[Parkinson's disease as a model of aging: prospective analysis of gait discorders].

Falls are a dramatic consequence of the age-related gait disorders. There are few prospective studies on falls predictive of the biomechanical features of gait. According to the literature, there are similarities between the gait observed in older people and in parkinsonian subjects. The objective of this study was to apply multiparametric gait analysis to demonstrate changes of the neuromotor gait pattern connected with falls. This prospective study included two groups of 16 subjects aged more than 60 years, who had not fallen during the previous year. One group included 16 minimally disabled parkinsonian patients off drugs, and the other group 16 healthy people. Gait recordings were obtained with a three-dimensional optoelectronic movement analysis system coupled with 2 force platforms in all persons who were followed for 1 year to collect data on all new events, particularly falls. Data analysis concerned spatiotemporal stride and three-dimensional power peaks developed in each lower limb joint. Cluster analysis of the 32 persons was used to determine various infraclinic neuromotor gait patterns. A post hoc analysis of variance was then applied to identify discriminating parameters. Three groups of subjects were identified with 3 different neuromotor gait patterns, independently of the presence of Parkinson disease. There were no fallers in first group (n=18). The second group (n=8) had 20 p.cent fallers and the third group (n=4) 100 p.cent fallers. The groups differed by 4 spatiotemporal parameters and 3 joint power peaks in the sagittal plane. Functional capacity was good in the first group with no falls recorded. This group of subjects had characteristics reported in the literature corresponding to a category of persons who compensate well for the phenomena of aging. Functional capacity was intermediary in the second group (20 p. cent were fallers). The kinematic pattern appeared to be less successful, revealing a tendency for stiff posture. The third group (100 p. cent fallers) exhibited inferior functional capacity. In this group, the kinematic pattern appeared to be disrupted. The subjects were unable to adapt satisfactorily to situations other than by stereotypical neuromotor reactions. In conclusion this study demonstrated a close determinism between physiological neuromotor aging and Parkinson's disease. The prospective follow-up demonstrated that falls that occurred were related to changes in neuromotor gait patterns. Three phases of gait pattern were also identified from minimal to major risk of falls.