What You Will Learn
- Why pressure ulcers are such a serious concern, particularly for SCI
- How your skin generates its own electrical healing signals
- How electrical stimulation can support wound healing
- The connection between muscle maintenance and pressure ulcer prevention
1. The Problem
Pressure ulcers are one of the most serious and persistent complications for people with spinal cord injury. Reduced sensation means you cannot feel the early warning signs of tissue breakdown. Impaired circulation compromises the tissue's ability to withstand sustained pressure. Prolonged sitting concentrates forces over the sitting bones. And muscle wasting removes the natural cushioning that healthy muscle provides between bone and skin.
Throughout this book, we have argued that electrical stimulation serves a dual purpose: functional recovery where achievable, and tissue health maintenance where denervation is permanent. The gluteal stimulation described in Chapter 9 aims to restore muscle bulk beneath the sitting bones, improving the tissue's pressure resilience. That is prevention.
This chapter addresses what happens when prevention has not been enough and a pressure ulcer has developed. The evidence that electrical stimulation can accelerate healing is substantial and endorsed by international wound care guidelines.
2. The Skin Battery
Your intact skin is not electrically neutral. The living layers of the skin contain tiny pumps that actively separate electrical charges, creating a voltage difference across the skin surface. Think of it as a biological battery: a living electrochemical cell continuously maintained by your body's energy.
This is not merely a curiosity. The voltage generated by this "skin battery" has profound consequences for wound healing.
3. When the Battery Breaks
When a pressure ulcer breaks the skin, it creates a pathway for the separated charges to flow. The voltage drops to near zero at the wound centre, but remains normal in the surrounding intact skin. This creates a voltage gradient: a natural electrical field pointing from the wound edges toward the wound centre.
This natural electric field is the primary directional signal that guides healing cells toward the wound. Skin cells, immune cells, and blood vessel cells all migrate along this electrical gradient toward the wound centre. Research has shown that when this electric field conflicts with other directional signals, it overrides them. It is the dominant compass for wound healing.
4. Why Chronic Pressure Ulcers Fail to Heal
In a chronic pressure ulcer, particularly in someone with SCI, several factors conspire to weaken this healing signal. Tissue damage may have compromised the surrounding skin's ability to maintain its battery. Poor blood flow (especially with denervation) reduces the energy available to drive the pumps. Wound infection can short-circuit the electrical field. And poor nutrition deprives healing cells of the resources they need.
The result is a wound where the body's own healing signals have failed. The cells that need to close the wound have lost their compass.
5. How Electrical Stimulation Helps
This is where external electrical stimulation becomes a biophysically rational intervention. There are three main approaches:
High-voltage pulsed current (HVPC) replaces the failed healing signal directly. An electrode placed near the wound imposes an electrical field that mimics the natural wound field, guiding healing cells toward the wound centre. This approach has the strongest evidence and the highest endorsement from international wound care guidelines. Studies show it approximately doubles the healing rate compared to standard wound care alone.
FES-type stimulation around the wound takes a different approach. By stimulating muscles around the wound margins, it enhances local blood flow and oxygen delivery, helping the skin battery "recharge" and supporting all phases of healing.
Low-intensity direct current augments the natural wound field at very low levels.
All three approaches are safe when properly applied and are used alongside (not instead of) standard wound care: proper pressure relief, wound management, and nutritional support.
6. The Prevention Connection
The connection to the rest of this book is direct. The tissue health argument we have made throughout, that electrical stimulation of paralysed muscle supports long-term health, extends naturally to wound healing. Prevention through muscle maintenance is the first line of defence: maintaining muscle bulk provides cushioning, improving circulation supports skin health, and preserving tissue quality reduces vulnerability.
When prevention fails, electrical stimulation for wound healing is the logical second line.
The economics reinforce the clinical argument. A Canadian study found that electrical stimulation plus standard wound care was cost-saving compared to standard care alone, primarily through reduced nursing visits and faster wound closure. When set against the enormous annual cost of wound care in the NHS, even modest adoption of this approach represents a compelling case.
Chapter Summary
Intact skin maintains a biological battery that generates electrical fields critical for wound healing. When a pressure ulcer disrupts this battery, the wound loses its primary healing signal. In chronic ulcers, especially in SCI, poor circulation, infection, and nutritional deficits further compromise the system. High-voltage pulsed current has the strongest evidence for wound healing and approximately doubles the healing rate. Electrical stimulation for wound healing is a natural extension of the tissue health principles that underpin this entire book: prevention through muscle maintenance is the first priority; when a pressure ulcer develops despite best efforts, electrical stimulation offers a scientifically grounded and clinically supported intervention.