Prospective study of selective peripheral denervation for botulinum-toxin resistant patients with cervical dystonia

Neurosurgical and pharmacological management of dystonia

Dystonia characterizes a group of neurological movement disorders characterized by abnormal muscle movements, often with repetitive or sustained contraction resulting in abnormal posturing. Different types of dystonia present based on the affected body regions and play a prominent role in determining the potential efficacy of a given intervention. For most patients afflicted with these disorders, an exact cause is rarely identified, so treatment mainly focuses on symptomatic alleviation. Pharmacological agents, such as oral anticholinergic administration and botulinum toxin injection, play a major role in the initial treatment of patients. In more severe and/or refractory cases, focal areas for neurosurgical intervention are identified and targeted to improve quality of life. Deep brain stimulation (DBS) targets these anatomical locations to minimize dystonia symptoms. Surgical ablation procedures and peripheral denervation surgeries also offer potential treatment to patients who do not respond to DBS. These management options grant providers and patients the ability to weigh the benefits and risks for each individual patient profile. This review article explores these pharmacological and neurosurgical management modalities for dystonia, providing a comprehensive assessment of each of their benefits and shortcomings.

Evaluation of outcome of different neurosurgical modalities in management of cervical dystonia

Background

Cervical dystonia is the most common form of focal dystonia and is managed by multiple modalities including repeated botulinum toxin injections, in addition to medical treatment with anticholinergics, muscle relaxants, and physiotherapy. However, surgical interventions could be beneficial in otherwise refractory patients. This study aims to report our experience in the neurosurgical management of cervical dystonia and evaluate patient outcomes using reliable outcome scores for the assessment of patients with cervical dystonia and possible complications. This case series study was conducted on 19 patients with cervical dystonia of different etiologies who underwent surgical management [ten patients underwent selective peripheral denervation, five patients underwent pallidotomy, and four patients underwent bilateral globus pallidus internus (GPi) deep brain stimulation (DBS)] in the period between July 2018 and June 2021 at Ain Shams University Hospitals, Cairo, Egypt. With the assessment of surgical outcomes using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and the Tsui scale 6 months postoperatively.

Results

Surgical management of patients with cervical dystonia of either primary or secondary etiology was associated with significant improvement in head and neck postures after 6 months without major complications associated with the different surgical procedures. The mean improvement in total TWSTRS and Tsui scores were 51.2% and 64.8%, respectively, compared with preoperative scores, while the mean improvement in the TWSTRS subscales (severity, disability, and pain) were 40.2%, 66.9%, and 58.3%, respectively.

Conclusion

Cervical dystonia patients in whom non-surgical options have failed to alleviate their symptoms can be managed surgically leading to significant improvements with minimal adverse effects. However, surgical treatment should be tailored according to several factors including but not limited to the etiology, pattern of dystonic activity, and comorbidities. Therefore, management should be tailored to achieve long-term improvement with minimal risk of complications.

Eligibility criteria in clinical trials for cervical dystonia

INTRODUCTION

Cervical dystonia (CD) is the most common form of adult-onset focal dystonia. Because of a heterogeneous clinical presentation, the diagnosis rests on clinical opinion. During the last decades, several clinical trials have tested safety and efficacy of medical and surgical treatments for CD. We analyzed all the published CD trials and reviewed the strategies adopted for patient enrollment.

METHODS

The review included clinical trials in patients with CD published in PubMed. Studies were excluded if reviews, meta-analyses, post-hoc analyses on pooled data, or if not reporting a treatment for CD.

RESULTS

A total of 174 articles were identified; 134 studies met inclusion criteria. Diagnosis of CD varied among studies and in most cases was based on clinical judgement, using different descriptors such as "cervical dystonia" (37 studies), "idiopathic or isolated CD" (35), "primary CD" (13), and "torticollis" (40). Clinical judgement was supported by a phenomenological description of dystonia in four studies, and by a specific diagnostic strategy in other four. Finally, one study adopted general diagnostic criteria for dystonia. Inclusion and exclusion criteria proved heterogeneous across trials and were defined only in 108 studies, mainly considering age or the phenomenological pattern of muscle involvement.

CONCLUSION

The review showed lack of consolidated diagnostic criteria and non-uniformity of eligibility criteria for CD across clinical trials. There is need to move beyond clinical judgement as diagnostic criterion for selecting participants. New trials assessing specific CD patient subgroups or comparing medical and surgical procedures will need grounds that are more consistent.

Modified McKenzie-Dandy operation for a cervical dystonia patient who failed selective peripheral denervation: A case report and literature review

Background:

Cervical dystonia (CD) is a rare and difficult-to-treat disorder. Various neurosurgical options are available, each with its own set of advantages and disadvantages. We investigated using the modified McKenzie-Dandy operation for a patient with CD who failed selective peripheral denervation (SPD).

Case Description:

A 42-year-old man presented left-sided rotational torticollis for 3 years. He was referred for surgery after treating with a variety of oral medications and repeated botulinum toxin injections that became ineffective. For the first operation, the patient underwent SPD (modified Bertrand’s operation); unfortunately, the postoperative outcome was unsatisfactory, and the operation was considered a failure. After his symptoms did not improve after 6 months, the modified McKenzie-Dandy operation was performed. Immediately following surgery, he experienced satisfactory outcomes. He was able to resume his normal activities and employment after 1 month after recovering from his temporary swallowing difficulties. He only complained of minor neck pain and no recurrence was observed after 3 years follow-up.

Conclusion:

For patients who have failed SPD, a modified McKenzie-Dandy procedure is a feasible and effective option. The procedure is relatively safe when performed properly, and the long-term effects can be maintained.

Pain in cervical dystonia: mechanisms, assessment and treatment

INTRODUCTION

In patients with cervical dystonia (CD), pain is a major contributor to disability and social isolation and is often the main reason patients seek treatment. Surveys evaluating patient perceptions of their CD symptoms consistently highlight pain as a troublesome and disabling feature of their condition with significant impact on daily life and work.

AREAS COVERED

In this article, the authors review the epidemiology, assessment, possible mechanisms and treatment of pain in CD, including a meta-analysis of randomized controlled trial data with abobotulinumtoxinA.

EXPERT OPINION

Mechanisms of pain in CD may be muscle-based and non-muscle based. Accumulating evidence suggests that non-muscle-based mechanisms (such as abnormal transmission and processing of nociceptive stimuli, dysfunction of descending pain inhibitory pathways as well as structural and network changes in the basal ganglia, cortex and other areas) may also contribute to pain in CD alongside prolonged muscle contraction. Chemodenervation with botulinum toxin is considered the first-line treatment for CD. Treatment with botulinum toxin is usually effective, but optimization of the injection parameters should include consideration of pain as a core symptom in addition to the motor problems.

Unilateral pallidotomy as a potential rescue therapy for cervical dystonia after unsatisfactory selective peripheral denervation

OBJECTIVE

Selective peripheral denervation (SPD) is a widely accepted surgery for medically refractory cervical dystonia (CD), but when SPD has failed, the available approaches are limited. The authors investigated the results from a cohort of CD patients treated with unilateral pallidotomy after unsatisfactory SPD.

METHODS

The authors retrospectively analyzed patients with primary CD who underwent unilateral pallidotomy after SPD between April 2007 and August 2019. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) was used to evaluate symptom severity before surgery, 7 days postsurgery, 3 months postsurgery, and at the last follow-up. TWSTRS subscores for disability and pain and the 24-item Craniocervical Dystonia Questionnaire (CDQ-24) were used to assess quality of life.

RESULTS

At a mean final follow-up of 5 years, TWSTRS severity subscores and total scores were significantly improved (n = 12, mean improvement 57.3% and 62.3%, respectively, p = 0.0022 and p = 0.0022), and 8 of 12 patients (66.7%) were characterized as responders (improvement ≥ 25%). Patients with rotation symptoms before pallidotomy showed greater improvement in TWSTRS severity subscores than those who did not (p = 0.049). The most common adverse event was mild upper-limb weakness (n = 3). Patients' quality of life was also improved.

CONCLUSIONS

Unilateral pallidotomy seems to offer an effective and safe option for patients with CD who have otherwise experienced limited benefits from SPD.

Quality of life in idiopathic dystonia: a systematic review

OBJECTIVE

Dystonia is characterised by sustained muscular contractions frequently producing repetitive, twisting and patterned movements. The primary aim of this systematic review was to establish how quality of life (QoL) is affected in idiopathic focal, multifocal and segmental dystonia. This review aimed to evaluate variations in QoL between different subtypes of dystonia, identify the determinants of QoL and assess the effects of different treatments on QoL.

METHODOLOGY

A systematic computer-based literature search was conducted using the PubMed database to search for papers on QoL in idiopathic focal, segmental, multifocal and generalized dystonia. We identified 75 studies meeting our inclusion criteria. Information was extracted regarding prevalence, demographics and response to treatment where indicated.

RESULTS

This review revealed QoL to be a significant yet often overlooked issue in idiopathic dystonia. Data consistently showed that dystonia has a negative effect on QoL in patients compared to healthy controls, when measured using disease-specific and generic QoL measures. The majority of studies (n = 25) involved patients with cervical dystonia, followed by benign-essential blepharospasm (n = 10). Along with the beneficial effect to the dystonia symptoms, treatment using Botulinum Toxin and Deep Brain Stimulation is also effective in improving overall QoL across the majority of subtypes.

CONCLUSION

The findings demonstrate that patients' QoL should routinely be assessed and monitored, as this may affect subsequent management. Further research will allow for more robust management of factors contributing to impaired QoL, aside from the physical defects found in dystonia.

Deep Brain Stimulation Versus Peripheral Denervation for Cervical Dystonia: A Systematic Review and Meta-Analysis

BACKGROUND

Cervical dystonia is a disabling medical condition that drastically decreases quality of life. Surgical treatment consists of peripheral nerve denervation procedures with or without myectomies or deep brain stimulation (DBS). The current objective was to compare the efficacy of peripheral denervation versus DBS in improving the severity of cervical dystonia through a systematic review and meta-analysis.

METHODS

A search of PubMed, MEDLINE, EMBASE, and Web of Science electronic databases was conducted in accordance with PRISMA guidelines. Preoperative and postoperative Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total scores were used to generate standardized mean differences and 95% confidence intervals (CIs), which were combined in a random-effects model. Both mean percentage and absolute reduction in TWSTRS scores were calculated. Absolute reduction was used for forest plots.

RESULTS

Eighteen studies met the inclusion criteria, comprising 870 patients with 180 (21%) undergoing DBS and 690 (79%) undergoing peripheral denervation procedures. The mean follow-up time was 31.5 months (range, 12-38 months). In assessing the efficacy of each intervention, forest plots revealed significant absolute reduction in total postoperative TWSTRS scores for both peripheral denervation (standardized mean difference 1.54; 95% CI 1.42-1.66) and DBS (standardized mean difference 2.07; 95% CI 1.43-2.71). On subgroup analysis, DBS therapy was significantly associated with improvement in postoperative TWSTRS severity (standardized mean difference 2.08; 95% CI 1.66-2.50) and disability (standardized mean difference 2.12; 95% CI 1.57-2.68) but not pain (standardized mean difference 1.18; 95% CI 0.80-1.55).

CONCLUSIONS

Both peripheral denervation and DBS are associated with a significant reduction in absolute TWSTRS total score, with no significant difference in the magnitude of reduction observed between the 2 treatments. Further comparative data are needed to better evaluate the long-term results of both interventions.

Comparison of 2 Operative Methods for Treating Laterocollis and Torticollis Subtypes of Spasmodic Torticollis: Follow-Up of 121 Cases

OBJECTIVE

The aim of this study was to compare the effects and complications of microvascular decompression (MVD) and neurectomy of spinal accessory nerve in the treatment of laterocollis and torticollis subtypes spasmodic torticollis (ST).

METHODS

Clinical data were retrospectively collected from 121 patients with laterocollis and torticollis subtypes of ST from January 1, 2012 to January 1, 2016. Among all the patients, 80 were treated by MVD and 41 were treated by neurectomy of spinal accessory nerve. The effect of the surgery was evaluated by the reduction in the Toronto Western spasmodic torticollis rating scale total scores before and after the operation. The mean duration of the postoperative follow-up period was 18.7 months (range, 12-27 months).

RESULTS

At the final follow-up, the Toronto Western spasmodic torticollis rating scale total score in the MVD group and in the neurectomy group was lowered by 50.43% ± 20.3% and 30.23% ± 19.4%, respectively, compared with the preoperative status (P < 0.05). In the MVD group, 25 (31.25%) patients achieved excellent relief, 44 (55%) patients improved moderate spasm, and 11 (13.75%) showed no relief. In the neurectomy group, 6 (14.63%) patients improved with excellent outcome, 7 (17.07%) had moderate relief, and 28 (68.29%) had no relief. There was no mortality or severe complication postoperatively, with the exception of hoarseness, shoulder numbness, and weakness.

CONCLUSIONS

MVD for ST of laterocollis and torticollis subtypes can provide satisfactory and lasting improvements without nerve impairment. MVD is to be preferred to neurectomy of accessory nerve in treating ST of laterocollis and torticollis subtypes.

Clinical Practice: Evidence-Based Recommendations for the Treatment of Cervical Dystonia with Botulinum Toxin

Cervical dystonia (CD) is the most frequent form of focal dystonia. Symptoms often result in pain and functional disability. Local injections of botulinum neurotoxin are currently the treatment of choice for CD. Although this treatment has proven effective and is widely applied worldwide, many issues still remain open in the clinical practice. We performed a systematic review of the literature on botulinum toxin treatment for CD based on a question-oriented approach, with the aim to provide practical recommendations for the treating clinicians. Key questions from the clinical practice were explored. Results suggest that while the beneficial effect of botulinum toxin treatment on different aspects of CD is well established, robust evidence is still missing concerning some practical aspects, such as dose equivalence between different formulations, optimal treatment intervals, treatment approaches, and the use of supportive techniques including electromyography or ultrasounds. Established strategies to prevent or manage common side effects (including excessive muscle weakness, pain at injection site, dysphagia) and potential contraindications to this treatment (pregnancy and lactation, use of anticoagulants, neurological comorbidities) should also be further explored.

Quality of life in cervical dystonia after treatment with botulinum toxin A: a 24-week prospective study

OBJECTIVE

This study aimed to identify possible improvements in disease-specific health-related quality of life (HRQoL) after multiple injections of botulinum toxin A over 24 weeks in Thai cervical dystonia (CD) patients.

MATERIALS AND METHODS

A 24-week prospective study comparing HRQoL of Thai CD patients before and after multiple injections of botulinum toxin A at 3-month intervals was performed. Disease-specific HRQoL was assessed by using the Cervical Dystonia Impact Profile-58 questionnaire (CDIP-58) and the Craniocervical Dystonia Questionnaire-24 (CDQ-24). General HRQoL was assessed by using the Medical Outcomes' 36-Item Short Form Health Survey (SF-36) and the EuroQoL 5-dimension questionnaire (EQ-5D). All the assessments were performed before and after the 24-week treatment period.

RESULTS

A total of 20 CD patients were enrolled in this study from April to December 2011. CDIP-58 and CDQ-24 scores, which assess disease-specific HRQoL, showed a significant improvement after 24 weeks of treatment by botulinum toxin A (P<0.001). However, EQ-5D and SF-36 scores, which assess general HRQoL, showed no significant improvement after the treatment (P>0.05).

CONCLUSION

CD patients' disease-specific HRQoL improved after being treated with multiple botulinum toxin A injections. However, general HRQoL was not improved.

Tremor in dystonia

Tremor has been recognized as an important clinical feature in dystonia. Tremor in dystonia may occur in the body part affected by dystonia known as dystonic tremor or unaffected body regions known as tremor associated with dystonia. The most common type of tremor seen in dystonia patients is postural and kinetic which may be mistaken for familial essential tremor. Similarly familial essential tremor patients may have associated dystonia leading to diagnostic uncertainties. The pathogenesis of tremor in dystonia remains speculative, but its neurophysiological features are similar to dystonia which helps in differentiating it from essential tremor patients. Treatment of tremor in dystonia depends upon the site of involvement. Dystonic hand tremor is treated with oral pharmacological therapy and dystonic head, jaw and voice tremor is treated with injection botulinum toxin. Neurosurgical interventions such as deep brain stimulation and lesion surgery should be an option in patients not responding to the pharmacological treatment.

Selective peripheral denervation for cervical dystonia: long-term follow-up

OBJECTIVE

61 procedures with selective peripheral denervation for cervical dystonia were retrospectively analysed concerning surgical results, pain, quality of life (QoL) and recurrences.

METHODS

The patients were assessed with the Tsui torticollis scale, Visual Analogue Scale (VAS) for pain and Fugl-Meyer scale for QoL. Evaluations were performed preoperatively, early postoperatively, at 6 months, then at a mean of 42 (13-165) months. All patients underwent electromyogram at baseline, which was repeated in cases who presented with recurrence of symptoms after surgery.

RESULTS

Six months of follow-up was available for 55 (90%) of the procedures and late follow-up for 34 (56%). The mean score of the Tsui scale was 10 preoperatively. It improved to 4.5 (p<0.001) at 6 months, and 5.3 (p<0.001) at late follow-up. VAS for pain improved from 6.5 preoperatively to 4.2 (p<0.001) at 6 months and 4 (p<0.01) at late follow-up. The Fugl-Meyer score for QoL improved from 43.3 to 46.6 (p<0.05) at 6 months, and to 51.1 (p<0.05) at late follow-up. Major reinnervation and/or change in the dystonic pattern occurred following 29% of the procedures, and led in 26% of patients to reoperation with either additional denervation or pallidal stimulation.

CONCLUSIONS

Selective peripheral denervation remains a surgical option in the treatment of cervical dystonia when conservative measures fail. Although the majority of patients experience a significant relief of symptoms, there is a substantial risk of reinnervation and/or change in the pattern of the cervical dystonia.

Diagnosis and treatment of dystonia

The dystonias are a group of disorders characterized by excessive involuntary muscle contractions leading to abnormal postures and/or repetitive movements. A careful assessment of the clinical manifestations is helpful for identifying syndromic patterns that focus diagnostic testing on potential causes. If a cause is identified, specific etiology-based treatments may be available. In most cases, a specific cause cannot be identified, and treatments are based on symptoms. Treatment options include counseling, education, oral medications, botulinum toxin injections, and several surgical procedures. A substantial reduction in symptoms and improved quality of life is achieved in most patients by combining these options.

Selective peripheral denervation for the treatment of spasmodic torticollis: long-term follow-up results from 648 patients

BACKGROUND

Selective peripheral denervation (SPD) is currently the primary surgical treatment for spasmodic torticollis (ST). Our objective here is to report on the outcome of patients treated with this procedure for ST in our department.

METHODS

Between June 1995 and June 2013, 648 patients underwent SPD for ST. We included 293 women (45.2 %) and 355 men (54.8 %) with a mean age of 41.1 years (range, 8-74 years) at the onset of dystonia. Surgery was performed at a mean of 3.6 years (range, 1-32 years) after onset of symptoms. Data on clinical presentation, radiological studies, operation tragedy, clinical outcomes and complications were analysed retrospectively. For evaluation of clinical outcomes, patients' responses were assessed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).

RESULTS

Results were obtained from all 648 patients with a follow-up period ranging from 11 months to 154 months (mean, 33.4 months). The mean preoperative TWSTRS score was 54.7 ± 18.3 points (range, 39-67 points), which decreased to 31.1 ± 11.6 points postoperatively (range, 1-67 points); a significant improvement was observed between preoperative and postoperative TWSTRS evaluation; the clinical improvement of TWSTRS was 73.5 ± 11.9 %. In addition, no deaths and serious complications occurred in this cohort of patients.

CONCLUSIONS

SPD is an effective surgical method for patients with ST. This procedure should be recommended if conservative therapy does not offer satisfactory relief of symptoms.

Effectiveness of selective peripheral denervation in combination with pallidal deep brain stimulation for the treatment of cervical dystonia

BACKGROUND

Selective peripheral denervation (SPD) and deep brain stimulation of the globus pallidus (GPi-DBS) are available surgical options for patients with medically refractory cervical dystonia (CD). There are few data available concerning whether patients who have unsatisfactory treatment effects after primary surgery benefit from a different type of subsequent surgery. The aim of this study was to assess whether combining these surgical procedures (SPD plus GPi-DBS) was effective in patients with unsatisfactory treatment effects after their initial surgery.

METHODS

Forty-one patients with medically refractory idiopathic CD underwent SPD and/or GPi-DBS. Patients who were dissatisfied with their primary surgery (SPD or GPi DBS) elected to subsequently undergo a different type of surgery. These patients were assessed with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).

RESULTS

SPD alone and GPi-DBS alone were performed in 16 and 21 patients, respectively. Four patients had unsatisfactory treatment effects after the initial surgery and subsequently underwent another type of surgery. Among them, two patients with persistent dystonia after SPD subsequently underwent GPi-DBS, and two other patients who had insufficient treatment effects following GPi-DBS were subsequently treated with SPD. All of these patients experienced sustained improvement from the combined surgical procedures according to the TWSTRS score during a long-term follow-up of 12-90 months.

CONCLUSIONS

Patients with unsatisfactory treatment effects after an SPD or GPi-DBS experienced improvement from subsequently undergoing other types of surgery. Therefore, combined surgical procedures are additional surgical options with good outcomes in the treatment of patients with residual symptoms after their initial surgery.

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.

Microvascular decompression surgery is effective for the laterocollis subtype of spasmodic torticollis: a long-term follow-up result

BACKGROUND

Spasmodic torticollis (ST) is characterized by sustained, involuntary, and painful spasms of specific muscle (s), which results into abnormal posture of the neck and head. Although various treatments for ST have been introduced, none of them shows absolute effectiveness. Earlier research from our department showed that microvascular decompression (MVD) surgery is effective in the short-term for ST patients with confirmed accessory nerve compression. However, the long-term outcome of MVD remains unknown.

METHOD

Twelve ST patients with confirmed accessory nerve compression received MVD surgery of their accessory nerves. We utilized the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) to evaluate the long-term outcome (5.4 ± 0.87 years).

RESULTS

The MVD lowered total TWSTRS scores by 42.8 % in all ST patients. This result, however, only counted for moderate relief. Interestingly, we observed that the laterocollis (LC) subtypes of ST (n = 3) obtained a higher TWSTRS score improvement (86.9 ± 6.2 %), compared to that of the non-LC (28.1 ± 12 %) (P =0.0001). Additionally, the disability (92.7 ± 2 %) subscale score in the LC subtypes had the most prominent improvement compared to the pain (88.1 ± 5.1 %) and severity (81.3 ± 10.5 %).

CONCLUSIONS

In the cases of confirmed accessory nerve compression, the MVD could be considered as a treatment alternative for ST, especially for the LC subtypes.

The treatment of dystonic tremor: a systematic review

Tremor is one of the clinical manifestations of dystonia; however, there are no specific therapeutic trials evaluating the efficacy of treatments for dystonic tremor (DT), tremor associated with dystonia or primary writing tremor (PWT). We systematically reviewed the literature available up to July 2013 on the treatment of these tremors and retrieved the data of 487 patients published in 43 papers detailing the effects of given interventions on tremor severity. Treatment outcome was highly variable, depending on the specific type of intervention and tremor distribution. No specifically designed studies were available for the treatment of tremor associated with dystonia. As for the other tremors, drug efficacy was generally disappointing and a moderate effect was only found with anticholinergics, tetrabenazine, clonazepam, β-blockers and primidone; levodopa was only efficacious on tremor due to dopa-responsive dystonia. The largest amount of data was available for botulinum toxin injections, which provided a marked improvement, particularly for the management of axial tremors (head or vocal cords). In refractory DTs, deep brain stimulation of several targets was attempted. Deep brain stimulation of globus pallidus internus, thalamus or subthalamic area led to a marked improvement of dystonic axial or appendicular tremors in most cases refractory to other treatments. Few other non-invasive treatments, for example, orthotic device in PWT, have been used with anecdotal success. In conclusion, considering the lack of good-quality studies, future randomised controlled trials are needed. In absence of evidence-based guidelines, we propose an algorithm for the treatment of DT based on currently available data.

Dystonia rating scales: critique and recommendations

Many rating scales have been applied to the evaluation of dystonia, but only few have been assessed for clinimetric properties. The Movement Disorders Society commissioned this task force to critique existing dystonia rating scales and place them in the clinical and clinimetric context. A systematic literature review was conducted to identify rating scales that have either been validated or used in dystonia. Thirty-six potential scales were identified. Eight were excluded because they did not meet review criteria, leaving 28 scales that were critiqued and rated by the task force. Seven scales were found to meet criteria to be "recommended": the Blepharospasm Disability Index is recommended for rating blepharospasm; the Cervical Dystonia Impact Scale and the Toronto Western Spasmodic Torticollis Rating Scale for rating cervical dystonia; the Craniocervical Dystonia Questionnaire for blepharospasm and cervical dystonia; the Voice Handicap Index (VHI) and the Vocal Performance Questionnaire (VPQ) for laryngeal dystonia; and the Fahn-Marsden Dystonia Rating Scale for rating generalized dystonia. Two "recommended" scales (VHI and VPQ) are generic scales validated on few patients with laryngeal dystonia, whereas the others are disease-specific scales. Twelve scales met criteria for "suggested" and 7 scales met criteria for "listed." All the scales are individually reviewed in the online information. The task force recommends 5 specific dystonia scales and suggests to further validate 2 recommended generic voice-disorder scales in dystonia. Existing scales for oromandibular, arm, and task-specific dystonia should be refined and fully assessed. Scales should be developed for body regions for which no scales are available, such as lower limbs and trunk.

What's new in surgical treatment for dystonia?

It is now established that pallidal deep brain stimulation (DBS) is effective in the treatment of generalized and segmental primary dystonia, although there is still insufficient evidence to support its benefit in focal and secondary dystonia. Because several studies have demonstrated that pallidal DBS improves quality of life (QoL), reduced QoL and disability that are nonresponsive to medical treatment are probably the main factors guiding the decision to consider surgery. Some studies have indicated that young patients with primary dystonia who have shorter disease duration and less severe dystonia are likely to have the best outcome from DBS. Therefore, surgery should not be delayed when disability and QoL are impaired to the extent that justifies the surgical risk. A case-by-case approach is recommended in patients who have secondary dystonia. The globus pallidus internus is considered the best target for dystonia. There are still not enough data about the effectiveness of thalamic, subthalamic nucleus, and premotor cortex stimulation. Targeting with multiple electrodes and intra-individual comparisons of outcomes may help determine which target would be more beneficial. With regard to the role of lesions, pallidotomy for dystonia is still performed in several countries and can play a role in selected patients. New technologies are already available to improve the stimulation programming for DBS patients and to increase battery longevity. In the near future, it is possible that we will be able to shape stimulation settings according to disease type and symptoms. © 2013 Movement Disorder Society.

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.

Selective peripheral denervation: comparison with pallidal stimulation and literature review

Patients with cervical dystonia who are non-responders to Botulinum toxin qualify for surgery. Selective peripheral denervation (Bertrand's procedure, SPD) and deep brain stimulation of the globus pallidus (GPi-DBS) are available surgical options. Although peripheral denervation has potential advantages over DBS, the latter is nowadays more commonly performed. We describe the long-term outcome of selective peripheral denervation as compared with GPi-DBS, along with the findings of literature review. Twenty patients with selective peripheral denervation and 15 with GPi-DBS were included. Tsui scale, a visual analogue scale, and the global outcome score of the Toronto Western Spasmodic Torticollis Rating Scale were used to define a "combined global surgical outcome". The "combined global surgical outcome" for patients with selective peripheral denervation or pallidal stimulation was respectively "bad" for 65 and 13.3 %, "fair-to-good" for 30 and 26.7 %, and "marked" improvement for 5 and 60 % (p < 0.001). Improvement on visual analogue scale (p < 0.002), global outcome score (p < 0.002), and Tsui score (p < 0.000) was larger for the pallidal stimulation group. Seventy-five percent of patients with selective peripheral denervation and 60 % of patients with pallidal stimulation reported side effects. Seven patients with selective peripheral denervation successively underwent GPi-DBS, with a further significant improvement in the Tsui score (-48.6 ± 17.4 %). GPi-DBS is to be preferred to selective peripheral denervation for the treatment of cervical dystonia because it produces larger benefit, even if it can have more potentially severe complications. GPi-DBS is also a valid alternative in case of failure of SPD.

Treatment of focal dystonia

OPINION STATEMENT

Dystonia is characterized by repetitive twisting movements or abnormal postures due to involuntary muscle activity. When limited to a single body region it is called focal dystonia. Examples of focal dystonia include cervical dystonia (neck), blepharospasm (eyes), oromandibular dystonia, focal limb dystonia, and spasmodic dysphonia, which are discussed here. Once the diagnosis is established, the therapeutic plan is discussed with the patients. They are informed that there is no cure for dystonia and treatment is symptomatic. The main therapeutic option for treating focal dystonias is botulinum toxin (BoNT). There have been several attempts to characterize the procedure, the type of toxin, dosage, techniques, and combination with physical measures in each of the focal dystonia forms. The general treatment principles are similar. The affected muscles are injected at muscle sites based on evidence and experience using standard dosages based on the type of toxin used. The injections are repeated after 3 to 6 months based on the individual response duration. In the uncommon event of nonresponse with BoNT, the dose and site are reassessed. Oral drug treatment could be considered as an additional option. Once the condition is thought to be medically refractory, the opinion from the deep brain stimulation (DBS) team for the suitability of the patient for DBS is taken. The successful use of DBS in cervical dystonia has led to increased acceptance for trial in other forms of focal dystonias. DBS surgery in focal dystonias other than cervical is, however, still experimental. The patients may be offered the surgery with adequate explanation of the risks and benefits. Patient education and directing the patients towards dystonia support groups and relevant websites that provide scientific information may be useful for long-term compliance and benefit.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

Botulinum toxin assessment, intervention and aftercare for cervical dystonia and other causes of hypertonia of the neck: international consensus statement

Dystonia in the neck region can be safely and effectively reduced with injections of Botulinum neurotoxin-A and B. People with idiopathic cervical dystonia have been studied the most. Benefits following injection include increased range of movement at the neck for head turning, decreased pain, and increased functional capacity (Class I evidence, level A recommendation). The evidence for efficacy and safety in patients with secondary dystonia in the neck is unclear based on the lack of rigorous research conducted in this heterogeneous population (level U recommendation). Psychometrically sound assessments and outcome measures exist to guide decision-making (Class I evidence, level A recommendation). Much less is known about the effectiveness of therapy to augment the effects of the injection (Class IV, level U recommendation). More research is needed to answer questions about safety and efficacy in secondary spastic neck dystonia, effective adjunctive therapy, dosing and favourable injection techniques.

Bilateral deep brain stimulation for cervical dystonia: long-term outcome in a series of 10 patients

BACKGROUND

Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) was shown to be effective in cervical dystonia refractory to medical treatment in several small short-term and 1 long-term follow-up series. Optimal stimulation parameters and their repercussions on the cost/benefit ratio still need to be established.

OBJECTIVE

To report our long-term outcome with bilateral GPi deep brain stimulation in cervical dystonia.

METHODS

The Toronto Western Spasmodic Torticollis Rating Scale was evaluated in 10 consecutive patients preoperatively and at last follow-up. The relationship of improvement in postural severity and pain was analyzed and stimulation parameters noted and compared with those in a similar series in the literature.

RESULTS

The mean (standard deviation) follow-up was 37.6 (16.9) months. Improvement in the total Toronto Western Spasmodic Torticollis Rating Scale score as evaluated at latest follow-up was 68.1% (95% confidence interval: 51.5-84.6). In 4 patients, there was dissociation between posture severity and pain improvement. Prevalently bipolar stimulation settings and high pulse widths and amplitudes led to excellent results at the expense of battery life.

CONCLUSION

Improvement in all 3 subscale scores of the Toronto Western Spasmodic Torticollis Rating Scale with bilateral GPi deep brain stimulation seems to be the rule. Refinement of stimulation parameters might have a significant impact on the cost/benefit ratio of the treatment. The dissociation of improvement in posture severity and pain provides tangible evidence of the complex nature of cervical dystonia and offers interesting insight into the complex functional organization of the GPi.

Adult-onset dystonia

Dystonia is defined as involuntary sustained muscle contractions producing twisting or squeezing movements and abnormal postures. The movements can be stereotyped and repetitive and they may vary in speed from rapid to slow; sustained contractions can result in fixed postures. Dystonic disorders are classified into primary and secondary forms. Several types of adult-onset primary dystonia have been identified but all share the characteristic that dystonia (including tremor) is the sole neurologic feature. The forms most commonly seen in neurological practice include cranial dystonia (blepharospasm, oromandibular and lingual dystonia and spasmodic dysphonia), cervical dystonia (also known as spasmodic torticollis) and writer's cramp. These are the disorders that benefit most from botulinum toxin injections. A general characteristic of dystonia is that the movements or postures may occur in relation to specific voluntary actions by the involved muscle groups (such as in writer's cramp). Dystonic contractions may occur in one body segment with movement of another (overflow dystonia). With progression, dystonia often becomes present at rest. Dystonic movements typically worsen with anxiety, heightened emotions, and fatigue, decrease with relaxation, and disappear during sleep. There may be diurnal fluctuations in the dystonia, which manifest as little or no involuntary movement in the morning followed by severe disabling dystonia in the afternoon and evening. Morning improvement (or honeymoon) is seen with several types of dystonia. Patients often discover maneuvers that reduce the dystonia and which involve sensory stimuli such as touching the chin lightly in cervical dystonia. These maneuvers are known as sensory tricks, or gestes antagonistes. This chapter focuses on adult-onset focal dystonias including cranial dystonia, cervical dystonia, and writer's cramp. The chapter begins with a review of the epidemiology of focal dystonias, followed by discussions of each major type of focal dystonia, covering clinical phenomenology, differential genetics, and diagnosis. The chapter concludes with discussions of the pathophysiology, the few pathological cases published of adult-onset focal dystonia and management options, and a a brief look at the future.

Nonprimary dystonias

Dystonias can be classified as primary or secondary, as dystonia-plus syndromes, and as heredodegenerative dystonias. Their prevalence is difficult to determine. In our experience 80-90% of all dystonias are primary. About 20-30% of those have a genetic background; 10-20% are secondary, with tardive dystonia and dystonia in cerebral palsy being the most common forms. If dystonia in spastic conditions is accepted as secondary dystonia, this is the most common form of all dystonia. In primary dystonias, the dystonic movements are the only symptoms. In secondary dystonias, dystonic movements result from exogenous processes directly or indirectly affecting brain parenchyma. They may be caused by focal and diffuse brain damage, drugs, chemical agents, physical interactions with the central nervous system, and indirect central nervous system effects. Dystonia-plus syndromes describe brain parenchyma processes producing predominantly dystonia together with other movement disorders. They include dopa-responsive dystonia and myoclonus-dystonia. Heredodegenerative dystonias are dystonic movements occurring in the context of other heredodegenerative disorders. They may be caused by impaired energy metabolism, impaired systemic metabolism, storage of noxious substances, oligonucleotid repeats and other processes. Pseudodystonias mimic dystonia and include psychogenic dystonia and various orthopedic, ophthalmologic, vestibular, and traumatic conditions. Unusual manifestations, unusual age of onset, suspect family history, suspect medical history, and additional signs may indicate nonprimary dystonia. If they are suspected, etiological clarification becomes necessary. Unfortunately, potential etiologies are legion. Diagnostic algorithms can be helpful. Treatment of nonprimary dystonias, with few exceptions, does not differ from treatment of primary dystonias. The most effective treatment for focal and segmental dystonias is local botulinum toxin injections. Deep brain stimulation of the globus pallidus internus is effective for generalized dystonia. Antidystonic drugs, including anticholinergics, tetrabenazine, clozapine, and gamma-aminobutyric acid receptor agonists, are less effective and often produce adverse effects. Dopamine is extremely effective in dopa-responsive dystonia. The Bertrand procedure can be effective in cervical dystonia. Other peripheral surgery, including myotomy, myectomy, neurotomy, rhizotomy, ramizectomy, and accessory nerve neurolysis, has largely been abandoned. Central surgery other than deep brain stimulation is obsolete. Adjuvant therapies, including orthoses, physiotherapy, ergotherapy, behavioral therapy, social support, and support groups, may be helpful. Analgesics should also be considered where appropriate.

Therapeutic challenges in dystonia

Because dystonia can vary in clinical presentation and etiology, proper diagnosis and classification of these disorders are important in making therapeutic decisions. In primary dystonia, treatment is generally geared toward alleviating symptoms rather than curing the underlying condition, therefore severity of contractions, pain, and functional and social impact are also factors to consider in determining if and how to initiate therapy. On the other hand, if a secondary cause is identified, then it is often appropriate to direct treatment toward the underlying disorder. Treatment options include physical and occupational therapy, oral medications, botulinum toxin, and surgery. This article briefly reviews the clinical features, pathophysiology, and classification of dystonia before reviewing current therapeutic options.

Treatment strategies for dystonia

IMPORTANCE OF THE FIELD

Dystonia is a neurological syndrome characterized by involuntary twisting movements and unnatural postures. It has many different manifestations and causes, and many different treatment options are available. These options include physical and occupational therapy, oral medications, intramuscular injection of botulinum toxins, and neurosurgical interventions.

AREAS COVERED IN THIS REVIEW

In this review, we first summarize the treatment options available, then we provide suggestions from our own experience for how these can be applied in different types of dystonia. In preparing this review article, an extensive literature search was undertaken using PubMed. Only selected references from 1970 to 2008 are cited.

WHAT THE READER WILL GAIN

This review is intended to provide the clinician with a practical guide to the treatment of dystonia.

TAKE HOME MESSAGE

Treatment of dystonia begins with proper diagnosis and classification, followed by an appropriate search for underlying etiology, and an assessment of the functional impairment associated with the dystonia. The therapeutic approach, which is usually limited to symptomatic therapy, must then be tailored to the individual needs of the patient.

Cervical Dystonia

Cervical dystonia, which is the most common form of focal dystonia, presents with sustained neck spasms, abnormal head posture, head tremor, and pain. One of the interesting and unique features of cervical dystonia is the geste antagoniste. There is not a well-described pathophysiology for cervical dystonia, but several hypotheses report involvement at the central and peripheral level. Treatment options include: oral medical therapy, botulinum toxin injection, and surgery. Oral medical therapy has limited efficacy in control of the symptoms of cervical dystonia. Two types of botulinum toxin, types A and B, are being used for treatment of cervical dystonia, with equivalent benefit. Surgery is an option when other treatments fail or become ineffective. The surgical procedures are brain lesioning, brain stimulation, and peripheral surgical intervention. Several trials are currently ongoing in the United States and Europe to evaluate the efficacy of deep brain surgery in cervical dystonia.

Cervical dystonia: disease profile and clinical management

Cervical dystonia, the most common focal dystonia, frequently results in cervical pain and disability as well as impairments affecting postural control. The predominant treatment for cervical dystonia is provided by physicians, and treatment can vary from pharmacological to surgical. Little literature examining more conservative approaches, such as physical therapy, exists. This article reviews the etiology and pathophysiology of the disease as well as medical and physical therapist management for people with cervical dystonia.

The Canadian multicentre study of deep brain stimulation for cervical dystonia

Deep brain stimulation (DBS) of the globus pallidus pars interna (GPi) is an effective treatment for generalized dystonia. Its role in the management of other types of dystonia is uncertain. Therefore we performed a prospective, single-blind, multicentre study assessing the efficacy and safety of bilateral GPi-DBS in 10 patients with severe, chronic, medication-resistant cervical dystonia. Two blinded neurologists assessed patients before surgery and at 6 and 12 months post-operatively using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The primary outcome measure was the severity subscore (range 0-30, higher scores indicating greater impairment). Secondary outcomes included disability (0 to 30), pain (0 to 40) subscores and total scores of the TWSTRS, Short Form-36 and Beck depression inventory. Swallowing and neuropsychological assessment were also performed at baseline and 12 months. One-way repeated measures analysis of variance was used to analyse the data. The TWSTRS severity score improved from a mean (SD) of 14.7 (4.2) before surgery to 8.4 (4.4) at 12 months post-operatively (P = 0.003). The disability and pain scores improved from 14.9 (3.8) and 26.6 (3.6) before surgery, to 5.4 (7.0) and 9.2 (13.1) at 12 months, respectively (both P < 0.001). General health and physical functioning as well as depression scores improved significantly. Complications were mild and reversible in four patients. Some changes in neuropsychological tests were observed, although these did not impact daily life or employment. Our results support the efficacy and safety of GPi-DBS for the treatment of patients with severe and prolonged cervical dystonia who have failed medical management.

Patient-based outcomes of cervical dystonia: A review of rating scales

Decisions on treatment choice for patients are based on trials and outcome studies that are wholly dependent upon the scientific quality of the rating scales used. This study reviewed rating scales used in cervical dystonia outcome research to determine the extent that they satisfy recommended criteria for rigorous measurement.

The Canadian multicenter trial of pallidal deep brain stimulation for cervical dystonia: preliminary results in three patients

OBJECT

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is beneficial for generalized dystonia and has been proposed as a treatment for cervical dystonia. The Canadian Stereotactic/Functional and Movement Disorders Groups designed a pilot project to investigate the following hypothesis: that bilateral DBS of the GPi will reduce the severity of cervical dystonia at 1 year of follow up, as scored in a blinded fashion by two neurologists using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Secondary outcome measures included pain and disability subscores of the TWSTRS, Short Form-36 quality of life index, and the Beck Depression Inventory.

METHODS

Three patients have undergone surgery in Calgary with a follow-up duration of 7.4 +/- 5.9 months (mean +/- standard deviation). One patient underwent inadvertent ineffective stimulation for the first 3 months and did not experience a benefit until DBS programming was corrected. All three patients had rapid response to stimulation, with the muscles relaxing immediately and abnormal movements improving within days. Total TWSTRS scores improved by 79%, and severity subscores improved significantly, from 15.7 +/- 2.1 to 7.7 +/- 2.9 (paired t-test, p = 0.02). Pain and disability subscores improved from 25.5 +/- 4.1 to 3.3 +/- 3.1 (paired t-test, p = 0.002) and from 13.3 +/- 4.9 to 3.3 +/- 4.2 (paired t-test, p = 0.06), respectively.

CONCLUSIONS

Although it is too early to reach broad conclusions, this report of preliminary results confirms the efficacy of DBS of the GPi for cervical dystonia.

Phenol block for cervical dystonia: effects and side effects

OBJECTIVE

To report on the effectiveness and side effects of 2% phenol block in patients with cervical dystonia (CD).

DESIGN

Case series.

SETTING

A rehabilitation department at a university medical center in Japan.

PARTICIPANTS

Sixteen patients (11 men, 5 women; mean age +/- standard deviation, 43.4+/-11.2y) with CD. The cause of the CD was unknown, and all cases were refractory to the oral medication and rehabilitation therapy.

INTERVENTION

Two percent phenol blocks guided by electromyography.

MAIN OUTCOME MEASURES

A blind analysis by neurologists of the Tsui score before and after 2 weeks of treatment with phenol block. Side effects were evaluated by another neurologist and patient report.

RESULTS

There was significant (P=.0002) improvement in neck movement and position, based on a reduced Tsui score, after the phenol block. However, 4 patients had a complication of sensory disturbance of the transverse cutaneous nerve of the neck area. The sensory disturbances decreased gradually and disappeared within 3 months, whereas the effects of the phenol block continued.

CONCLUSIONS

Phenol block can reduce the impact of CD that is refractory to therapy.

Microelectrode-guided implantation of deep brain stimulators into the globus pallidus internus for dystonia: techniques, electrode locations, and outcomes

Object

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a promising new procedure for the treatment of dystonia. The authors present their technical approach for placement of electrodes into the GPi in awake patients with dystonia, including the methodology used for electrophysiological mapping of the GPi in the dystonic state, clinical outcomes and complications, and the location of electrodes associated with optimal benefit.

Methods

Twenty-three adult and pediatric patients who had various forms of dystonia were included in this study. Baseline neurological status and improvement in motor function resulting from DBS were measured using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Implantation of the DBS lead was performed using magnetic resonance (MR) imaging–based stereotaxy, single-cell microelectrode recording, and intraoperative test stimulation to determine thresholds for stimulation-induced adverse effects. Electrode locations were measured on computationally reformatted postoperative MR images according to a prospective protocol.

Conclusions

Physiologically guided implantation of DBS electrodes in patients with dystonia is technically feasible in the awake state in most cases, with low morbidity rates. Spontaneous discharge rates of GPi neurons in dystonia are similar to those of globus pallidus externus neurons, such that the two nuclei must be distinguished by neuronal discharge patterns rather than by rates. Active electrode locations associated with robust improvement (> 50% decrease in BFMDRS score) were located near the intercommissural plane, at a mean distance of 3.7 mm from the pallidocapsular border. Patients with juvenile-onset primary dystonia and those with the tardive form benefited greatly from this procedure, whereas benefits for most secondary dystonias and the adult-onset craniocervical form of this disorder were more modest.

A difficult airway is not more prevalent in patients suffering from spasmodic torticollis: a case series

PURPOSE

We designed this retrospective study to assess the frequency of difficult airway and difficult intubation in patients with spasmodic torticollis and compare it to that of the general population.

METHODS

After Institutional Review Board approval, data were collected from the charts of all the patients with spasmodic torticollis who underwent selective peripheral denervation at our institution between 1988 and 2001. The intubation grade was determined using the Cormack and Lehane laryngoscopic classification. The best laryngeal view was recorded.

RESULTS

Data from 342 patients were available for analysis. Fourteen patients had a difficult airway. In two patients, intubation was difficult with three attempts at laryngoscopy in one patient and use of fibreoptic bronchoscopy in the other. Twelve (3.5%) patients presented with laryngoscopic grades of III or IV. The combined prevalence of laryngoscopic view grade III and IV and difficult intubation was 4.4%.

CONCLUSIONS

This study assesses the frequency of difficult intubation in patients suffering from spasmodic torticollis. When compared to the general population, these patients do not appear to have a higher frequency of difficult airway or difficult intubation.

Computed tomographically-controlled injection of botulinum toxin into the longus colli muscle in severe anterocollis

We report on a 44-year-old man who suffered from severe anterocollis. Repeated computed tomographically controlled injections of botulinum toxin into the right longus colli muscle allowed a precise location of the needle and injection of the toxin, leading to clear improvement of symptoms.

[Botulinum toxin type B in the management of dystonia non-responsive to botulinum toxin type A]

BACKGROUND

Botulinum toxin (BTX) injection is the first choice treatment for focal dystonias. However 10% or more of patients who receive repetitive injections of BTX type A (BTX-A) lose response (secondary non-responders). One of the strategies to manage such patients is to treat them with another serotype. The aim of this article is to describe my experience with BTX type B (BTX-B) in the management of patients with focal dystonia who became secondary non-responders to BTX-A.

METHOD

Open-label non-controlled use of BTX-B injections to treat dystonia patients who developed secondary nonresponse to BTX-A Response to treatment was rated on a 0-4 scale (Jankovic).

RESULTS

Four patients entered the study. Pacient 1- At age 48 this man developed idiopathic cervical dystonia. Five years later he also presented with blepharospasm and idiopathic oromandibular dystonia. He was treated with 7604U of BTX-A along 23 sessions separated by a mean interval of 18.8 weeks (range 6-39). Loss of response was noticed after the seventh session. First treatment with BTX-B consisted of injection of 20000U with response rated 3 but duration of 3 weeks. Second session, 23500U, resulted in score 4 with response lasting 12 weeks. Patient 2- This man, with Tourette syndrome since age 8 years, developed tardive blepharospasm at age 51. On 8 sessions of BTX-A injections he received a cumulative dosage of 550U with a mean interval between sessions of 8.8 weeks (range 6-12). Decline of response was noticed after the fifth session. First treatment with BTX-B, 3000U, had a response rated 3 with duration of 12 weeks. Second session, 6000U, resulted in score 4. Patient 3- This woman noticed onset of blepharospasm at age 58 and developed oromandibular and laryngeal dystonia as well as cervical dystonia, respectively, at ages 59 and 65. In other institutions she received 6 sessions of BTX-A. In my service she received a dosage of 1404U along 8 sessions with a mean interval between sessions of 17.4 weeks (range 16-18). She became secondary non-responder after the ninth session. First treatment with BTX-B, 6000U, was rated 0. Second session, 12000U, was rated 4. Patient 4- At age 69 this man developed idiopathic cranial dystonia. Prior to follow up with me, he received 6 sessions of BTX-A in other services. In my institution he was treated with a cumulative dosage of 730U along 4 sessions with a mean interval between sessions of 16.3 weeks (range 15-18). He developed loss of response on the sixth session. Treatment with BTX-B, 12000U, was rated 4 and lasted 20 weeks. Side-effects: local pain (all patients) and dryness of mouth and ptosis (one patient each).

CONCLUSION

My findings confirm that BTX-B injections are a safe and effective option for the management of dystonia patients who become secondary non-responders to BTX-A. The results also underscore the need of individualizing dosage regimens before optimum results are achieved.