Does freezing in Parkinson's disease change limb coordination? A kinematic analysis

The aim of this study was to analyse the kinematic characteristics of the strides before freezing and compare this with a voluntary stop and ongoing gait. Also, we investigated whether gait profiles were different as a function of the side of the body. Ten patients were included with a mean age of 64.8 years (SD 5.1). Within a Vicon 3D gait laboratory, patients performed several trials of normal walking and voluntary stops or were exposed to circumstances, which provoked freezing in the off-phase of the medication cycle. Spatiotemporal and key kinematic data of the four strides prior to freezing were compared between body sides and walking conditions using multiple regression models for repeated measures. Prior to freezing patients had severely decreased movement ranges in the sagittal plane (ranging between 31% and 61.5%), most notably in the ankle and hip joints. The general shape of movement remained in the pre-freezing profiles with largely intact dissociation of knee and hip movement in stance but reduced dissociation in swing. Also present were reduced push-off movements in the ankle with fixed dorsiflexion, increased flexion in hip and knee and anterior tilt of the pelvis. During both voluntary (stopping) and involuntary deceleration (freezing), the body side with the last complete stride before the freeze, showed significantly smaller joint ranges (p < .01). Body side differences were larger than sequential deterioration of consecutive steps within each side. Freezing is distinct from normal deceleration of gait in that the reduction of propulsive movement is much greater. Despite hastening of steps, timing deficits did not affect overall movement shapes, except for the tendency to have a flexed walking pattern. The side of the body where gait terminated before freezing was in most cases the side of symptom-dominance, but not consistently so.