ABSTRACT
INTRODUCTION Defi nition and Classifi cations Inherited dystonias are a clinically and genetically heterogeneous group of movement disorders. Despite this variability, there is considerable overlap between different forms of dystonia, as they all share the common features of involuntary twisting and repetitive movements resulting in abnormal postures (1). More recently, efforts have been made to clarify the terminology of the dystonias, but confusing defi nitions remain. The term “dystonia” itself conveys three different meanings: fi rst, a physical sign; second, a syndrome of sustained muscle contractions; and third, the disease “idiopathic (or primary) dystonia” (2). The latter term “idiopathic dystonia” or “primary dystonia” usually refers to the genetic forms of dystonia that clinically manifests as dystonia and sometimes as tremor (3).
