This application addresses PA 10-006 Mechanisms, Models, Measurement, and Management in Pain Research (R01). The majority of children with cerebral palsy (CP) live with spasticity and spasticity-induced disabling chronic pain. One of the front-line treatments for spasticity involves surgically implanting a pump to intrathecally deliver baclofen (ITB). Doing so avoids the problems with orally administered baclofen but creates problems of its own including general surgical risks but also procedure specific issues such as cerebral spinal fluid (CSF) leaks and catheter malfunction leading to serious withdrawal complications. Thus, the procedure is not without risk, but on balance the evidence is tilted toward efficacy for spasticity outcomes by reducing spasticity. It is less clear, however, whether the chronic pain is also and always reduced. There are mixed and muddled results specific to pain outcomes; mixed because in some studies pain is reported to decrease but in others there is no apparent change, muddled because the majority of the studies are poorly designed with pain poorly measured and so the results are scientifically uncertain and clinically ambiguous. This specific problem - whether or not pain improves following ITB treatment - is part of a much broader general issue - whether we can use scientific advances from pain research to improve our clinical understanding of pain and disability among children with significant intellectual, motor, and communicative impairments associated with neurodevelopmental disorders. The overall goal of this application is to initiate a line of research with the primary objective of improving our scientific understanding of changes in chronic pain in response to treatment among children with significant neurodevelopmental disabilities. The specific purpose of this interdisciplinary translational proposal is to clarify the clinical ambiguity in pain outcomes in relation to ITB treatment by prospectively studying a sample of children with CP and spasticity before and after ITB implant. By doing so, we will be able to (a) examine in detail the relation between changes in spasticity and pain, (b) evaluate whether pain that persists even in the presence of reduced spasticity will be associated with poorer functional outcomes, and (c) empirically test whether treatment parameters associated with the pump implant, clinical features associated with CP, or physiological variables associated with pain, stress, and inflammation interact to influence pain specific treatment outcomes. To date, there has been no comprehensive study specific to chronic pain among children with CP treated with ITB pump implants. Considering the vulnerable clinical population for the proposed project, we believe there is an urgent imperative to try to make scientific advances from the 'bench' relevant to real-world pain and disability problems. Ultimately, the knowledge gain should transfer into a clinical decision making aide with respect to improving patient selection criteria and by informing patients, their families, and healthcare providers more completely about the full range of expected outcomes with respect to pain and function.
Chronic pain associated with spasticity among children with cerebral palsy (CP) is a significant public health problem. Their spasticity is increasingly treate surgically by implanting intrathecal baclofen pumps for which it seems clear that although spasticity tends to respond (be reduced), a sizable subgroup of children continue to experience considerable pain and it is not clear whether this 'analgesic failure' is related to characteristic of their disability, psychosocial processes, treatment parameters associated with the pump, or individual differences in physiology relevant to pain, stress, and inflammation. The purpose of this study is discover whether there are clinically relevant marker variables that would improve our ability to predict who is more or less likely to be a 'pain responder' to ITB treatment.
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