Richard T. Lauer, Ph.D. - US grants

[unreadable] DESCRIPTION (provided by applicant): Cerebral palsy (CP) is a heterogeneous collection of non-progressive motor disorders of the developing brain that may occur before or after birth up to the age of two years. The incidence of CP in the United States, Western Europe, and Australia across multiple studies is between 2 and 3 cases per 1000 live births, with an estimated net lifetime economic cost of over $900,000 and estimated medical costs of over $1,100,000 (2003 dollars). Due to the high incidence and costs associated with CP, there is the need for the continual development of clinical interventions to improve motor function, and a need for the development of improved assessment strategies to gauge the effects of clinical intervention. Several methods exist to evaluate motor function in the child with CP and are used to assess the outcome of a clinical intervention. However, these scales are not directed towards measuring the changes in muscle activity patterns that can result from the intervention. For example, there are classification scales aimed at measuring motor function and functional abilities, and indices of gait function. These scores, while providing a way to quantify function and mechanics, do not directly measure muscle activation characteristics. Therefore, these tests may be insensitive to how the intervention has directly affected muscle function, which is usually the focus of the intervention (i.e. botulinum toxin, functional electrical stimulation, dorsal rhizotomy). Muscle biopsies and motor evoked potentials can provide information about the muscle activation characteristics, however, they are invasive and there are concerns about using these techniques on the pediatric population and/or the practicality of clinical implementation, especially since they do not provide insight into how the muscle behaves during a functional task. One method that can be used to provide insight into muscle activity in a non-invasive and clinically meaningful manner is the use of surface electromyography (sEMG). Surface EMG is typically a routine part of clinical assessment and the evaluation of motor impairment in CP. However, the analysis of the data has been limited in most cases to examination of signal amplitude or differences in muscle onset and offset timing. The long-term goal of this research is to develop an analysis method for sEMG that can be used during functional tasks for treatment planning, diagnostic, assessment purposes in CP. This is to be accomplished through the use of the continuous wavelet transform (CWT). By developing an assessment method based on muscle activity, it is believed that a clinically viable measurement tool can be devised that will provide a level of insight into the effects of an intervention on muscle pathophysiology that is not currently available. The first step in progressing towards this long-term goal is to determine the variability and range of expected time-frequency patterns that can be expressed in a given population (i.e., cerebral palsy) during the execution of a meaningful task (gait), and relate the time-frequency information back to more standard assessments [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Individuals with Cerebral Palsy (CP) present with considerable functional heterogeneity, and demonstrate a marked decrease in functional status with age due to the development of disturbances in somatosensory function, secondary neuromuscular impairments, and poor control over the trunk muscles. These factors promote balance instability, result in an increased fall risk, and contribute to lost functional capabilitis. Little is known about the progression of neuromotor and somatosensory impairments as individuals with CP age, thus a knowledge gap exists concerning postural control and balance in the adult with CP, particularly which those associated with aging (primary) and those associated with compensatory behaviors. The objective of this proposal is to explore mechanisms behind abnormal motor response in postural control in the adult with CP. We HYPOTHESIZE that somatosensory reliance, as well as muscle passive and active properties, change with aging and functional adaptation. In order to address our central hypothesis, we propose the following specific aims: SPECIFIC AIM 1: To examine the central disturbances of sensory processing and sensorimotor integration that contribute to abnormal postural control in young adults with CP. We will: a) determine the effect of visual dependence on postural control in the adult with CP as directly measured with a test for visual dependence; and b)relate the presence of visual dependence to the effect of disturbances of the visual flow field on the center of mass (CoM) and center of pressure (CoP) responses in the adult with CP; and c) determine the relationship between central disturbances of sensory processing and sensorimotor integration on functional balance as measured by standardized clinical assessments of balance and fall risk. SPECIFIC AIM 2: To examine the peripheral alterations in passive muscle-tendon properties that could contribute to abnormal postural control in young adults with CP. We will determine the effects of a disturbance of the base of support, a disturbance to the visual flow field, and a combined disturbance of the two on joint kinematics, CoP, and CoM responses in the adult with CP using functional principal component (time-series) analyses. SPECIFIC AIM 3: To examine the impaired muscle activation and loss of selectivity over muscle control that contributes to abnormal postural control in young adults with CP. We will determine the effects of a disturbance of the base of support, a disturbance to the visual flow field, and a combined disturbance of the two on the surface electromyographic (sEMG) activity of lower limb and trunk muscles using wavelet analyses. At the conclusion of this study, we will have characterized postural control strategies employed by adults with CP in the presence of somatosensory and biomechanical perturbations. The combination of our innovative methodology to challenge all aspects of the sensorimotor system, with our analytical approach of both time series and wavelet analysis of the data, will allow us to separate the primary dynamic postural deficits from compensatory actions, a critical distinction for optimizing treatment interventions. PUBLIC HEALTH RELEVANCE: The results of this study will have an impact upon public heath policy as adults with cerebral palsy (CP) present a growing and underserved population in the United States. At the conclusion of this study, we will have identified the means by which the adult with CP maintains their upright position, which is essential for activities of daily living ad for movement. With this knowledge, it will be possible to develop clinical and rehabilitation interventions that will improve their arm and leg function, and reduce the risk of falls for the adlt with CP.