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.

Comparative study of plaque and gingivitis prevention by AmF/SnF2 and NaF. A clinical and microbiological 9-month study.

This comparative clinical 9-month study was designed to examine the efficacy of amine/stannous fluoride (AmF/SnF2) (Meridol) and sodium fluoride (NaF). 150 probands with chronic gingivitis or early signs of periodontitis were divided into 3 randomised groups. Group 1 was given a NaF toothpaste and an NaF mouthrinse, group 2 AmF/SnF2 toothpaste and mouthrinse, and group 3 AmF/SnF2 toothpaste and NaF mouthrinse. The probands were examined at intervals (0, 1, 3 and 9 months) under conditions of a clinical double-blind study. The parameters recorded were the plaque index (PlI), the approximal plaque index (API), the gingival index (GI) and the mod. sulcus bleeding index (SBI). The probing depths (PD) were also measured. The composition of the supragingival plaque was evaluated by dark-field microscopy. A highly significant reduction in all clinical parameters was recorded in all 3 groups in the course of the study. The most pronounced reduction in PlI, API, SBI and PD was recorded in group 2. In the group comparison, however, no significant differences were recorded. Microbiological examination revealed a highly significant increase in cocci and a decrease in rods in all 3 groups. There was also a significant reduction in spirochetes, filaments and fusiforms in groups 2 and 3. In group 1, there was a significant fall only in fusiforms and small spirochetes. Overall, no significant difference in clinical parameters was recorded in the group comparison. However, the use of AmF/SnF2 toothpaste and mouthrinse (group 2) and, to a lesser degree, the combined use of AmF/SnF2 toothpaste and NaF mouthrinse display a favorable microbiological effect. The results from the present double-blind study reveal a reduction in gingival inflammation and supragingival plaque accumulation with a positive change in plaque flora in all groups. The reduction in potentially gingivopathogenic bacteria was slightly higher in the amine/stannous fluoride group.