Clinical measures of the neurophysiological mechanisms of rehabilitation-induced improvements in chronic stroke

Stroke is a leading cause of disability with up to 83% of survivors suffering persistent hemiparesis. The only means to improve motor-function in the post-acute phase is with rehabilitation. The first study of this thesis investigated changes in proprioception at the elbow and wrist in comparison to healthy age- and sex-matched people. Differences in the magnitude and direction of perception varied with joint and motor-function status. This study emphasises the specificity of proprioception deficits and the need for quantitative testing for this input to motor control that may be independent of the reduced descending drive from the lesioned hemisphere. The subsequent studies investigated the physiological mechanisms of post-stroke recovery during Wii-based Movement Therapy (WMT) using wireless telemetry to record joint goniometry, lower-limb muscle activation and heart rate. Joint kinematics measured during therapy is the most direct measure of movement ability. Faster acceleration and peak deceleration reflected better movement control. Kinematic data were correlated with functional assessments measured pre- and post-therapy but not with active or passive range-of-motion, suggesting that range-of-motion is not a good test of functional improvements in chronic stroke. Lower-limb muscle activation was recorded bilaterally from tibialis anterior. Muscle symmetry and peak activation improved differently both within and between patients and WMT activities, and these correlated with improvements in lower-limb functional assessments. Finally, a post-hoc comparison between the cardiovascular responses with WMT and modified Constraint-Induced Movement Therapy (mCIMT) revealed a significant increase in peak heart rate and faster heart rate recovery time by late-therapy for WMT indicating increased cardiovascular fitness. Peak heart rate was always higher and heart rate recovery faster during mCIMT but neither changed by late-therapy, suggesting a sympathetic stress response to mCIMT activities that emphasise movement speed and high repetition rates. This thesis highlights the need for sensitive quantitative measures of post-stroke function. It is the first to report functional progress during an upper-limb therapy program. Finally, the results show that the functional capacity to improve post-stroke can be extended into the chronic period and that a targeted upper-limb protocol such as WMT can be multifactorial with ancillary lower-limb and cardiovascular benefits

Investigation and Quantification of FES Exercise – Isometric Electromechanics and Perceptions of Its Usage as an Exercise Modality for Various Populations

Functional Electrical Stimulation (FES) is the triggering of muscle contraction by use of an electrical current. It can be used to give paralyzed individuals several health benefits, through allowing artificial movement and exercise. Although many FES devices exist, many aspects require innovation to increase usability and home translation. In addition, the effect of changing electrical parameters on limb biomechanics is not entirely understood; in particular with regards to stimulation duty cycle. This thesis has two distinct components. In the first (public health component), interview studies were conducted to understand several issues related to FES technology enhancement, implementation and home translation. In the second (computational biomechanics component), novel signal processing algorithms were designed that can be used to measure mechanical responses of muscles subjected to electrical stimulation. These experiments were performed by changing duty cycle and measuring its effect on quadriceps-generated knee torque. The studies of this thesis have presented several ideas, toolkits and results which have the potential to guide future FES biomechanics studies and the translatability of systems into regular usage for patients. The public health studies have provided conceptual frameworks upon which FES may be used in the home by patients. In addition, they have elucidated a range of issues that need to be addressed should FES technology reach its true potential as a therapy. The computational biomechanics studies have put forward novel data analysis techniques which may be used for understanding how muscle responds to electrical stimulation, as measured via torque. Furthermore, the effect of changing the electrical stimulation duty cycle on torque was successfully described, adding to an understanding of how electrical stimulation parameter modulation can influence joint biomechanics