Sparse Approximation Via Iterative Thresholding

The well-known shrinkage technique is still relevant for contemporary signal processing problems over redundant dictionaries. We present theoretical and empirical analyses for two iterative algorithms for sparse approximation that use shrinkage. The GENERAL IT algorithm amounts to a Landweber iteration with nonlinear shrinkage at each iteration step. The BLOCK IT algorithm arises in morphological components analysis. A sufficient condition for which General IT exactly recovers a sparse signal is presented, in which the cumulative coherence function naturally arises. This analysis extends previous results concerning the Orthogonal Matching Pursuit (OMP) and Basis Pursuit (BP) algorithms to IT algorithms

Targeted Selection of Stimulation Parameters for Restoration of Motor and Autonomic Function in Individuals With Spinal Cord Injury

Study Design: This is a report of methods and tools for selection of task and individual configurations targeted for voluntary movement, standing, stepping, blood pressure stabilization, and facilitation of bladder storage and emptying using tonic-interleaved excitation of the lumbosacral spinal cord. Objectives: This study aimed to present strategies used for selection of stimulation parameters for various motor and autonomic functions. Conclusions: Tonic-interleaved functionally focused neuromodulation targets a myriad of consequences from spinal cord injury with surgical implantation of the epidural electrode at a single location. This approach indicates the sophistication of the human spinal cord circuitry and its important role in the regulation of motor and autonomic functions in humans

Training-Induced Functional Gains following SCI

We previously demonstrated that daily, hour-long training sessions significantly improved both locomotor (limb kinematics, gait, and hindlimb flexor-extensor bursting patterns) and nonlocomotor (bladder function and at-level mechanical allodynia) functions following a moderate contusive spinal cord injury. The amount of training needed to achieve this recovery is unknown. Furthermore, whether this recovery is induced primarily by neuronal activity below the lesion or other aspects related to general exercise is unclear. Therefore, the current study objectives were to (1) test the efficacy of 30 minutes of step training for recovery following a clinically relevant contusion injury in male Wistar rats and (2) test the efficacy of training without hindlimb engagement. The results indicate that as little as 30 minutes of step training six days per week enhances overground locomotion in male rats with contusive spinal cord injury but does not alter allodynia or bladder function. Thirty minutes of forelimb-only exercise did not alter locomotion, allodynia, or bladder function, and neither training protocol altered the amount of in-cage activity. Taken together, locomotor improvements were facilitated by hindlimb step training for 30 minutes, but longer durations of training are required to affect nonlocomotor systems

Lumbosacral spinal cord epidural stimulation improves voiding function after human spinal cord injury

AbstractDeficits in urologic function after spinal cord injury (SCI) manifest both as a failure to store and empty, greatly impacting daily life. While current management strategies are necessary for urological maintenance, they oftentimes are associated with life-long side effects. Our objective was to investigate the efficacy of spinal cord epidural stimulation (scES) as a promising therapy to improve bladder control after SCI. A bladder mapping study was undertaken for sixteen sessions over the course of four months in an individual with chronic, motor complete SCI. Varying combinations of stimulating cathode electrodes were initially tested during filling cystometry resulting in the identification of an effective configuration for reflexive bladder emptying at the caudal end of the electrode array. Subsequent systematic testing of different frequencies at a fixed stimulus intensity and pulse width yielded lowest post-void residual volumes at 30 Hz. These stimulation parameters were then tested in four additional research participants and found to also improve reflexive voiding efficiency. Taken together with SCI studies on step, stand, voluntary motor control and cardiovascular regulation, these findings further corroborate that scES has an all-encompassing potential to increase the central state of excitability, allowing for the control of multiple body functions, including the urological system.</jats:p

Health Care Utilization and Cost Associated With Urinary Tract Infections in a Privately Insured Spinal Cord Injury Population

BackgroundUrinary tract infections (UTIs) are the most common secondary medical complication following spinal cord injury (SCI), significantly impacting health care resource utilization and costs.ObjectivesTo characterize risk factors and health care utilization costs associated with UTIs in the setting of SCI.MethodsIBM’s Marketscan Database from 2000–2019 was utilized to identify individuals with traumatic SCI. Relevant ICD-9 and ICD-10 codes classified individuals into two analysis groups: having ≥ 1 UTI episode or no UTI episodes within 2 years following injury. Demographics (age, sex), insurance type, comorbidities, level of injury (cervical, thoracic, lumbar/sacral), and health care utilization/payments were evaluated.ResultsOf the 6762 individuals retained, 1860 had ≥ 1 UTI with an average of three episodes (SD 2). Younger age, female sex, thoracic level of injury, noncommercial insurance, and having at least one comorbidity were associated with increased odds of UTI. Individuals with a UTI in year 1 were 11 times more likely to experience a UTI in year 2. As expected, those with a UTI had a higher rate and associated cost of hospital admission, use of outpatient services, and prescription refills. UTIs were associated with 2.48 times higher cumulated health care resource use payments over 2 years after injury.ConclusionsIn addition to bladder management-related causes, several factors are associated with an increased risk of UTIs following SCI. UTI incidence substantially increases health care utilization costs. An increased understanding of UTI-associated risk factors may improve the ability to identify and manage higher risk individuals with SCI and ultimately optimize their health care utilization.</jats:sec