Table 2.

Use of TSCS in motor recovery in persons with SCI.

Transcutaneous Spinal Cord Stimulation- Motor recovery and ambulation
S. No.	Study	No. of subjects	AIS; Neurological level	Place	Primary Outcome	Device	Stimulation site/Electrode Placement	Stimulation Parameters	Intervention & Follow Up	Concurrent Therapy
1	Gerasimenko et al., 2015 65	5	NA	St. Petersburg, Russia/Los Angeles, CA, USA	Motor recovery Induced rhythmic leg movements and corresponding coordinated movement EMG activity in leg muscles with stimulation	Custom system	Cathodal electrodes paraspinal T11 – T12 or Coccyx 1; Anodal electrodes iliac crests	Pulse mode: Train Frequency: Carrier10 kHz; T11 – T12; 5 Hz Coccyx Pulse width: 1 μs (monophasic) Intensity: 80–180 mA (induce stepping movement at supramotor and voluntary stepping at submotor threshold)	45-min/stimulation, 1 session/week, 18 weeks (18 sessions)	Passive stepping like motion while in weight supported side laying
2	Hofstoetter et al., 2015 68	3	D; C5-T9	Vienna, Austria	Ambulation Motor outputs augmentative and step-phase dependent during stimulation, increased hip flexion during swing by 11.3° ± 5.6° across all subjects	Stimulette r2x+, (Dr. Schuhfried Medizintechnik GmbH, Austria)	Stimulating electrodes paraspinal T11 – T12; Indifferent electrodes paraumbilical level of umbilicus	Pulse mode: Continuous Frequency: 30 Hz Pulse width: 1 μs (biphasic) Intensity: sub motor threshold	Single session, 10 gait cycles	Active treadmill stepping
3	Minassian et al., 2016 69	4	A; C8-T8	Vienna, Austria	Motor recovery Increased number of rhythmically responding muscles, augmented thigh muscle activity, and suppressed clonus with stimulation	DS7AH (Digitimer Ltd, England)	T11 – T12	Pulse mode: Continuous Frequency: 30 Hz Pulse width: single, paired, and continuous Intensity:100–170 mA – motor threshold	Single session with and without momentary stimulation	Weight supported stepping using a robot driven gait orthosis treadmill
4	Powell et al., 2016 70	6	4C, 2D; C6-L1	Louisville, KY, USA	Motor recovery No significant differences in change of MEP amplitudes were found between the 3 conditions.	NeuroConn Eldith (Magstim, UK)	Active electrode T10-T11; Reference electrode left deltoid	Frequency: Not reported Pulse mode: Continuous Intensity: 2.5 mA	Intervention consisted of 3 sessions, separated by at least 1 week, in which each subject received the conditions cathodal, anodal, and sham TSCS	None
5	Gad et al., 2017 71	1	A; T9	Los Angeles, CA, USA	Ambulation Increased patient generation of level of effort, improved coordination patterns of the lower limb muscles, smoother stepping motion, increased blood pressure and heart rate	Custom system from (Gerasimenko Y. et al., 2015)	Cathodal electrodes paraspinal T11 – T12 or Coccyx 1; Anodal electrodes iliac crests	Pulse mode: Continuous Frequency: Hz T11 – T12; 5 Hz Coccyx Intensity: Optimized efficacy and comfort	7 weeks training, 60-min, 4 weeks baseline training, 1-week TSCS, 1-week pharmacological, 1-week, & 1-week TSCS/pharmacological	Exoskeleton supported active and passive stepping
6	Powell et al., 2018 72	6	4C, 2D; C6-L1	Louisville, KY, USA	Motor recovery No significant differences in change of MEP amplitudes were found between the 3 conditions	NeuroConn Eldith (Magstim, UK)	Cathodal electrodes between T10 – T11; Anodal electrodes deltoid	Pulse mode: Continuous Frequency: Not reported Intensity: 2.5 mA	Intervention consisted of 3 sessions, separated by at least 1 week, in which each subject received the conditions cathodal, anodal, and sham TSCS.	None
7	Rath et al., 2018 73	8	6A, 2C; C4-T9	Los Angeles, CA, USA	Motor recovery During TSCS, subjects were able to achieve a more erect posture and sustain wider perturbations, as compared to sitting without TSCS.	Custom system from (Gerasimenko Y. et al., 2015)	Active electrodes T11 & L1; Reference electrode iliac crests	Pulse mode: Continuous Frequency: 30 Hz T11; 15 Hz L1; carrier 10 kHz Pulse width: 1 μs Intensity: 10–150 mA	Single session, with and without stimulation (1–2 min stimulation per activity)	Postural control
8	Sayenko et al., 2019 74	15	11A, 1B, 3C; C4-T12	Los Angeles, CA, USA	Motor recovery All participants could maintain upright standing with stimulation, some (7/15) without external assistance applied to the knees or hips, using their hands for upper body balance as needed.	Custom system from (Gerasimenko Y. et al., 2015)	Cathodal electrode T11–12 or L1 – L2; Anodal electrodes iIliac crests	Pulse mode: Burst Frequency: T11-30 Hz, L1-15Hz; carrier 10 kHz Pulse width: 1 μs (monophasic) Intensity: up to 150 mA	15 × 120-min stimulation, 3 sessions/week, 4 weeks (12 sessions)	Standing
9	Meyer et al., 2020 75	10	D; C3-T10	Zurich, Switzerland	Motor recovery mmediate significant improvements in ankle motility were observed at 30 Hz, with suppression of pathological activity, assessed by polysynaptic spinal reflex. Non-significant improvements in walking speed were also observed.	Dantec Keypoint Focus Workstation, Natus Medical Incorporated, CA, USA)	Active electrodes T11 – T12; Indifferent electrodes paraumbilical level of umbilicus	Pulse mode: Train Frequency: 15, 30 & 50 Hz Pulse width: 1 μs (monophasic) Intensity: 15–70 mA, Highest level comfortably tolerated	2 sessions 1–21 days apart, immediate effects of stimulation only	Volitional ankle movement & body weight supported gait activities
10	Shapkova et al., 2020 76	19	12A, 4B, 3C; C5-T12	St Petersburg, Russia.	Ambulation Exoskeleton walk training with stimulation improved weight loading capacity and decreased gait asymmetry. Higher frequencies (67 Hz) had an antispasticity effect allowing independent walking. Subjects reported changes in proprioception, sensation, and paresthesias while walking with TSCS.	Viking Select stimulator (USA)	Cathodal electrode T12; Anodal electrodes paraumbilical level of umbilicus	Pulse mode: Not reported Frequency: 1, 3 or 67 Hz Pulse width: 0.5 μs (monophasic) Intensity: 1.3–1.4 of motor threshold	∼45-min stimulation, 3–5 sessions/week, 2 weeks (6–10 sessions)	Exoskeleton walk training
11	Wiesener et al., 2020 77	2	A; T5-T6	Berlin, Germany	Motor recovery TSCS support yielded mean decreases of swimming pool lap times by∼19.3% and 20.9% for Subjects A and B, respectively.	RehaMove3 (Hasomed GmbH, Germany)	Active electrodes L2 – S2; Indifferent electrode abdomen	Pulse mode: Train Frequency: 50Hz Pulse width: 150–250 or 200–300 μs (biphasic) Intensity: 30–50 or 40–60 mA	30–45 min stimulation, 10 weeks (6–7 sessions), 9-month follow up	Swimming
12	McHugh et al., 2020 78	10	4C, 6D; C4-T9	Baltimore, Maryland, USA	Ambulation Subjects demonstrated significant improvements in walking speed, endurance, and quality following 8 weeks of training. No subjects reported pain with stimulation. Some subjects reported improvement in bowel, bladder, and pain markers.	Vectra Neo (Chattanooga, TN, USA)	Active electrodes T11 – T12; Indifferent electrodes paraumbilical level of umbilicus	Pulse mode: Continuous Frequency: 50 Hz Pulse width: 1 μs (biphasic) Intensity: 20–80 mA, sub motor threshold	1-week baseline, 30-min stimulation, 3 sessions/week, 8 weeks (23 sessions)	Gaiting activities
	TSCS- Upper limb function
1	Gad et al., 2018 79	6	2B, 4C; C4–C8	Los Angeles, CA, USA	Upper extremity function Improved voluntary hand function occurred within a single session in every subject tested.	Transcutaneous Electrical Spinal Cord Stimulator (NeuroRecovery Technologies, Inc., CA, USA))	Cathodal electrode between C3 – C4, C6 – C7; Anodal electrodes iliac crests	Pulse mode: Continuous Frequency: 30 Hz, carrier 10 kHz Pulse width: 1 μs (biphasic or monophasic) Intensity: 70–180 mA (maximize handgrip)	3 baseline assessments over 10 days, 60–120 min stimulation, 4 sessions/week (38 sessions)	Functional hand therapy
2	Inanici et al., 2018 66	1	D; C3-4	Seattle, WA, USA	Upper extremity function Graded Redefined Assessment of Strength, Sensation, and Prehension (GRASSP) test score increased 52 points and upper extremity motor score improved 10 points. Sensation recovered on trunk dermatomes, and overall neurologic level of injury improved from C3 to C4.	Transcutaneous Electrical Spinal Cord Stimulator (NeuroRecovery, Technologies Inc., CA, USA)	Cathodal electrodes between C3 – C4, C6 – C7; Anodal electrodes iliac crests	Pulse mode: Continuous Frequency: 30 Hz, carrier 10 kHz z Pulse width: 1 μs (biphasic) Intensity: 80–120 mA	2 weeks baseline, 90 min sessions, 4–5 days/week, 9 weeks (4 weeks therapy and TSCS, 4 weeks therapy only, 1 week therapy and TSCS), 3 month follow up	Functional upper extremity therapy
3	Inanici et al., 2021 80	6	2B, 2C, 2D; C3–C5	Seattle, WA, USA	Upper extremity function Rapid and sustained recovery of hand and arm function. Muscle spasticity reduced and autonomic functions including heart rate, thermo- regulation, and bladder function improved.	Custom device (ONWARD Medical BV, Netherlands)	Cathodal electrodes 1 above and one below level of lesion; Anodal electrodes iliac crests	Pulse mode: Continuous Frequency: 30 Hz, carrier 10 kHz Pulse width: 1 μs (biphasic and monophasic) Intensity: 40–90 mA, sub motor threshold	4 weekly baseline assessments, 4 weeks task training, up to 120-min stimulation, 3 sessions/week, 4 weeks (12 sessions) 3 months follow up	Functional hand activities
4	Zhang et al., 2020 81	1	A; C5	Newark, NJ, USA	Upper extremity function UE function (GRASSP, NRS, grip strength) improved after 18 sessions of task specific training with TSCS. These gains were maintained without stimulation at 3 months	Transcutaneous Electrical Spinal Cord Stimulator (NeuroRecovery Technologies Inc., CA, USA).	Cathodal electrodes C3 – C4 & C7 – T1; Anodal electrodes iliac crests	Pulse mode: Continuous Frequency: 30 Hz, carrier 10 kHz Pulse width: 1 μs (monophasic) Intensity: 50 and 15 mA	1-week baseline, 60-min stimulation, 2–3 sessions/week, 8 weeks (18 sessions), 3-month follow-up once per month	Functional hand activities

Abbreviations: AIS, American Spinal Injury Association Impairment Scale; C, Cervical vertebrae L, Lumbar vertebrae; T, Thoracic vertebrae; S, Sacral vertebrae.