Interface pressure and cutaneous hemoglobin and oxygenation changes under ischial tuberosities during sacral nerve root stimulation in spinal cord injury

Abstract

Abstract-Noninvasive functional magnetic stimulation (FMS)of the sacral nerve roots can activate gluteal muscles. We propose the use of sacral anterior root stimulator (SARS) implants to prevent ischial pressure ulcers in the spinal cord injury (SCI) population. In this study, we (1) investigated the acute effects of sacral FMS on ischial pressure, skin blood content, and oxygenation changes in people with SCI and demonstrated the utility of FMS as an assessment tool, and (2) showed that similar effects are possible with electrical stimulation via a SARS implant. Results indicated that sacral nerve root stimulation, either by FMS or implanted electrical stimulation, induced sufficient gluteus maximus contraction to significantly change subjects' ischial pressures and cutaneous hemoglobin and oxygenation during sitting. In addition to these beneficial acute effects, chronic stimulation via a SARS implant may build gluteal muscle bulk and prevent or reduce pressure ulcers in the SCI population.

Gluteal blood flow and oxygenation during electrical stimulation-induced muscle activation versus pressure relief movements in wheelchair users with a spinal cord injury

“…[7][8][9][10][11] Levine et al 8,9 used surface ES in the gluteal muscles of individuals with an SCI and found a changed buttock tissue shape 8 and increased muscle BF. 9 Ferguson et al 7 stimulated the quadriceps muscles and found a decrease in interface pressure as well.…”

Physical activity and transcutaneous oxygen pressure in men with spinal cord injury

“…A combination of this specialized cushion for pressure reduction and pressurerelief movements, in which the wheelchair user performs "push-ups" or "forward leans," is considered the best option for PU prevention in people with SCI [10][11][12][13]. However, pressure-relief movements require good upper-limb strength and continued motivation, which are not always present in people with high-level lesions [14]. The incidence of PUs remains unacceptably high [15][16][17][18].…”

“…For the individual characterization of the mechanical pressure of the wheelchair cushion, the measure of the interface pressure between the person and the seating surface is the most common test performed in clinical settings [14,[19][20]. However, the mechanical properties are not the only characterizations that indicate the risk of tissue damage.…”

“…The application of electrostimulation (ES) training to relieve the ischial pressure zone in sitting [10,[30][31][32], functional magnetic electrostimulation, and ES of the sacral nerve root (sacral anterior root stimulator [SARS]) [14,19] have been used to improve the behavior of vascular flow in relationship to clinical variables.…”

“…Recently, implanted muscular functional ES of gluteal muscles [54] and SARS implants in the suprasacral area [14,19] have been shown to benefit seat pressure and tissue oxygenation. Therefore, recent studies have focused on evaluating the different effects of wheelchair tilt-in-space and recline angle on skin perfusion over the IT in wheelchair users with SCI by using laser doppler flowmetry [55].…”