Functional Electrical Stimulation as a Neuroprosthesis for Sitting Balance: Measuring Respiratory Function and Seated Postural Control in Able-bodied Individuals and Individuals with Spinal Cord Injury (original) (raw)
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Trunk Stability Enabled by Noninvasive Spinal Electrical Stimulation after Spinal Cord Injury
Journal of Neurotrauma, 2018
Electrical neuromodulation of spinal networks improves the control of movement of the paralyzed limbs after spinal cord injury (SCI). However, the potential of noninvasive spinal stimulation to facilitate postural trunk control during sitting in humans with SCI has not been investigated. We hypothesized that transcutaneous electrical stimulation of the lumbosacral enlargement can improve trunk posture. Eight participants with non-progressive SCI at C3-T9, American Spinal Injury Association Impairment Scale (AIS) A or C, performed different motor tasks during sitting. Electromyography of the trunk muscles, three-dimensional kinematics, and force plate data were acquired. Spinal stimulation improved trunk control during sitting in all tested individuals. Stimulation resulted in elevated activity of the erector spinae, rectus abdominis, and external obliques, contributing to improved trunk control, more natural anterior pelvic tilt and lordotic curve, and greater multi-directional seated stability. During spinal stimulation, the center of pressure (COP) displacements decreased to 1.36-0.98 mm compared with 4.74-5.41 mm without stimulation (p = 0.0156) in quiet sitting, and the limits of stable displacement increased by 46.92-35.66% (p = 0.0156), 36.92-30.48% (p = 0.0156), 54.67-77.99% (p = 0.0234), and 22.70-26.09% (p = 0.0391) in the forward, backward, right, and left directions, respectively. During self-initiated perturbations, the correlation between anteroposterior arm velocity and the COP displacement decreased from r = 0.5821 (p = 0.0007) without to r = 0.5115 (p = 0.0039) with stimulation, indicating improved trunk stability. These data demonstrate that the spinal networks can be modulated transcutaneously with tonic electrical spinal stimulation to physiological states sufficient to generate a more stable, erect sitting posture after chronic paralysis.
Archives of Physical Medicine and Rehabilitation, 2013
Objective-To determine the stimulated strength of the paralyzed gluteal and paraspinal muscles and their effects on the seated function of individuals with paralysis. Design-Case series with subjects acting as their own concurrent controls. Setting-Hospital-based clinical biomechanics laboratory. Participants-Eight users of implanted neuroprostheses for lower extremity function with lowcervical or thoracic level injuries. Interventions-Dynamometry and digital motion capture both with and without stimulation to the hip and trunk muscles. Main Outcome Measure(s)-Isometric trunk extension moment at 0, 15 and 30 degrees of flexion; seated stability in terms of simulated isokinetic rowing; pelvic tilt, shoulder height, loaded and unloaded bimanual reaching to different heights, and subjective ratings of difficulty during unsupported sitting. Results-Stimulation produced significant increases in mean trunk extension moment (9.2±9.5Nm, p=0.0001) and rowing force (27.4±23.1N, p=0.0123) over baseline volitional values. Similarly, stimulation induced positive changes in average pelvic tilt (16.7±15.7deg) and shoulder height (2.2±2.5cm) during quiet sitting and bimanual reaching, and increased mean reach distance
Artificial organs, 2015
This is a case series study with the objective of comparing two motion sensor automated strategies to avert knee buckle during functional electrical stimulation (FES)-standing against a conventional hand-controlled (HC) FES approach. The research was conducted in a clinical exercise laboratory gymnasium at the University of Sydney, Australia. The automated strategies, Aut-A and Aut-B, applied fixed and variable changes of neurostimulation, respectively, in quadriceps amplitude to precisely control knee extension during standing. HC was an "on-demand" increase of stimulation amplitude to maintain stance. Finally, maximal FES amplitude (MA) was used as a control condition, whereby knee buckle was prevented by maximal isometric muscle recruitment. Four AIS-A paraplegics undertook 4 days of testing each, and each assessment day comprised three FES standing trials using the same strategy. Cardiorespiratory responses were recorded, and quadriceps muscle oxygenation was quantifie...
PM&R, 2013
Objective: To investigate whether combined trunk and gluteal neuromuscular electrical stimulation (NMES) alters seated posture and improves pelvic tissue health in persons with a spinal cord injury. Design: Intervention study; case series. Setting: Research laboratory, medical center. Participants: Seven persons with spinal cord injury recruited from a group of experienced implanted lower extremity NMES system users. Intervention: Combined trunk and gluteal NMES in the sitting position. Five minutes of preintervention sitting was assessed, followed by 5 minutes of NMES application, and then 5 minutes of postintervention. Main Outcome Measures: Pelvic tissue health was evaluated by concurrently measuring transcutaneous oxygen tension (T c PO 2 ) bilaterally over the ischia and the seating interface pressure (IP). T c PO 2 data were binned into low (Ͻ10 mm Hg), medium (10-30 mm Hg), and high (Ͼ30 mm Hg) ranges, and the percentage time that T c PO 2 was in each range was calculated. Ischial and sacral regions of interest were defined and the maximum region of interest and mean IP were determined, together with the maximum IP gradient for the entire contact area. Initial seating postures varied; 4 persons were initially sacral sitters. Tissue health responses to NMES were reviewed for sacral and nonsacral sitters. Results: For sacral sitters, the sacral region IP and the maximum IP gradient tended to decrease during NMES and increased again after the intervention. Mean ischial T c PO 2 increased during NMES and remained elevated after the intervention, increasing high T c PO 2 percentage time for 50% of the sacral sitters both during and after the intervention. Nonsacral sitters showed few changes in tissue health as the result of the application of NMES. Conclusions: Trunk and gluteal stimulation acutely corrects anterior/posterior IP distribution, improving regional tissue health for sacral sitters. This correction requires constant application of NMES. The potential for positive changes in tissue health would be maximized by regular NMES use incorporating weight shifting.
Posture of Healthy Subjects Modulated by Transcutaneous Spinal Cord Stimulation
Transcutaneous electrical stimulation of the spinal cord is used to restore locomotion and body weight support in patients with severe motor disorders. We studied effects of this non-invasive stimulation on postural control in healthy subjects. Stimulation at the L1-L2 vertebrae was performed to activate the extensor muscles of the lower limbs. Because postural regulation depends on the cognitive style, the effects of the stimulation were analyzed separately in field-dependent (FD) and field-independent (FI) participants. During the study young adults (N=16, half FD and half FI participants, all right dominant leg) stood on a force platform in a soundproof chamber with their eyes closed. Stimulation was applied in the midline between the L1-L2 vertebrae or over the left or right dorsal roots of the spinal cord; under control condition there was no stimulation. Stimulation destabilized posture in healthy subjects, whereas patients with movement disorders usually showed an improvement...
Gait & Posture, 2008
This study investigated the effects of altering foot placement for two individuals with spinal cord injuries (SCI) that stood using functional neuromuscular stimulation (FNS) as compared to an ablebodied subject group. FNS-assisted standers used parallel bars as needed for support, while the ablebodied group stood hands-free. Three different foot placements were tested: side-by-side, wide, and modified tandem. For SCI subjects, the percentage of body weight loaded on the feet was not greatly affected by foot placement, which potentially could be altered to provide postural benefits during functional tasks. Anterior/posterior (A/P) center of pressure (COP) origins tended to be located more anterior in the base of support for SCI subjects as compared to able-bodied subjects. SCI subjects also tended to have medial/lateral (M/L) COP excursions that were larger than able-bodied subjects. The sacrum appeared to hold some promise as a sensor location for monitoring A/P postural sway, but movements in the M/L direction were inconsistent and will require additional study. General guidelines such as positioning the A/P COP more posterior in the base of support and feedback concerning excessive M/L COP displacements may be useful to improve standing performance for SCI subjects. In addition, the modified tandem placement was an effective alternative for making postural adjustments in one SCI subject who experienced excessive right knee flexion with other foot placements.
Journal of Clinical Medicine, 2020
Spinal cord stimulation may enable recovery of volitional motor control in people with chronic Spinal Cord Injury (SCI). In this study we explored the effects of adding SCS, applied transcutaneously (tSCS) at vertebral levels T10/11, to a sit-to-stand training intervention in people with motor complete and incomplete SCI. Nine people with chronic SCI (six motor complete; three motor incomplete) participated in an 8-week intervention, incorporating three training sessions per week. Participants received either tSCS combined with sit-to-stand training (STIM) or sit-to-stand training alone (NON-STIM). Outcome measures were carried out before and after the intervention. Seven participants completed the intervention (STIM N = 5; NON-STIM N = 2). Post training, improvements in International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) motor scores were noted in three STIM participants (range 1.0–7.0), with no change in NON-STIM participants. Recovery of voliti...
2001
Fourteen Spinal Cord Injured (SCI) and 15 Ablebodied (AB) individuals participated in two 30 minutes (min) standing sessions. The control groups (SCICONT, ABCONT) consisted of both AB and SCI standing still with no muscle contraction. The experimental groups consisted of both SCI subjects (SCIEXP) standing with use of Functional Electrical Stimulation (FES)-induced muscle activation of four lower limb muscle groups and AB subjects (ABEXP) standing while performing tiptoe exercises for 30 min. A computerized impedance cardiograph was used to measure the changes of heart rate (HR), stroke volume (SV), cardiac output (CO), systolic, diastolic and mean arterial blood pressure (SBP, DBP, MAP) and total peripheral resistance (TPR) during sitting, and at 0, 5 and 30 min of standing. Change in position from sitting to standing caused significant drop in SBP, DBP, and MAP during SCICONT, while these values were maintained during SCIEXP. There were no significant changes in AB subjects in BP values. During SCIEXP standing, SCI maintained their hemodynamics at pre standing values at 5 min and 30-min post standing. These values decreased significantly during SCICONT, while TPR increased. The Able-bodied (AB) responded during ABCONT by a significant drop in SV and CO while TPR only increased at 30 min of standing. It was concluded that FES has equal or even better effect on improving blood circulation during standing than voluntary activation of the physiologic muscle pump and may be used to improve tolerance to tilting and standing in SCI.