Brain Advance Access originally published online on November 9, 2005
Brain 2006 129(1):36-46; doi:10.1093/brain/awh665
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Silent event-related fMRI reveals deficient motor and enhanced somatosensory activation in orofacial dystonia
Departments of 1 Neurology, 2 Radiology and 3 Nuclear Medicine, Klinikum rechts der Isar Muenchen, 4 Neurologisches Krankenhaus Muenchen, Germany
Correspondence to: Christian Dresel, MD, Klinikum rechts der Isar, Department of Neurology, Technische Universitaet Muenchen, Moehlstrasse 28, D-81675 Munich, Germany E-mail: dresel{at}lrz.tu-muenchen.de
Previous studies showed cortical dysfunction and impaired sensorimotor integration in primary generalized and focal hand dystonia. We used a whistling task and silent event-related fMRI to investigate functional changes in patients with blepharospasm and patients with a combination of blepharospasm and oromandibular dystonia (Meige's syndrome). Whistling served as a model for a skilful orofacial movement with a high demand on sensorimotor integration. It allowed us to study the oromandibular motor system that is clinically affected in Meige's syndrome but not in isolated blepharospasm. In Meige's syndrome, functional MRI revealed deficient activation of the primary motor and ventral premotor cortex within the mouth representation area during whistling. Compared with healthy controls, both forms of orofacial dystonia had increased activation of bilateral somatosensory areas and the caudal supplementary motor area (SMA) in common. While overactivity of somatosensory areas and caudal SMA in Meige patients was partly reversed by botulinum toxin treatment, impaired motor activation was not. We conclude that impaired motor activation appears to be specific for the clinically affected oromandibular motor system in Meige's syndrome while enhanced somatosensory activation is a common abnormality in both forms of orofacial dystonia independent of the affected motor system. Somatosensory overactivity indicates an altered somatosensory representation in orofacial dystonia while impaired motor activation may be a functional correlate of reduced cortical inhibition during oromandibular motor execution in Meige's syndrome.
Key Words: fMRI; functional reorganization; orofacial movements; focal dystonia; blepharospasm
Abbreviations: BA = Brodmann area; BLEPH = patients with blepharospasm; BTX = botulinum toxin; CONTR = healthy control subjects; MEIGE = patients with Meige's syndrome; postBTX = after botulinum toxin therapy; preBTX = before botulinum toxin therapy; RMS = root mean square; SMA = supplementary motor area; S1 = primary somatosensory cortex; TMS = transcranial magnetic stimulation; UDRS = Unified Dystonia Rating Scale
Received June 9, 2005. Revised August 18, 2005. Accepted September 20, 2005.
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