Abstract
Spasticity and chronic pain are both prevalent consequences of spinal cord injury (SCI), are commonly considered problematic, and are associated with reduced quality of life after SCI. This study investigated factors that contribute to the perceived impact of spasticity on daily life and how pain and spasticity are related. Analysis to characterize the strength of relationships between the impact of spasticity on life and physiological, environmental, and psychosocial factors can aid in identifying factors most strongly related to negative or positive impacts of spasticity. These factors may become candidates for experimental interventions aimed at reducing the problematic impact of spasticity on life. Therefore, the objective of this dissertation work was to improve understanding of the problematic impact of spasticity on life by characterizing associations between physiological, psychological, and functional measures of spasticity and pain in persons with SCI. A need exists to focus spasticity research on its problematic aspects. Spasticity is commonly reported to interfere with daily activities such as transfers between seats, though spasticity has also been reported to be helpful for activities such as transfers. Characterizing the strength of relationships between physiological aspects of spasms during transfers with the perceived impacts of spasticity can help guide spasticity research towards physiological aspects most related to problematic impacts. In Chapter 2, relationships between spasms evoked in a quadriceps muscle by seating transfers, the perceived impact of spasticity on activities of daily living, and clinically-rated spasticity severity were examined in persons with SCI and spasticity. There were no significant associations between the perceived impact of spasticity on daily activities and spasm duration, spasm magnitude, or clinical extensor spasticity score. However, the inter-day reliability of spasm magnitude and duration measured with electromyography was good to excellent, and spasm duration was positively associated with a clinical rating of extensor spasticity. The results imply that, for our non-ambulatory participants, involuntary muscle activity in quadriceps is not a strong determinant of the impact of spasticity on activities of daily living. Exploring other factors beyond physiological factors, such as pain and psychological characteristics, may lead to better understanding of how persons with SCI perceive the impact of spasticity on their lives. Although the role of psychological factors in people with SCI and chronic pain is well-studied, their associations with the psychosocial impact of spasticity is largely unexplored. Spasticity is often experienced by individuals who also experience various chronic pain conditions. Spasms in these individuals can therefore cause or exacerbate pain, but little is known about how these sequelae of SCI influence each other. Interactions between pain, spasticity, and psychosocial impact are likely and need clarification in order to understand better how spasticity affects daily life. In Chapter 3, relationships between chronic pain and spasticity after SCI were examined with respect to severity, impact on daily life, and psychological factors. Significant relationships between the severity of pain and spasticity, and between problematic impact of pain and of spasticity on daily life were found. Multiple factors explained variance in two measures of problematic impact of spasticity; specifically, greater self-rated spasticity severity, less resilience, greater time since injury, and greater difficulty of dealing with pain were associated with greater problematic impact of spasticity on life. In addition, persons who experienced painful spasticity had significantly higher overall chronic pain severity and more problematic impact of spasticity on sleep than persons who did not experience painful spasticity. The results suggest that spasticity and pain are strongly interrelated and painful spasticity may exacerbate chronic pain in persons with SCI. Another implication of the present studies is that interventions that target psychosocial factors may result in improved management of spasticity and pain after SCI.