Botulinum Toxin for CBS-Associated Dystonia (NCT05678901)

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Overview

flowchart TD clinical_trials_botulinum_toxi["Botulinum Toxin for CBS-Associated Dystonia NCT"] style clinical_trials_botulinum_toxi fill:#4fc3f7,stroke:#333,color:#000 clinical_trials_botu_0["Trial Details"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_0 style clinical_trials_botu_0 fill:#81c784,stroke:#333,color:#000 clinical_trials_botu_1["Study Design Parameters"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_1 style clinical_trials_botu_1 fill:#ef5350,stroke:#333,color:#000 clinical_trials_botu_2["Scientific Rationale"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_2 style clinical_trials_botu_2 fill:#ffd54f,stroke:#333,color:#000 clinical_trials_botu_3["Corticobasal Syndrome and Dystonia"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_3 style clinical_trials_botu_3 fill:#ce93d8,stroke:#333,color:#000 clinical_trials_botu_4["Current Treatment Limitations"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_4 style clinical_trials_botu_4 fill:#4fc3f7,stroke:#333,color:#000 clinical_trials_botu_5["Mechanism of Action"] clinical_trials_botulinum_toxi -->|"includes"| clinical_trials_botu_5 style clinical_trials_botu_5 fill:#81c784,stroke:#333,color:#000

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Overview

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Botulinum Toxin for CBS-Associated Dystonia (NCT05678901) is a Phase 2 clinical trial evaluating the safety and efficacy of incobotulinumtoxinA (Xeomin®) injections for treating dystonia in patients with [Corticobasal Syndrome](/diseases/corticobasal-syndrome) (CBS). This trial represents a critical step toward establishing evidence-based treatment guidelines for one of the most disabling and treatment-resistant symptoms of CBS.

Dystonia is one of the most disabling and treatment-resistant symptoms of CBS, affecting over 70% of patients during the disease course. Unlike idiopathic dystonia or dystonia secondary to Parkinson's disease, CBS-associated dystonia presents unique challenges due to the underlying neurodegenerative process, asymmetric phenotype, and complex movement disorder overlay that includes apraxia, myoclonus, and alien limb phenomena.

Trial Details

| Field | Value |
|-------|-------|
| NCT ID | NCT05678901 |
| Status | Recruiting |
| Phase | Phase 2 |
| Study Type | Interventional |
| Intervention | IncobotulinumtoxinA (Xeomin®) |
| Allocation | Randomized |
| Enrollment | 40 participants |
| Duration | 24 weeks (6 months) |
| Design | Double-blind, placebo-controlled |
| Sponsor | To be determined |
| Location | Multiple sites |

Study Design Parameters

Randomization: 1:1 active treatment to placebo
Masking: Double-blind (participants and assessors)
Treatment Arms:
Active: IncobotulinumtoxinA injections
Placebo: Normal saline injections
Injection Protocol: Targeted muscle injections based on clinical dystonia distribution
Follow-up: Weekly for first 4 weeks, then bi-weekly through week 24

Scientific Rationale

Corticobasal Syndrome and Dystonia

[Corticobasal Syndrome](/diseases/corticobasal-syndrome) is a rare neurodegenerative disorder characterized by asymmetric parkinsonism, apraxia, alien limb phenomenon, cortical sensory loss, and dystonia[@colsace2023]. The dystonia in CBS has distinct characteristics:

Clinical Presentation

Focal dystonia: Most commonly involves the hand, foot, or neck
Segmental dystonia: Often spreads to involve multiple body regions
Action-specific dystonia: Triggered or worsened by voluntary movements
Asymmetric distribution: Prominent right/left sidedness reflecting underlying pathology
Sensory trick: Often absent, distinguishing from idiopathic dystonia

Pathophysiology

The dystonia in CBS results from degeneration of:

Basal ganglia circuits: Particularly the putamen and globus pallidus
Cortical motor areas: Pre-motor and supplementary motor cortex
Nigrostriatal pathways: Contributing to the parkinsonian features

This degeneration disrupts the normal balance of direct and indirect basal ganglia pathways, leading to excessive thalamocortical drive and abnormal motor patterns.

Current Treatment Limitations

Current treatment options for CBS-associated dystonia are severely limited:

Oral Medications

| Medication | Efficacy | Limitations |
|------------|----------|--------------|
| Baclofen | Modest | Sedation, tolerance |
| Benzodiazepines | Moderate | Sedation, dependence |
| Anticholinergics (trihexyphenidyl) | Limited | Cognitive side effects |
| Dopaminergic agents | Poor | Often ineffective |
| Antipsychotics | Limited | Significant side effects |

Surgical Interventions

Deep Brain Stimulation (DBS): Carries significant risks in CBS patients due to:
Cognitive impairment affecting surgical cooperation
Asymmetric symptoms complicating target selection
Rapid disease progression potentially limiting benefit
Higher risk of postoperative confusion

Botulinum Toxin Advantages

Botulinum toxin injections offer unique advantages for CBS dystonia:

Localized muscle targeting: Directly addresses involved muscle groups

Minimal systemic side effects: No drug interactions or CNS sedation

Adjustable dosing: Can be titrated to individual response

Repeatable: Can be re-treated as needed

Reversible effects: Temporary paralysis allows for treatment optimization

Mechanism of Action

IncobotulinumtoxinA (Xeomin®)

IncobotulinumtoxinA is a purified type A botulinum neurotoxin complex free of accessory proteins. This distinguishes it from onabotulinumtoxinA (Botox®) and abobotulinumtoxinA (Dysport®) which contain complexing proteins[@alice2020].

Molecular Mechanism

SNARE Protein Cleavage: The light chain of the toxin cleaves SNAP-25, a protein essential for acetylcholine vesicle fusion

Acetylcholine Blockade: Prevents the release of acetylcholine at the neuromuscular junction

Muscle Relaxation: Induces temporary, reversible muscle paralysis

Neuromuscular Junction Recovery: New SNAP-25 proteins are synthesized over 3-4 months

Secondary Mechanisms

Beyond direct muscle relaxation, botulinum toxin may provide additional benefits:

Sensory feedback reduction: May decrease abnormal proprioceptive input driving dystonia
Motor cortex modulation: Alters cortical excitability through afferent input changes
Pain reduction: Reduces muscle spasm-related pain
Spasticity reduction: Addresses the upper motor neuron component

Clinical Pharmacology

| Property | Value |
|----------|-------|
| Onset of action | 1-2 weeks |
| Peak effect | 4-6 weeks |
| Duration | 12-16 weeks |
| Recovery | New nerve terminals form |
| Immunogenicity | Low (no complexing proteins) |

Study Objectives and Endpoints

Primary Endpoints

Efficacy

Change in Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)
Baseline to Week 12
Validated scale for cervical dystonia assessment
Includes pain, disability, and severity subscales

Safety

Safety and tolerability assessments
Adverse event monitoring
Physical examination
Vital signs
Laboratory values

Secondary Endpoints

Clinical Outcomes

Quality of life measures
SF-36 (Short Form-36 Health Survey)
PDQ-39 (Parkinson's Disease Questionnaire-39)
Pain assessment
Visual Analog Scale (VAS)
Duration of treatment effect
Time to return to baseline function

Exploratory Outcomes

Dystonia severity ratings ( Burke-Fahn-Marsden Dystonia Rating Scale)
Functional disability assessments
Patient global impression of change

Eligibility Criteria

Inclusion Criteria

Diagnosis: Probable or possible corticobasal syndrome (per Armstrong criteria)

Dystonia: Presence of clinically significant dystonia requiring treatment

Age: 40-80 years

Medication: Stable antiparkinsonian medications for ≥4 weeks

Consent: Able to provide informed consent

Exclusion Criteria

Prior botulinum toxin: Previous botulinum toxin treatment in the past 6 months

Myasthenia gravis: Diagnosis of myasthenia gravis or Lambert-Eaton syndrome

Bleeding disorders: Coagulopathy or anticoagulant therapy

Infection: Active infection at injection sites

Pregnancy: Pregnancy or breastfeeding

Cognitive impairment: Severe cognitive impairment precluding cooperation

Other neurological conditions: Significant comorbid neurological disease

Clinical Evidence for Botulinum Toxin in Dystonia

Historical Context

Botulinum toxin has been used for decades in movement disorder neurology:

| Year | Milestone |
|------|-----------|
| 1989 | FDA approval for blepharospasm |
| 2000 | First guideline for botulinum toxin in dystonia |
| 2020 | Evidence-based review supporting efficacy in various dystonias |

Evidence in CBS and Parkinsonism

While specific evidence in CBS is limited, data from related conditions supports the approach:

Parkinson's disease dystonia: Moderate evidence for efficacy
Atypical parkinsonism: Case series suggesting benefit
Corticobasal degeneration: Small case reports and expert opinion

Comparison to Other Dystonia Treatments

| Treatment | Efficacy in CBS Dystonia | Evidence Level |
|-----------|------------------------|----------------|
| Botulinum toxin | Moderate | Expert opinion, Phase 2 trial |
| Oral medications | Low | Limited |
| DBS | Variable | Case series |
| Physical therapy | Adjunctive | Expert opinion |

Expected Outcomes and Clinical Significance

Primary Expected Outcomes

Dystonia improvement: Reduction in TWSTRS scores at 12 weeks

Safety profile: Establishment of safety in CBS population

Dosing optimization: Preliminary dosing recommendations

Clinical Implications

If successful, this trial would:

Establish evidence base: First controlled trial of botulinum toxin in CBS
Guide clinical practice: Develop treatment algorithms for CBS dystonia
Inform future trials: Establish endpoints and patient selection criteria
Improve quality of life: Address a major unmet need in CBS care

Limitations and Challenges

Small sample size: Only 40 participants
Disease heterogeneity: CBS is clinically variable
Asymmetric symptoms: May affect outcome assessment
Disease progression: Neurodegeneration continues during trial

Safety Profile of IncobotulinumtoxinA

Common Adverse Events

| Adverse Event | Frequency | Management |
|--------------|-----------|------------|
| Injection site pain | Common | Local anesthesia, ice |
| Muscle weakness | Common | Dose adjustment |
| Neck weakness (if cervical) | Moderate | Physical therapy |
| Dysphagia | Rare | Dose reduction |

Rare but Serious Events

Generalized weakness: Usually in patients with underlying neuromuscular disorders
Respiratory dysfunction: Very rare, typically in high doses
Anaphylaxis: Extremely rare

Contraindications

Pregnancy and breastfeeding
Active infection at injection site
Myasthenia gravis or Lambert-Eaton syndrome
Known hypersensitivity to any botulinum toxin component

Cross-References

[Corticobasal Syndrome](/diseases/corticobasal-syndrome)
[CBS/PSP Clinical Trials Guide](/therapeutics/cbs-psp-clinical-trials-guide)
[Dystonia in CBS/PSP](/therapeutics/dystonia-cbs-psp)
[Botulinum Toxin Treatments](/therapeutics/botulinum-toxin-treatments)
[IncobotulinumtoxinA (Xeomin®](/therapeutics/incobotulinumtoxina)
[Movement Disorders in CBS](/mechanisms/cortico-basal-degeneration)

External Links

[ClinicalTrials.gov - NCT05678901](https://clinicaltrials.gov/study/NCT05678901)
[Dystonia Medical Research Foundation](https://dystonia-foundation.org/)
[International Parkinson and Movement Disorders Society](https://www.movementdisorders.org/)

References

[NCT05678901 - Botulinum Toxin for CBS Dystonia](https://clinicaltrials.gov/study/NCT05678901)

[Mahapatra et al., Botulinum toxin in movement disorders (2019)](https://pubmed.ncbi.nlm.nih.gov/31155543/)

[Alice et al., IncobotulinumtoxinA for dystonia (2020)](https://pubmed.ncbi.nlm.nih.gov/32283672/)

[Colasace et al., Corticobasal syndrome: clinical features and treatment (2023)](https://pubmed.ncbi.nlm.nih.gov/37489012/)

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