Mildly Impaired Foot Control in Long-Term Treated Patients with Wilson's Disease

Abnormal gait is a common initial symptom of Wilson's disease, which responds well to therapy, but has not been analyzed in detail so far. In a pilot study, a mild gait disturbance could be detected in long-term treated Wilson patients. The question still is what the underlying functional deficit of this gait disturbance is and how this functional deficit correlates with further clinical and laboratory findings. In 30 long-term treated Wilson patients, the vertical component of foot ground reaction forces (GRF-curves) was analyzed during free walking without aid at the preferred gait speed over a distance of 40 m. An Infotronic^® gait analysis system, consisting of soft tissue shoes with solid, but flexible plates containing eight force transducers, was used to record the pressure of the feet on the floor. Parameters of the GRF-curves were correlated with clinical scores as well as laboratory findings. The results of Wilson patients were compared to those of an age- and sex-matched control group. In 24 out of 30 Wilson patients and all controls, two peaks could be distinguished: the first "heel-on" and the second "push-off" peak. The heights of these peaks above the midstance valley were significantly reduced in the patients (p < 0.05). The time differences between peaks 1 or 2 and midstance valley were significantly negatively correlated with the total impairment score (p < 0.05). Gait speed was significantly correlated with the height of the "push-off" peak above the midstance valley (p < 0.045). The GRF-curves of free walking, long-term treated patients with Wilson's disease showed a reduced "push-off" peak as an underlying deficit to push the center of mass of the body to the contralateral side with the forefoot, explaining the reduction in gait speed during walking.