Targeting pain in the long-term treatment of cervical dystonia with botulinum toxin A

External Factors Modulating Pain and Pain-Related Functional Impairment in Cervical Dystonia

BACKGROUND

Little is known about factors modulating pain and pain-related functional impairment in isolated cervical dystonia (CD).

OBJECTIVE

The aim was to assess the prevalence and interrelationship between pain-modulating factors and pain-related determinants of functional impairment and quality of life in CD.

METHODS

We analyzed pain-aggravating and pain-relieving external factors, the degree of pain-related functional impact on routine activities, and the relationship between these and pain severity, using cross-sectional data collected using the Pain in Dystonia Scale (PIDS) from 85 participants with CD. Pairwise correlation analyses and age- and sex-adjusted linear regression models estimated the relationship between pain-modulating factors and pain severity, and the impact of pain severity, dystonia severity, and psychiatric symptoms on pain-related functional impairment and disease-specific quality of life (measured using the Craniocervical Dystonia Questionnaire-24).

RESULTS

Stress and prolonged fixed position were the most frequent and impacting pain triggers, with women reporting larger impact. The average impact of pain-relieving factors was lower than that of pain triggers. Physical exercise and social gatherings were the most impacted activities by pain in CD. The intensity of external modulating factors was a predictor of pain severity. Severity of pain, CD, and psychiatric symptoms independently predicted pain-related functional impairment, whereas quality of life was predicted by pain severity, pain-related functional impairment, and psychiatric symptom severity, but not dystonia severity.

CONCLUSION

The PIDS provides insight into external modulation and functional impact of pain in CD. The pattern of external modulation of pain in CD is in line with a multifactorial modulation and complex physiology.

[Pain and cervical dystonia]

BACKGROUND

Dystonia is a hyperkinetic movement disorder that results in twisting, cramps and tremors due to sustained or intermittent muscle contractions. Cervical dystonia is the most common form of dystonia, in which the head, neck and/or shoulder areas are affected. In addition to these motor symptoms, pain and psychiatric symptoms are frequent in (cervical) dystonia.

OBJECTIVE

Description of the incidence and evaluation of pain in cervical dystonia, summary and discussion of treatment options and effects.

MATERIAL AND METHODS

In this review article the results in the scientific literature on pain in dystonia are summarized and discussed.

RESULTS

Compared to other forms of dystonia, pain occurs most frequently in patients with cervical dystonia. A large proportion of patients with cervical dystonia suffer from pain, which contributes most to impairment of the patient. The motor symptoms of dystonia are usually treated with botulinum toxin injections. These have a muscle relaxing effect and also relieve pain. The study situation on the occurrence and treatment of pain in other forms of dystonia is so far very limited. Pain can dominate the clinical picture in patients with cervical dystonia. Evaluation of pain in cervical dystonia can be performed using standardized questionnaires.

CONCLUSION

It is important to ask patients with cervical dystonia about pain and to consider it in treatment planning and evaluation. Vice versa, if pain is present the possibility of a causative dystonia should also be considered. For pain assessment there are some newly developed questionnaires to assess pain in a standardized way in patients with dystonia. Further research is needed to better understand the pathomechanisms of pain in dystonia.

Botulinum Neurotoxins: From Toxin to Medicine

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Pain Reduction in Cervical Dystonia Following Treatment with IncobotulinumtoxinA: A Pooled Analysis

This analysis pooled pain severity data from four phase 3 and 4 studies of incobotulinumtoxinA (incoBoNT-A) for the treatment of cervical dystonia (CD) in adults. CD-related pain severity was assessed at baseline, each injection visit, and 4 weeks after each injection of incoBoNT-A using the Toronto Western Spasmodic Torticollis Rating Scale pain severity subscale or a pain visual analog scale. Both were analyzed using a score range of 0-10 and pain was categorized as mild, moderate, or severe. Data for 678 patients with pain at baseline were assessed and sensitivity analyses evaluated pain responses in the subgroup not taking concomitant pain medication (n = 384 at baseline). At Week 4 after the first injection, there was a mean change of -1.25 (standard deviation 2.04) points from baseline pain severity (p < 0.0001), with 48.1% showing ≥ 30% pain reduction from baseline, 34.4% showing ≥50% pain reduction from baseline, and 10.3% becoming pain free. Pain responses were sustained over five injection cycles with a trend to incremental improvements with each successive cycle. Pain responses in the subgroup not taking concomitant pain medication demonstrated the lack of confounding effects of pain medications. These results confirmed the pain relief benefits of long-term treatment with incoBoNT-A.

The Dystonia Coalition: A Multicenter Network for Clinical and Translational Studies

Dystonia is a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal postures, repetitive movements, or both. Research in dystonia has been challenged by several factors. First, dystonia is uncommon. Dystonia is not a single disorder but a family of heterogenous disorders with varied clinical manifestations and different causes. The different subtypes may be seen by providers in different clinical specialties including neurology, ophthalmology, otolaryngology, and others. These issues have made it difficult for any single center to recruit large numbers of subjects with specific types of dystonia for research studies in a timely manner. The Dystonia Coalition is a consortium of investigators that was established to address these challenges. Since 2009, the Dystonia Coalition has encouraged collaboration by engaging 56 sites across North America, Europe, Asia, and Australia. Its emphasis on collaboration has facilitated establishment of international consensus for the definition and classification of all dystonias, diagnostic criteria for specific subtypes of dystonia, standardized evaluation strategies, development of clinimetrically sound measurement tools, and large multicenter studies that document the phenotypic heterogeneity and evolution of specific types of dystonia.