Efficacy and Safety of Long-term Botulinum Toxin Treatment in Craniocervical Dystonia: A Systematic Review

Immunogenicity of Botulinum Toxin A: Insights

BACKGROUND

Botulinum toxin A (BoNT-A) is widely used in treating dystonia and spasticity to managing chronic migraine and cosmetic applications. However, its immunogenic potential presents challenges, such as the development of neutralizing antibodies that lead to diminished therapeutic efficacy over time, known as secondary nonresponse.

OBJECTIVE

This review aims to bridge the knowledge gap regarding the immunogenic mechanisms of BoNT-A and to explore effective management strategies to mitigate these immune responses.

MATERIALS AND METHODS

The authors conducted a systematic search in databases including PubMed, Embase, and Web of Science, using keywords related to BoNT-A's immunogenicity. The selection process refined 157 initial articles down to 23 relevant studies, which underwent analysis to investigate the underlying mechanisms of immunogenicity and the factors influencing it.

RESULTS

The analysis revealed that both the neurotoxin component and the neurotoxin-associated proteins could elicit an immune response. However, only antibodies against the core toxin influence therapeutic outcomes. Various patient-specific factors such as genetic predispositions and prior immune experiences, along with treatment-related factors such as dosage and frequency, play crucial roles in shaping these responses.

CONCLUSION

Understanding the specific immunogenic triggers and responses to BoNT-A is critical for optimizing treatment protocols and improving patient outcomes.

Does botulinum toxin affect psycho-social aspects in dystonia?

Dystonia is a movement disorder in which sustained muscle contractions give rise to abnormal postures or involuntary movements. It is a disabling and disfiguring disorder that affects activities of daily living and gives people a bizarre appearance often associated with psychological morbidity, embarrassment and social avoidance. Intramuscular injection of botulinum toxin (BoNT) is the most effective treatment for motor symptoms in focal dystonia, but little is known about its impact on the psycho-social dimension. The main aim of this study was to evaluate psycho-social changes in patients with focal dystonia after starting BoNT treatment using self-reported scales. The Beck Depression Inventory (BDI-II), the 36-Item Short Form Health Survey (SF-36), the Body Uneasiness Test (BUT), the State-Trait Anxiety Inventory (STAI) and the Visual Analogue Scale (VAS) assessing body self-image, satisfaction with physical aspects, social avoidance, self-reported depression, and self-distress were completed by 11 patients with dystonia and 9 patients with hyperhidrosis as a control group before BoNT (T0). VAS was then performed after four weeks (T1) to assess whether BoNT induced changes in the psychosocial dimension. Our results showed that only depressive symptoms and rumination about body defects improved in patients with dystonia after BoNT treatment, while improvement in self-distress and satisfaction with physical aspects was also found in hyperhidrosis. Individuals with hyperhidrosis experience poorer psychological well-being and suffer from higher levels of distress compared to dystonic patients. This suggests that individuals with this disabling condition are more vulnerable to social impact than dystonic patients.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Botulinum toxin A and neuropathic pain: An update

Botulinum toxin type A is a widely used neurotoxin for the treatment of muscle hyperactivity such as dystonia and spasticity. Several clinical trials have also reported an efficacy of subcutaneous or intradermal administrations of botulinum toxin A on various neuropathic pain conditions including idiopathic trigeminal neuralgia and found that specific sensory phenotypes were predictors of the response. This narrative review summarizes the potential mechanisms of action, efficacy and safety of botulinum toxin A in neuropathic pain as well as its place in the therapeutic algorithm of neuropathic pain.

Efficacy and safety of long-term botulinum toxin treatment for acquired cervical dystonia: a 25-year follow-up

Botulinum toxin A (BoNT/A) is the first-line treatment for idiopathic cervical dystonia (ICD) and is widely used in the clinical setting. To date, scanty data are available on the effectiveness of BoNT in treating acquired cervical dystonia (ACD). Here we present a long-term follow-up of ACD patients treated with BoNT/A that focused on safety and efficacy. The study included subjects who had received at least six treatments of three commercially available BoNT/A drugs [abobotulinumtoxinA (A/Abo), incobotulinumtoxinA (A/Inco) and onabotulinumtoxinA (A/Ona)]. Safety and efficacy were assessed based on patients' self-reports regarding adverse effects (AE), duration of improvement of dystonia and/or pain relief. Global clinical improvement was measured on a six-point scale. 23 patients with ACD were administered 739 treatments (A/Abo in 235, A/Inco in 72, A/Ona in 432) with a mean number of treatments of 31 ± 20 (range 6-76) and duration of 10 ± 6 weeks (range 2-25). The mean dose was 737 ± 292 U for A/Abo, 138 ± 108 U for A/Inco and 158 ± 80 U for A/Ona. The average benefit duration was 89 ± 26 (A/Abo), 88 ± 30 days (A/Inco), and 99 ± 55 days (A/Ona) (p = 0.011); global clinical improvement for all sessions was 4 ± 1. ANOVA one-way analysis indicated that A/Ona had the best profile in terms of duration (p < 0.05), whereas A/Abo had the best pain relief effect (p = 0.002). Side effects were reported in 9% of treatments (67/739), with ten treatments (1%) complicated by two side effects. Most side effects were rated mild to moderate; severe side effects occurred following three treatments with the three different BoNT; two required medical intervention. No allergic reactions were reported. Even after 25 years of repeated treatments, all serotypes of BoNT demonstrate positive effects in treating ACD with long-lasting efficacy and safety.

Outcome of pallidal deep brain stimulation for treating isolated orofacial dystonia

BACKGROUND

Isolated orofacial dystonia is a rare segmental neurological disorder that affects the eye, mouth, face, and jaws. Current literature on pallidal surgery for orofacial dystonia is limited to case reports and small-scale studies. This study was to investigate clinical outcomes of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in patients with isolated orofacial dystonia.

METHODS

Thirty-six patients who underwent GPi DBS at Incheon St. Mary's Hospital, The Catholic University of Korea, between 2014 and 2019 were included in this study. Burke-Fahn-Marsden Dystonia Rating Scale, Unified Dystonia Rating Scale, and Global Dystonia Severity Rating Scale were retrospectively retrieved for analysis before surgery, at 6-month follow-up as short-term outcome, and at follow-up over 1 year (12 months to 69 months) as long-term results.

RESULTS

Mean total BFMDRS-M scores at the three time points (baseline, 6 months, and over 1 year follow-up) were 11.6 ± 4.9, 6.1 ± 5.2 (50.3 ± 29.9% improvement, p < 0.05), and 4.3 ± 4.2 (65.0 ± 24.2% improvement, p < 0.05), respectively. In terms of UDRS and GDS, improvement rates were 45.1% (p < 0.001) and 47.7% (p < 0.001) at 6 months, and 63.8% (p < 0.001) and 65.7% (p < 0.001) at over 1 year after surgery, respectively.

CONCLUSIONS

Bilateral GPi DBS in isolated orofacial dystonia can be effective if conservative treatment option fails. Its benefit is not only observed in a short term, but also maintained in a long-term follow-up.

Long-term adherence, safety, and efficacy of repeated onabotulinumtoxinA over five years in chronic migraine prophylaxis

BACKGROUND

OnabotulinumtoxinA (BoNTA) demonstrated a positive benefit-risk in chronic migraine (CM) patients in PREEMPT I and II phase III trials and many subsequent real-world studies. We herein aimed at evaluating the adherence to repeated BoNTA over a period of five years, while secondary objectives included the assessment of its long-term safety/efficacy and patients' satisfaction to treatment.

METHODS

We studied 56 CM patients who had successfully received consequent cycles of BoNTA over five years. Adherence was calculated as the percentage of patients actively choosing to follow with repeated BoNTA treatment, as instructed. Safety and efficacy data were collected throughout the study period. The overall patients' belief in and satisfaction by the efficacy of treatment was assessed at last follow-up, using the self-report 7-point measure patient global impression of change (PGIC).

RESULTS

A total of 36 (64.3%) out of 56 patients remained adherent to BoNTA over five years. Long-term BoNTA exposure was safe and well-tolerated, without severe side-effects justifying treatment discontinuation. The mean monthly headache days and associated clinical efficacy outcomes remained consistent and quite low at last follow-up with evidence of continuous improvements in headache monthly frequency between year three and over five years of therapy. All patients who were able to maintain treatment over five years (n = 36), remained very satisfied and scored at least 5 in PGIC.

CONCLUSION

Considerably high adherence, considerable satisfaction and sustained safety/efficacy were observed in patients followed up for five years, supporting a favorable benefit/risk profile for consistently delivering long-term BoNTA in CM.

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.

A patient-initiated treatment model for blepharospasm and hemifacial spasm: a randomized controlled trial

Background

To test, in a two-arm, single center, superiority, randomized controlled trial, the effectiveness of and costs associated with a patient-initiated treatment model for people with hemifacial spasm (HFS) and blepharospasm (BEB) in comparison to usual care.

Methods

One hundred and thirty patients with HFS or BEB, aged 18 years or over, were recruited from a nurse-led botulinum toxin type A clinic at an eye hospital in the United Kingdom (UK), completed baseline measures and were randomized (1:1). The intervention group determined their own botulinum toxin type A (BoNT/A) treatment schedule during the trial period (9 months) and received an information leaflet with a “hotline” number to book an appointment. Usual care appointments were scheduled by treating clinicians. Data analysts were blind to study group. The primary outcomes were disease severity and functional disability, as measured by the Jankovic Rating Scale and Blepharospasm Disability Index, respectively. Secondary outcomes included quality of life, anxiety and depression, satisfaction with care, confidence in the service, economic costs and employment days lost.

Results

Sixty-five patients were randomized to each group. The intervention demonstrated no statistically significant difference to usual care for any of primary outcomes. On secondary outcomes the levels of anxiety differed significantly (F_{2, 142.39} = 1.65, p = 0.02), with the intervention arm exhibiting a decrease and the control arm an increase (Hedges’ g = − 0.26 [99% CI -0.83, 0.32]). No other statistically significant differences were found for secondary outcomes. Overall healthcare costs and costs to the patient were on average £198.95 less (95% CI -£256.76, £654.67; p = 0.10) per participant for those in the intervention compared to usual care, although this finding was not significant.

Conclusions

We did not observe differences between the patient-initiated treatment model and usual care for people with BEB or HFS, on any primary outcome measure, quality of life, or depression. The patient-initiated treatment model may, however, have the potential to save healthcare costs and reduce anxiety. Patients using this new model were also equally as satisfied in the service and confident in their care as those receiving treatment as usual.

Trial registration

Clinicaltrials.gov ID NCT02577224, 16th October 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02603-7.

Immunogenicity to Botulinum Toxin Type A: A Systematic Review With Meta-Analysis Across Therapeutic Indications

BACKGROUND

Botulinum toxin A (BTX-A) is commonly employed as a neuromodulator in several neurological diseases and aesthetic indications. Formation of neutralizing antibodies (NAbs) after BTX-A injections may be responsible for treatment failure.

OBJECTIVES

The authors sought to quantify the prevalence of NAbs following treatment with Abobotulinumtoxin A, Incobotulinumtoxin A, and Onabotulinumtoxin A for therapeutic indications.

METHODS

An electronic systematic search (2000-2020) of PubMed, Scopus, Web of Science, and Embase was conducted. Original studies reporting prevalence of NAbs were included. Data analysis was carried out through open meta-analysis softwares.

RESULTS

Forty-three studies involving 8833 patients were included in this meta-analysis. The incidence of NAbs was 1.8% (summary estimate = 0.018, 95% CI [0.012, 0.023]); a meta-regression analysis revealed that BTX-A duration was significantly associated with increased incidence of NAbs (P = 0.007). Patients with dystonia had the highest incidence (7.4%) of NAbs against BTX-A (summary estimate = 0.074, 95% CI = [0.045, 0.103], I2 = 93.%, P < 0.00) followed by patients with spasticity (6.7%) and urological indications (6.2%). Abobotulinumtoxin A was associated with the highest incidence of NAbs (7.4%) (summary estimate = 0.074, 95% CI = [0.053, 0.096], I2 = 97.24%, P < 0.00) by the Incobotulinumtoxin A and Onabotulinumtoxin A 0.3% (summary estimate <0.003%, 95% CI = [-0.001, 0.007], P < 0.003).

CONCLUSIONS

Although the overall incidence of NAbs following BTX-A injections is relatively low, patients with secondary nonresponse to BTX-A with no apparent causes should be investigated for NAbs. A consensus needs to be developed for the optimal management of such patients.

LEVEL OF EVIDENCE: 2

Long-term efficacy and safety of botulinum toxin treatment for cervical dystonia: a critical reappraisal

Introduction: Botulinum toxin (BoNT) injections represent the gold standard treatment for cervical dystonia (CD). Different types of BoNT have been used for the treatment of CD, but only two serotypes, BoNT type A (BoNT-A) and type B (BoNT-B), have been approved by regulatory agencies. Efficacy and safety of BoNT have been well documented by many short-term studies, but the longterm effects have been investigated only relatively recently.Areas covered: In the present review, we aimed to critically reappraise the existing evidence on the long-term efficacy and safety of BoNT treatment in CD. The examined studies mainly explored BoNT-A serotypes. Only a few studies examined the long-term effects of BoNT-B serotypes, and only one head-to-head comparison between BoNT-A and BoNT-B was found. BoNT was consistently reported to be an effective and safe treatment for CD patients, with good outcomes and a few adverse events in the long-term. However about a third of patients still drop out from the treatment during a long-term follow-up.Expert opinion: We conclude that BoNT is safe and effective in the long-term treatment of patients with CD. Additional studies are needed to further explore patients real-life experiences and perspectives to better understand the long-term outcomes and reasons for discontinuation of treatment.

Cervical dystonia: factors deteriorating patient satisfaction of long-term treatment with botulinum toxin

OBJECTIVES

Botulinum toxin (BoNT) is an effective first-line treatment for cervical dystonia (CD). Despite generally good therapeutic efficacy, approximately 20-40% of CD patients do not achieve acceptable relief of the dystonic symptoms. The aim of this study was to identify factors of low patient satisfaction of long-term BoNT therapy for CD.

METHODS

In this case-control study CD patients treated with BoNT intramuscular injections for up to 24 years were assessed by two independent assessors in three validated scales: TWSTRS, Tsui and VAS for pain measurement. Data on received BoNT doses and treatment duration were obtained from medical history. All of participants rated their long-term treatment satisfaction compared to the therapy onset on a 0-3 scale.

RESULTS

Study was completed by 58 participants who were treated with BoNT for 9.0 ± 6.3 years and received a median of 19 injection cycles. None/low therapy satisfaction was reported by 20.7% of participants. Compared to moderate/good treatment satisfaction, CD patients with none/low BoNT efficacy had increased incidence of cervical pain (p =.018), enhanced mean VAS score for pain (p =.037) and had higher coexistence of oromandibular dystonia (p =.018). In addition, worse treatment satisfaction correlated with shorter time intervals between treatment cycles, enhanced scores of Tsui total, TWSTRS total, as well as TWSTRS subscales: severity, disability and pain.

CONCLUSION

Cervical pain and coexistence of oromandibular dystonia deteriorated long-term treatment satisfaction in CD patients. Higher scores of Tsui and TWSTRS subscales were correlated with worse subjective BoNT treatment response.

Impact of abobotulinumtoxinA on the clinical features of cervical dystonia in routine practice

INTRODUCTION

The efficacy and safety of abobotulinumtoxinA in the management of cervical dystonia has been established in randomized, controlled trials that use a selected trial population. In this meta-analysis of observational data, we evaluated the real-life effectiveness of abobotulinumtoxinA as delivered in routine clinical practice.

METHODS

Meta-analysis of patient-level data for adult patients with cervical dystonia treated with abobotulinumtoxinA from three prospective, multicenter, observational studies (NCT01314365, NCT00833196 and NCT01753349).

RESULTS

We report data for patients treated with abobotulinumtoxinA over one injection cycle at 181 neurology centers in 35 countries. CD clinical features as assessed by Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) Total scores (N = 920) significantly reduced by a mean [95%CI] of -12.9 [-13.9, -11.8] points at Week 4 (N = 449) and -3.2 [-3.8, -2.7] points at the end of the injection cycle (N = 890). All three TWSTRS domains (symptom severity, disability and pain) contributed to the overall improvement. Patients were generally content with symptom control at peak effect of the treatment cycle, with 86% reporting overall satisfaction.

CONCLUSION

Findings from this meta-analysis of observational studies confirm the effectiveness of abobotulinumtoxinA in routine practice. Despite inclusion of a broader population sample, the magnitude of improvements observed is consistent with that seen in the pivotal, randomized controlled trials.

Repeated intrastriatal application of botulinum neurotoxin-A did not influence choline acetyltransferase-immunoreactive interneurons in hemiparkinsonian rat brain - A histological, stereological and correlational analysis

In Parkinson's disease, dopamine depletion leads to hyperactivity of cholinergic interneurons in the caudate-putamen (CPu). Botulinum neurotoxin-A (BoNT-A) inhibits the release of acetylcholine in the peripheral nervous system and is also thought to act as a local anticholinergic drug when injected intrastriatally. In hemiparkinsonian (hemi-PD) rats, a unilateral intrastriatal injection of 1 ng BoNT-A significantly diminished apomorphine-induced rotation behavior for at least 3 months, the effect fading thereafter. A second intrastriatal BoNT-A application, 6 months after the first one, led to a stronger and longer-lasting, beneficial behavioral reaction. As a single BoNT-A injection was not cytotoxic in the rat striatum and resembled BoNT-A treatment in clinical practice, here, we investigated the structural outcome of repeated intrastriatal BoNT-A injections with respect to striatal volume, the number of choline acetyltransferase-immunoreactive (ChAT-ir) interneurons and of the length of their dendritic arbors, and the numeric density of ChAT-ir BoNT-A-induced varicosities (BiVs). Repeated unilateral intrastriatal BoNT-A application decreased the volume of the injected CPu, but did not significantly change the number of striatal ChAT-ir interneurons. Also, the total dendrite length of ChAT-ir interneurons after repeated BoNT-A application resembled the values in double vehicle-injected hemi-PD rats. In repeatedly BoNT-A-injected hemi-PD rats, the numeric density of ChAT-ir BiVs in the CPu was increased compared with rats only intrastriatally injected once with BoNT-A. Even repeated BoNT-A injections in rat striata did not cause substantial morphological changes in ChAT-ir neuron, except for the increased numeric density of ChAT-ir BiVs.

Which factors impact on quality of life for adults with blepharospasm and hemifacial spasm?

Purpose: Benign essential blepharospasm (BEB) and hemifacial spasm (HFS) are debilitating conditions causing spasms to the eyes and/or face and can significantly impact on quality of life (QoL). Initial research has highlighted potential factors impacting on QoL in BEB, but there remains a wealth of demographic, clinical, and psychosocial factors that may contribute to QoL but have not received attention. Methods: Cross-sectional baseline data were collected before a single-masked randomised controlled trial from 130 adults with BEB and HFS recruited from botulinum toxin clinics at Moorfields Eye Hospital, London. QoL was measured using the 24-item Craniocervical Dystonia Questionnaire (CDQ24), which provides a total score and five subscale scores relating to Stigma, Emotional state, Pain, Activities of daily living (ADL), and Social/family life. Treating clinicians provided clinical data. Hierarchical multiple regressions were performed on this baseline data to identify significant predictors of QoL. Results: ADL and Stigma were the areas most impacted upon whilst patients experienced better adjustment in relation to Pain, Social/family life, and Emotional state. CDQ24 Total scores were explained by the model (80% variance) and were significantly associated with appearance concerns, emotional representations, perceived negative consequences of the condition, mood, and dose of botulinum toxin. Conclusions: Patients with BEB and HFS report a detrimental impact on ADL and perceived stigma in relation to their condition. Predominantly, individual perceptions and mood are associated with QoL in this population, rather than demographic and clinical factors, signifying areas to target in the design of future healthcare services or interventions.

Treatment of blepharospasm and Meige's syndrome with abo- and onabotulinumtoxinA: long-term safety and efficacy in daily clinical practice

INTRODUCTION

Thirty years after their approval, botulinum toxin injections still are the first-line therapy for blepharospasm. The aim of our study was to analyze long-term data concerning safety and efficacy in a large cohort over decades.

METHODS

Treatment data of all patients with blepharospasm and Meige´s syndrome in our outpatient clinic having undergone at least three subsequent treatment sessions with current onabotulinumtoxinA or abobotulinumtoxin A were analyzed with respect to the course of dose, effect duration, side effects, patients´ satisfaction and occurrence/reasons for treatment discontinuation.

RESULTS

The observation period was up to 18 years for onabotulinumtoxinA and 29 years for abobotulinumtoxinA with a total of 1778 and 9319 treatment sessions in 69 patients with onabotulinumtoxinA, 281 with abobotulinumtoxin A and 2 of these having used both products. The dose increased in the first years followed by a stable dose in the following years. The mean dose was 39.1/198.7 mouse units (onabotulinumtoxinA/abobotulinumtoxinA). In over 25% of all sessions, inhibition of the eyelid opening was effectively treated with pretarsal injections. The most common adverse events included ptosis (4%/5%), epiphora/sicca (4%/5%), double vision (1%/1%) and facial asymmetry (1%/1%). Reasons for therapy discontinuation were change to a nearby doctor, age, other diseases, spontaneous improvement, side effects or possible treatment failure. Only one patient was tested positive for neutralizing antibodies against botulinum toxin A.

CONCLUSION

The treatment of blepharospasm and Meige's syndrome with onabotulinumtoxinA and abobotulinumtoxinA is safe and effective, also over a long observation period of up to 29 years.

How satisfied are cervical dystonia patients after 3 years of botulinum toxin type A treatment? Results from a prospective, long-term observational study

Background

Patients with cervical dystonia (CD) typically require regular injections of botulinum toxin to maintain symptomatic control. We aimed to document long-term patient satisfaction with CD symptom control in a large cohort of patients treated in routine practice.

Methods

This was a prospective, international, observational study (NCT01753349) following the course of adult CD treated with botulinum neurotoxin type A (BoNT-A) over 3 years. A comprehensive clinical assessment status was performed at each injection visit and subjects reported satisfaction in two ways: satisfaction with symptom control at peak effect and at the end of treatment cycle.

Results

Subject satisfaction remained relatively stable from the first to the last injection visit. At 3 years, 89.9% of subjects reported satisfaction with symptom control at peak effect and 55.6% reported satisfaction with symptom control at end of treatment cycle. By contrast, objective ratings of CD severity showed an overall reduction over 3 years. Mean ± SD Toronto Western Spasmodic Rating Scale (TWSTRS) Total scores (clinician assessed at end of treatment cycle) decreased from 31.59 ± 13.04 at baseline to 24.49 ± 12.43 at 3 years (mean ± SD reduction from baseline of − 6.97 ± 11.56 points). Tsui scale scores also showed gradual improvement; the percent of subjects with a tremor component score of 4 reduced from 12.4% at baseline to 8.1% at 3 years.

Conclusions

Despite objective clinical improvements over 3 years, subject satisfaction with symptom control remained relatively constant, indicating that factors other than symptom control also play a role in patient satisfaction.

Electronic supplementary material

The online version of this article (10.1007/s00415-019-09527-2) contains supplementary material, which is available to authorized users.

Immunogenicity induced by botulinum toxin injections for limb spasticity: A systematic review

BACKGROUND

The imputability of neutralizing antibodies (NABs) in secondary non-response (SnR) to botulinum toxin (BoNT) injections for limb spasticity is still debated.

OBJECTIVE

This systematic literature review aimed to determine the prevalence of NABs after BoNT injections for limb spasticity and analyze their determinants and their causal role in SnR.

METHODS

We searched MEDLINE via PubMed, Cochrane and Embase databases for articles published during 1990-2018. Two independent reviewers extracted the data and assessed the quality of studies with a specific scale (according to PRISMA and STROBE guidelines). Because the techniques used to detect NABs did not influence the results, we calculated the global (all studies) sensitivity and specificity of NAB positivity to reveal SnR.

RESULTS

We included 14 articles published from 2002 to 2018 (including an epublication) describing 5 randomized controlled trials and 5 interventional and 4 observational studies. The quality was satisfactory (mean score 18/28 arbitrary units). NAB detection was the primary criterion in 5 studies and a secondary criterion in 9. In total, 1234 serum samples for 1234 participants (91% with stroke) were tested after injection. NAB prevalence was about 1%, with no significant difference among formulations. NAB positivity seemed favoured by long-duration therapy with high doses and a short interval between injections. The identification of non-response by NAB positivity had poor global sensitivity (56%) but very high specificity (99.6%). No consensual criteria were used to diagnose non-response to BoNT injection.

CONCLUSIONS

NAB prevalence is much lower after BoNT treatment for limb spasticity than cervical dystonia. Consensual criteria must be defined to diagnose non-response to BoNT injection. Because immunogenicity is not the most common cause of non-response to BoNT injection, NABs should be sought in individuals with SnR with no other cause explaining the treatment inefficacy. A test with 100% specificity is recommended. In cases for which immunogenicity is the most likely cause of non-response to BoNT injections, some biological arguments suggest trying another BoNT, but no clinical evidence supports this strategy.

Cervical Kyphotic Deformity Worsening After Extensor Cervical Muscle Paralysis from Botulinum Toxin Injection

BACKGROUND

Botulinum toxin (Botox) has long been used therapeutically to treat a variety of diseases, including migraine headaches, cervical spine dystonia, and chronic cervical spine pain, among many others. Although quite useful, Botox has been reported to cause adverse events, some of which may lead to devastating morbidity.

CASE DESCRIPTION

An elderly woman presented with severe neck pain after a motor vehicle collision. She underwent Botox administration to the neck extensor muscles, after which she developed severe cervical kyphotic deformity, a complication previously reported only in patients with a history of cervical fusion. In addition, the patient had a pre-existing cervical spine degenerative disc disease with listhesis resulting in cervical kyphotic deformity and loss of cervical lordosis.

CONCLUSIONS

This case illustrates a potential danger of using Botox in the neck of an elderly patient who may have pre-existing cervical spine instability, underlying cervical musculature weakness, and pre-existing cervical kyphosis. It demonstrates the need to evaluate patients who are predisposed to developing cervical kyphotic deformities before offering them Botox treatment.

Repeated Intrastriatal Botulinum Neurotoxin-A Injection in Hemiparkinsonian Rats Increased the Beneficial Effect on Rotational Behavior

Injection of botulinum neurotoxin-A (BoNT-A) into the striatum of hemiparkinsonian (hemi-PD) rats reduced apomorphine-induced rotation behavior significantly, for at least 3 months. Thereafter, rotation behavior increased again. We injected hemi-PD rats with 1 ng BoNT-A twice, the second injection following 6 months after the first one and tested the rats for apomorphine-induced rotations and spontaneous motor behaviors, i.e., corridor task and stepping test. To test the hypothesis that BoNT-A reduced striatal hypercholinism in hemi-PD rats, the acetylcholinesterase inhibitor donepezil was injected prior to separate apomorphine-induced rotation tests. In hemi-PD rats, the first BoNT-A injection led to a clear reduction of the apomorphine-induced rotations, and the second BoNT-A injection to a more massive and prolonged reaction. In hemi-PD rats whose apomorphine-induced rotation behavior was strongly reduced by an intrastriatal BoNT-A, subsequent donepezil injections led to significant increases of the rotation rate. Concerning corridor task and stepping test, neither first nor second BoNT-A injections changed hemi-PD rats' behavior significantly. The data give evidence for the possibility of repeated intrastriatal administrations of BoNT-A, for treatment of motor symptoms in experimental hemi-PD over a longer time.

Randomised controlled trial of escitalopram for cervical dystonia with dystonic jerks/tremor

OBJECTIVE

Trials for additional or alternative treatments for cervical dystonia (CD) are scarce since the introduction of botulinum neurotoxin (BoNT). We performed the first trial to investigate whether dystonic jerks/tremor in patients with CD respond to the selective serotonin reuptake inhibitor (SSRI) escitalopram.

METHODS

In a randomised, double-blind, crossover trial, patients with CD received escitalopram and placebo for 6 weeks. Treatment with BoNT was continued, and scores on rating scales regarding dystonia, psychiatric symptoms and quality of life (QoL) were compared. Primary endpoint was the proportion of patients that improved at least one point on the Clinical Global Impression Scale for jerks/tremor scored by independent physicians with experience in movement disorders.

RESULTS

Fifty-threepatients were included. In the escitalopram period, 14/49 patients (29%) improved on severity of jerks/tremor versus 11/48 patients (23%) in the placebo period (P=0.77). There were no significant differences between baseline and after treatment with escitalopram or placebo on severity of dystonia or jerks/tremor. Psychiatric symptoms and QoL improved significantly in both periods compared with baseline. There were no significant differences between treatment with escitalopram and placebo for dystonia, psychiatric or QoL rating scales. During treatment with escitalopram, patients experienced slightly more adverse events, but no serious adverse events occurred.

CONCLUSION

In this innovative trial, no add-on effect of escitalopram for treatment of CD with jerks was found on motor or psychiatric symptoms. However, we also did not find a reason to withhold patients treatment with SSRIs for depression and anxiety, which are common in dystonia.

TRIAL REGISTRATION NUMBER

NTR2178.

Four-dimensional ultrasound guidance for pelvic floor Botulinum toxin-A injection in chronic pelvic pain: a novel technique

OBJECTIVE

Botulinum toxin-A (BoNT-A) is used in the treatment of pelvic floor muscle overactivity associated with chronic pelvic pain (CPP) when conservative methods such as physiotherapy are not effective or appropriate. Traditional injection techniques require finger-guided palpation of pelvic floor muscles with concurrent insertion of the needle. The aim of this study was to describe a novel technique for the injection of BoNT-A into the pelvic floor musculature using four-dimensional ultrasound (4D-US) guidance.

METHODS

Thirty-one BoNT-A injections were performed using the new technique between October 2013 and January 2016, on women scheduled to have BoNT-A injection for pelvic floor muscle overactivity and CPP. The pelvic floor was assessed by 4D-US. A test injection of saline was performed to confirm location of the needle, then BoNT-A was injected into the muscle under ultrasound guidance, using 4D-US to confirm that the fluid expanded and tracked along muscle fibers.

RESULTS

The saline test confirmed correct location of the needle following a median of 1 (range, 1-3) attempt at needle placement. In all 31 instances, satisfactory injection of BoNT-A, with 4D-US confirmation of fluid expansion within the muscle body, was performed.

CONCLUSIONS

Injection of BoNT-A under 4D-US guidance is feasible and allows accurate placement into the target muscle in women with pelvic floor muscle overactivity associated with CPP. This technique may provide a safer alternative to finger-guided methods, owing to a lower likelihood of operator needle-stick injury. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Ixcellence Network®: an international educational network to improve current practice in the management of cervical dystonia or spastic paresis by botulinum toxin injection

Botulinum toxin is a well-established treatment for a number of conditions involving muscle hyperactivity, such as focal dystonia and spastic paresis. However, current injection practice is not standardized and there is a clear need for structured training. An international group of experts in the management of patients with cervical dystonia (CD) and spastic paresis created a steering committee (SC). For each therapeutic area, the SC developed a core slide set on best practice, based on the literature. International sites of expertise were identified for training and courses were designed to include lectures and casebased learning. Where possible, courses received accreditation from the European Union of Medical Specialists (UEMS). Each course was peer reviewed by the SC, the UEMS accreditation board and the attendees themselves (through evaluation questionnaires). Attendees' feedback was shared with the SC and the trainers to tailor future training sessions. From the program launch in 2012 to December 2014, 328 physicians from 34 countries were trained in a total of 58 courses; 67% of the courses focused on spastic paresis and 33% on CD. Of the 225 (69%) physicians who completed feedback forms, 95% rated their course as 'above average/excellent' in meeting the preset learning objectives. Most (90%) physicians declared that attending a course would lead them to change their practice. The development of the 'Ixcellence Network' for continuous medical education in the fields of spastic paresis and CD has provided a novel and interactive way of training physicians with previous experience in botulinum toxin injection.

Onabotulinumtoxin A for the management of chronic migraine in current clinical practice: results of a survey of sixty-three Italian headache centers

BACKGROUND

Chronic migraine is a complex clinical condition often undertreated. Onabotulinumtoxin A (OBT-A) was approved in Italy in 2013 for symptom relief in patients with chronic migraine who have failed, or do not tolerate, oral prophylactic treatments. However, the impact of OBT-A in clinical practice remains to be defined.

METHODS

To investigate the current management of chronic migraine with OBT-A in clinical practice, a web-based survey was conducted among clinicians working in third-level headache centers across Italy. A 26-item questionnaire was designed and developed by a group of 10 Italian headache specialists to address the following issues: treatment paradigm and OBT-A injection intervals, frequency of treatment and retreatment, definition of responders/non-responders, satisfaction with treatment potential impact of early treatment with OBT-A. Ninety-six headache centers were selected and contacted via e-mail. The online survey was anonymous and carried out using a secure website.

RESULTS

Overall, 64 of the 96 centers (66.7%) completed the questionnaire. Most centers (98.4%) had been using OBT-A for >1 year. OBT-A was administered according to the PREEMPT paradigm in most centers (88.9%). While during the first year of prophylaxis with OBT-A most clinicians (93.6%) repeated OBT-A treatment every 3 months, as recommended, in the following years interval duration was variable. Response to OBT-A was defined as a ≥ 50% reduction in the headache days by 58.7% of the clinicians, and as a ≥ 30% reduction by 25.4% of them. Almost 60% of the clinicians considered OBT-A as a long-lasting therapy, while for one-third of them treatment could be discontinued in patients showing a benefit for ≥6 months. According to 80% of the clinicians, early administration of OBT-A after the onset of chronic migraine was associated with better outcomes, and 47.6% felt that OBT-A should be recommended as a first-line option.

CONCLUSIONS

This survey indicates that in third-level headache centers in Italy OBT-A is used in good compliance with current recommendations. There is agreement about the definition of response as a reduction in headache days by 30% to 50%. Additional effort is required to define response to OBT-A and to establish optimal treatment duration.

Long-term Treatment Benefits and Prolonged Efficacy of OnabotulinumtoxinA in Patients Affected by Chronic Migraine and Medication Overuse Headache over 3 Years of Therapy

Background

Chronic migraine (CM) affects about the 2% of the general population and it has been recognized as one of the most-disabling conditions worldwide by the World Health Organization. CM is often associated with the overuse of abortive medication, which determines the worsening of headache itself and the development of a secondary headache called medication overuse headache. The management of these associated conditions is difficult, but a growing amount of evidence is pointing out the effectiveness and the good safety profile of OnabotulinumtoxinA (OnabotA). Despite this, data on OnabotA effects and safety in long-term use lack. The purpose of the present article is to retrospectively assess the efficacy and safety of OnabotA in a cohort of chronic migraineurs with drug overuse from the 18th month of treatment until the third year.

Materials and methods

90 chronic migraineurs with medication overuse were enrolled between January 2013 and February 2017. All patients were treated with OnabotA according to PREEMPT dictates. Before every injection session the headache index, the analgesic consumption, the visual analog scale for pain score, the 36-items short form health survey questionnaire score, the 6-items headache impact test (HIT-6) score and the Zung self-rating anxiety and depression scale scores were collected. Adverse events were carefully registered. A simple linear regression was performed to explore the mean changes in the abovementioned parameters for a single injection session and mean comparison tests were performed using the one-way analysis of variance followed by Tukey–Kramer post-hoc test.

Results

A significantly improvement for a single injection was registered for all the above-mentioned parameters. Headache index, analgesic consumption, visual analog pain scale, and 6-items HIT-6 scores were significantly lower than baseline from the 18th month of treatment onwards. The 36-items short form health survey questionnaire scores were significantly higher than baseline at every injections session from the 18th months onwards. Zung scales did not change. No serious adverse events were assessed and no adverse events-related drop-outs were seen.

Conclusion

OnabotA effectiveness and safety last until 3 years of therapy, raising the possibility of the use of this therapy even for many years in CM prevention.

Neutralizing Antibody and Botulinum Toxin Therapy: A Systematic Review and Meta-analysis

The formation of neutralizing antibodies (NAbs) directed specifically against the active neurotoxin part of the botulinum neurotoxin (BoNT) complex is often cited as a major cause of secondary non-responsiveness (SnR) to treatment. This systematic and meta-analytic review evaluates the frequency of NAbs among patients treated with BoNT therapy for any clinical indication. A comprehensive database search strategy was designed to retrieve relevant clinical data from the published literature up to April 2013. All English-language publications that analyzed NAbs prevalence in more than ten patients were included, regardless of BoNT formulation, assay method, and study design. For the meta-analysis, patients were divided into three categories: secondary nonresponse (SnR) patients, clinically responding patients and all patients, independently of BoNT responsiveness. The meta-analysis included 61 studies reporting data for 8525 patients; 4972 dystonic patients, 1170 patients with spasticity, 294 patients with urologic indications, 396 patient with hyperhidrosis, 1659 patients with glabellar line, and 34 patients with hypersalivation. Among the ‘‘all patients’’ group NAbs frequency was 20%for dystonia, 5.9%for spasticity, and 2.7% for urologic patients and 1.1% for other conditions. The prevalence of NAbs was lower (3.5%) among clinically responding patients and higher in 53.5%SnR patients. About a half of patients with SnR do not have NAbs. NAbs was high among patients treated with RIMA but it was not associated with clinical non-responsiveness. Meta-analysis of the frequency of NAbs and SnR are limited by the heterogeneity of study design and reported outcomes. Indeed the analysis of several factors that can influence the development of NAbs, i.e.,MHCof patients, frequency and site of injection, injection technique, cumulative dose, and toxin denaturation, was not specifically evaluated due to the paucity and heterogeneity of data. The identification of all these missing data should be taken into account in order to improve the methodology of future studies.

Effectiveness and cost-effectiveness of a patient-initiated botulinum toxin treatment model for blepharospasm and hemifacial spasm compared to standard care: study protocol for a randomised controlled trial

Background

Blepharospasm and hemifacial spasm are debilitating conditions that significantly impact on patient quality of life. Cyclical treatment with botulinum toxin injections offers temporary relief, but the duration of treatment efficacy is variable. The standard model of patient care defines routine fixed-time based scheduled treatment cycles which may lead to unnecessarily frequent treatment for some patients and experience of distressing symptoms in others, if symptoms return before the scheduled follow-up period.

Methods/Design

A randomised controlled trial will compare a patient-initiated model of care, where patients determine botulinum toxin treatment timing, to the standard model of care in which care is scheduled by the clinical team. A sample of 266 patients with blepharospasm or hemifacial spasm will be recruited from Moorfields Eye Hospital (MEH), London. The trial will be accompanied by a mixed-methods evaluation of acceptability of the new service. Patients who meet eligibility criteria will be assessed at baseline and those in the intervention group will be provided with instructions on how to book their own treatment appointments. Patients in both groups will be followed up 3 and 9 months into the trial and all patients will be returned to usual care after 9 months to meet safety protocols. Primary outcome measures include disease severity (questionnaire), functional disability (questionnaire) and patient satisfaction with care (questionnaire). Secondary outcomes include disease-specific quality of life (questionnaire), mood (questionnaire), illness and treatment perceptions (questionnaire and semi-structured interviews), economic impact (questionnaire) and acceptability (questionnaire and semi-structured interviews).

Discussion

This trial will assess the effectiveness and cost-effectiveness of a patient-led care model for botulinum toxin therapy. If the new model is shown to be effective in reducing distress and disability in these populations and is found to be acceptable to patients, whilst being cost-effective, this will have significant implications for service organisation across the NHS.

Trial registration

UK Clinical Research Network (UKCRN) Portfolio 18660. Clinicaltrials.gov ID NCT102577224 (registered 29 October 2015)

Clinical differences between botulinum neurotoxin type A and B

In humans, the therapeutic use of botulinum neurotoxin A (BoNT/A) is well recognized and continuously expanding. Four BoNTs are widely available for clinical practice: three are serotype A and one is serotype B: onabotulinumtoxinA (A/Ona), abobotulinumtoxinA (A/Abo) and incobotulinumtoxinA (A/Inco), rimabotulinumtoxinB (B/Rima). A/Abo, A/Inco, A/Ona and B/Rima are all licensed worldwide for cervical dystonia. In addition, the three BoNT/A products are approved for blepharospasm and focal dystonias, spasticity, hemifacial spasm, hyperhidrosis and facial lines, with remarkable regional differences. These toxin brands differ for specific activity, packaging, constituents, excipient, and storage. Comparative literature assessing the relative safety and efficacy of different BoNT products is limited, most data come from reports on small samples, and only a few studies meet criteria of evidence-based medicine. One study compared the effects of BoNT/A and BoNT/B on muscle activity of healthy volunteers, showing similar neurophysiological effects with a dose ratio of 1:100. In cervical dystonia, when comparing the effects of BoNT/A and BoNT/B, results are more variable, some studies reporting roughly similar peak effect and overall duration (at a ratio of 1:66, others reporting substantially shorter duration of BoNT/B than BoNT/A (at a ratio 1/24). Although the results of clinical studies are difficult to compare for methodological differences (dose ratio, study design, outcome measures), it is widely accepted that: BoNT/B is clinically effective using appropriate doses as BoNT/A (1:40-50), injections are generally more painful, in most of the studies on muscular conditions, efficacy is shorter, and immunogenicity higher. Since the earliest clinical trials, it has been reported that autonomic side effects are more frequent after BoNT/B injections, and this observation encouraged the use of BoNT/B for sialorrhea, hyperhidrosis and other non-motor symptoms. In these indications the efficacy of toxins A and B are comparable and dose ratio is 1:25-30.

Practical guidance for CD management involving treatment of botulinum toxin: a consensus statement

Cervical dystonia is a neurological movement disorder causing abnormal posture of the head. It may be accompanied by involuntary movements which are sometimes tremulous. The condition has marked effects on patients’ self-image, and adversely affects quality of life, social relationships and employment. Botulinum neurotoxin (BoNT) is the treatment of choice for CD and its efficacy and safety have been extensively studied in clinical trials. However, current guidelines do not provide enough practical information for physicians who wish to use this valuable treatment in a real-life setting. In addition, patients and physicians may have different perceptions of what successful treatment outcomes should be. Consequently, an international group of expert neurologists, experienced in BoNT treatment, met to review the literature and pool their extensive clinical experience to give practical guidance about treatment of CD with BoNT. Eight topic headings were considered: the place of BoNT within CD treatment options; patient perspectives and desires for treatment; assessment and goal setting; starting treatment with BoNT-A; follow-up sessions; management of side effects; management of non-response; switching between different BoNT products. One rapporteur took responsibility for summarising the current literature for each topic, while the consensus statements were developed by the entire expert group. These statements are presented here along with a discussion of the background information.

Diffuse decreased gray matter in patients with idiopathic craniocervical dystonia: a voxel-based morphometry study

Background: Recent studies have addressed the role of structures other than the basal ganglia in the pathophysiology of craniocervical dystonia (CCD). Neuroimaging studies have attempted to identify structural abnormalities in CCD but a clear pattern of alteration has not been established. We performed whole-brain evaluation using voxel-based morphometry (VBM) to identify patterns of gray matter (GM) changes in CCD.

Methods: We compared 27 patients with CCD matched in age and gender to 54 healthy controls. VBM was used to compare GM volumes. We created a two-sample t-test corrected for subjects’ age, and we tested with a level of significance of p < 0.001 and false discovery rate (FDR) correction (p < 0.05).

Results: Voxel-based morphometry demonstrated significant reductions of GM using p < 0.001 in the cerebellar vermis IV/V, bilaterally in the superior frontal gyrus, precuneus, anterior cingulate and paracingulate, insular cortex, lingual gyrus, and calcarine fissure; in the left hemisphere in the supplementary motor area, inferior frontal gyrus, inferior parietal gyrus, temporal pole, supramarginal gyrus, rolandic operculum, hippocampus, middle occipital gyrus, cerebellar lobules IV/V, superior, and middle temporal gyri; in the right hemisphere, the middle cingulate and precentral gyrus. Our study did not report any significant result using the FDR correction. We also detected correlations between GM volume and age, disease duration, duration of botulinum toxin treatment, and the Marsden–Fahn dystonia scale scores.

Conclusion: We detected large clusters of GM changes chiefly in structures primarily involved in sensorimotor integration, motor planning, visuospatial function, and emotional processing.

Patient considerations in the treatment of cervical dystonia: focus on botulinum toxin type A

Cervical dystonia is the most common form of focal dystonia characterized by involuntary muscle contractions causing abnormal movements and posturing of the head and neck and is associated with significant pain. Botulinum toxin is considered first-line therapy in the treatment of pain and abnormal head posturing associated with cervical dystonia. There are currently three botulinum toxin type A neurotoxins and one botulinum type B neurotoxin commercially available and US Food and Drug Administration (FDA) labeled for the treatment of cervical dystonia. This review will focus on the efficacy, safety, and therapeutic use of botulinum type A neurotoxins in the treatment of cervical dystonia. We conclude with a discussion of factors influencing toxin selection including therapeutic effect, duration of effect, side effect profile, cost, and physician preference.

Long-term therapy of benign essential blepharospasm and facial hemispasm with botulinum toxin A: retrospective assessment of the clinical and quality of life impact in patients treated for more than 15 years

Botulinum toxin type A (BoNT-A) is recognized as the treatment of choice for patients with blepharospasm and facial hemispasm. We report the results of long-term BoNT-A therapy (15-20 years) in a group of patients with blepharospasm (9 patients) and hemifacial spasm (18 patients). We evaluated the number of treatment sessions, duration of therapeutic effects, side effects and their frequency during long-term therapy, and the differences between these two groups of patients. We used patient self-assessment and a patient questionnaire to evaluate the influence of the treatment on their quality of life. We have concluded that BoNT-A is an effective and safe long-term treatment of these facial dyskinesias. Despite the different pathophysiology of blepharospasm and facial hemispasm, the therapy effectiveness is comparable. The only differences were in the side effects. In patients with blepharospasm, the side effect frequency was higher and manifested by double vision or eyelid ptosis. In patients with facial hemispasm, the most frequent side effect was lower facial weakness. No association between therapy duration and side effect frequency was determined. Based on patient questionnaires, all patients believed that the treatment was safe and effective with a positive impact on their quality of life, especially in social communication.

Factors influencing secondary non-response to botulinum toxin type A injections in cervical dystonia

BACKGROUND

The development of secondary non-response (SNR) to botulinum neurotoxin type-A (BoNT-A) is considered a key issue in the management of cervical dystonia (CD). This case-controlled study was performed to systematically identify factors influencing SNR during BoNT-A therapy.

METHODS

This was a retrospective, international, non-interventional study of CD patients. Patients with SNR were matched with up to three responder patients (control) on the basis of duration of therapy and number of injection cycles. Factors influencing the development of SNR were screened using a univariate logistic regression model and confirmed using a multivariate conditional logistic regression model.

RESULTS

216 patients were enrolled, and 201 (SNR = 52; responder = 149) were matched and subdivided into blocks (doublets, triplets or quadruplets). At baseline, a significantly higher proportion of SNR patients had received previous or concomitant therapies (p = 0.038) and surgery for CD (p = 0.007) compared with controls. Although disease severity at onset was similar between groups, a significantly higher proportion of SNR patients experienced severe CD at the time of SNR compared with controls at the last documented visit. Multivariate analyses identified five factors that were significantly associated in predicting SNR (odds ratio [OR] > 1 indicated higher chances for being SNR): previous surgical procedure for CD (OR 9.8, p = 0.013), previous BoNT-A related severe adverse event (AE) (OR 5.6 p = 0.027), physical therapy (OR 4.6, p = 0.028), neuroleptic use (OR 3.3, p = 0.019) and average BoNT-A dose (OR 2.7, p = 0.010).

CONCLUSIONS

These findings suggest that SNR may not reflect true pharmacological resistance to BoNT-A therapy, but may be related to underlying disease severity.

Long-term efficacy, safety, and side effect profile of botulinum toxin in dystonia: a 20-year follow-up

Most long-term studies of the efficacy and safety profile of botulinum toxin (BoNT) in the treatment of dystonia are limited by lack of objective assessments, relatively small sample size, or short follow-up periods. We present one of the longest follow-up studies of BoNT treatment. This is a retrospective, longitudinal study that analyzes data on 89 patients treated with BoNT for dystonia at our Movement Disorders Clinic for up to 26 years (mean follow-up period of 18.5 years). The mean ages at the time of the first and last injections were 49 and 68 years old, respectively. The most common diagnoses were cervical dystonia (N = 51), blepharospasm (N = 34), and oromandibular dystonia (N = 26). The total number of onabotulinumtoxinA units received during the first injection was 140.3 as compared to 224.5 at the last injection (p < 0.0001). The global response effect was 3.18 after the first injection session and 3.57 after the last injection (p < 0.0001). The duration of response after the initial injection session and at the last injection was 16.33 weeks versus 19.42 weeks (p 0.0037), respectively. Adverse events, typically related to injection site, were reported in 19% of the visits. This series of dystonia patients with the longest reported treatment with BoNT provide evidence that in selected patients repeated chemodenervation is associated with sustained symptomatic benefit, decreased latency effect, and prolonged duration of therapeutic response. Despite the higher requirement of mean units per visit over time, only 19% of all treatment cycles are associated with adverse, but tolerable, side effects.

Update on treatments for dystonia

Oral medication, botulinum toxin injections, and deep brain stimulation are the current mainstays of treatment for dystonia. In addition, physical and other supportive therapies may help prevent further complications (eg, contractures) and improve function. This review discusses evidence-based medical treatment of dystonia with an emphasis on recent advances in treatment. We will also review the current treatment approaches and suggest ways in which these therapies can be applied to individuals with dystonia.

Dystonia

PURPOSE OF REVIEW

The purpose of this review is to provide an update on the classification, phenomenology, pathophysiology, and treatment of dystonia.

RECENT FINDINGS

A revised definition based on the main phenomenologic features of dystonia has recently been developed in an expert consensus approach. Classification is based on two main axes: clinical features and etiology. Currently, genes have been reported for 14 types of monogenic isolated and combined dystonia. Isolated dystonia (with dystonic tremor) can be caused by mutations in TOR1A (DYT1), TUBB4 (DYT4), THAP1 (DYT6), PRKRA (DYT16), CIZ1 (DYT23), ANO3 (DYT24), and GNAL (DYT25). Combined dystonias (with parkinsonism or myoclonus) are further subdivided into persistent (GCHI [DYT5], SGCE [DYT11], and ATP1A3 [DYT12], with TAF1 most likely but not yet proven to be linked to DYT3) and paroxysmal (PNKD [DYT8], PRRT2 [DYT10], and SLC2A1 [DYT18]). Recent insights from neurophysiologic studies identified functional abnormalities in two networks in dystonia: the basal ganglia-sensorimotor network and, more recently, the cerebellothalamocortical pathway. Besides the well-known lack of inhibition at different CNS levels, dystonia is specifically characterized by maladaptive plasticity in the sensorimotor cortex and loss of cortical surround inhibition. The exact role (modulatory or compensatory) of the cerebellar-cortical pathways still has to be further elucidated. In addition to botulinum toxin for focal forms, deep brain stimulation of the globus pallidus internus is increasingly recognized as an effective treatment for generalized and segmental dystonia.

SUMMARY

The revised classification and identification of new genes for different forms of dystonia, including adult-onset segmental dystonia, enable an improved diagnostic approach. Recent pathophysiologic insights have fundamentally contributed to a better understanding of the disease mechanisms and impact on treatment, such as functional neurosurgery and nonpharmacologic treatment options.

Treatment of dystonia

Selecting the appropriate treatment for dystonia begins with proper classification of disease based on age, distribution, and underlying etiology. The therapies available for dystonia include oral medications, botulinum toxin, and surgical procedures. Oral medications are generally reserved for generalized and segmental dystonia. Botulinum toxin revolutionized the treatment of focal dystonia when it was introduced for therapeutic purposes in the 1980s. Surgical procedures are available for medication-refractory dystonia, markedly affecting an individual's quality of life.

Long-term efficacy and safety of botulinum toxin injections in dystonia

Local chemodenervation with botulinum toxin (BoNT) injections to relax abnormally contracting muscles has been shown to be an effective and well-tolerated treatment in a variety of movement disorders and other neurological and non-neurological disorders. Despite almost 30 years of therapeutic use, there are only few studies of patients treated with BoNT injections over long period of time. These published data clearly support the conclusion that BoNT not only provides safe and effective symptomatic relief of dystonia but also long-term benefit and possibly even favorably modifying the natural history of this disease. The adverse events associated with chronic, periodic exposure to BoNT injections are generally minor and self-limiting. With the chronic use of BoNT and an expanding list of therapeutic indications, there is a need to carefully examine the existing data on the long-term efficacy and safety of BoNT. In this review we will highlight some of the aspects of long-term effects of BoNT, including efficacy, safety, and immunogenicity.

Botulinum toxin physiology in focal hand and cranial dystonia

The safety and efficacy of botulinum toxin for the treatment of focal hand and cranial dystonias are well-established. Studies of these adult-onset focal dystonias reveal both shared features, such as the dystonic phenotype of muscle hyperactivity and overflow muscle contraction and divergent features, such as task specificity in focal hand dystonia which is not a common feature of cranial dystonia. The physiologic effects of botulinum toxin in these 2 disorders also show both similarities and differences. This paper compares and contrasts the physiology of focal hand and cranial dystonias and of botulinum toxin in the management of these disorders.