Patients with primary cervical dystonia have evidence of discrete deficits in praxis

Background: Functional imaging and electrophysiological data from patients with primary dystonia reveal widespread abnormalities in brain areas associated with higher motor functions but to date there has been little investigation of the functional consequences of these abnormalities. The aim of this study was to use a battery of tests of praxis, based on those tests used in routine clinical examination, to uncover evidence of higher motor dysfunction in patients with primary cervical dystonia. Methods: Praxis was assessed in 13 patients with primary cervical dystonia without hand involvement and in 29 age and sex matched controls. A semiquantitative praxis assessment was used which combined timed tests of meaningful and meaningless movements with copying of transitive and intratransitive hand movements and pantomime of tool use. Control tasks consisted of evaluation of motor speed, strength and a number of additional cognitive tasks. Results: Patients made significantly more errors in copying meaningless gestures and were slow in the performance of meaningless sequences of hand movements. Copying meaningful gestures and performance of meaningful sequences of hand movements were normal. Conclusion: This study has identified a discrete deficit in praxis in dystonia patients and suggests additional functional consequences from the widespread pathophysiological abnormalities seen in primary dystonia.