Diagnosis of dystonic syndromes—a new eight-question approach
Department of Neurology, Alfred Hospital, Commercial Road, Melbourne, VIC 3004, Australia. Nature Reviews Neurology
(Impact Factor: 15.36).
03/2012; 8(5):275-83. DOI: 10.1038/nrneurol.2012.39
Dystonia is a syndrome of abnormal involuntary movements that are repetitive, twisting or patterned, and can result in abnormal postures. Dystonia may be generalized or focal, and can occur as a primary syndrome or secondary to another disease--over 50 clinical conditions are reported to cause dystonia. Classification of dystonia is based on genetic background, anatomical distribution, age at onset, and neurodegenerative processes. In many cases, manifestations of dystonia are identical regardless of the aetiology, which makes accurate diagnosis challenging, if not impossible, without additional investigations. Exhaustive lists of the causes of dystonia are not practical to aid clinicians when attempting to determine if a hyperkinetic movement can be diagnosed as dystonic. The existing diagnostic algorithms for dystonic syndromes rely on the clinician's experience, without a streamlined diagnostic pathway. Non-specialist clinicians and neurologists may, therefore, find diagnosis of dystonic syndromes difficult. In this Review, an eight-question approach is proposed, with a summary of the evidence for investigations that enable successful diagnosis of dystonic syndromes. The aim of this approach is to inform both specialists and general neurologists on the appropriate diagnostic test for each patient who presents with a possible dystonic syndrome.
Available from: Carmelo Chisari
- "In 1984, an ad hoc committee of the Dystonia Medical Research Foundation defined dystonia as a syndrome of involuntary, sustained muscle contractions affecting one or more sites of the body, frequently causing twisting and repetitive movements or abnormal postures . There are several classifications of dystonia , based on genetic background, anatomical distribution, age at onset, and neurodegenerative processes . The one most used in clinical practice is aetiological classification, which includes primary dystonia (idiopathic), secondary dystonia , dystonia-plus syndromes, and paroxysmal dystonia. "
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ABSTRACT: Treatment options for dystonia are not curative but symptomatic; the treatment of choice for focal dystonias is repeated botulinum toxin injections. Here, we present the case of a 46-year-old beautician with focal dystonia in her left hand that affected her ability to work. Pharmacological treatment with clonazepam and gabapentin failed to resolve her symptoms and was discontinued due to side effects (sleepiness, gastrointestinal disorders). Intramuscular injection of botulinum toxin (incobotulinumtoxinA, Xeomin) into the extensor digitorum communis (35 U), flexor carpi radialis (35 U), and flexor digitorum superficialis (30 U) muscles resulted in complete resolution of symptoms at clinical assessments at 1, 3, 6, and 10 months after the injections, confirmed by the results of surface electromyography 10 months after treatment. The patient was able to work again 1 month after treatment. No reinjection has been necessary at the last evaluation (12 months after treatment). In conclusion, botulinum toxin is an effective treatment for focal dystonia that can have long-lasting effects and can improve patients' ability to work and quality of life.
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ABSTRACT: Dystonia is a neurological disorder characterized by abnormal involuntary movements that are prolonged and often cause twisting and turning. Several genetically modified worms, fruit flies, and rodents have been generated as models of genetic dystonias, in particular DYT1, DYT11, and DYT12 dystonias. Although these models do not show overt dystonic symptoms, the rodent models exhibit motor deficits in specialized behavioral tasks, such as the rotarod and beam-walking tests. For example, in a rodent model of DYT12 dystonia, which is generally stress triggered, motor deficits are observed only after the animal is stressed. Moreover, in a rodent model of DYT1 dystonia, the motor and electrophysiological deficits can be rescued by trihexyphenidyl, a common anticholinergic medication used to treat dystonic symptoms in human patients. Biochemically, the DYT1 and DYT11 animal models also share some similarities to patients, such as a reduction in striatal D2 dopamine receptor and binding activities. In addition, conditional knockout mouse models for DYT1 and DYT11 dystonia demonstrate that loss of the causal dystonia-related proteins in the striatum leads to motor deficits. Interestingly, loss of the DYT1 dystonia causal protein in Purkinje cells shows an improvement in motor performance, suggesting that gene therapy targeting of the cerebellum or intervention in its downstream pathways may be useful. Finally, recent studies using DYT1 dystonia worm and mouse models led to a potential novel therapeutic agent, which is currently undergoing clinical trials. These results indicate that genetic animal models are powerful tools to elucidate the pathophysiology and to further develop new therapeutics for dystonia. © 2013 Movement Disorder Society.
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Multiple studies have demonstrated decreases in striatal D2-like (D2, D3) radioligand binding in primary focal dystonias. Although most investigations have focused on D2-specific receptors (D2R), a recent study suggests that the decreased D2-like binding may be due to a D3-specific (D3R) abnormality. However, only limited data exist on the role of D1-specific receptors (D1R) and the D1R-mediated pathways within basal ganglia in dystonia. Metabolic positron emission tomography (PET) data in primary generalized dystonia suggest resting state over activity in the D1R-mediated direct pathway, leading to excessive disinhibition of motor cortical areas. This work investigated whether striatal D1-like receptors are affected in primary focal dystonias.
Striatal-specific (caudate and putamen) binding of the D1-like radioligand [(11)C]NNC 112 was measured using PET in 19 patients with primary focal dystonia (cranial, cervical, or arm) and 18 controls.
No statistically significant difference was detected in striatal D1-like binding between the two groups. The study had 91% power to detect a 20% difference, indicating that false-negative results were unlikely.
Because [(11)C]NNC 112 has high affinity for D1-like receptors, very low affinity for D2-like receptors, and minimal sensitivity to endogenous dopamine levels, we conclude that D1-like receptor binding is not impaired in these primary focal dystonias.
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