A STEP TOWARDS UNDERSTANDING BALANCE CONTROL IN INDIVIDUALS WITH INCOMPLETE SPINAL CORD INJURY

Purpose: Frequent falls are reported by individuals with spinal cord injury (SCI) suggesting impairments in their balance control. This thesis examined balance assessment and balance control in individuals with SCI. Methods and Results: To investigate the effects of light touch on standing balance, center of pressure (COP) sway during standing was measured in 16 participants with incomplete SCI (iSCI) and 13 able-bodied (AB) participants. Participants with iSCI showed reduction in COP sway with light touch similar to AB participants. To study the association between stability during normal walking (NW) and unexpected slip intensity, NW behaviour and intensity of an unexpected slip perturbation were assessed in 20 participants with iSCI, and 16 AB participants. Participants with iSCI demonstrated greater stability by walking slower, taking shorter steps, and more time in double support. Walking slower was associated with lower slip intensity in individuals with iSCI. To study reactive balance control, change in margin of stability with a compensatory step, activation of lower extremity muscles, and change in limb velocity trajectories in response to an unexpected slip perturbation were studied in 16 participants with iSCI and 13 AB participants. Participants with iSCI demonstrated limitations in reactive responses including a smaller increase in lateral margin of stability, slower onset of trail limb tibialis anterior activity, and decreased magnitude of trail limb soleus activity. To identify balance measures specific to individuals with SCI, a systematic review of 127 articles was conducted. Thirty balance measures were identified; 11 evaluated a biomechanical construct and 19 were balance scales designed for use in clinical settings. All balance scales had high clinical utility. The Berg Balance Scale and Functional Reach Test were valid and reliable, while the Mini Balance Evaluation Systems Test was most comprehensive. Conclusions: Individuals with iSCI have impaired balance control, as evidenced by limitations in reactive balance; however, they have the ability to modify their balance, as demonstrated by greater stability during NW and with light touch while standing. No single balance measure met all criteria of a useful measure - high clinical utility, strong psychometric properties, and comprehensiveness in the SCI population. Combined, the findings highlight the need for the comprehensive assessment and rehabilitation of balance control after iSCI