Multiple Sclerosis, 1 October 2003, vol. 9, no. 5, pp. 492-502(11)
Feys P.; Helsen W.F.; Liu X.; Lavrysen A.; Loontjens V.; Nuttin B.; Ketelaer P.
 Katholieke Universiteit Leuven, Department of Kinesiology, Leuven, Belgium; West London Neuroscience Centre, Division of Neurosciences and Psychological Medicine, Charing Cross Hospital, London, United Kingdom; Katholieke Universiteit Leuven, Dep  Katholieke Universiteit Leuven, Department of Kinesiology, Leuven, Belgium  West London Neuroscience Centre, Division of Neurosciences and Psychological Medicine, Charing Cross Hospital, London, United Kingdom  Katholieke Universiteit Leuven, Department of Neurosciences and Psychiatry, Leuven, Belgium  National Multiple Sclerosis Center, Melsbroek, Belgium
The effect of visual information on step-tracking movements was studied in 18 patients with intention tremor due to multiple sclerosis (MS) and 15 healthy controls.
Participants performed a slow wrist step-tracking task with stationary targets under five visual feedback conditions.
The display of the target and movement cues was selectively withdrawn to examine the effects of visual information on intention tremor and movement accuracy.
Results showed that intention tremor was most pronounced when visual display of both target and movement cues was available.
Withdrawing visual information of the limb movement reduced tremor more than withdrawing the visual display of the target cues.
Both the patient and control group was less accurate when the display of limb movement was occluded.
Patients, however, were more dependent on visual information of the limb movement for accurate motor performance than healthy controls.
When the visual display of the limb movement was partially occluded between or near to the targets, tremor decreased without deterioration of movement accuracy.