Table 1.

Description of neuromodulation techniques alongside their pros and cons.

Neuromodulation device	Description	Pros	Cons
Surface functional electrical stimulation (sFES)	Electrical stimulation applied to the skin surface to activate muscles and improve motor function	Non-invasive Improves muscle strength and coordination in SCI patients with incomplete injuries (Peckham and Knutson, 2005) Enhances functional activities such as hand grasp (Doucet et al., 2012)	Limited control over specific muscle groups (e.g., precise targeting difficult due to surface application) Ineffective in complete SCI cases (Peckham and Knutson, 2005)
Transcranial magnetic stimulation (TMS)	Magnetic fields applied to the scalp to induce electric currents in the brain, modulating neural activity	Non-invasive Effective in reducing spasticity and enhancing motor cortex plasticity in post-stroke rehabilitation (Lefaucheur et al., 2020) Targeting of motor cortex can improve motor function in some SCI cases (Nielsen, 2002)	Limited depth of penetration, typically reaches only superficial cortical layers Skilled operators required to achieve consistent results Effects often temporary and variable across studies (Lefaucheur et al., 2020)
Peripheral nerve stimulation (PNS)	Electrical stimulation applied directly to peripheral nerves to modulate neural activity	Target-specific, effective for peripheral nerves associated with pain relief (Deer et al., 2016) Long-term benefits observed for neuropathic pain in some cases (Ilfeld et al., 2019)	Invasive, requiring surgical implantation Risk of infection or nerve damage in ~10% of cases (Deer et al., 2016) Limited long-term data on effectiveness for motor function improvement
Muscular electrical stimulation (MES)	Electrical stimulation applied directly to muscles (semi invasively or non-invasively) to improve strength and function	Improves muscle strength and endurance in patients with muscular atrophy (Bax et al., 2005) Effective for specific muscle targeting to aid motor rehabilitation (Snyder-Mackler et al., 1994)	Limited control over fine movements, especially for hand muscles (Bax et al., 2005) Fatigue reported in up to 30% of sessions (Snyder-Mackler et al., 1994) Not suitable for complete SCI due to lack of neural connection
Transcranial direct current stimulation (tDCS)	Low electrical currents applied to the scalp to modulate cortical excitability	Non-invasive and relatively easy to apply Shows potential in enhancing motor learning tasks in stroke and SCI patients (Dedoncker et al., 2016)	Effects highly variable; optimal parameters (intensity, duration) are not fully established (Dedoncker et al., 2016) Effects are often transient, with benefits lasting hours to days post-treatment (Nitsche and Paulus, 2000)
Invasive spinal cord stimulation (iSCS)	Electrical stimulation applied to the spinal cord to modulate neural activity and alleviate pain	Well-documented pain relief for chronic neuropathic pain (North et al., 1996) Shows functional improvement in some SCI cases, specifically in lower limb strength (Kriek et al., 2022)	Invasive procedure requiring surgical implantation Side effects like discomfort or paresthesia in 15% of patients (Kriek et al., 2022) Limited evidence for motor function improvement in cases of complete SCI
Non-invasive spinal cord stimulation (nSCS)	Transcutaneous electrical stimulation applied over skin directed to the spinal cord to modulate neural activity	Effective for pain relief in chronic pain patients without invasive surgery (Estores et al., 2021) Observed improvements in motor function in incomplete SCI patients, with ~20% showing progress (Yadav and Ahmed, 2018)	Potential for discomfort and paresthesia in ~10% of sessions (Yadav and Ahmed, 2018) Limited specificity in targeting due to skin application
Laparoscopic implantation of neuroprosthesis (LION)	Laparoscopic implantation of neuroprosthesis to modulate neural activity	Targeted neural modulation, showing promise in SCI cases with retained sensory pathways Minimally invasive with quicker recovery time than open surgery (Possover and Forman, 2015)	Limited long-term data; lack of extensive clinical trials for motor improvement (Possover and Forman, 2017) Complex procedure, requiring specialized training and carries risks associated with laparoscopy (Lemos et al., 2023; Possover and Forman, 2015)