Etiological and pathophysiological aspects of cervical dystonia Dystonias present in many different ways and can vary widely in the number of body areas and systems involved, as well as in clinical features, age of onset, natural history, and etiology. Cervical dystonia (CD) may be isolated or a part of more complex dystonias, be they primary or secondary. The majority of CDs are primary and focal, that is, they have no other associated clinical or neuroimaging features and they remain restricted to the neck and shoulder girdle muscles. Secondary CD can be drug induced or caused by a peripheral or central nervous system (CNS) lesion or genetic metabolic defects. We will provide an overview of data derived from genetic, posttraumatic, and tardive etiologies of CD. This will be followed by a more in-depth discussion of potential loci of pathological changes within the CNS and discussion of the motor and sensory features that result will follow. The evidence presented will focus on studies of CD and will be complemented with studies from other dystonias. For an expanded discussion of the epidemiology, clinical presentation, and classification of CD, see Dr. Stacy's article in this supplement.