinum toxin therapy and at the endpoint. The effects differed significantly (p < 0.001) among the groups (repeated-measures analysis of variance). The mean improvement (0%, no effect; 100%, complete recovery) at the endpoint was 86.8% for trigeminal neuralgia, 80.8% for myofascial pain, and 75.4% for oromandibular dystonia. Injection of the botulinum toxin can be a highly effective and safe method to treat trigeminal neuralgia, myofascial pain, and oromandibular dystonia.

Biphasic Injection for Masseter Muscle Reduction with Botulinum Toxin

Masseter Muscle Hypertrophy (MMH) is a well-known clinical benign condition that is not gender-specific and it can be monolateral or bilateral. Botulinum Toxin type A (BoNTA) injection has been widely described for MMH treatment and non-surgical facial slimming. BoNTA masseter injections have high efficacy and safety profile, but the risks of side effects remain. Muscular bulging during mastication is a complication due to the superficial overcompensation of masseteric fibers in response to neurotoxic weakening of the deep masseter. We present a biphasic-injection technique for BoNTA administration, based following anatomical concept and developed in order to prevent paradoxical bulging. A total of 98 treatments from 2015 to 2020 were performed with this technique. No remarkable complications occurred in our study. No cases of loss of full smile, difficulty in mouth opening, dizziness, headache, neurapraxia, and xerostomia were reported. A case of asymmetric smiling was self-resolved within a week. No patient claimed transient muscle weakness as distressing. No cases of paradoxical bulging were observed. Extensive knowledge of muscular anatomy and appropriate injection technique are key factors in achieving the desired result and avoiding complications. We feel that sharing this tip could be helpful for all the physicians involved in MMH treatment with BoNTA.

Best Practices in the Clinical Management of Progressive Supranuclear Palsy and Corticobasal Syndrome: A Consensus Statement of the CurePSP Centers of Care

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS; the most common phenotype of corticobasal degeneration) are tauopathies with a relentless course, usually starting in the mid-60s and leading to death after an average of 7 years. There is as yet no specific or disease-modifying treatment. Clinical deficits in PSP are numerous, involve the entire neuraxis, and present as several discrete phenotypes. They center on rigidity, bradykinesia, postural instability, gait freezing, supranuclear ocular motor impairment, dysarthria, dysphagia, incontinence, sleep disorders, frontal cognitive dysfunction, and a variety of behavioral changes. CBS presents with prominent and usually asymmetric dystonia, apraxia, myoclonus, pyramidal signs, and cortical sensory loss. The symptoms and deficits of PSP and CBS are amenable to a variety of treatment strategies but most physicians, including many neurologists, are reluctant to care for patients with these conditions because of unfamiliarity with their multiplicity of interacting symptoms and deficits. CurePSP, the organization devoted to support, research, and education for PSP and CBS, created its CurePSP Centers of Care network in North America in 2017 to improve patient access to clinical expertise and develop collaborations. The directors of the 25 centers have created this consensus document outlining best practices in the management of PSP and CBS. They formed a writing committee for each of 12 sub-topics. A 4-member Steering Committee collated and edited the contributions. The result was returned to the entire cohort of authors for further comments, which were considered for incorporation by the Steering Committee. The authors hope that this publication will serve as a convenient guide for all clinicians caring for patients with PSP and CBS and that it will improve care for patients with these devastating but manageable disorders.

Smell and taste in idiopathic blepharospasm

The pathophysiology of blepharospasm is incompletely understood. Current concepts suggest that blepharospasm is a network disorder, involving basal ganglia, thalamus, cortex, and, possibly, the cerebellum. Tracing, imaging, and clinical studies revealed that these structures are also concerned with olfaction and taste. Because of this anatomical overlap, dysfunction of the chemical senses in blepharospasm is expected. Injections of botulinum toxin into the eyelid muscles are the first-line treatment of blepharospasm. Yet, the effects of botulinum toxin on the chemical senses have not been systematically assessed. To contribute to a better understanding of blepharospasm, olfactory and gustatory abilities were assessed in 17 subjects with blepharospasm and 17 age-/sex-matched healthy controls. Sniffin Sticks were used to assess odor threshold, odor discrimination, and odor identification. Results of these three Sniffin Sticks subtests were added to the composite olfactory score. The Taste Strips were applied to assess taste. In an adjacent study, we assessed the sense of smell and taste in eight subjects with blepharospasm before and 4 weeks after botulinum toxin treatment. Subjects with blepharospasm had significantly lower (= worse) scores for odor threshold and for the composite olfactory score than healthy controls, while odor discrimination, odor identification, and the composite taste score were not different between groups. The adjacent study revealed that botulinum toxin did not impact the chemical senses. In this study, subjects with blepharospasm had a lower (= worse) odor threshold than healthy controls. As olfaction is important in daily life, findings justify further research of olfaction in blepharospasm.

Perspectives on the pharmacological management of dystonia

Introduction: Treatment of dystonia is particularly complex due to various etiologies and heterogeneous clinical manifestation, as well as different degrees of disability. In absence of causative treatment, all symptomatic therapy should be predominantly tailored to ameliorate those symptoms (motor and non/motor) that mostly affect patients' daily life and regular activities. Many different treatment options, including oral medications, neurosurgical interventions, physical and occupational therapy are available in treatment of dystonia.Areas covered: The aim of this perspective is to point out different possibilities in pharmacological management of dystonic movements. Due to pure clinical presentation, the authors concentrate mainly on the isolated dystonias, which are presented solely as dystonic movements. Combined and complex dystonias are not instructive due to compound clinical presentation and consequently, complicated treatment. The article is based on a literature search from sources including PubMed, the Cochrane Library, Web of Science, PiCarta, and PsycINFO.Expert opinion: Although dystonia therapy should be adapted according to the individual needs, severity, age, type, symptoms distribution and acceptable side-effect profile, certain principles should be followed to reach the optimal result. Furthermore, the authors believe that a better understanding of the pathophysiology of dystonia will bring with it the development of new and improved treatment approaches and medications.

Botulinum Toxin: From Poison to Possible Treatment for Spasticity in Spinal Cord Injury

Botulism has been known for about three centuries, and since its discovery, botulinum toxin has been considered one of the most powerful toxins. However, throughout the 20th century, several medical applications have been discovered, among which the treatment of spasticity stands out. Botulinum toxin is the only pharmacological treatment recommended for spasticity of strokes and cerebral palsy. Although its use as an adjuvant treatment against spasticity in spinal cord injuries is not even approved, botulinum toxin is being used against such injuries. This article describes the advances that have been made throughout history leading to the therapeutic use of botulinum toxin and, in particular, its application to the treatment of spasticity in spinal cord injury.

Assessment of Botulinum Neurotoxin Injection for Dystonic Hand Tremor: A Randomized Clinical Trial

Importance

There is an unmet need for safe and efficacious treatments for upper-extremity dystonic tremor (DT). To date, only uncontrolled retrospective case series have reported the effect of botulinum neurotoxin (BoNT) injections on upper-extremity DT.

Objective

To assess the effect of BoNT injections on tremor in patients with upper-extremity DT.

Design, Setting, and Participants

In this placebo-controlled, parallel-group randomized clinical trial, 30 adult patients with upper-extremity DT treated at a movement disorder clinic in a tertiary care university hospital were randomized in a 1:1 ratio to BoNT or saline injection, 0.9%, using a computer-generated randomization sequence. Randomization was masked using opaque envelopes. The participant, injector, outcome assessor, and statistician were blinded to the randomization. Participants were recruited between November 20, 2018, and December 12, 2019, and the last follow-up was completed in March 2020.

Interventions

Participants received electromyographically guided intramuscular injections of BoNT or placebo into the tremulous muscles of the upper extremity. Injection patterns and doses were individualized according to tremor phenomenologic findings.

Main Outcomes and Measures

The primary outcome was the total score on the Fahn-Tolosa-Marin Tremor Rating Scale 6 weeks after the intervention. Outcomes were assessed at baseline, 6 weeks, and 12 weeks. All patients were offered open-label BoNT injections after 12 weeks and reassessed 6 weeks later.

Results

A total of 48 adult patients with a diagnosis of brachial dystonia with DT were screened. Fifteen were ineligible and 3 refused consent; therefore, 30 patients (mean [SD] age, 46.0 [18.6] years; 26 [86.7%] male) were recruited, with 15 randomized to receive BoNT and 15 to receive placebo. In the intention-to-treat group, the Fahn-Tolosa-Marin Tremor Rating Scale total score was significantly lower in the BoNT group at 6 weeks (adjusted mean difference, -10.9; 95% CI, -15.4 to -6.5; P < .001) and 12 weeks (adjusted mean difference, -5.7; 95% CI, -11.0 to -0.5; P = .03). More participants in the BoNT group reported global improvement on the Global Impression of Change (PGIC) assessment (PGIC 1, 2, and 3: BoNT: 4 [26.7%], 6 [40.0%], and 5 [33.3%]; placebo: 5 [33.3%], 10 [66.7%], and 0, respectively; P = .047). Subjective hand weakness (BoNT: 6 [40.0%]; placebo: 4 [28.6%], P = .52) and dynamometer-assessed grip strength (mean difference, -0.2 log10[kgf/m2]2/Hz-Hz; 95% CI, -0.9 to 0.4 log10[kgf/m2]2/Hz-Hz; P = .45) were similar in both groups.

Conclusions and Relevance

In this randomized clinical trial, botulinum neurotoxin injections were superior to placebo in reducing tremor severity in upper-extremity DT. An individualized approach to muscle selection and dosing was beneficial without unacceptable adverse effects.

Trial Registration

Clinical Trials Registry of India (http://ctri.nic.in) Identifier: CTRI/2018/02/011721.

[Therapeutic strategies for oromandibular dystonia]

Oromandibular dystonia is characterized by tonic or clonic involuntary spasms of the masticatory, lingual and / or muscles in the stomatognathic system. It is often misdiagnosed as craniomandibular dysfunction or psychiatric disease. According to clinical features, the oromandibular dystonia is classified into 6 subtypes (jaw closing-, jaw opening-, tongue-, jaw deviation-, jaw protrusion-, and lip dystonia). There are several treatment methods like botulinum toxin injection, muscle afferent block (injection of lidocaine and alcohol into the masticatory or tongue muscles for blocking muscle afferents from muscle spindle), occlusal splint, and oral surgery (coronoidotomy). Most of patients can be treated successfully according to subtype by combination of these treatments. Special treatment recommendations for each subtype were described in this focus article. Accurate diagnosis and treatment of oral dystonia requires comprehensive knowledge and skills of both oral and maxillofacial surgery and neurology. Therefore, collaboration among these departments is very important.

Use of Botulinum Neurotoxin in Parkinson's Disease: A Critical Appraisal

For well over 30 years, the botulinum neurotoxin (BoNT) has been used for a large number of indications, some of which however have not been licensed. Admittedly, approval varies in many countries and this permits a large spectrum for evaluation. Thus, BoNT is used for patients with Parkinson’s disease (PD) and other Parkinson’s syndromes (PS) in varying degrees of frequency. We have to distinguish between (1) indications that are either approved or (2) those not approved, (3) indications that might be a result of PS and (4) finally those which appear independent of PS. The most important indication for BoNT in PS patients is probably sialorrhea, for which approval has been granted in the majority of countries. Cervical dystonia is a frequent symptom in PS, with anterocollis as a specific entity. A further indication is blepharospasm in the different forms, especially the inhibition of eyelid opening in atypical PS. The use of BoNT in cases of camptocormia, the Pisa syndrome and neck rigidity is still a matter of debate. In dystonia of the extremities BoNT can be recommended, especially in dystonia of the feet. One well-known indication, for which however sufficient data are still lacking, involves treating tremor with BoNT. As to autonomic symptoms: Focal hyperhidrosis and detrusor hyperactivity can be mentioned, in this last case BoNT has already been approved. A number of further but rare indications such as freezing-of-gait, dyskinesia, and dysphagia will be discussed and evaluated.

Botulinum Toxin in Movement Disorders: An Update

Since its initial approval in 1989 by the US Food and Drug Administration for the treatment of blepharospasm and other facial spasms, botulinum toxin (BoNT) has evolved into a therapeutic modality for a variety of neurological and non-neurological disorders. With respect to neurologic movement disorders, BoNT has been reported to be effective for the treatment of dystonia, bruxism, tremors, tics, myoclonus, restless legs syndrome, tardive dyskinesia, and a variety of symptoms associated with Parkinson's disease. More recently, research with BoNT has expanded beyond its use as a powerful muscle relaxant and a peripherally active drug to its potential central nervous system applications in the treatment of neurodegenerative disorders. Although BoNT is the most potent biologic toxin, when it is administered by knowledgeable and experienced clinicians, it is one of the safest therapeutic agents in clinical use. The primary aim of this article is to provide an update on recent advances in BoNT research with a focus on novel applications in the treatment of movement disorders. This comprehensive review of the literature provides a critical review of evidence-based clinical trials and highlights recent innovative pilot studies.

Botulinum Neurotoxin Therapy for Depression: Therapeutic Mechanisms and Future Perspective

Depression is one of the most common mental disorders, which causes global burden. Antidepressants and psychotherapies are the mainstay of treatment for depression, which have limited efficacy. Thus, alternative approaches for preventing and treating depression are urgently required. Recent clinical trials and preclinical researches have clarified that peripheral facial injection of botulinum neurotoxin type A (BoNT/A) is a rapid, effective and relative safe therapy for improving some symptoms of depression. Despite its safety and efficacy, the underlying therapeutic mechanisms of BoNT/A for depression remains largely unclear. In the present review, we updated and summarized the clinical and preclinical evidence supporting BoNT/A therapy for the treatment of depression. We further discussed the potential mechanisms underlying therapeutic effects of BoNT/A on depression. Notably, we recently identified that the anti-depressant effects of BoNT/A associated with up-regulation of 5-HT levels and brain-derived neurotrophic factor (BDNF) expression in the hippocampus in a preclinical mouse model. In summary, these studies suggest that BoNT/A therapy is a potential effective and safe intervention for the management of depression. However, fundamental questions remain regarding the future prospects of BoNT/A therapy, including safety, efficacy, dose-response relationships, identification of potential predictors of response, and the precise mechanisms underlying BoNT/A therapy.

Improvement in Quality of Life with OnabotulinumtoxinA for Cervical Dystonia: POSTURe

Introduction:

Symptoms of cervical dystonia (CD) can vary in severity and cause significant pain. OnabotulinumtoxinA is an approved treatment for CD. This study assessed health-related quality of life (HRQoL) in patients with CD who received multiple onabotulinumtoxinA treatments.

Methods:

This prospective, observational standard-of-care study was conducted at multiple neurology centers in Québec, Canada. Patients reported the health impact of CD using the Cervical Dystonia Impact Profile (CDIP)-58, before and after up to eight onabotulinumtoxinA treatments. Other measures included the Cervical Dystonia Severity Rating Scale by physician, employment status using the Work Productivity Questionnaire and pain using the Pain Numeric Rating Scale (PNRS). Adverse events (AEs) were recorded.

Results:

Sixty-two patients were enrolled (safety population, n = 61; modified efficacy population, n = 58). Participants were mostly females who were employed; most (79.3%) had torticollis. In all, 21/62 patients (33.9%) discontinued the study. At the final visit, there was a statistically significant (p < 0.001) improvement in all eight CDIP-58 subscales, particularly head and neck symptoms (−31.0) and psychosocial functioning (−28.2). Employment increased from baseline (55%) to the end of the study (64%), and there was improvement in work productivity. There was a significant (p < 0.0001) reduction in pain measured by the PNRS, from −0.5 post-treatment 1 to −2.4 at end of study. AEs (neck pain, muscular weakness, dysphagia, nausea) were consistent with onabotulinumtoxinA use.

Conclusion:

These real-world data indicate that after repeated, long-term use, onabotulinumtoxinA continues to be a safe and effective treatment for CD, improving HRQoL and work productivity.

An Update on Botulinum Toxin in Neurology

Botulinum neurotoxin (BoNT) is an effective treatment for many neurologic disorders. This article gives a comprehensive overview of the clinical applications of BoNT across the field of neurology.

Olfaction as a Marker for Dystonia: Background, Current State and Directions

Dystonia is a heterogeneous group of hyperkinetic movement disorders. The unifying descriptor of dystonia is the motor manifestation, characterized by continuous or intermittent contractions of muscles that cause abnormal movements and postures. Additionally, there are psychiatric, cognitive, and sensory alterations that are possible or putative non-motor manifestations of dystonia. The pathophysiology of dystonia is incompletely understood. A better understanding of dystonia pathophysiology is highly relevant in the amelioration of significant disability associated with motor and non-motor manifestations of dystonia. Recently, diminished olfaction was found to be a potential non-motor manifestation that may worsen the situation of subjects with dystonia. Yet, this finding may also shed light into dystonia pathophysiology and yield novel treatment options. This article aims to provide background information on dystonia and the current understanding of its pathophysiology, including the key structures involved, namely, the basal ganglia, cerebellum, and sensorimotor cortex. Additionally, involvement of these structures in the chemical senses are reviewed to provide an overview on how olfactory (and gustatory) deficits may occur in dystonia. Finally, we describe the present findings on altered chemical senses in dystonia and discuss directions of research on olfactory dysfunction as a marker in dystonia.

Rodent model of disuse-induced bone loss by hind limb injection with botulinum toxin A

Bone loss materializes rapidly after immobilization or mechanical unloading. Hind limb injection with botulinum toxin A (BTX) is a highly reproducible animal model for disuse-induced bone loss. Here we describe an easy-to-use and enhanced version of the method employing multiple hind limb injections with BTX to induce a pervasive muscle paralysis and thereby disuse of the hind limb. Thirty-six 12-14-week-old female Wistar rats were stratified into three groups: Baseline (Base), Control (Ctrl), and BTX. Disuse was achieved by injecting BTX directly into the right quadriceps femoris muscle, the hamstring muscles, and the posterior calf muscles. The rats were sacrificed after six weeks, and the right rectus femoris muscle and femur were isolated and analyzed. Hind limb disuse resulted in a significant and substantial loss of both muscle mass and bone mass. The loss of bone mass was accompanied by a reduction of trabecular bone mass and a deterioration of the trabecular micro-architecture with a reduction of trabecular thickness and trabecular number compared to Ctrl. In addition, the trabeculae changed from a more plate-like towards a more rod-like shape as indicated by an increase in the structure model index.•Multiple injections with BTX targeting muscles on both the anterior and posterior thigh and the calf ensure a uniform and pervasive muscle paralysis and hind limb disuse.•Hind limb injections with BTX results in a substantial loss of muscle and bone mass and deterioration of the trabecular micro-architecture.•The induction of hind limb disuse with BTX is highly reproducible.

Current Management of Tics and Tourette Syndrome: Behavioral, Pharmacologic, and Surgical Treatments

Tourette syndrome is a heterogeneous neurobehavioral disorder manifested by childhood-onset motor and phonic tics, often accompanied by a variety of behavioral comorbidities, including attention deficit and obsessive compulsive disorder. Treatment must be tailored to the needs and goals of the individual patients and their families. All patients should receive education on the condition and, if possible, engage behavioral therapy targeted towards tics and/or comorbidities. Pharmacological therapies, such as alpha agonists, topiramate, and vesicular monoamine transport type 2 inhibitors, are generally used as first-line therapies in patients with troublesome tics that are not controlled by behavioral therapy or when the latter is not available or accessible. Botulinum toxin injections can be used in patients with bothersome focal tics. Second-line therapy includes antipsychotics, such as fluphenazine, aripiprazole, risperidone, and ziprasidone. These medications are generally efficacious but carry the risk of metabolic syndrome, tardive dyskinesia, and other side effects. Much more research is needed before novel therapies such as cannabis-derived products or transcranial magnetic stimulation can be recommended. There is promise in ongoing clinical trials with D1 receptor antagonist ecopipam and other experimental therapeutics. Patients with tics that are refractory to conventional treatments may be candidates for deep brain stimulation, but further studies are needed to determine the optimal target selection.

[Cervical dystonia: ways to improve the effectiveness of botulinum therapy]

Cervical dystonia is one of the most complex movement disorders, in which type A botulinum toxin (BTA) preparations are used. A significant number of types of dystonic installation of the head and neck determines a large number of different muscle patterns, sometimes with outwardly similar manifestations. Objective difficulties in choosing the actual pathological muscle pattern for subsequent injection in some cases determine the low effectiveness of botulinum therapy. Given this situation, it is necessary to adapt the anatomical approach to the correct choice of dystonic muscles in order to improve the results of botulinum therapy of cervical dystonia.

Assessment and Management of Tic Disorders in Pediatric Primary Care Settings

Purpose of Review

Pediatricians and other primary care providers are often the first and sole healthcare clinicians of patients who present with tics. However, limited primary care pediatric training in neuropsychiatric concerns, as well as perceived lack of comfort and preparation, make it challenging for these clinicians to confidently identify and manage tic disorders.

Recent Findings

Current empirical findings of tic disorder management relevant to pediatric physicians, including assessment, psychoeducation, behavioral interventions, psychotropic medications, and alternative treatments are reviewed.

Summary

This article discusses neuropsychiatric and medical complexities of tic disorder assessment, with particular emphasis on differential and comorbid diagnoses. Tiered referral recommendations, based on symptom severity, impairment, and consideration of comorbid conditions, are provided. Future directions for tic management, including dissemination of evidence-based treatments of tic disorders and multidisciplinary teams within pediatric primary care settings, are included.

FDA Approvals and Consensus Guidelines for Botulinum Toxins in the Treatment of Dystonia

In 2016, the American Academy of Neurology (AAN) published practice guidelines for botulinum toxin (BoNT) in the treatment of blepharospasm, cervical dystonia, adult spasticity, and headache. This article, focusing on dystonia, provides context for these guidelines through literature review. Studies that led to Food and Drug Administration (FDA) approval of each toxin for dystonia indications are reviewed, in addition to several studies highlighted by the AAN guidelines. The AAN guidelines for the use of BoNT in dystonia are compared with those of the European Federation of the Neurological Societies (EFNS), and common off-label uses for BoNT in dystonia are discussed. Toxins not currently FDA-approved for the treatment of dystonia are additionally reviewed. In the future, additional toxins may become FDA-approved for the treatment of dystonia given expanding research in this area.

Frequency and risk factors of antibody-induced secondary failure of botulinum neurotoxin therapy

Objective

To investigate the risk factors of neutralizing antibody (NAB)–induced complete secondary treatment failure (cSTF) during long-term botulinum neurotoxin (BoNT) treatment in various neurologic indications.

Methods

This monocenter retrospective cohort study analyzed the data of 471 patients started on BoNT therapy between 1995 and 2015. Blood samples of 173 patients were investigated for NABs using the mouse hemidiaphragm test (93 with suspected therapy failure, 80 prospective study participants). The frequency of NAB-cSTF was assessed for various indications: hemifacial spasm, blepharospasm, cervical dystonia, other dystonia, and spasticity. A priori defined potential risk factors for NAB-cSTF were evaluated, and a stepwise binary logistic regression analysis was performed to identify independent risk factors.

Results

Treatment duration was 9.8 ± 6.2 years (range, 0.5–30 years; adherence, 70.6%) and number of treatment cycles 31.2 ± 22.5 (3–112). Twenty-eight of 471 patients (5.9%) had NAB-cSTF at earliest after 3 and at latest after 103 treatment cycles. None of the 49 patients treated exclusively with incobotulinumtoxinA over 8.4 ± 4.2 (1–14) years developed NAB-cSTF. Independent risk factors for NAB-cSTF were high BoNT dose per treatment, switching between onabotulinumtoxinA and other BoNT formulations (except for switching to incobotulinumtoxinA), and treatment of neck muscles.

Conclusions

We present a follow-up study with the longest duration to date on the incidence of NAB-cSTF in patients treated with various BoNT formulations, including incobotulinumtoxinA. Whereas the overall risk of NAB-cSTF is low across indications and BoNT formulations, our findings underpin the recommendations to use the lowest possible dose particularly in cervical dystonia, and to avoid unnecessary switching between different formulations.

Use of Botulinum Toxin in Ophthalmology

Botulinum toxin is an important treatment for many conditions in ophthalmology, including strabismus, nystagmus, blepharospasm, hemifacial spasm, spastic and congenital entropion, corneal exposure, and persistent epithelial defects. The mechanism of action of botulinum toxin for both strabismus and nystagmus is the neuromuscular blockade and transient paralysis of extraocular muscles, but when botulinum toxin is used for some forms of strabismus, a single injection can convey indefinite benefits. There are two unique mechanisms of action that account for the long-term effect on ocular alignment: (1) the disruption of a balanced system of agonist-antagonist extraocular muscles and (2) the reestablishment of central control of alignment by the binocular visual system. For other ocular conditions, botulinum toxin acts through transient paralysis of periocular muscles. Botulinum toxin is a powerful tool in ophthalmology, achieving its therapeutic effects by direct neuromuscular blockade of extraocular and periocular muscles and by unique mechanisms related to the underlying structure and function of the visual system.

Endoscopic assisted microvascular decompression versus new antiepileptics and BOTOX in treatment of hemifacial spasm: a clinical trial

Introduction

Hemifacial spasm (HFS) is a chronic movement disorder characterized by twitching of muscles of facial expression which is innervated by the facial nerve. The condition is unilaterally, beginning in the orbicularis occuli, and later on progress to involve the perioral, platysma, and other muscles of facial expression. Endoscopic assisted microvascular decompression is considered the state of the art in hemi-facial spasm surgery. New antiepileptic have emerged with a new hope for good control with few side effects. Botulinum toxin is still a good option for some patients.

Methods

This study is a prospective study that was conducted on 30 patients with primary hemifacial spasm. Bilateral and secondary cases where excluded. All patients were subjected to proper pre-treatment assessment including; proper history taking, clinical examination, and proper radiological investigations (MRI, FISTA) when needed. They were divided into three groups according to treatment modality: group A where patient's general condition was unfit for surgical intervention, received oral medications (gabapentin or levetiracetam); group B included those patients unfit for surgical intervention and did not respond to oral therapy, received Botox injection; and group C underwent endoscopic assisted microvascular decompression. Follow-up period ranged from 6 to 24 months. Outcome of different treatment modalities were compared among different groups.

Results

Among group A patients, one patient showed excellent response to treatment (Gabapentin 1200 mg), three patients had good response, four patients had fair response, and three patients had poor response to treatment (one used levetiracetam, two used gabapentin). Overall success rate is 72.7%. Among group B patients, four patients enjoyed excellent response. Another four patients had good response, while three patients had fair response. Only one patient had poor response. Overall success rate was 83.3%. Among group C patients, five cases had excellent outcome and two cases had good outcome. Overall success rate is 100%.

Conclusion

Endoscopic assisted microvascular decompression offers the best chance to permanent cure with low complication rate. New antiepileptics (levetiracetam, gabapentin) provide a safe therapy for patients refusing surgical intervention. Botox is an attractive local therapy with reversible complications but with non-sustainable effect. From our results, we conclude that endoscopic assisted microvascular decompression is superior to either BOTOX or antiepiletics for the permanent cure of hemifacial spasm.