Kinematic effects of subthalamic stimulation on reach-to-grasp movements in Parkinson's disease.

BACKGROUND: Parkinsonian patients demonstrate particular difficulties when performing sequential motor tasks compared to simple movements indicating an important role of the basal ganglia in switching between different motor programs. OBJECTIVE: To investigate the impact of subthalamic stimulation on the kinematics of composed reach-to-grasp movements and on isolated movement segments. METHODS: 11 age matched controls and 16 PD patients with subthalamic stimulation were examined without medication with stimulation switched on and off. All subjects were instructed to perform three different externally cued hand movements: 1) The complete reach-to-grasp movement consisting of hand transport to and precision grip around a target. 2) The isolated reach movement to the grip device 3) The isolated precision grip and button press. Kinematic data were recorded with a 3D ultrasound movement analysis system (CMS 70 P4-V5, Zebris, Germany). RESULTS: The effect of subthalamic stimulation was accentuated during the reach phase compared to the grip formation during the composed movement. Stimulation induced kinematic changes of the composed movement were comparable to those of both isolated submovements. CONCLUSION: Subthalamic stimulation improved certain aspects of all three hand movement types but did not differentially impact the composed reach-to-grasp task compared to the simple submovements. We assume that the complete reach-to-grasp task is encoded in a single generalised motor program which is affected by stimulation.

Classification system based on kinematic MR imaging in cervical spondylitic myelopathy.

BACKGROUND AND PURPOSE: Functional myelographic studies are often used to evaluate the dynamic changes of the cervical spinal canal during flexion and extension. The purposes of this study were to use kinematic MR imaging to assess the dynamic changes of the cervical spine in patients at different stages of degenerative disease and to describe a classification system based on static and dynamic factors in the pathogenesis of cervical spondylitic myelopathy. METHODS: Eighty-one patients with different stages (I-IV) of degenerative disease of the cervical spine were examined with MR imaging. In the neutral position (0 degrees) and at maximum flexion and extension, spinal stenosis was classified for each segment according to the following grading system: 0 = normal, 1 = partial obliteration of the anterior or posterior subarachnoid space, 2 = complete obliteration of the anterior or posterior subarachnoid space, and 3 = cervical cord compression or displacement. RESULTS: At flexion and extension, the prevalence of spinal stenosis and cervical cord impingement increased as the stage of degenerative disease progressed. With regard to a pincer effect (anterior and posterior cord impingement) and cord encroachment at multiple segments, statistically significant differences were observed at stages III and IV as compared with stages I and II. Significant increase in cord impingement was seen in 22 (27%) of 81 patients at extension, as compared with four (5%) of 81 patients at flexion. CONCLUSION: Regardless of the stage of degenerative disease and grade of spinal stenosis at the neutral position (0 degrees), cervical spinal motion may contribute to the development of cervical spondylitic myelopathy.