Gait analysis in healthy subjects and Parkinsonian patients

In order to get further informations about the pathophysiology of parkinsonian gait, we examined the EMG-pattern of muscles of the lower extremity [tibialis anterior (TA), medial head of gastrocnemius (GC), vastus medialis (VM), biceps femoris (BF), iliopsoas (IP) and gluteus maximus (GM)] in 20 parkinsonian patients and 15 normal controls during normal gait on a treadmill. The different phases of a step were identified by pressure sensors. The begin of a step-cycle was defined by the increase of heel-pressure. The duration of the EMC-activity was given as percentage of the normalized step-cycle, and the amplitude of the EMG-activity was given as percentage of the maximal isometric activity. 14-76 step-cycles were averaged. The gait velocity was significantly reduced in parkinsonian patients, whereas there was no difference of the step-duration. Within the step-cycle, the stance phase was significantly prolonged in parkinsonian patients. This can be explained by an increased duration and amplitude of EMG-activity of VM and BF in the stance phase. In both groups, TA and GC showed an antagonistic EMC-pattern, the amplitude of TA was significantly increased in parkinsonian patients. In addition, moderately affected patients (Webster-scale) showed a decreased duration of GC-activity which can also result in a prolonged stance phase. The proximal muscle groups showed synergistic activities. In parkinsonian patients, BF was delayed during swing phase. Together with an increased amplitude of VM, this can explain the reduced extent of knee-flexion. The amplitude of the CRA was significantly increased which can detoriate hip-flexion. These alterations were more pronounced in moderately affected in comparison with slightly affected patients. These findings were related to the severity of clinical affection and correspond to the clinical signs of the short-stepped and stiff gait of parkinsonian patients.