Trans-Spinal Electrical Stimulation Therapy for Functional Rehabilitation after Spinal Cord Injury: Review

Abstract

Spinal cord injury (SCI) is one of the most debilitating injuries in the world. Complications after SCI, such as respiratory issues, bowel/bladder incontinency, pressure ulcers, autonomic dysreflexia, spasticity, pain, etc., lead to immense suffering, a remarkable reduction in life expectancy, and even premature death. Traditional rehabilitations for people with SCI are often insignificant or ineffective due to the severity and complexity of the injury. However, the recent development of noninvasive electrical neuromodulation treatments to the spinal cord have shed a ray of hope for these individuals to regain some of their lost functions, a reduction in secondary complications, and an improvement in their life quality. For this review, 250 articles were screened and about 150 were included to summarize the two most promising noninvasive spinal cord electrical stimulation methods of SCI rehabilitation treatment, namely, trans-spinal direct current stimulation (tsDCS) and trans-spinal pulsed current stimulation (tsPCS). Both treatments have demonstrated good success in not only improving the sensorimotor function, but also autonomic functions. Due to the noninvasive nature and lower costs of these treatments, in the coming years, we expect these treatments to be integrated into regular rehabilitation therapies worldwide.

Keywords: neuromodulation; rehabilitation; spinal cord injury; transcutaneous electrical stimulation.

Figure 1

(A) Trans-spinal direct current stimulation (tsDCS) at the cervical (dotted red) or thoracic (solid red) spinal level with the reference electrode commonly placed on the shoulder. (B) Typical tsDCS signal with several seconds of ramp up and ramp down current. The treatment intensity and duration are adjusted by the DC Amplitude and DC Timeframe.

Figure 2

(A) Multisite trans-spinal pulsed current stimulation at the cervical (dotted red) and thoracolumbar (solid red) levels with reference electrodes commonly placed above the iliac crests. (B) Typical tsPCS signal delivered at a frequency of 5–30 Hz with a 0.1–1 ms pulse width modulated at 10 kHz biphasic stimulation.