The aim of this study is to conduct a multicentre phase I/IIa open label study to determine the safety and tolerability of the AMPA antagonist, perampanel in subjects with primary cervical dystonia. Exploratory analysis will determine effects on dystonia disability and subjective measures including quality of life and global impression of change. The importance of such an initial safety study is due to the lack of knowledge related to the use of this class of drug (AMPA antagonist) in this population of patients. The longer term aim is thus to generate preliminary data for further randomised controlled efficacy studies.