The Reproducibility and Special Features of Hemiparetic Gait in People With Acquired Brain Injury (ABI) Assessed With an Instrumented Treadmill (Zebris)

Introduction The term hemiplegia/hemiparesis is used for the neural deficit that may occur in patients after acquired brain injury (ABI), such as cerebral palsy, traumatic injury to the brain, or cerebrovascular accident. The word hemiplegia means the neuromuscular disorder that involves one-half of the body in the frontal plane while the other half is not involved.

Hemiparetic gait following ABI is grossly characterized by decreased speed of walking, increased stance time on the unaffected side, and decreased stance time on the affected side. Joint-angle disturbances include reduction or loss of the knee flexion phase in stance, reduction of knee flexion in the swing phase, sometimes loss of dorsiflexion of the ankle in the swing phase and at initial contact, and generally reduced joint excursions. Lehmann et all [1] have reported a greater-than-normal internal knee flexion moment at mid-stance in persons with hemiplegia, a feature that was thought to be related to anterior movement of the center of gravity. ("Internal" moments are expressed as those internal to the link-segment model; "external" moments are expressed as those acting upon the link-segment model.) The internal moment is usually the result of muscle activity, though tension of structures posterior to the knee may also be involved if the knee is fully extended. Patients with hemiplegia exhibit disturbed mechanical energy patterns and overall energy costs that are above normal [2]. The affected limb characteristically has shown tonic extensor activity, co-activation of major muscle groups, and loss of selective muscle control during stance [3]. The patterns of activity and the presence of co-activation during walking have been used to classify the gait of subjects with hemiplegia [4]. Muscle power patterns at major lower-limb joints during walking have been near normal in shape but reduced in amplitude, with the muscles of the affected side providing about 40% of the positive work [5].

These abnormalities are associated with a complex pattern of dysfunction including muscle weakness, spasticity, impaired sensory-motor control and long-term mechanical changes in muscles and joints [4], [6], [7], [8], [9], and cognitive impairments e.g. attention.

At this stage of our knowledge it is still unclear which kinetic and kinematic parameters of hemiparetic gait provide insight about the different components of the complex pattern of dysfunction.

Subjects with hemiparesis will show different reactions to change pattern of the treadmill, like gait velocity and inclination in comparison to healthy subjects. Especially performing the investigation under these challenging conditions may reveal the relevant insight in the contribution of these different components to the complex pattern of hemiparetic gait. Qualitative and quantitative evaluation of gait performed during clinical examination and gait examination in a gait laboratory deliver temporal and spatial parameters. These parameters relate to automatism and symmetry which are the two main components of gait.