Basal ganglia and gait control: apomorphine administration and internal pallidum stimulation in Parkinson's disease

Gait coordination was analyzed (four-camera 100 Hz ELITE system) in two gro ups of idiopathic Parkinson disease (PD) patients. Five patients underwent continuous infusion of apomorphine and were recorded in two different sessi ons (APO OFF and APO ON) in the same day. Three patients with a previous ch ronic electrode implantation in both internal globi pallidi (GPi) were reco rded in the same experimental session with the electrodes on and off (STIM ON and STIM OFF). The orientation of both the trunk and the lower-limb segm ents was described with respect to the vertical in the sagittal plane. Lowe r-limb inter-segmental coordination was evaluated by analyzing the co-varia tion between thigh, shank, and foot elevation angles by means of orthogonal planar regression. At least 30 gait cycles per experimental condition were processed. We found that the trunk was bent forward in STIM OFF, whereas i t was better aligned with the vertical in STIM ON in both PD groups. The le gs never fully extended during the gait cycle in STIM OFF, whereas they ext ended before heel strike in STIM ON. The multisegmental coordination of the lower limb changed almost in parallel with the changes in trunk orientatio n. In STIM OFF, both the shape and the spatial orientation of the planar ga it loops (thigh angle vs, shank angle vs, foot angle) differed from those o f physiological locomotion, whereas in STIM ON the gait loop tended to resu me features closer to the control. Switching the electrodes on and off in p atients with GPi electrodes resulted in quasi-parallel changes of the trunk inclination and of the planar gait loop. The bulk of the data suggest that the basal-ganglia circuitry may be relevant in locomotion by providing an appropriate spatio-temporal framework for the control of posture and moveme nt in a gravity-based body-centered frame of reference. Pallido-thalamic an d/or pallido-mesencephalic pathways may influence the timing of the inter-s egmental coordination for gait.