ABSTRACT
Cervical dystonia (CD) is characterized by involuntary spasms of neck muscles that cause abnormal head and neck movements and postures (1). The term spasmodic torticollis is frequently used to describe this condition, but it applies only to one type of CD manifested by jerky (spasmodic) head movement associated with head turning (torticollis). CD is the preferred term to describe focal dystonia that involves neck muscles. CD is the most common type of adult onset focal dystonia (2). CD prevalence is estimated at 9/100,000, but it is likely higher as that number was based on a retrospective chart review (3). The etiology of CD varies. The majority of patients have idiopathic CD, which means that there is no identifiable cause. Some patients with idiopathic CD have a genetic cause; however, genetic contribution to focal dystonia has been much less studied compared to generalized dystonias like DYT1 (4). The most common symptomatic causes of CD are drugs and trauma (5). Drug-induced CD can occur as an acute reaction to neuroleptics or related compounds, which is reversible with discontinuation of the drug, or can be a manifestation of tardive dyskinesia, in which case it is chronic with low chance for remission (6). The relationship between CD and peripheral neck injury remains debated (7,8). A number of patients report ‘‘significant’’ neck injury within a year prior to onset of CD. The causality of such injury has not been established, but the possibility of the
contribution of peripheral mechanisms to development of CD via involvement of the sensory feedback loops cannot be excluded (9,10). A number of other neurological and non-neurological conditions can present with abnormal head postures and should not be misdiagnosed as CD (11). The most important conditions for screening include atlanto-axial dislocation, cervical fracture, or other bone abnormalities of the cervical spine (11). In the majority of cases, these conditions lead to a fixed and sustained abnormal posture of the neck, which is atypical for CD. Appropriate imaging of the cervical spine and brain should be performed when a structural cause of CD is suspected.
