Assessment of patients with isolated or combined dystonia: An update on dystonia syndromes

Abstract

The clinical evaluation of a patient with dystonia is a stepwise process, beginning with classification of the phenomenology of the movement disorder(s), then formulation of the dystonia syndrome, which in turn leads to a targeted etiological differential diagnosis. In recent years there have been significant advances in our understanding of the etiological basis of dystonia, aided especially by discoveries in imaging and genetics. In this article, we provide an update on the assessment of a patient with dystonia, including the phenomenology of dystonia and highlighting how to integrate clinical, imaging, blood and neurophysiological investigations in order to formulate a dystonia syndrome. Evolving or emerging dystonia syndromes are reviewed and potential etiologies of these as well as established dystonia syndromes listed in order to guide diagnostic testing.

Diagnosis and Treatment of Dystonia

“…A careful delineation of the syndromic pattern, along with neuroimaging characteristics, is important because it aids in narrowing down the long list of potential etiologies for more targeted diagnostic testing. 7 …”

“…The diagnostic approach in younger individuals with isolated dystonia is quite different, because there is a much higher likelihood of disclosing a cause. 7 Neuroimaging is important for all early-onset cases, regardless of body distribution. Genetic testing for early-onset isolated dystonias should target the TOR1A gene for DYT1 dystonia and the THAP1 gene for DYT6 dystonia.…”

“…A recent review summarized more than 100 different disorders where dystonia may be combined with other features, organized in 18 tables according to the associated clinical features and age at onset. 7 Neuroimaging is useful in virtually all combined dystonias, because it can provide important diagnostic clues. Genetic testing for DYT1 and DYT6 dystonia is not useful in combined dystonia syndromes.…”

“…7 Some dystonias are inherited, others are acquired (Table 2). Some dystonias have no apparent pathology in the nervous system, while others are associated with defects that can be detected by neuroimaging or post-mortem histopathological studies.…”

Designing Clinical Trials for Dystonia

“…Dystonia encompasses a spectrum of complex and variable movements and postures, the distribution of which may be focal, segmental, or generalized, and the cause of which may be idiopathic, genetic, or acquired [7,8]. Phenomenologically, the disorder classically is defined as "a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures" [9].…”