A point locator/stimulator is nothing more than a device that emits a small electrical current and then monitors the resistance or conductance of the area beneath the point of the device.
Most of these devices have a light (visual cue) and an audible cue (sound) so the technician can hold the wand/pen and receive signals visually and audibly as they treat the patient. The price of these devices can range from $100 up to several thousands of dollars. The device size can range from small, hand-held, not much larger than a ball point pen, to a clinical unit that is 24" long, 12" tall and 18" deep with many bells and whistles.
The machine emits a higher pitched sound, and the light bar races to the top of the scale, when the conductance at a point on the skin is high. This indicates to the technician to treat this area. The device is then switched from monitoring the area to treating the area. The intensity of the current is increased and the point is stimulated generally for no more than 60 seconds. Upon completion of the stimulatory session, the area is checked again to see if the resistance has increased or, conversely, if the conductance has decreased.
The basic theory behind the device is there tends to be a correlation between points of high conductance and pain. Following injury, or in the case of chronic pain patients, these devices identify points in the pain area by measuring the resistance/conductance, and the patient has many more conductive points in the immediate area of pain which are treated. Upon completion of the treatments, the patient's pain level has been reduced.
The actual points are often referred to as "trigger" points rather than "acupuncture" points. Acupuncture points refer to specific anatomical distances and trigger points refer to electrical characteristics. The point locator/stimulator helps to identify the resistance and conductance of those specific areas.