Clinical comparison of tardive and idiopathic cervical dystonia

It has been suggested that tardive cervical dystonia may be clinically indistinguishable from the idiopathic form and that the diagnosis rests solely on documenting an exposure to dopamine antagonist medications. To investigate this, we performed a retrospective evaluation of patient records on 102 patients with idiopathic and 20 patients with tardive cervical dystonia seen in our Movement Disorder Clinic over the past 8 years. Several clinical and demographic variables were compared and a number of differences were observed. The presence of extracervical involvement, retrocollis, and spasmodic head movements were individually found to be predictive of tardive cervical dystonia. Torticollis, laterocollis, and trick maneuvers were predictive of idiopathic cervical dystonia. Head tremor (42.2%) and family history of dystonia (9.8%) were present only in the idiopathic group. Cervical muscle hypertrophy was significantly more common in the idiopathic group (100% versus 75%). No difference was found between the two groups in their response to treatment with botulinum toxin A. These results indicate that clinical differences between idiopathic and tardive cervical dystonia exist. These differences may help to distinguish them in the clinical setting, improve diagnostic accuracy, and support the existence of a causal relationship between exposure to dopamine antagonist medications and chronic dystonia.