One factor, which may contribute to slowed movement in dystonia, is impairment in controlling the voluntary rate of motor output. This study examined the ability of patients with focal hand dystonia to rapidly turn force on and off at the wrist and elbow joints. Dystonic patients were slower than controls in rapidly turning on force from rest at both joints, passively relaxing force and rapidly reversing force output from a steady-state flexion contraction. Adding a preload did not improve the ability of dystonic subjects to rapidly turn on force. These results support the idea that dystonia is a disorder of impaired motor cortical activation, possibly due to basal ganglia dysfunction.
Bibliographical noteFunding Information:
We would like to thank the staff at the Section for Movement Disorders in the Department of Neurological Sciences at Rush University Medical Center and Dr. Tanya Simuni in the Department of Neurology at Northwestern Memorial Hospital for their assistance in patient recruitment. Also, we thank Dr. Annette Weis-McNulty and Ms. Emily Gilley for their assistance with some aspects of data collection. This study was supported in part by the National Institutes of Health Grants AR33189, NS21827, and NS40902.
- Basal ganglia
- Motor control
- Writer's cramp