Implanted Electrical Stimulation of the Trunk for Seated Postural Stability and Function After Cervical Spinal Cord Injury: A Single Case Study

Abstract

Objective(s)-To explore and quantify the physical and functional effects of stabilizing the torso with electrical stimulation of the paralyzed hip and trunk musculature after motor complete tetraplegia.Design-Single-subject case study with repeated measures and concurrent controls. Setting-Academic outpatient rehabilitation center.Participants-Forty-four year old male with C4 ASIA A tetraplegia 20 years post spinal cord injury.Intervention-A surgically implanted multichannel pulse generator and intramuscular stimulating electrodes to activate lumbar erector spinae, quadratus lumborum, and gluteus maximus muscles bilaterally.Main Outcome Measure(s)-Outcomes assessed with and without stimulation included a) spinal alignment and pelvic orientation, b) pulmonary function and ventilatory volumes, c) forward bimanual reaching distance, d) seated stability and resistance to externally applied disturbances, e) maximal force and speed of rowing-like movements, and the ability to f) independently return to an erect seated position from full forward or lateral flexion, and g) roll in bed without assistance. SUPPLIERSThe custom multichannel implanted pulse generator, stimulating electrodes, external controller and associated software utilized in this study were designed, fabricated and supplied by the Technical Development Laboratory of the Cleveland FES and Advanced Platform Technology Centers of Excellence of the US Department of Veterans Affairs, 3 rd Floor Bingham Building, Case Western Reserve University, 10900 Euclid Avenue, Cleveland OH 44106. These custom devices are for investigational use only and are unavailable for sale. The VICON 370 motion capture system is a product of VICON (London, UK), the business entity formed by the combination of Vicon Motion Systems and Peak Performance Inc. Vicon is a subsidiary of Oxford Metrics Group (OMG), a public company trading on the London stock exchange. The Biodex System 3 robotic dynamometer is a product of Biodex Medical Systems, 20 Ramsay Road, Shirley, New York, 11967-4704.We certify that no party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organization with which we are associated AND, if applicable, we certify that all financial and material support for this research (eg, NIH or NHS grants) and work are clearly identified in the title page of the manuscript. NIH Public Access Author ManuscriptArch Phys Med Rehabil. Author manuscript; available in PMC 2010 February 1. Results-Stimulation improved spinal convexity and kyphosis by 26° and 21°, reduced posterior pelvic tilt by 11°; increased forced expiratory volume and vital capacity by 10% and 22%, and improved forward reach by > 7 cm. Average resistance to sagittal disturbances increased by > 40% (p<0.002) and mean force exerted during underhanded pulling more than doubled (p=0.014) with stimulation. Restoration of upright sitting in both sagittal and coronal planes and bed turning were made possible through appropriately timed ac...

Low-intensity functional electrical stimulation can increase multidirectional trunk stiffness in able-bodied individuals during sitting

“…Furthermore, recent developments in the field of neurorehabilitation suggest that also neuroprostheses utilizing functional electrical stimulation (FES) may have the potential to facilitate or even restore trunk control during sitting and other functional tasks. For example, FES has been used in open-loop control schemes to activate the paralyzed trunk musculature during sitting to increase seated postural stability [16,17] and facilitate bimanual tasks that individuals with SCI are otherwise unable to complete [16,18]. In addition, Yang et al examined the effect of FES on wheelchair performance, concluding that stimulation resulted in an increase in the user's control with respect to wheelchair propulsion speed [19].…”

“…At the same time, larger FES activation levels that can stabilize the upper body against external perturbations have been shown to lead to muscle fatigue [17][18][19][20], compromising the functional abilities and safety of the user. Another method of using FES technology is to apply low-intensity FES with the goal of increasing trunk stiffness and damping.…”

Feasibility of closed-loop controller for righting seated posture after spinal cord injury

“…Stiffening the otherwise paralyzed trunk and hip extensor muscles with continuous electrical stimulation can correct kyphotic seated posture, expand bimanual workspace, improve ventilation, alter interface pressures, statically stabilize the trunk, and improve manual wheelchair propulsion efficiency [1,[15][16][17][18]. However, this strategy substitutes one statically stable posture for another.…”

“…Pulse widths were tuned for each stimulation channel to maintain sagittal and coronal alignment of the trunk in a static, erect seated posture. This continuous pattern was generally used by the participants in their home environments [15,[17][18]. For all subjects, stimulus pulse widths and amplitudes were chosen that would avoid interference with respiration or the discomfort sometimes associated with activating the abdominal muscles or sensory fibers near the stimulating electrode.…”

Neuroprosthetic technology for individuals with spinal cord injury

“…36 Implantable FES electrodes have been used to stimulate the lumbar erector spinae (and other muscles) and demonstrated an improvement in posture, forward reach and effort required for transfers. 19,37 Since trunk stabilization is desired anytime the user is not lying down, additional research is needed to develop a controller capable of stimulating tonically at levels that do not cause fatigue, and in closed-loop fashion using postural feedback to maintain balance during a variety of activities. 38 While stimulation of truck muscles has standalone benefits, some individuals may also need trunk stabilization in order to take advantage of FES for walking or upper extremity function.…”