Evaluation of the Edrophonium Challenge Test for Cervical Dystonia

OBJECTIVE: To examine whether or not an edrophonium challenge test is useful for diagnosing cervical dystonia. PATIENTS: We evaluated 10 patients with cervical dystonia and 10 with hemifacial spasms (disease controls). We administered edrophonium and saline in this double-blinded study. Before and after the injection, we recorded the participants' clinical signs using a video camera to assess the objective symptoms every two minutes. Ten minutes after the saline and edrophonium injections, participants evaluated their subjective clinical signs using a visual analog scale. The objective signs on the video recordings were scored by specialists who were blinded to the treatment. The mean visual analog scale scores were compared using the Wilcoxon rank-sum test for paired continuous variables. RESULTS: The clinical signs of participants with cervical dystonia were amplified by edrophonium. In contrast, the clinical signs in participants with hemifacial spasms were not affected by the edrophonium challenge test. CONCLUSION: The edrophonium challenge test may be useful for diagnosing cervical dystonia.