High Voltage Galvanic Stimulation (HVGS) is a specialized electrotherapeutic modality used in physical medicine and rehabilitation. This non-invasive treatment utilizes a unique electrical current to interact with the body’s tissues, promoting physiological changes aimed at managing pain and encouraging tissue recovery. The therapy delivers controlled electrical energy through the skin to the targeted area, influencing nerve and cellular activity.
Defining the Electrical Pulse
HVGS uses a monophasic, pulsed direct current, meaning the electrical flow moves in only one direction and is delivered in distinct, brief bursts. This unidirectional flow is what makes the current “galvanic,” establishing a fixed electrical polarity with one electrode always acting as the positive pole (anode) and the other as the negative pole (cathode).
The term “high voltage” refers to the peak electrical potential, which can range up to 500 volts, allowing the current to overcome the natural resistance of the skin with minimal discomfort. Despite this high voltage, the total electrical energy delivered is quite low because the current is delivered in a twin-peak waveform with an extremely short pulse duration, typically lasting only a few microseconds. This combination of high peak voltage and brief pulse duration results in a very low average current, minimizing the risk of tissue damage. Maintaining fixed polarity allows the clinician to select a specific charge to achieve a desired therapeutic effect, such as attracting or repelling charged ions within the tissue.
Primary Clinical Uses
The fixed polarity and high-voltage characteristics of the current translate directly into three primary therapeutic applications. One significant use is the reduction of acute swelling, or edema, particularly following a recent injury. By selecting the negative electrode (cathode) as the active treatment site, the electrical field can help drive negatively charged proteins and fluid away from the area, facilitating their reabsorption into the circulatory system. This mechanism helps to reduce the volume of fluid accumulation in the damaged tissue.
The modality is also frequently employed for pain management by selectively stimulating sensory nerves to produce an analgesic effect. The electrical impulses can activate a complex mechanism involving the central nervous system, helping to interrupt the transmission of pain signals to the brain. This sensory nerve stimulation is thought to activate the body’s natural pain-suppressing systems, offering temporary relief from discomfort associated with musculoskeletal injuries.
A third major application is promoting tissue repair and accelerating the healing of chronic wounds, such as pressure ulcers. In this context, the fixed polarity is used to attract specific, charged cellular components necessary for the repair process, a phenomenon known as galvanotaxis. For instance, the negative electrode may be used initially to attract positively charged cells like macrophages and neutrophils to the wound bed to clear debris and fight infection. Later, the polarity may be switched to attract fibroblasts, which are responsible for producing collagen and rebuilding the tissue matrix, thereby accelerating the closure of the wound.
What to Expect During Treatment
A typical HVGS session begins with the placement of two electrodes: a small active electrode over the treatment area and a larger dispersive electrode placed on an adjacent, non-involved skin site to complete the electrical circuit. The therapist selects the appropriate polarity, positive or negative, based on the treatment goal. The skin beneath the electrodes is prepared, often using a conductive gel or moist sponge, to enhance the flow of the electrical current.
Once the machine is activated, the therapist will gradually increase the intensity of the current while monitoring the patient’s sensation. The sensation felt is typically described as a comfortable, rapid tapping or a strong pins-and-needles feeling, known as paresthesia, rather than a deep, sustained muscle contraction. A typical treatment session usually lasts between 10 to 30 minutes, during which the patient remains still while the current is delivered.
Conditions Where Stimulation Is Not Recommended
There are specific circumstances where the use of HVGS is not advised.
- The presence of a demand-type cardiac pacemaker or other implanted electronic devices, such as an internal defibrillator, due to the risk of electrical interference.
- Application of the current directly over the carotid sinus in the neck, as stimulation can trigger a sudden drop in blood pressure.
- Over an area of known or suspected malignancy, due to the theoretical concern that electrical stimulation could influence cancer growth.
- Over the abdomen, pelvis, or lower back of a patient who is pregnant, as safety effects on the developing fetus have not been established.
- In patients with unstable heart conditions or when electrode placement crosses the chest area, due to the risk of unwanted effects on heart rhythm.