Table 2.
eSCS treatment characteristics.
| Author (Year) | Stimulator Type | Lead Placement | No. of Leads | Lead Levels | Stimulation Parameters | Stimulation Optimization | Rehabilitation | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Frequency | Pulse Width (μs) |
Amplitude | Pre–Op | Post–Op | |||||||
| 1 | Barolat (1986) [107] | Clinical Technology Corporation | PC | 1 | T1–T2 | 75 Hz | 250 | – | Stimulation parameters optimised for paraesthesia. Frequencies of 30–100 Hz were tested | No | No |
| 2 | Katz (1991) [119] | Medtronic | Paddle | 4 | – | – | – | – | Parameters optimized for spasticity | No | No |
| 3 | Dimitrijevic (1998) [30] | Medtronic | – | T11–L1 | 25–50 Hz | 200–500 | 5–9 V | Muscle twitches were tested using 3 cathode leads, followed by testing frequencies of 1–120 Hz and amplitude 1–10 V | No | No | |
| 4 | Herman (2002) [32] | Medtronic | PC | 4 | LS enlarge–ment | – | – | – | A variety of electrical parameters were tested for efficacy in promoting gait | ||
| 5 | Cahart (2004) [31] | Medtronic | PC | 4 | T10–T12 | 40–60 Hz | 800 | Midpoint between sensory and motor thresholds | A wide range of parameters were tested, with selection of pulse widths > 500 μs and frequencies of 40–60 Hz | Yes | Yes |
| 6 | Jilge (2004) [134] | Medtronic | PC | 4 | T12–L1 | 5–60 Hz | 210–450 | 1–10 V | Muscle twitches were elicited using a single electrode, with the stimulation amplitude being increased to the point of eliciting brief muscle contractions | No | No |
| 7 | Minassian (2004) [34] | Medtronic | PC | 4 | T10–L1 | 2.2–50 Hz | – | 1–10 V | Optimized for spasticity by applying strengths of 1–10 V at frequencies 2.2–100 Hz using different contact combinations of electrodes | No | No |
| 8 | Ganley (2005) [135] | – | PC | 4 | T10–T12 | 20–60 Hz | 800 | Between sensory and motor thresholds in S1 and at motor threshold in S2 |
Parameters adjusted on an individual basis |
Yes | No |
| 9 | DiMarco (2006) [109] | Neuro–Control Corp | PC | 1 | T9, T11, L1 | 53 Hz | 150 –200 μs | 40 V | Pulse width of 150 μs at T9, and 200 μs at T11 and L1. | No | No |
| 10 | Huang (2006) [33] | Medtronic | PC | 4 | T10–L2 | 20–40 Hz | 800 | 3–8.5 V | Stimulation intensity was set between sensory threshold and motor threshold but closer to motor threshold, during gait training sessions |
||
| 11 | Minassian (2007) [136] | Medtronic | PC | 4 | T10–L1 | 2.2–50 Hz | 210 | 1–10 V | – | No | No |
| 12 | DiMarco (2009) [100] | Neuro–Control Corp | PC | 1 | T9, T11, L1 | 30–40 Hz | 150–200 | 30–40 V | – | No | No |
| 13 | Harkema (2011) [22] | Medtronic | Paddle | 16 | L1–S1 | 5–40 Hz | 210 or 450 | 0.5–10 V | Variable combinations were tested to optimize standing and stepping. 15 Hz, 8V of the caudal level (L5–S1) was used for standing caudal; 30–40 Hz and sensory cues for manually facilitated stepping | Yes | Yes |
| 14 | Monshonkina (2012) [116] | Cooner Wire Co. | PC | 2–4 | L2–L4, S2 | 1–12 Hz | – | – | Therapeutic mono/bipolar (stimulation frequency of 1–12 Hz) 2 times for 30 min in addition to routine pharmacotherapy | Yes | No |
| 15 | Minassian (2013) [118] | Medtronic | PC | 4 | Lumbar spinal cord | 2–42 Hz | – | – | – | No | No |
| 16 | Angeli (2014) [35] | Medtronic | Paddle | 16 | L1–S1 | 25–30 | – | – | Stimulation parameters optimized for each leg and joint movement, with optimal frequency set at either 25 or 30 Hz | Yes | Yes |
| 17 | Sayenko (2014) [62] | Medtronic | Paddle | 16 | L1–S2 | 2 Hz | 210 | 0.5–10 V | Bilateral-evoked potentials from leg muscles were collected and evaluated by spatial, temporal, and amplitude characteristics to optimize location and symmetry of electrode placement | No | No |
| 18 | Danner (2015) [137] | Medtronic | PC | 4 | T11–L1 | 2–130 Hz | 210 | 0–10.5 V | – | No | No |
| 19 | Hoefstoetter (2015) [138] | Medtronic | PC | 4 | T11–L1 | 2–130 Hz | 210 | 0–10.5 V | – | No | No |
| 20 | Rejc (2015) [36] | Medtronic | Paddle | 16 | L1–S1 | 25–60 Hz | – | 1.0–9.0 V | For standing, a sub–motor threshold of 25 Hz was used followed by adjustments to activate specific motor neuron pools | Yes | Yes |
| 21 | Lu (2016) [117] | Boston Scientific | Paddle | 16 | C4/C5–T1 | 2–40 Hz | 210 | 0.1–10.0 mA | Different bipolar electrode configurations were tested to identify electrode pairs with greatest hand motor responses | No | Yes |
| 22 | Grahn (2017) [139] | Medtronic | Paddle | 16 | Lumbar enlarge–ment | 15–40 Hz | 210 | 0–6 | Tested wide–field vs. local–field electrode configurations using a pre–selected algorithm. Frequencies used were 25 and 40 Hz (for volitional control and stepping) and 15 Hz (for standing) | Yes | Yes |
| 23 | Rejc (2017) A [37] | Medtronic | Paddle | 16 | L1–S1 | 30–65 Hz | – | 0.4–3.5 V | The following electrode configurations were used for the following activities: (1) standing: combination of 40–60 Hz and 0.6–1V at T1–T2 and T3–T8; (2) stepping: 30–55 Hz and 0.7–3.5 V at T2–T3, T5–T6 and T7–T9; and (3) voluntary movement: 30–65 Hz and 0.4–2.2 V at T1–T3 | Yes | Yes |
| 24 | Rejc (2017) B [38] | Medtronic | Paddle | 16 | L1–S1 | 15–60 Hz | – | 1.2–10 V | Parameters were optimized to generate continuous EMG patterns for standing after stand training. | Yes | Yes |
| 25 | Angeli (2018) [39] | Medtronic | Paddle | 16 | L1–S1/S2 | 5–50 | – | 1–10 V | Simulation parameters were optimized for each individual to achieve the best motor performance task. Both standing and stepping configurations were modified every 2–4 weeks | Yes | Yes |
| 26 | Aslan (2018) [140] | Medtronic | Paddle | 16 | T11–L1 | 2–35 | – | 0–10 V | Unique electrode configurations for each subject were used. For EMG and cardiovascular response to rostral and caudal configuration of the electrode, a constant frequency of 2 Hz was used while amplitude increased from 0–10 V | No | No |
| 27 | DiMarco (2018) [101] | – | PC | 2 | T9–T11 | 50 | 200 | 40 V | – | No | No |
| 28 | Formento (2018) [40] | Medtronic | Paddle | 16 | Lumbo–sacral | 40 | – | 3–9 mA | Different frequencies and amplitudes were tested in random order to characterise the ability of eSCS to modulate motor output | No | No |
| 29 | Gill (2018) [41] | Medtronic | Paddle | 16 | T11–L1 | 20–25 | 210 | 3.3–6 V | Initial frequency based on prior literature. Subsequently, parameters and configurations were modified to enable voluntary control |
Yes | Yes |
| 30 | Harkema (2018) A [77] | Medtronic | Paddle | 16 | T11–L1 | – | 450 | – | Configurations were optimized to maintain a target SBP of 110–120 mmHg or 105–115 mmHg and then adjusted as needed | No | No |
| 31 | Harkema (2018) B [131] | Medtronic | Paddle | 16 | T11–L1 | – | 450 | – | Configurations were optimized to maintain a target SBP of 110–120 mmHg or 105–115 mmHg and then adjusted as needed | No | No |
| 32 | Herrity (2018) [129] | Medtronic | Paddle | 16 | L1–S1 | 5–30 | 450 | Increased in steps of 0.1 V | Stimulation parameters were initiated using a global configuration that satisfied 4 rules, including the use of a fixed frequency (from 5 Hz) and pulse width (450 μs), with voltage ramped up slowly (0.1 V increments | Yes | Yes |
| 33 | Wagner (2018) [42] | Medtronic | Paddle | 16 | T11–L1 | 20–129 | – | 0.6–8 mA | Configurations were tested as monopolar pulses in EMG with selected configurations further tested for joint torque production. | No | Yes |
| 34 | Walter (2018) [125] | Medtronic | Paddle | 16 | T11–L1 | 25–45 | 300–450 | 4–7 V | The frequency and pulse width were pre–set, but the participant can use the stimulator as needed | No | No |
| 35 | West (2018) [78] | Medtronic | Paddle | 16 | T11–L1 | 35 | 300 | 3.5 V | A series of tests was conducted over 2 weeks to determine optimum stimulation parameters to increase blood pressure | No | No |
| 36 | Calvert (2019) [43] | Medtronic | Paddle | 16 | T11–L1 | 40 | 210 | 0–10 V | Electrode configurations from previous literature were used to assess volitional activity | Yes | No |
| 37 | Cheng (2019) [44] | Medtronic | Paddle | 16 | L1–S1 | 25 | 200 | – | The choice of stimulating electrodes was modified using a machine learning algorithm to search for optimal stimulation patterns | Yes | No |
| 38 | Darrow (2019) [45] | Abbott | Paddle | 16 | L2–S2 | 16–400 | 200–500 | 2–15 mA | Tested eSCS settings at each visit were chosen as the best by the participant’s experience over each month from an objectively determined setting list provided by a Bayesian optimization | No | No |
| 39 | Nightingale (2019) [130] | Medtronic | Paddle | 16 | T11–L1 | 35–40 | 300–420 | 3.5–6.0 V | Abdominal settings: 40 Hz, 420 μs, 3.5–6.0 V; Cardiorespiratory settings: 35 Hz, 300 μs, 3.5–6.0 V; | No | No |
| 40 | Terson de Paleville (2019) [122] | Medtronic | Paddle | 16 | L1–S1 | 10–45 | – | – | Stimulation configurations were specific for each individual, with specific configurations selected to enable the specific motor task. Standing configuration ranged from 10–40 Hz, and stepping 25–45 Hz | Yes | Yes |
| 41 | DiMarco (2020) [102] | – | PC | 2 | T9–T11 | 50 | 200 | 30–40 V | Stimulus parameters were set based on previous studies, which resulted in near maximal positive airway pressure generation | No | No |
| 42 | Gorgey (2020) [46] | Medtronic | Paddle | 16 | T12–S2 | 40 | 420 | 6–7 V | Parameters were modified based on patient performance | No | Yes |
| 43 | Penã Pino (2020) [47] | Abbott | Paddle | 16 | L2–S2 | – | – | – | Participants were provided with a programmer and allowed to adjust specific stimulation settings for specific tasks such as volitional movements, spasticity control, core strength, and autonomic functions | No | No |
| 44 | Beck (2021) [120] | Medtronic | Paddle | 16 | T12–L1 | – | – | – | An optimization period of 3 weeks was used to determine task–specific parameters, which were adjusted throughout a 12–month period | Yes | Yes |
| 45 | Calvert (2021) [48] | Medtronic | Paddle | 16 | T11–L1 | 0.2–2 | 210 | 0–10 V | Electrode configurations were defined empirically based on the motor output of each patient that enabled specific motor activation | Yes | Yes |
| 46 | DiMarco (2021) [123] | Ardiem Medical | PC | 2 | T9–T11 | 50 | 200 | 20–30 V | Each subject self–selected the number of stimulations and voltages applied. Typically, 2–3 applications of SCS (20–30 V, 50 Hz, 0.2 pulse width) were applied every 2–7 min and repeated several times | No | No |
| 47 | Gill (2021) [141] | Medtronic | Paddle | 16 | 20–30 | 200–450 | 2.0–4.1 V | Stimulation parameters were adjusted incrementally during initial sessions of stimulation–enabled task–specific training, and refined during BWST training sessions | Yes | Yes | |
| 48 | Herrity (2021) [121] | Medtronic | Paddle | 16 | L1–S1 | – | – | – | – | No | Yes |
| 49 | Ibánēz (2021) [49] | Medtronic | Paddle | 16 | T11–L1 | 10–40 | 450–1000 | 1.8–8.6 mA; 8 V | Parameters were optimized based on individualized maps of motor pools activation, previous evidence of lower limb extension pattern generation, and topographical organization of the activation pattern | No | No |
| 50 | Linde (2021) [50] | Medtronic | Paddle | 16 | Lumbo-sacral | – | – | – | Stimulation parameters optimized for movement were determined by participants | Yes | Yes |
| 51 | Mesbah (2021) [51] | Medtronic | Paddle | 16 | T12–L2 | 2 or 30 | 450 or 1000 | Increased from 0.1 V–0.5 V with 0.1 V | Stimulation parameters were further optimized for individual joint movement | No | No |
| 52 | Squair (2021) [98] | Medtronic | Paddle | 16 | T10–L1 | 120 | 450 | 0–7.5 mV | Parameters were optimized to recruit lower spinal segments and to increased blood pressure | No | No |
| 53 | Gorgey (2022) [52] | Medtronic | PC | 8 | T11–T12 | 2–40 | 150–210 | 0–10 V | Stimulation parameters were initially set at 2 Hz, 150 μs and 0–10 V. They were subsequently optimized to 20–30 Hz and 210 μs to ensure target achievements of functional movements in the supine position | No | No |
| 54 | Herrity (2022) [142] | Medtronic | Paddle | 16 | L1–S1 | 15–90 | 300–1000 | 0–12 mA | Bladder storage and voiding parameters were optimization tested and refined to build cohorts for multisystem stimulation. Parameters were: (1) bladder compliance: 60 Hz, 0–5 mA, 450 μs; and (2) voiding: 30 Hz, 4 mA, 1000 μs | No | No |
| 55 | Kandhari (2022) A [114] | Medtronic | PC | 8 | T1–T5 | 40 | 210 | 0–3.5 V | Different stimulation settings were tested over a period of 2 weeks | No | No |
| 56 | Kandhari (2022) B [143] | Medtronic | Paddle | 16 | T11–L1 | 15–60 | 210–400 | 1–6 V | A self–training program was implemented with sub–threshold stimulation levels at 60 Hz, 1–1.5 V and 270 μs to maintain the excitability of spinal neural networks | Yes | Yes |
| 57 | Rowald (2022) [53] | Medtronic | Paddle | 16 | T12–S2 | 20 or 100 | 500 | 0.5 V | Stimulation parameters were optimized based on responses elicited by eSCS, which where then optimized for each participant. These parameters were further fine–tuned through a stimulation scheduler software. | No | Yes |
| 58 | Smith (2022) [115] | Medtronic | Paddle | 16 | Lumbo-sacral | – | – | – | Individualized maps of motor pools activation were generated followed by selection of stimulation parameters based on guidelines | No | No |
| 59 | Boakye (2023) [108] | Medtronic | Paddle | 16 | T11–L1 | 2 | 450 | Increased from 0.1–0.5 V with 0.1 V | Initial testing of rostral and caudal electrode configurations was done to assess activation sequence of lower extremity muscles. Re–testing of these configurations allowed optimization of rostral muscles | No | Yes |
| 60 | Gorgey (2023) A [109] | Medtronic | PC | 2–8 | T10–L2 | 2–40 | 250–1000 | 1–10 mA | Spinal mapping was done daily after temporary (1 week) and permanent (2 weeks) implantation, as well after the first 6 months of the study (4 weeks) to identify optimal configurations to enable multiple functions and movements without inducing unwanted activity | No | Yes |
| 61 | Gorgey (2023) B [110] | Medtronic | PC | 2–8 | Lumbo-sacral enlarge-ment | 2–25 | 250–1000 | 1–10 mA | Configurations were tested at 2 Hz at three pulse widths (250 μs, 500 μs and 1,000 μs) at current 1–10 mA. For exoskeleton–assisted walking, configuration was optimized at 25 Hz, 250 μs, and 3 mA | No | Yes |
| 62 | Gupta (2023) [111] | – | – | 16 | Lumbo-sacral | 14–90 | 210–350 | – | – | No | No |
| 63 | Hoover (2023) [112] | Abbott | Paddle | – | – | – | – | – | – | No | Yes |
| 64 | Samijema (2023) [113] | Medtronic | Paddle | 16 | Lumbo-sacral | 17–35 | 300–500 | 4–6.8 V | – | No | No |
LS: lumbosacral; PC: percutaneous; SBP: systolic blood pressure. PC: percutaneous; SBP: systolic blood pressure.