Visual control of locomotion in Parkinson's disease

Abstract

The effect of placing parallel lines on the walking surface on parkinsonian gait was evaluated. To identify the kind of visual cues (static or dynamic) required for the control of locomotion, we tested two visual conditions: normal lighting and stroboscopic illumination (three flashes/s), the latter acting to suppress dynamic visual cues completely. Sixteen subjects with idiopathic Parkinson's disease (nine males, seven females; mean age 68.8 years) and the same number of age-matched controls (seven males; nine females, mean age 67.5 years) were studied. During the baseline phase, Parkinson's disease patients walked with a short-stepped, slow velocity pattern. The double limb support duration was increased and the step cadence was reduced relative to normal. Under normal lighting, visual cues from the lines on the walking surface induced a significant improvement in gait velocity and stride length in Parkinson's disease patients. With stroboscopic illumination and without lines, both groups reduced their stride length and velocity but the changes were significant only in the Parkinson's disease group, indicating greater dependence on dynamic visual information. When stroboscopic light was used with stripes on the floor, the improvement in gait due to the stripes was suppressed in parkinsonian patients. These results demonstrate that the perceived motion of stripes, induced by the patient's walking, is essential to improve the gait parameters and thus favour the hypothesis of a specific visual-motor pathway which is particularly responsive to rapidly moving targets. Previous studies have proposed a cerebellar circuit, allowing the visual stimuli to by-pass the damaged basal ganglia.

Walking performance of vestibular-defective patients before and after unilateral vestibular neurotomy

“…Decreased walking velocity can be considered as a behavioural strategy to avoid imbalance and fall, as reported by some subjects and as already seen in behavioural investigations in our cat model [28]. In addition, slow or reduced locomotion velocity by taking shorter steps was also reported for non-pathological subjects over 65 years [15], as well as in pathological cases including Parkinson's disease [2] and neuropathic patients [13]. Taken together, the similar changes in gait parameters found both with aging and in different pathologies strongly suggest that they are unlikely related directly to a specific sensory loss (unilateral vestibular deficit, herein) but rather to a reduction in self-selected walking speed.…”

Subjective visual vertical perception and sense of smell in Parkinson disease

“…It has also been reported that there is an increased visual dependence perceptually in patients with PD [8]. Interest in visual dysfunction is enhanced by the possible relationships between gait disorders and visual perception [9]. Gait problems such as festination and freezing are thought to be strongly influenced by visual stimulation [10].…”

The competition with a concurrent cognitive task affects posturographic measures in patients with Parkinson disease

“…Beyond this natural aging process, other factors may contribute to balance disruption facing sensory disturbance, in this population. Loss of automation in performing postural changes can increase the dependence on visual information 26 . Studies of Ickenstein et al 7 .…”