Balance control for cervical spondylotic myelopathy : spatial, temporal domain features and compensatory neuroplasticity

Abstract

Cervical spondylotic myelopathy (CSM) is regarded as the most common cause of spinal cord dysfunction in the elderly. Patients with CSM can have difficulty in keeping balance due to proprioception loss, which raises the risk of secondary injury and remarkably reduces their quality of life. In general, balance control is a highly complex process relying on the integration of multiple sensory modalities. Given the neuroplasticity of human brain networks, we have reason to believe that enhanced visual function may be associated with balance control in CSM to compensate for proprioception loss. However, the full nature of the adaptive changes of visual participation in the balance control in CSM has yet to be clarified. This thesis aims to investigate the spatial and temporal domain features of balance control in CSM patients with/without vision and the neural mechanism of visual participation in balance control under pathological conditions. Several analyses were conducted.

First, the detailed description of balance control was discussed. Based on this description, a quantitative posturography experiment was designed. Coarse and fine control of balance in CSM was quantitatively studied under both eyes open/closed conditions. When depriving vision, the spatial and temporal domain features of balance control of CSM patients were not well correlated, and the balance control of CSM patients deteriorated in terms of both fine and coarse control, which could be a result of proprioception loss. When allowing vision, the coarse control of balance of CSM patients was still deteriorated, but fine control was not as affected, which implies visual participation may be increased to aid balance.

Second, the relationship between the coarse/fine control performance and the contribution of visual perception to the balance control of CSM patients was investigated using Romberg ratio analysis, which should answer whether and how vision compensates balance control. The contribution of visual perception was increased to compensate for the deteriorated fine balance control in CSM, which positively correlated with performance. The increased contribution of visual perception did not enhance coarse control performance, possibly because enhanced visual reliance usurps the limited cognitive resources from other functions, and causes conflict with impaired proprioceptive information. A conceptual model was built up to describe the global picture of information flow in neural network reorganization with regard to balance control in CSM.

This thesis provides a framework for further research on adaption in balance control under pathological conditions and offers novel insights into understanding neural network reorganization in CSM patients. Some of the findings could be directly applied to help CSM patients avoid falls and thereby improve their daily lives.