Table 1.
Characteristics of 21 included studies
| Study and Year |
Design | Subjects (n) |
Age (yr) mean ± SD |
Level of injury and AIS classification |
Post-SCI (yr) |
Neuromodulation type |
Stimulation setting | Stimulation region | Assessment | Outcomes |
|---|---|---|---|---|---|---|---|---|---|---|
|
(Kukke and Triolo, 2004) |
Preliminary study |
n = 4; M = 3 F = 1 |
35.2 ± 9.2 |
C7 - T8; AIS A − 2 AIS B − 2 |
6.7 ± 6.8 | Implanted functional electrical stimulation | Pulse duration 0-200 µs and increased to greatest amount until trunk extension was observed. | Intramuscular electrodes implanted between L1–L2 or T12–L1 spinal segments. | Motion capture system, bimanual reaching maneuvers, sagittal reaching length. | Improvement in seated posture and increased bimanual reaching distance. |
|
(Yang 2005) (2005) |
Repeated measurement study |
n = 12; M = 10 F = 2 |
41.6 ± 9.1 |
C6 - T10; AIS A − 8 AIS B − 3 AIS C-1 |
17.5 ± 8.5 | Functional electrical stimulation | Biphasic stimulation, frequency 30 Hz, pulse width 300 µs, amplitude 80 mA. | Abdominal and back muscles stimulated. | Electromyography, wheel chair propulsion, trunk flexion, maximum voluntary contraction. | Abdominal and back muscles were highly activated, trunk stability increased. |
|
(Triolo et al. 2009) (2009) |
Case study | n = 1; M | 40 |
C4 AIS - A |
20 | Implanted electrical stimulation | Biphasic stimulation, stimulus amplitude (0.1–20 mA), pulse duration (0-255 µs), frequency 14 Hz. | L1 and T12 spinal roots. | Forward bimanual reaching distance, seated stability, rolling in bed without assistance. | Improved forward reach, restoration of upright sitting and bed turning was also improved. |
| (Triolo et al. 2013a) | Case series |
n = 6; M = 4 F = 2 |
46 ± 10.8 |
C6 - T10; AIS A − 3 AIS B − 2 AIS C-1 |
8.6 ± 2.8 | Implanted electrical stimulation | Biphasic stimulation, intensity 20 mA, frequency 20 Hz, pulse width 0-250 µs. | L1 - L2 spinal nerves. | Maximum forward trunk lean, pushrim kinematics (peak shoulder moment and propulsion) | Increase in forward reach by 19–26% stabilizing the trunk. |
| (Triolo et al. 2013b) | Case series |
n = 8; M = 6 F = 2 |
46 ± 9.9 |
C5 - T10; AIS A − 3 AIS B − 3 AIS C-2 |
11.5 ± 6.9 | Implanted electrical stimulation | Biphasic stimulation, stimulus amplitude (2–20 mA), frequency 20 Hz, pulse width 0-250 µs. | L1 - L2 spinal nerves. | Trunk extension strength, seated stability, bimanual reaching. | Increase in trunk extension and forward reach distance with improved sitting posture. |
| (Audu et al. 2015) | Case series |
n = 5; M = 3 F = 2 |
53.4 ± 7.7 |
C7 - T10; AIS − 2 AIS B − 2 AIS C − 1 |
10 ± 4.3 | Implanted functional neuromuscular stimulation |
Frequency 20 Hz, 50 ms, interpulse interval. |
Hip and back extensor muscles stimulated. |
Seated balance under external perturbations (forward flexion), trunk tilt, erect posture. |
Improved forward trunk tilt flexion and erect posture. |
| (Momeni et al. 2016) | Case series | n = 3 | 21.0 ± 1.0 | AIS - B | 10 ± 3.5 | Electrical stimulation |
Biphasic pulses of 300 µs at 35 Hz, Intensity increased till visible muscle contraction. |
Rectus femoris, biceps femoris, gastrocnemius, and tibialis anterior. | Surface electromyography, 10-meter walk test. | Trunk muscle activation and improved trunk stability. |
| (Rath et al. 2018) | Non-RCT within-subject crossover study |
n = 8; M = 7 F = 1 |
29.9 ± 7.7 |
C4 - T9; AIS A − 6 AIS C − 2 |
7.5 ± 3.3 | Transcutaneous electrical spinal cord stimulation | Monophasic rectangular 1ms pulses, frequency 30 Hz at T11, and 15 Hz at L1, carrier frequency 10 kHz, intensity 10 to 150mA | Between T11 and T12; and between L1 and L2 hereafter referred to as T11 and L1. | Electromyography of the trunk muscles, three-dimensional kinematics, and force plate data were acquired. | Elevated activity of the trunk muscles contributing to improved trunk control, and increased multi-directional seated stability. |
| (Armstrong et al. 2018) | Clinical trial |
n = 4; M = 2 F = 2 |
48.7 ± 8.0 |
C7 - T4; AIS A -2 AIS B − 2 |
13.0 ± 6.2 | Functional neuromuscular stimulation | Pulse amplitudes (0 to 20 mA), pulse durations (0 to 250 µsec), frequency (0 to 20 Hz). | Inserted at T12-L2 spinal nerves to activate the paraspinal muscles. | Turning events, superior-inferior angular velocity and displacement of trunk and pelvis measured. | Activation of the paraspinal and hip muscles, recovery of upright sitting, restoring a stable and erect posture. |
| (Bergmann et al. 2019) | Non-RCT Crossover study | n = 5; M | 39.2 ± 7.1 |
C5-C6; AIS B − 4 AIS C − 1 |
10.8 ± 6.0 | Functional electrical stimulation | Frequency 3–18 Hz, pulse width 275 µs, intensity increased till strong visible muscle contraction. |
Erector spinae and rectus abdominis muscles. |
Muscle oscillation frequency, characterizing muscle tone, limits of stability, and characterizing sitting balance were measured. | Increased trunk muscle tone and improved dynamic sitting balance during flexion movement. |
| (Friederich et al. 2020) | Single-subject experimental design |
n = 4; M = 2 F = 2 |
50.7 ± 8.3 |
C5-T4; AIS A − 1 AIS B − 2 AIS C − 1 |
11.2 ± 6.9 | Functional neuromuscular stimulation | Pulse width (0-250 µs), stimulus amplitude (2–20 mA), frequency 20 Hz. | Set of trunk muscles stimulated. | Electromyography, isometric muscle contraction. | Stimulated muscles were activated with increase in muscle force. |
| (Bergmann et al. 2020) | Non-RCT crossover study | n = 5; M | 39.0 ± 7.0 |
C5 - C6; AIS B – 4 AIS C − 1 |
10.8 ± 6.0 | Functional electrical stimulation | Frequency 8–18 Hz, pulse width 275 µs, intensity increased till strong visible muscle contraction. | Placed on thoraco-lumbar area of the erector spinae and rectus abdominis muscles bilaterally. |
EMG (maximum voluntary isometric contraction), manual muscle test hand-held dynamometer. |
Improved trunk muscle force generation and muscle fatigue reduced. |
| (Gill et al. 2020) | Clinical trial | n = 2; M | 31.5 ± 7.8 |
T3 & T6 AIS - A |
4.5 ± 2.1 | Epidural spinal electrical stimulation | Frequency 20–25 Hz, pulse width 200–400 µsc, stimulation intensity 3.8–5.0 V. | T11 - L1 vertebral region. | Reaching performance, modified functional reach test. | Improved reaching performance and seated position, increase in reaching distance. |
| (Rahimi et al. 2020) | Randomised controlled trial |
n = 16; M = 13 F = 3 |
37.0 ± 5.7 |
T5 - T12; AIS - A |
13.0 ± 5.7 |
Functional electrical stimulation |
Rectangular pulses, pulse width 400 µs, frequency 40 Hz, amplitude 20 to 200 mA increased to a visible contraction. |
Quadriceps and gastrocnemius muscles. | Spinal Cord Independence Measure-III, quadruped unilateral reaching. | Improved ability to perform transfers, increased unilateral reaching. |
| (Keller et al. 2021) | Prospective within-subject design |
n = 8; M = 5 F = 3 |
8.4 ± 3.9 | Cervical-thoracic | NA | Transcutaneous electrical spinal cord stimulation | Frequency 30 Hz, intensity 134–140 mA. | T11 and L1 spinal levels. | Electromyography, trunk kinematics, center of pressure displacement, segmental assessment of trunk control. | Increased trunk extension, enabled upright sitting posture. |
| (Friederich et al. 2021) | Case study | n = 1; F | 48 |
C 7 AIS - B |
22 | Functional neuromuscular stimulation | Frequency 20 Hz, pulse 250 µs and amplitude set at 20mA. | Applied to nerves innervating the lumbar erector spinae, quadratus lumborum, adductor magnus, gluteus maximus, gluteus medius, and hamstring semimembranosus. | Trunk tilt, functional tasks in sitting, motion capture system. | Increased trunk movement and improved erect upright sitting posture. |
| (Tharu et al. 2022b) | Case series |
n = 5; M = 2 F = 3 |
42 ± 13.7 |
C4 - C7; AIS - A |
9.3 ± 7.4 | Transcutaneous electrical spinal cord stimulation | Biphasic stimulation, Frequency 20–30 Hz, pulse width 0.1-1.0 ms, intensity 90–115 mA. |
T11-T12 and L1-L2 spinal levels. |
Functional reach test, trunk control test and function in sitting test, electromyography, motion capture system. | Improved trunk and sitting functions with increased static and dynamic balance. |
| (Kouwijzer et al. 2022) | Cross-sectional study |
n = 11; M = 10 F = 1 |
41.6 ± 10.1 |
C4 - C7; Complete − 8 Incomplete- 3 |
17.5 ± 13.3 | Electrical stimulation | Biphasic pulses, frequency 30 Hz, pulse duration 300 µs, amplitude 30–100 mA. | Rectus abdominis, obliquus externus abdominis and erector spinae muscles. | Electromyography, trunk stability measured through reaching tasks, Isokinetic test on dynamometer. | Induced trunk muscle activation, trunk stability increased with increased reaching distance. |
| (Gorgey and Gouda 2022) | Case report | n = 1; M | 25 |
T3; AIS - A |
3.8 | Epidural spinal electrical stimulation | Frequency 20 Hz, pulse width 240 µs, amplitude of the current gradually increased from 0–10 V. | T11–T12 vertebral region. | Electromyography, perturbation of trunk control. | Activation of abdominal muscles, immediate restoration of trunk control during seated position. |
| (Rowald et al. 2022) | Clinical trial | n = 3; M | 34.0 ± 6.2 |
T4 - T7; AIS A − 1 AIS B − 2 |
4.3 ± 4.1 | Epidural spinal electrical stimulation |
Frequency 70–80 Hz, single pulses (0.5 Hz) were delivered at increasing amplitude to elicit muscle responses. |
L1 and L2 spinal segments. | Inspecting muscular activity and kinematics, activity-specific stimulation programs, quantification of muscle mass. |
Motor neurons innervating the trunk and abdominal musculatures were activated and facilitated improved trunk posture. |
| (Friederich et al. 2022) | Feasibility study |
n = 5; M = 3 F = 2 |
46.8 ± 9.0 |
C5 - T10; AIS A − 3 AIS B − 1 AIS C − 1 |
13.2 ± 6.6 | Functional neuromuscular stimulation | Frequency 40 Hz, pulse 250 µs and amplitude set at 20mA. | Applied to nerves innervating the erector spinae, quadratus lumborum, adductor magnus, gluteus maximus, gluteus medius, and hamstring semimembranosus. | Trunk angles measured using motion capture system, postural sway, reaching movements. | Postural sway reduced, reaching ability increased, time required for maintaining upright posture improved. |