Dopa-responsive dystonia caused by tyrosine hydroxylase deficiency: Three cases report and literature review

RATIONAL

Tyrosine hydroxylase deficiency (THD) is a rare cause of dopa-responsive dystonia (DRD). Although the symptoms of DRD may be improved by treatment with L-dopa, the low morbidity of THD can lead to its misdiagnosis. Thus, it is important for physicians to be aware of THD as a cause of DRD.

PATIENT CONCERNS

We report 3 cases of THD. A 5-year-old boy with DRD was diagnosed with THD and found to have compound heterozygous mutations of the TH gene, including TH:c.647G>C from his mother and TH:c.646G>A from his father. Two female siblings also were found to have TH:c.698G>A from their mother and TH:c.710T>C from their father. The younger daughter, at age 3.5 years, was diagnosed with DRD caused by THD, and then the diagnosis of the older daughter, at age 11 years, was changed from cerebral palsy to DRD caused by THD.

DIAGNOSIS

The diagnosis of dopa-responsive dystonia caused by tyrosine hydroxylase deficiency was determined by whole exome sequencing.

INTERVENTION

They all treated with low dose levodopa and benserazide tablets.

OUTCOMES

The boy had a very good therapeutic effect, and he could walk very well by the second day of treatment. The younger sister of the siblings had a partial therapeutic effect, but her elder sister was only little effective with a milder improvement of dystonia and improvement of myodynamia.

CONCLUSION

The characteristics of THD are heterogeneous, and its phenotypes are classified as type A or type B according to increasing severity. Generally, L-dopa has a good therapeutic effect in cases with type A phenotypes. We reviewed 87 cases of reported in the literature and found that c.698G>A and c.707T>C are hot spot mutations. Changes on cerebral magnetic resonance imaging were nonspecific. Analysis of neurotransmitter levels in cerebrospinal fluid is an invasive means of achieving a biochemical diagnosis.

Oral appliances in the treatment of oromandibular dystonia: a systematic review

Oromandibular dystonia (OMD) is a clinically and etiologically heterogeneous form of focal dystonia with variable social and functional implications. The results of pharmacological treatment and botulinum toxin infiltrations are often unsatisfactory. We performed a systematic review on the effects of oral and dental appliances in patients with OMD. Most of the reports in the literature are single subject descriptions or small case series with a considerable variability in the type of dystonia, the type of evaluated appliances and in the outcome measures. Only one report included a large group of unselected patients that were evaluated with a mixture of outcome measures. Although it appears that a number of OMD patients, especially those who benefit from sensory tricks, may sustain some improvement with the use of oral appliances, no definitive conclusions can be drawn about the type of patients that may benefit, nor about the preferred type or mode of appliance. More research in this field is needed, using standardized approaches and clearly defined outcome measures in larger cohorts of OMD patients that are clinically and diagnostically well characterized.

Botulinum Toxin Effects on Sensorimotor Integration in Focal Dystonias

(1) Background: In dystonia, the somatosensory temporal discrimination threshold (STDT) is abnormally increased at rest and higher and longer-lasting during movement execution in comparison with healthy subjects (HS), suggesting an abnormal sensorimotor integration. These abnormalities are thought to depend on abnormal proprioceptive input coming from dystonic muscles. Since Botulinum toxin-A (BT-A) reduces proprioceptive input in the injected muscles, our study investigated the effects of BT-A on STDT tested at rest and during voluntary movement execution in patients with focal dystonia. (2) Methods: We enrolled 35 patients with focal dystonia: 14 patients with cervical dystonia (CD), 11 patients with blepharospasm (BSP), and 10 patients with focal hand dystonia (FHD); and 12 age-matched HS. STDT tested by delivering paired stimuli was measured in all subjects at rest and during index finger abductions. (3) Results: Patients with dystonia had higher STDT values at rest and during movement execution than HS. While BT-A did not modify STDT at rest, it reduced the abnormal values of STDT during movement in CD and FHD patients, but not in BSP patients. (4) Conclusions: BT-A improved abnormal sensorimotor integration in CD and FHD, most likely by decreasing the overflow of proprioceptive signaling from muscle dystonic activity to the thalamus.

Caregiver burden and health-related quality of life in idiopathic dystonia patients under botulinum toxin treatment: a cross-sectional study

Dystonia is a chronic movement disorder that is associated with a reduction in health-related quality of life (HR-QoL) and restriction of activities of daily living. Botulinum neurotoxin (BT) improves disease-specific HR-QoL by reducing abnormal movements, postures, and pain. We examined the burden of the corresponding primary caregiver as a potential important factor for disease management and HR-QoL of dystonia patients under treatment with BT. 114 patients with focal, segmental, or generalized dystonia were recruited, together with 93 corresponding caregivers, whose burden was investigated using the Caregiver Burden Inventory. In addition, all participants were assessed for cognitive impairment, depression, anxiety, alexithymia, and HR-QoL. Only a small proportion of caregivers suffered from caregiver burden. Despite BT therapy, patients' HR-QoL was decreased compared to the age-matched general German population. Psychological symptoms, notably anxiety, and depression correlated significantly with reduced HR-QoL. Our data imply that caregiver burden emerged to be an issue in subgroups of dystonia patients. Furthermore, HR-QoL of dystonia patients is reduced even under optimized BT treatment in a specialized center.

Acute onset of orofacial dystonia from promethazine treatment: A case report

RATIONALE

Promethazine is an antihistamine agent used commonly for nausea and allergy. Along with its anticholinergic and antidopaminergic functions, promethazine is also used for psychiatric symptoms, such as troubling sleep, anxiety, and agitation. Previous studies have reported that promethazine may occasionally elicit acute dystonia in some individuals, especially for young children and pregnant women.

PATIENT CONCERNS

The 68-year-old female patient was admitted to our hospital because of feeling anxious and intermittent palpitation for over 1 year. She developed acute orofacial dystonia following promethazine treatment.

DIAGNOSES

Her diagnoses was generalized anxiety disorder.

INTERVENTIONS

Discontinuation of the offending agent, promethazine, and injection of Botulinum toxin.

OUTCOMES

The acute orofacial dystonia was finally alleviated by local injection of Botulinum toxin.

LESSONS

Careful assessment of the risk of developing acute dystonia is also needed in old patients when initiating the promethazine treatment.

The Use of Botulinum Toxin for Treatment of the Dystonias

Dystonias are characterized by involuntary muscle contractions, twisting movements, abnormal postures, and often tremor in various body regions. However, in the last decade several studies have demonstrated that dystonias are also characterized by sensory abnormalities. While botulinum toxin is the gold standard therapy for focal dystonia, exactly how it improves this disorder is not entirely understood. Neurophysiological studies in animals and humans have clearly demonstrated that botulinum toxin improves dystonic motor manifestations by inducing chemodenervation, therefore weakening the injected muscles. In addition, neurophysiological and neuroimaging evidence also suggests that botulinum toxin modulates the activity of various neural structures in the CNS distant from the injected site, particularly cortical motor and sensory areas. Concordantly, recent studies have shown that in patients with focal dystonias botulinum toxin ameliorates sensory disturbances, including reduced spatial discrimination acuity and pain. Overall, these observations suggest that in these patients botulinum toxin-induced effects encompass complex mechanisms beyond chemodenervation of the injected muscles.

Dopa-responsive dystonia

BAKGRUNN

Doparesponsiv dystoni er en gruppe sykdommer som gir endrede nivåer av nevrotransmittere. Dette kan behandles med god effekt. Økt innsikt i patofysiologiske årsaksforhold har bedret forståelsen av sykdommene.

KUNNSKAPSGRUNNLAG

Artikkelen bygger på 39 artikler fra et systematisk søk i databasen Medline, to nettsteder og en lærebok.

RESULTATER

Doparesponsiv dystoni debuterer som oftest i barne- eller ungdomsårene og gir motoriske, kognitive, psykiatriske og/eller autonome symptomer og funn. Disse kan være uspesifikke og lett mistolkes som annen nevrologisk sykdom. Sykdommen skyldes feilkoding i ett enkelt gen og arves autosomalt recessivt eller dominant. Sykdomsgivende varianter er beskrevet fra tre ulike gener: guanosintrifosfat (GTP)-syklohydrolase-1-genet, sepiapterinreduktase-genet og tyrosinhydroksylase-genet. De sykdomsgivende variantene fører til enzymdefekt og gir tidlig debuterende dystoni, som responderer godt på levodopa. Nivåbestemmelse av pteriner, biogene monoaminer og deres metabolitter i spinalvæsken samt genetiske undersøkelser gir den eksakte diagnosen.

FORTOLKNING

Dagens kunnskap baserer seg på kasuistikker og mindre pasientmaterialer. Her fremgår det at pasientgruppen har stor nytte av levodopa. Diagnostikken har blitt enklere de siste årene med nyere biokjemiske og molekylærgenetiske analysemetoder. Basert på dagens litteratur er det grunn til å tro at vi har udiagnostiserte pasienter i Norge med doparesponsiv dystoni.

Compound heterozygous mutations in the TH gene in a Chinese family with autosomal-recessive dopa-responsive dystonia: A case report

RATIONALE

Autosomal-recessive dopa-responsive dystonia (DRD) is a rare clinical disorder presenting as bradykinesia, dystonia, tremor and even severe encephalopathy, and caused by tyrosine hydroxylase deficiency (THD). We report a case of compound heterozygous mutations in the TH gene in a Chinese family with autosomal-recessive DRD herein.

PATIENT CONCERNS

A 16-month-old Chinese boy presented with symptoms of movement disorder and growth retardation in his infant period.

DIAGNOSES

The genetic test revealed compound heterozygous mutations in the TH gene at c.457C>T and c.698G>A, which are pathogenic of DRD.

INTERVENTIONS

The patient was administrated low-dose levodopa.

OUTCOMES

The treatment resulted in the substantial improvement of dystonia. His long-term neurological outcome need follow-up for years.

LESSONS

Gene mutation analysis is helpful and necessary to diagnose DRD and has important guiding significance for the subsequent treatment.

Treatment of focal dystonia involving multiple muscles with a single injection of botulinum toxin A to 1 muscle: A case report

RATIONALE

Botulinum toxin A (BTX-A) injection is effective in treating focal dystonia. However, there are no prior reports regarding the treatment of progressive focal dystonia by a single BTX-A injection that affect a distant muscle.

PATIENT CONCERNS

A 19-year-old male was referred to the rehabilitation clinic with a complaint of involuntary movement in his left big toe. The involuntary movement pattern was initially observed in the abduction direction only; however, it progressed to irregular mixed patterns in the flexion and abduction directions.

DIAGNOSES

In needle electromyography, abnormal dystonic patterns were observed in the left abductor hallucis (AH), flexor hallucis longus, and flexor hallucis brevis muscles.

INTERVENTIONS AND OUTCOMES

These symptoms resolved with a single BTX-A injection to the AH muscle.

LESSONS

In this case, a single BTX-A injection to 1 muscle for treating progressive focal dystonia was effective on a distant noninjected muscle.

Comparison of botulinum toxin and propranolol for essential and dystonic vocal tremors

OBJECTIVES

Vocal tremors, which cause social difficulties for patients, may be classified as resting or action tremors. Of the vocal action tremors, essential and dystonic tremors are the most common. Botulinum toxin and oral medications have been used to treat vocal tremors, but no comparative clinical trials have been performed. The aim of this study was to compare the effects of botulinum toxin injection and the oral administration of propranolol in the treatment of essential and dystonic vocal tremors.

METHODS

This clinical trial recruited 15 patients, divided into essential and dystonic vocal tremor groups. Patients in both groups received successive treatment with botulinum toxin and propranolol. The treatments were administered at different times; the order of treatment was randomly selected. Patients were assessed with flexible nasofibrolaryngoscopy and with perceptual and acoustic voice evaluations. A statistical significance level of 0.05 (5%) was used.

RESULTS

Botulinum toxin produced statistically significant improvements in perceptual measures of vocal instability in patients with dystonic vocal tremors compared with baseline values and treatment with propranolol. The acoustic measure of variability in the fundamental frequency was significantly lower in patients with dystonic vocal tremors after treatment with botulinum toxin.

CONCLUSION

Essential and dystonic vocal tremors responded differently to treatment. Dystonic vocal tremors responded significantly to treatment with botulinum toxin but not oral propranolol. Essential vocal tremors did not respond significantly to either treatment, perhaps due to the small number of patients, which is a limitation of this research.

[Laryngeal dystonia: novel forms of therapeutic administration of botulinum toxin by direct routes]

AIM

To describe our experience in the treatment of laryngeal dystonia (in abduction and adduction), with special emphasis given to the technical aspects (approach procedure, dosage and type of botulinum toxin type A used), as well as treatment response and possible side effects.

PATIENTS AND METHODS

We conducted a cross-sectional descriptive study of a sample of patients with laryngeal dystonia treated by means of transoral administration of onabotulinumtoxinA or incobotulinumtoxinA over a period of 10 years (2007-2017). Data collected include demographic and clinical variables, treatment response (based on a self-rating scale), the duration of treatment and the appearance of side effects.

SAMPLE SIZE

15 patients (11 women; mean age: 44.06 years) with laryngeal dystonia (mean time since onset of 40 months; 12 patients with dystonia in adduction) and 174 administrations (92% incobotulinumtoxinA; average dosage of 5 U in each vocal cord). The procedure took an average of 11.7 minutes to perform. Response was good in 31% of the procedures and very good in 57.5%. Side effects were recorded in 14.4% of the procedures, although always mild and transitory, with a predominance of dysphagia and dysphonia.

CONCLUSION

In our experience, transoral administration of botulinum toxin type A to treat laryngeal dystonia has proved to be a simple, quick, effective and safe technique.

Novel founder intronic variant in SLC39A14 in two families causing Manganism and potential treatment strategies

Congenital disorders of manganese metabolism are rare occurrences in children, and medical management of these disorders is complex and challenging. Homozygous exonic mutations in the manganese transporter SLC39A14 have recently been associated with a pediatric-onset neurodegenerative disorder characterized by brain manganese accumulation and clinical signs of manganese neurotoxicity, including parkinsonism-dystonia. We performed whole exome sequencing on DNA samples from two unrelated female children from the United Arab Emirates with progressive movement disorder and brain mineralization, identified a novel homozygous intronic mutation in SLC39A14 in both children, and demonstrated that the mutation leads to aberrant splicing. Both children had consistently elevated serum manganese levels and were diagnosed with SLC39A14-associated manganism. Over a four-year period, we utilized a multidisciplinary management approach for Patient 1 combining decreased manganese dietary intake and chelation with symptomatic management of dystonia. Our treatment strategy appeared to slow disease progression, but did not lead to a cure or reversal of already established deficits. Clinicians should consider testing for noncoding mutations in the diagnosis of congenital disorders of manganese metabolism and utilizing multidisciplinary approaches in the management of these disorders.

Pilot Single-Blind Trial of AbobotulinumtoxinA in Oromandibular Dystonia

Oromandibular dystonia (OMD) causes involuntary movements of masticatory and lingual muscles impairing eating, speaking, and swallowing. Treatment options are limited. The objective of this study was to determine the safety and efficacy of abobotulinumtoxinA (aboBoNTA) in OMD. A dose-finding study (phase 1) followed by a single session, prospective, single-blind trial (phase 2) was carried out. OMD subjects were evaluated at baseline, 6 and 12 weeks. Muscles injected were tailored to individual symptoms using EMG guidance, but the aboBoNTA dose for each muscle was pre-specified based on phase 1 results. Evaluations were Global Dystonia Rating Scale (GDS), Unified Dystonia Rating Scale (UDRS), Clinical Global Impression (CGI) improvement and severity, and quality of life (OMDQ-25). Adverse events were monitored. The lowest dosage in phase 1 resulted in adverse effects in two of three patients and thus was used in phase 2. In phase 2, adverse effects were observed in 50% of subjects including dysphagia, voice change, and soft palate weakness. Most were mild. Significant improvement was seen in quality of life (OMDQ-25), speech (BFMq21), and change in GDS, UDRS, CGI severity assessed by the unblinded investigator, but not in blinded video ratings. We conclude that aboBoNTA therapy in this study was associated with improved quality of life and was generally well tolerated in OMD, but occurrence of dysphagia dictated the importance of using low genioglossus dosing. Face to face assessment appears to be more sensitive than video assessment for change in OMD severity. Consideration of the disability in OMD places constraints on traditional placebo-control trial design. Development of novel trial designs is warranted.

[Myths and evidence on the use of botulinum toxin: neuropharmacology and dystonia]

INTRODUCTION

Botulinum toxin type A (BTA) is a bacterial endotoxin, whose therapeutic use has had a dramatic impact on different neurological disorders, such as dystonia and spasticity.

AIM

To analyze and summarize different questions about the use of BTA in our clinical practice.

DEVELOPMENT

A group of experts in neurology developed a list of topics related with the use of BTA. Two groups were considered: neuropharmacology and dystonia. A literature search at PubMed, mainly for English language articles published up to June 2016 was performed. The manuscript was structured as a questionnaire that includes those questions that, according to the panel opinion, could generate more controversy or doubt. The initial draft was reviewed by the expert panel members to allow modifications, and after subsequent revisions for achieving the highest degree of consensus, the final text was then validated. Different questions about diverse aspects of neuropharmacology, such as mechanism of action, bioequivalence of the different preparations, immunogenicity, etc. were included. Regarding dystonia, the document included questions about methods of evaluation, cervical dystonia, blepharospasm, etc.

CONCLUSION

This review does not pretend to be a guide, but rather a tool for continuous training of residents and specialists in neurology, about different specific areas of the management of BTA.

Atypical presentation of dopa-responsive dystonia in Taiwan

The typical clinical presentation of dopa-responsive dystonia, which is also called Segawa disease, is a young age of onset, with predominance in females, diurnal fluctuation of lower limb dystonia, and fair response to low-dose levodopa. This disease has both autosomal dominant and autosomal recessive inheritance. Autosomal dominant Segawa disease is caused by GCH1 mutation on chromosome 14q22.1-q22.2. Here, we report the case of a male patient with genetically confirmed Segawa disease and atypical presentations including no diurnal symptom fluctuation and insufficient response to levodopa. The patient's father who had the same mutation presented parkinsonism in old age. We also review the literature to address the broad clinical heterogeneity of Segawa disease and the influence of onset age on clinical presentation.

Patient Evaluation and Selection for Movement Disorders Surgery: The Changing Spectrum of Indications

This report summarizes the state-of-the-art and controversies around patient selection for deep brain stimulation (DBS) for various conditions. Parkinson's disease (PD): several class I studies have shown superiority of DBS over best medical treatment for advanced PD with fluctuations and further inclusion criteria. One class I study suggests that PD patients with early motor complications might gain more quality of life if operated within 3 years after the onset of fluctuations. The subthalamic nucleus (STN) is still the standard target. STN DBS has an impact on impulse control disorders though the exact mechanism is unclear. Tremor: essential tremor (ET) patients found to be eligible for DBS surgery should first be treated with primidone, propranolol, and with a combined therapy preoperatively. Second-line drugs (i.e., topiramate and gabapentin) may be useful. No class I studies exist for DBS treatment of ET. The optimal target of DBS in ET might be the posterior subthalamic area. Dystonia: there is class I evidence for primary generalized and segmental dystonia and for some botulinum-resistant focal dystonias. The impact of age, symptom duration, and DYT-mutation status in primary dystonia on the outcome of DBS surgery clearly demands more studies. DBS has a role in SCGE-mutation positive myoclonus dystonia and tardive dystonia. Finally, neurostimulation in secondary dystonia might be considered in selected patients based on an individual patient's approach.

Medical Management of Movement Disorders

Pharmacological treatment is the cornerstone in the management of movement disorders. Although most available treatment options have no impact on the underlying process of each movement disorder, symptomatic therapies can significantly improve patient's quality of life and level of disability. Here, we review the current knowledge on clinical symptomatic management of Parkinson's disease (both early and advanced stages), essential tremor, dystonia, and chorea. Ideally, treatment should be carried out by specialists with reasonable experience in movement disorders, as it needs to be tailored for each patient depending on several appraisals, including but not limited to patients' needs, compliance issues, potential side effects, caregiver support, and presence of comorbidities. When medications fail to improve patient's disability, stereotactic surgery is a well-established option for most of these disorders.

Abnormal striatal plasticity in a DYT11/SGCE myoclonus dystonia mouse model is reversed by adenosine A2A receptor inhibition

Striatal dysfunction is implicated in many movement disorders. However, the precise nature of defects often remains uncharacterized, which hinders therapy development. Here we examined striatal function in a mouse model of the incurable movement disorder, myoclonus dystonia, caused by SGCE mutations. Using RNAseq we found surprisingly normal gene expression, including normal levels of neuronal subclass markers to strongly suggest that striatal microcircuitry is spared by the disease insult. We then functionally characterized Sgce mutant medium spiny projection neurons (MSNs) and cholinergic interneurons (ChIs). This revealed normal intrinsic electrophysiological properties and normal responses to basic excitatory and inhibitory neurotransmission. Nevertheless, high-frequency stimulation in Sgce mutants failed to induce normal long-term depression (LTD) at corticostriatal glutamatergic synapses. We also found that pharmacological manipulation of MSNs by inhibiting adenosine 2A receptors (A_2AR) restores LTD, again pointing to structurally intact striatal circuitry. The fact that Sgce loss specifically inhibits LTD implicates this neurophysiological defect in myoclonus dystonia, and emphasizes that neurophysiological changes can occur in the absence of broad striatal dysfunction. Further, the positive effect of A_2AR antagonists indicates that this drug class be tested in DYT11/SGCE dystonia.

[Botulinum toxin for treatment of the focal dystonia]

Dystonia is defined as a movement disorder characterized by sustained or intermittent muscles contraction causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned and twisting, and may be tremulous. The precis diagnosis of dystonia is difficult for physicians because neurological brain imaging does not provide enough practical information. The diagnosis is depend on clinical experience of physicians. Botulinum toxin treatment is the accepted standard of care for patients with focal dystonia. Botulinum toxin treatment results in significant improvement of decreasing the symptom of dystonia. The success of treatment is dependent on muscle selection for treating involved muscles. Usually performance of botulinum toxin treatment is injected according to clinical experience of surface anatomy or clinical location method. However, the benefit of guidance of botulinum toxin treatment is improve outcome in dystonia. Injection techniques with ultra sound echogram or EMG guidance to identify dystonic muscles can be more benefit for patients.

Chewing-induced facial dystonia: a rare presentation of task-specific dystonia

This case is an addition to scarce literature available for a rare condition, chewing-induced task-specific dystonia. The patient was a 63-year-old woman who presented with a 4-year history of progressive difficulty in eating food only during chewing associated with abnormal facial grimaces without any difficulty in drinking, swallowing, speaking or singing. Examination revealed dystonia of facial muscles every time she chewed but absent during drinking and speaking. As movements were consistent and reproducible with the specific task, other differential diagnosis like motor tics, psychogenic disorder, tardive dystonia and parkinsonism syndrome were excluded leading to a diagnosis of task-specific facial dystonia triggered by chewing. Treatment was started with trihexyphenidyl and later on tetrabenazine was also added but she got only mild relief of symptoms. As she did not agreed for botulinum toxin therapy, so we continued with the same treatment without much improvement.

Haptic Feedback Manipulation During Botulinum Toxin Injection Therapy for Focal Hand Dystonia Patients: A Possible New Assistive Strategy

Abnormality of sensorimotor integration in the basal ganglia and cortex has been reported in the literature for patients with task-specific focal hand dystonia (FHD). In this study, we investigate the effect of manipulation of kinesthetic input in people living with writer's cramp disorder (a major form of FHD). For this purpose, severity of dystonia is studied for 11 participants while the symptoms of seven participants have been tracked during five sessions of assessment and Botulinum toxin injection (BoNT-A) therapy (one of the current suggested therapies for dystonia). BoNT-A therapy is delivered in the first and the third session. The goal is to analyze the effect of haptic manipulation as a potential assistive technique during BoNT-A therapy. The trial includes writing, hovering, and spiral/sinusoidal drawing subtasks. In each session, the subtasks are repeated twice when (a) a participant uses a normal pen, and (b) when the participant uses a robotics-assisted system (supporting the pen) which provides a compliant virtual writing surface and manipulates the kinesthetic sensory input. The results show (p-value using one-sample t-tests) that reducing the writing surface rigidity significantly decreases the severity of dystonia and results in better control of grip pressure (an indicator of dystonic cramping). It is also shown that (p-value based on paired-samples t-test) using the proposed haptic manipulation strategy, it is possible to augment the effectiveness of BoNT-A therapy. The outcome of this study is then used in the design of an actuated pen as a writing-assistance tool that can provide compliant haptic interaction during writing for FHD patients.

Medication use in childhood dystonia

BACKGROUND

Data around current prescription practices in childhood dystonia is limited. Medication use may be limited by side effects, the incidence of which is uncertain. For a large cohort assessed by our supra-regional service we aimed to: i) Review medications used at the point of referral. ii) Determine the prevalence of adverse drug responses (ADR) resulting in discontinuation of drug use. iii) Identify clinical risk factors for ADR.

METHODS

Case note review of 278 children with dystonia referred to our service. Data collected on medications, ADR, dystonia aetiology, Gross Motor Function Classification System (GMFCS) level and motor phenotype (pure dystonia/mixed dystonia-spasticity). Logistic regression analysis was used to identify risk factors for ADR.

RESULTS

At referral 82/278 (29.4%) children were taking no anti-dystonic medication. In the remainder the median number of anti-dystonic medications was 2 (range 1-5). Medications use increased with worsening GMFCS level. The commonest drugs used were baclofen (118/278: 42.4%), trihexyphenidyl (98/278: 35.2%), l-Dopa (57/278: 20.5%) and diazepam (53/278: 19%). Choice of medication appeared to be influenced by dystonia aetiology. ADR had been experienced by 171/278 (61.5%) of children. The commonest drugs responsible for ADR were trihexyphenidyl (90/171: 52.3%), baclofen (43/171: 25.1%) and l-Dopa (26/171: 15.2%). Binary logistic regression demonstrated no clinical risk factors for ADR.

CONCLUSIONS

ADR is commonly experienced by children with dystonia, regardless of dystonia severity or aetiology. A wide variation in drug management of dystonia was identified. Collectively these findings highlight the need for a rational approach to the pharmacological management of dystonia in childhood.

Frozen versus fresh reconstituted botox for laryngeal dystonia

Objectives

To compare the efficacy and side effects of frozen versus fresh reconstituted botulinum toxin type A (BTX-A) in the treatment of laryngeal dystonia.

Study Design and Setting

Prospective open-label crossover study; 43 adult patients with adductor spasmodic dysphonia were randomly treated with fresh or refrozen reconstituted BTX-A at a private voice center. Treatment outcomes were assessed by duration of action and self-rated satisfaction (7 point Likert scale). Side effects of breathiness and dysphagia for liquids were assessed as well.

Results

There was no statistically significant difference in the duration of action (mean, 16.2 ± 8.5 vs 16.0 ± 7.6 weeks) and self-rated satisfaction of the treatment (median, 6.0 vs 6.0 points). The side effects were similar for both BTX-A injection types. In addition, there were no instances of infection for refrozen injections.

Conclusions

BTX-A may be safely used after being reconstituted and frozen or refrozen without a significant loss of effectiveness or additional side effects. In our experience, the period of freezing was on 2 occasions for up to 8 weeks.

Significance

Refrozen BTX-A may be a cost-effective use of an expensive drug. EBM rating: B-2b

Conversion Ratio between Botox®, Dysport®, and Xeomin® in Clinical Practice

Botulinum neurotoxin has revolutionized the treatment of spasticity and is now administered worldwide. There are currently three leading botulinum neurotoxin type A products available in the Western Hemisphere: onabotulinum toxin-A (ONA) Botox(®), abobotulinum toxin-A (ABO), Dysport(®), and incobotulinum toxin A (INCO, Xeomin(®)). Although the efficacies are similar, there is an intense debate regarding the comparability of various preparations. Here we will address the clinical issues of potency and conversion ratios, as well as safety issues such as toxin spread and immunogenicity, to provide guidance for BoNT-A use in clinical practice. INCO was shown to be as effective as ONA with a comparable adverse event profile when a clinical conversion ratio of 1:1 was used. The available clinical and preclinical data suggest that a conversion ratio ABO:ONA of 3:1-or even lower-could be appropriate for treating spasticity, cervical dystonia, and blepharospasm or hemifacial spasm. A higher conversion ratio may lead to an overdosing of ABO. While uncommon, distant spread may occur; however, several factors other than the pharmaceutical preparation are thought to affect spread. Finally, whereas the three products have similar efficacy when properly dosed, ABO has a better cost-efficacy profile.