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Molecular dissection and anatomical basis of dystonia: X-linked recessive dystonia-parkinsonism (DYT3).

Pathological findings in dystonia have been unclear. X-linked recessive dystonia-parkinsonism (XDP, DYT3), endemic in the Panay island, the Philippines, is characterized by the clinical onset with dystonia followed by parkinsonism. It provides a unique opportunity to explore the anatomical basis of dystonia, because it has discernible pathological changes even at its early phase of dystonia. After extensive searches for the anatomical basis in XDP, we found selective loss of striosomal neurons in the striatum in dystonic patients' brain. Because striosomal neurons inhibit nigrostriatal dopaminergic neurons via GABAergic innervation, the striosomal lesion could account for dopamine excess in the striatum, which in turn causes a hyperkinetic state or dystonia. We also identified the causative gene as one of the general transcription factor genes, TAF1. XDP has certain similarities to Huntington disease not only in pathological and clinical findings, but also the molecular mechanism, which disturbs expression of genes essential for striatal neurons, such as DRD2. Therapeutic intervention may become possible through pharmacological measures that affect gene expression.

Chromosomes, Human, X↗

[Molecular and anatomical bases of dystonia: X-linked recessive dystonia-parkinsonism (DYT3)].

Pathological findings in dystonia have been unclear. X-linked recessive dystonia-parkinsonism (XDP, DYT3), endemic in the Panay island, the Philippines, is characterized by the clinical onset with dystonia followed by parkinsonism. It provides a unique opportunity to explore the anatomical basis of dystonia, because it has discernible pathological changes even at its early phase of dystonia. After extensive searches for the anatomical basis in XDP, we found selective loss of striosomal neurons in the striatum in dystonic patients' brain. Because striosomal neurons inhibit nigrostriatal dopaminergic neurons via GABAergic innervation, the striosomal lesion could account for dopamine excess in the striatum, which in turn causes a hyperkinetic state or dystonia. We also identified the causative gene as one of the general transcription factor genes, TAF1. This abnormality markedly reduced the expression of dopamine D2 receptor gene (DRD2) in neurons. XDP has certain similarities to Huntington disease not only in pathological and clinical findings, but also the molecular mechanism, which disturbs expression of genes essential for striatal neurons, such as DRD2. Therapeutic intervention may become possible through pharmacological measures that affect gene expression.

Corpus Striatum↗

Effects of locally administered pentylenetetrazole on nigral single unit activity and severity of dystonia in a genetic model of paroxysmal dystonia.

The dt(sz) hamster is a well-established animal model of idiopathic paroxysmal dystonia. Previous investigations of this mutant have indicated dysfunctions of the gamma-aminobutyric acid (GABA)-ergic system within the basal ganglia. Systemic administration of the central stimulant pentylenetetrazole (PTZ) aggravated dystonia at subconvulsant doses, whereas GABA-mimetic drugs have beneficial effects in dt(sz) hamsters. GABA mimetics also provide clinical benefit in humans with idiopathic paroxysmal dystonia. The spontaneous discharge rates of substantia nigra pars reticulata (SNr) neurons was unaltered in anesthetized dt(sz) hamsters, but systemic application of subconvulsant doses of PTZ caused significantly greater increases of discharge rates in dystonic hamsters compared with nondystonic controls. The present study tested the hypothesis that SNr neurons are more sensitive to local application of PTZ in dt(sz) hamsters than in nondystonic hamsters. PTZ applied locally by pressure injection at 2, 3, and 5 mM to the SNr during in vivo single unit recordings revealed a dose-dependent increase of SNr discharge rates in mutants and controls relative to predrug rates, with a significantly greater increase in mutants at 3 mM PTZ. To examine the functional relevance of the increased susceptibility of SNr neurons to PTZ in mutants, the effects of PTZ on severity of dystonia were investigated after microinjections into the SNr of freely moving dt(sz) hamsters. Bilateral nigral microinjection of 40 ng PTZ did not aggravate dystonia but exerted moderate antidystonic effects. Therefore, the previous findings of prodystonic effects of systemic administration of PTZ in dt(sz) hamsters are related to extranigral effects rather than to the elevation of nigral discharge rates in response to systemic, or locally applied, PTZ. The greater susceptibility of neurons within the SNr to PTZ suggests dysfunctions of the GABA(A) receptor in dt(sz) mutants.

Action Potentials↗

Neural mechanisms of dystonia: evidence from a 2-deoxyglucose uptake study in a primate model of dopamine agonist-induced dystonia.

The neural mechanisms that mediate dystonia were investigated in a novel experimental primate model of dopamine agonist-induced dystonia. This condition was produced by long-term (15 months) dopamine agonist therapy of a macaque monkey that had been rendered hemiparkinsonian by unilateral infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine into the right common carotid artery. The 2-deoxyglucose (2-DG) metabolic mapping technique was applied to the animal during the expression of active unilateral dystonia, and regional brain uptake of 2-DG was assessed autoradiographically. The results demonstrate that dystonia is associated with marked increases in 2-DG uptake in the constituent nuclei of the basal ganglia (caudate nucleus, putamen, medial and lateral segments of the globus pallidus) and in the subthalamic nucleus, but decreased uptake in the structures that receive output of the basal ganglia (ventral anterior/ventral lateral thalamic complex and lateral habenula). Based on these findings it is suggested that dystonia is characterized by increased activity in the putaminopallidal and pallidosubthalamic pathways, and decreased activity in the subthalamopallidal and pallidothalamic pathways.

Animals↗

Novel mutation in the TOR1A (DYT1) gene in atypical early onset dystonia and polymorphisms in dystonia and early onset parkinsonism.

Dystonia is a movement disorder involving sustained muscle contractions and abnormal posturing with a strong hereditary predisposition and without a distinct neuropathology. In this study the TOR1A (DYT1) gene was screened for mutations in cases of early onset dystonia and early onset parkinsonism (EOP), which frequently presents with dystonic symptoms. In a screen of 40 patients, we identified three variations, none of which occurred in EOP patients. Two infrequent intronic single base pair (bp) changes of unknown consequences were found in a dystonia patient and the mother of an EOP patient. An 18-bp deletion (Phe323_Tyr328del) in the TOR1A gene was found in a patient with early onset dystonia and myoclonic features. This deletion would remove 6 amino acids close to the carboxy terminus, including a putative phosphorylation site of torsinA. This 18-bp deletion is the first additional mutation, beyond the GAG-deletion (Glu302/303del), to be found in the TOR1A gene, and is associated with a distinct type of early onset dystonia.

Adolescent↗

Idiopathic fluctuating dystonia: a case of foot dystonia and writer's cramp responsive to L-dopa.

A forme fruste of progressive idiopathic dystonia is reported in a girl, starting at eight years and followed to 24 years of age. The first symptom was isolated dystonia of the left foot and later writer's cramp developed in the hands. Fluctuations of the dystonia occurred later in the course of the disorder, which were not related to the sleep-walking cycle. Complete remission of symptoms was obtained with low dosage of L-dopa. This case broadens the spectrum of fluctuating dopa-sensitive progressive childhood dystonias and provides evidence for writer's cramp being a form of focal dystonia.

Adult↗

Early onset torsion dystonia (Oppenheim's dystonia).

Early onset torsion dystonia (EOTD) is a rare movement disorder characterized by involuntary, repetitive, sustained muscle contractions or postures involving one or more sites of the body. A US study estimated the prevalence at approximately 1 in 30,000. The estimated prevalence in the general population of Europe seems to be lower, ranging from 1 in 330,000 to 1 in 200,000, although precise numbers are currently not available. The estimated prevalence in the Ashkenazi Jewish population is approximately five to ten times higher, due to a founder mutation. Symptoms of EOTD typically develop first in an arm or leg in middle to late childhood and progress in approximately 30% of patients to other body regions (generalized dystonia) within about five years. Distribution and severity of symptoms vary widely between affected individuals. The majority of cases from various ethnic groups are caused by an autosomal dominantly inherited deletion of 3 bp (GAG) in the DYT1 gene on chromosome 9q34. This gene encodes a protein named torsinA, which is presumed to act as a chaperone protein associated with the endoplasmic reticulum and the nuclear envelope. It may interact with the dopamine transporter and participate in intracellular trafficking, although its precise function within the cell remains to be determined. Molecular genetic diagnostic and genetic counseling is recommended for individuals with age of onset below 26 years, and may also be considered in those with onset after 26 years having a relative with typical early onset dystonia. Treatment options include botulinum toxin injections for focal symptoms, pharmacological therapy such as anticholinergics (most commonly trihexiphenydil) for generalized dystonia and surgical approaches such as deep brain stimulation of the internal globus pallidus or intrathecal baclofen application in severe cases. All patients have normal cognitive function, and despite a high rate of generalization of dystonia, 75% of those patients are able to maintain ambulation and independence, and therefore a comparatively good quality of life, with modern treatment modalities.

Age of Onset↗

Safety, effectiveness, and duration of effect of BOTOX after switching from Dysport for blepharospasm, cervical dystonia, and hemifacial spasm dystonia, and hemifacial spasm.

BACKGROUND: Local injection of botulinum toxin type A is first-line treatment of blepharospasm, cervical dystonia, and hemifacial spasm; however, there is uncertainty about the optimal dose of toxin for each indication as well as dose-conversion ratios that should be used when switching products in clinical practice. OBJECTIVE: The goal of this study was to compare the safety, effectiveness, and duration of clinical effect of BOTOX and Dysport and Dysportdagger after drug switching (Dysport to BOTOX) among patients with movement disorders. METHODS: A total of 48 patients diagnosed with blepharospasm (n = 27), cervical dystonia (n = 12), or hemifacial spasm (n = 9) were evaluated during a single-arm, crossover-design study in which each patient was his/her own historical control using a 5:1 or 4:1 conversion ratio of Dysport to BOTOX units. Patients were assessed (using Jankovic, Visual Analog Scale, general pain scale, Toronto Western Spasmodic Torticollis Rating Scale [TWSTRS] scores) after the last injection of Dysport and the first injection of BOTOX. Moreover, each patient kept a diary during treatment to track onset and duration of therapeutic effect. RESULTS: Although BOTOX and Dysport were both clinically effective, this effect was more significant with BOTOX compared to Dysport based on TWSTRS for cervical dystonia (p = 0.012), and Jankovic scores for blepharospasm (p = 0.006). Longer duration of effect also was noted with BOTOX than with Dysport (blepharospasm, 62.2 days vs 47.4 days (p = 0.001); cervical dystonia, 64.3 days vs 44.6 days (p = 0.014); hemifacial spasm, 65.1 days vs 41.8 days (p < 0.014), respectively). Of the 48 patients, 19 experienced at least one adverse drug reaction (ADR) during Dysport treatment, with the most commonly reported ADRs being ptosis for blepharospasm and hemifacial spasm and neck weakness for cervical dystonia. No patient reported an ADR during BOTOX treatment. CONCLUSIONS: Results suggest therapeutic effectiveness is enhanced with BOTOX compared to Dysport at a dosing ratio between 5:1 and 4:1 (Dysport:BOTOX). Safety and duration of therapeutic effect also are enhanced with BOTOX. Further research is needed.

Adult↗

Early onset dystonia decreasing with development. Case report of two children with familial myoclonic dystonia.

Two related girls had the onset of unilateral leg dystonia in the neonatal period and at 13 months, respectively. The dystonic signs subsided with motor development and resolved completely in one of the girls by the age of 5 years. There was no response to L-dopa. From 2-3 years of age segmental myoclonus with a shoulder girdle distribution appeared. Family investigation results were compatible with autosomal dominant myoclonic dystonia responsive to alcohol. The onset and resolution of dystonia have not been described previously. This disorder is genetically separate from torsion dystonia. No linkage has been found to the dopamine beta-hydroxylase gene locus. Genetically determined disorders of neurotransmission may add to our knowledge of the normal development of motor control and thus merit further study.

Age of Onset↗

Soleus H-reflex tests in causalgia-dystonia compared with dystonia and mimicked dystonic posture.

Dystonia in the causalgia-dystonia syndrome is characterized by a fixed dystonic posture. To identify involvement of central pathophysiologic mechanisms, we analyzed soleus H-reflex tests in five patients with causalgia-dystonia. Soleus H-reflex test results in these patients differed from those in healthy controls but were similar to those in purely dystonic patients and healthy controls mimicking dystonic posture. The results suggest involvement of supraspinal mechanisms in the abnormal posture of causalgia-dystonia.

Adult↗

Cervical dystonia due to spinal cord ependymoma: involvement of cervical cord segments in the pathogenesis of dystonia.

We report a patient with a progressive motor disorder dominated by pyramidal signs in all four extremities and cervical dystonia in the form of torticollis, who had imaging features of cervical cord tumor on magnetic resonance imaging (MRI) scanning. Ependymoma was the final diagnosis by histology. Cervical dystonia presenting as a manifestation of an identified focal central nervous system (CNS) lesion is infrequent. We believe our patient to be the first adult example of cervical cord tumor giving rise to cervical dystonia. Adding this entity to the list of differential diagnosis of torticollis is considered, and its mechanisms are discussed.

Adult↗

Long-term treatment of cervical dystonia with botulinum toxin A: efficacy, safety, and antibody frequency. German Dystonia Study Group.

Data from 616 patients suffering from idiopathic cervical dystonia were analyzed to determine the efficacy and safety of treatment with botulinum neurotoxin type A (BoNT/A). Since the specific purpose of this study was to determine the long-term effects of this treatment, the analysis focused specifically on the patients (n = 303) having received six or more injections. Statistical analysis of a standardized documentation showed sustained significant benefit as measured by a disease severity score independent of the type of cervical dystonia. Furthermore, pronounced individual differences were found in response to this treatment although initial clinical scores and doses of BoNT/A were similar. There was no indication of previously unknown adverse events, the only risk being the development of serum antibodies against the toxin. As in previous studies on short-term effects of BoNT/A treatment, the most frequent adverse event was dysphagia, which occurred on average 9.7 days after injection and lasted on average 3.5 weeks. While secondary nonresponse was seen in approx. 5% of patients, antibody tests revealed neutralizing serum antibodies in only 2%. On the basis of the present data, therapy of cervical dystonia with BoNT/A seems to be safe and yields good stable results even after 5 years of treatment.

Adolescent↗

Blepharospasm-oromandibular dystonia syndrome (Brueghel's syndrome). A variant of adult-onset torsion dystonia?

Thirty-nine patients with the idiopathic blepharospasm-oromandibular dystonia syndrome are described. All presented in adult life, usually in the sixth decade; women were more commonly affected than men. Thirteen had blepharospasm alone, nine had oromandibular dystonia alone, and 17 had both. Torticollis or dystonic writer's camp preceded the syndrome in two patients. Eight other patients developed toritocollis, dystonic posturing of the arms, or involvement of respiratory muscles. No cause or hereditary basis for the illness were discovered. The evidence to indicate that this syndrome is due to an abnormality of extrapyramidal function, and that it is another example of adult-onset focal dystonia akin to spasmodic torticollis and dystonic writer's cramp, is discussed.

Adult↗

Comparison of striatal 18F-dopa uptake in adult-onset dystonia-parkinsonism, Parkinson's disease, and dopa-responsive dystonia.

We studied six patients with adult-onset dystonia-parkinsonism (DYS-P) with 18F-6-fluoro-dopa (18F-dopa) positron emission tomography and compared their influx constants (Ki values) with those of six patients with classical childhood-onset dopa-responsive dystonia (DRD), 12 age-matched Parkinson's disease (PD) patients without dystonia, and 21 normal controls. The DYS-P group had significantly reduced mean caudate (67% of normal) and putamen (45% of normal) 18F-dopa uptake. These Ki values were similar to mean caudate and putamen Ki values obtained for the PD group. In contrast, the DRD group showed minor reductions in mean caudate (9%) and putamen (18%) 18F-dopa uptake when compared with normals. The mean caudate:putamen Ki ratio was 1.7 in the DYS-P group and 2.1 in the PD group. In the DRD and normal groups, the caudate:putamen ratios were close to unity. The findings of this study are that adult-onset DYS-P targets the nigrostriatal dopaminergic projections in a pattern similar to PD, with the putamen being more affected. This provides support for the hypothesis that DYS-P may be a phenotypic variant of Lewy body disease. DYS-P seems distinct from childhood-onset DRD, in which striatal 18F-dopa uptake is either normal or only mildly reduced.

Adult↗

Silencing primary dystonia: lentiviral-mediated RNA interference therapy for DYT1 dystonia.

DYT1 is the most common inherited dystonia. Currently, there are no preventive or curative therapies for this dominantly inherited disease. DYT1 dystonia is caused by a common three-nucleotide deletion in the TOR1A gene that eliminates a glutamic acid residue from the protein torsinA. Recent studies suggest that torsinA carrying the disease-linked mutation, torsinA(DeltaE) acts through a dominant-negative effect by recruiting wild-type torsinA [torsinA(wt)] into oligomeric structures in the nuclear envelope. Therefore, suppressing torsinA(DeltaE) expression through RNA interference (RNAi) could restore the normal function of torsinA(wt), representing a potentially effective therapy regardless of the biological role of torsinA. Here, we have generated short hairpin RNAs (shRNAs) that mediate allele-specific suppression of torsinA(DeltaE) and rescue cells from its dominant-negative effect, restoring the normal distribution of torsinA(wt). In addition, delivery of this shRNA by a recombinant feline immunodeficiency virus effectively silenced torsinA(DeltaE) in a neural model of the disease. We further establish the feasibility of this viral-mediated RNAi approach by demonstrating significant suppression of endogenous torsinA in mammalian neurons. Finally, this silencing of torsinA is achieved without triggering an interferon response. These results support the potential use of viral-mediated RNAi as a therapy for DYT1 dystonia and establish the basis for preclinical testing in animal models of the disease.

Animals↗

[Living with dystonia. A questionnaire study among members of the Swedish Dystonia Patient Association].

The dystonias are movement disorders with sustained muscle contractions causing twisting movements or abnormal postures. A patient survey sent to 268 members of the Swedish Dystonia Patient Association was returned by 221 (82%). Most of the patients (81%) were women and the most common form was cervical dystonia (spasmodic torticollis). Median age at onset was 41.6 years. The time from onset of symptoms to correct diagnosis was on average 6 years. 21% had relatives with movement derangements. Injection with Botulinum toxin and physical therapy were ranked as the most effective treatments. Many patients expressed a need for more physical therapy as well as a desire to meet the same physician each time and to receive more intensive psychological support.

Adult↗

Treatment of cervical dystonia and focal hand dystonia by high cervical continuously infused intrathecal baclofen: a report of 2 cases.

We describe 2 patients, one with cervical dystonia (CD) combined with focal hand dystonia (writer's cramp) and another with idiopathic CD, who were unresponsive to oral medications and became resistant to botulinum toxin type A and B injections. Both patients were successfully treated with high cervical (C1-3) continuously infused intrathecal baclofen (ITB). Neck range of motion (ROM) was measured by using a 3-dimensional electromagnetic cervical ROM system. Pain, disability, and severity were assessed by using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The patient with CD and writer's cramp did well on a continuous baclofen dose of 186.1 microg/d. Her total TWSTRS score improved significantly, her electromagnetic measurements showed an increased in total neck flexion and extension, and her handwriting improved. Unfortunately, this patient (a heavy smoker) developed small cell carcinoma of the lung and died 9 months after her pump was placed. Total TWSTRS score and electromagnetic measurements also significantly improved after pump implant in the patient with CD. He continues to do well on a periodic bolus dose using a combination of 50 microg of baclofen and 25 microg of hydromorphone (Dilaudid) every 4 hours. Our findings suggest the potential usefulness of this therapy in other patients with focal dystonia. To our knowledge, this is the first reported successful treatment of CD and CD combined with writer's cramp with high cervical continuously infused ITB.

Baclofen↗