Susan Jill Harkema - US grants

[unreadable] DESCRIPTION (provided by applicant): Clonus is one manifestation of spasticity, and produces involuntary neuromuscular responses that can interfere with the ability to walk after spinal cord injury (SCI). Clonus results in oscillatory efferent output generated by repetitive afferent input and the activation of central neural oscillators. The frequency of clonus is similar when driven by different types of repetitive afferent stimuli such as during standing and stepping. Clonus can radiate across several spinal cord segments and the oscillatory efferent output is modulated by interneurons. Thus, clonus can be used as a physiological probe to understand the functional organization of interneuronal circuits. [unreadable] We propose to study clonus during manual stretch of the plantarflexors, standing, and stepping to assess whether repetitive afferent input can alter the functional interneuronal organization of the human spinal cord. [unreadable] We will assess whether the specific afferent input related to loading modulates the central oscillators that generate clonus to modify efferent output after severe SCI. We hypothesize that manual stretch of the plantarflexors, standing and stepping will result in different co-activation patterns of clonic EMG among ipsilateral and contralateral flexors and extensors. Also, if a higher level of load to the legs is provided during standing and stepping, the clonic EMG activity will be reduced with an increase in tonic activity of bilateral flexors and extensors. We have observed that when individuals after severe spinal cord injury undergo multiple stand or step training sessions clonus and spasticity are reduced. We propose that intensive training that provides specific sensory information related to loading can reconfigure spinal networks to modify and reduce clonus after severe SCI. We suggest that the repetitive afferent input related to loading induces significant and persistent functional reorganization of interneuronal circuits. We hypothesize that after intensive training the same afferent input will alter clonic EMG activity. [unreadable] The proposed studies will further our understanding of the mechanisms of clonus after severe SCI. Further, we will learn whether the spinal neural networks responsible for clonus interact with those that generate standing and stepping. We will also understand whether the repetitive presentation of specific sensory information by training can reconfigure spinal neural networks to generate more functional motor output. Clonus is routinely treated with drugs, or even invasive strategies, with the intent to diminish clonus to enhance motor function. Unfortunately, side effects, rebound spasticity and limited recovery of function are often reported. We suggest that anti-spasticity medication may actually be interfering with the neural circuits needed for standing and walking. If this is the case, then specific training that uses task appropriate sensory cues for standing and walking may alleviate clonus and spasticity, reduce the need for medication, and improve motor function in individuals with severe SCI. [unreadable] [unreadable]

[unreadable] DESCRIPTION (provided by applicant): [unreadable] [unreadable] The decision to surgically decompress the spinal cord following spinal cord injury (SCI) is controversial, as is the timing of decompression. Multicenter, randomized controlled studies of early surgical decompression have not been performed in humans. MR images of the spine reflect the anatomical picture of the spinal cord but do not reflect metabolic status of the tissue or the CSF surrounding the spinal cord and thus may not indicate the precise degree of compression on the spinal cord. We hypothesize that: [unreadable] 1) quantitative cine phase-contrast magnetic resonance imaging (C-MR), which non-invasively measures flow velocity of cerebrospinal fluid (CSF) above and below the injury, will provide additional objective data to assist the decision-making process for surgical decompression and whether use of this data results in better long-term functional outcome following SCL. Within 8 hours after admission, all patients will undergo T1- and T2-weighted MR scans followed immediately by a C-MR. Patients with cord compression and evidence of CSF block will undergo immediate decompression surgery. Patients with no MR evidence of spinal cord compression or CSF block will be treated with the best medical care (non-surgical). Patients in whom the anatomical picture (MR scan), and CSF flow pattern (C-MR) are not concordant will be randomized into surgical and non-surgical groups. A variety of functional outcome measures will be performed on admission, weekly for one month, and at 3, 6, 9, 12, 18, and 24 months following SCI, to determine whether use of C-MR data results in a better functional outcome. [unreadable] 2) integrated PET/CT can determine the metabolic status at the site of the injury (as early as possible, but within 3 days) after the injury. We will use 18F-deoxyglucose to assess uptake and utilization. This information will attempt to assess whether the injury is complete (irreversible) or incomplete (reversible). We will answer the question if PET/CT is performed early can it be used to predict the outcome of spinal decompression surgery? [unreadable] 3) tcMMEP and SSEP can be used as non-invasive tools to assess spinal compression. We will measure them on the day of admission and after decompression, and correlate them post hoc with the MR and C-MR data, all of which will be entered into an NIH-sponsored national SCI database. We will also assess whether these tests can be used to more accurately determine if decompressive surgery can improve the long-term functional outcome by performing these tests weekly for one month, and at 3, 6, 9, and 12 months following SCI. [unreadable] 4) oximetry at the site of SCI can be used over the first week as a non-invasive monitor of cord ischemia that results from compression and, thus, as a decision-making tool for decompression. This can be done by correlating the data of each patient [unreadable] post hoc with other measures of Aims 1-3. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Spinal cord injury (SCI) results in impairments of locomotor, sensory and autonomic functions, severely affecting overall health and quality of life. Recent discoveries related to activity-dependent plasticity in humans have led to a widely implemented rehabilitation intervention, Locomotor Training, which includes stepping using body weight support on a treadmill with manual facilitation. Evidence suggests that this particular type of task specific training optimizes the lumbosacral spinal circuitry. We have intriguing evidence from four SCI individuals who are unable to stand or walk showing improved bladder and sexual function after undergoing Locomotor Training. These changes in urogenital function may be due to activity-dependent plasticity of lumbosacral circuitry that mediates micturition and erectile functions. Proper bladder management post-SCI is necessary to decrease the risk of upper urinary tract disease, a major source of morbidity. The life-long urologic care is required for SCI individuals, yet most efforts treat symptoms but do not improve intrinsic function. In addition, paraplegics rank sexual function as the function post-injury that should be given the highest priority in order to enhance quality of life. This proposal focuses on the mechanisms involved in the reorganization of spinal cord circuits for bladder and sexual function in response to activity-dependent plasticity induced by step training after SCI, with and without epidural stimulation. Stand training and/or arm crank exercise serve as controls. Of potential mechanistic importance is that neurotrophins have been implicated in modulating bladder function. It is therefore hypothesized that weight bearing task specific training for locomotion post-SCI induces plasticity of neural networks that mediate not just walking but bladder and sexual function as well and may do so for bladder function by reducing specific neurotrophins that are elevated post-SCI. Our unique approach will utilize the expertise of each investigator to 1) To determine whether the effect of weight-bearing task-specific training for locomotion on voiding frequency and urodynamic parameters is due to an interaction between locomotor and urinary bladder circuitry after traumatic incomplete upper motor neuron SCI in humans (versus standing or general exercise); 2) To assess the effect of LT on urine (biomarkers) and bladder (biopsy tissue) NGF and BDNF levels after severe incomplete SCI; 3) To determine the effect of weight-bearing task-specific training for locomotion on erectile function and sexual satisfaction after traumatic incomplete upper motor neuron SCI in humans; and 4) To assess the effect of epidural stimulation in combination with LT on voiding frequency, urodynamic parameters, erectile function, and bladder/urine NGF and BDNF levels after complete and motor complete/sensory incomplete upper motor neuron SCI in humans. Our innovative multi-disciplinary study may lead to the translation of a combination approach of weight bearing step training, epidural stimulation, and neurotrophic factor manipulation to promote functional recovery for multiple systems following SCI.

PROJECT SUMMARY/ABSTRACT The overall objective of this functional bladder mapping study is to identify the spinal cord epidural stimulation (scES) configurations (anode/cathode selection, amplitude, frequency and pulse width) at the lumbosacral level that can promote neural control of bladder storage (capacity) and voiding efficiency after spinal cord injury (SCI). This comprehensive functional mapping study in both humans and animals in parallel involves a novel clinical application of a marketed Medtronic device for bladder dysfunction after SCI. The mapping (human and animal) and training (human) experiments address several specific objectives of the SPARC Program initiative per RFA-RM-15-018 including neural circuit maps regarding functional connectivity (Aim 1), neural plasticity related to stimulation (bladder training experiments ? Aim 2), variability (animal-to- animal and patient-to-patient), and research on what organ functions results from different types of stimulation (storage vs voiding and identifying any additional effects on bowel and/or sexual function). The long-term reduction in the cost to the health care system, care givers and society would be dramatic. SCI results in impairments of locomotor, sensory and autonomic functions, severely affecting overall health and quality of life. Proper bladder management post-SCI is necessary to decrease the risk of upper urinary tract disease, a major source of morbidity. Life-long urologic care is required for SCI individuals, yet most efforts treat symptoms but do not improve intrinsic function. Current therapies for bladder management after SCI include catheterization, pharmacologic and surgical interventions, functional electrical stimulation (peripheral), and urethral stents, but all have deleterious effects. We have exciting data from multiple individuals with severe injuries (AIS A and B) indicating improved bladder function after undergoing a widely implemented activity-based rehabilitation, locomotor training (LT), which includes stepping using body weight support on a treadmill with manual facilitation. In addition, we have intriguing preliminary data from several completely paralyzed individuals receiving scES in combination with task specific training that recovered standing and voluntary movement and showed improvements in both bladder capacity and voiding efficiency. Our most recent pilot data also indicate an immediate benefit of scES alone on bladder function. Thus, we propose to determine the functional gains that can be achieved in the storage and voiding phases of lower urinary tract function as a result of activation of spinal circuits with scES in humans with SCI and in a clinically- relevant rodent SCI model. We will test the general hypothesis that bladder capacity and voiding efficiency increases with scES post-SCI and to an even greater extent with scES bladder training over time. This proposal involves the collaboration of clinicians and scientists with extensive experience in animal and human SCI models. Our unique approach will utilize the expertise of a multi-disciplinary team (expertise in bladder function, neuromodulation, rehabilitation, engineering, and statistics) to 1) determine the optimal stimulation parameters for storage and voiding in SCI research participants already implanted with the scES Medtronic device (16-electrode array from L1-S1); 2) quantify the long-term effects of daily bladder training using optimal stimulation parameters (all the same research participants); 3) measurement of secondary benefits (bladder medication usage, susceptibility to urinary tract infections, indirect cardiovascular, bowel and sexual function benefits) of long-term bladder training; and 4) address with a small animal model the impact of location, lesion severity, chronicity and gender. Our innovative approach and novel application of this Medtronic Specify 5-6-5 device will allow us to determine specific types of scES needed for bladder function which will lay the groundwork for expedient translation of this promising technique to larger numbers of individuals with SCI in the next phase of the SPARC initiative, with additional refinement in parallel using a large animal SCI model (pig) that is currently under development within the Kentucky Spinal Cord Research Center.