1. The Field of the Invention
This invention relates to interferential electrical current therapy devices and, more particularly, to novel systems and methods for positioning the region of beneficial interference in a patient's body during interferential therapy.
2. The Background Art
For many years, medical therapists have used interferential electrical current therapy in treating various physiological aliments. For example, therapists have found such interferential therapy to be helpful in the treatment of both pain and edema.
Interferential electrical current therapy is typically carried out using two pairs of electrodes which are adapted to be secured directly to a patient's body. During treatment of the patient, a separate electrical signal passes through the patient's body between each pair of electrodes. Importantly, the two electrical signals are selected such that a region of beneficial interference is provided in the patient's body to effect the desired treatment.
For example, a first electrical signal having a substantially constant frequency may be passed through a portion of a patient's body between the first pair of electrodes. A second electrical signal is simultaneously passed through substantially the same portion of the patient's body between the second pair of electrodes. Significantly, the frequency of the second electrical signal differs from that of the first electrical signal by a predetermined amount. As a result, a region of beneficial interference is formed in the patient's body due to the interaction of the two electrical signals.
The desired difference between the frequencies of the two electrical signals generally depends upon the nature of the physiological aliment being treated. When treating edema, for example, it is generally desirable that the difference between the frequencies of the two electrical signals be within the range from approximately 0 to 10 Hertz. When treating pain, on the other hand, it is typically desirable that the difference in frequencies be within in the range of from approximately 80 to 150 Hertz.
When using interferential electrical current therapy, a therapist generally attempts to position the region of beneficial interference in the patient's body so as to coincide as closely as possible to the localized area of the patient's body under treatment. For example, if a patient is to undergo treatment for pain located in the shoulder area, the therapist would generally attempt to position the region of beneficial interference so as to lie in the patient's shoulder area. Unfortunately, the accurate positioning of the region of beneficial interference has heretofore proved extremely difficult.
A therapist has conventionally positioned the region of beneficial interference in a patient's body by attempting to select and adjust the position of each pair of electrodes. However, this prior art method for positioning the region of interference is both imprecise and unpredictable, since the path of an electrical signal through a patient's body is highly dependent upon the shape, structure, and conductivity of the surrounding tissue. Consequently, one cannot generally determine the location of the region of interference in a patient's body simply by observing the position of the electrodes.
The inherent difficulty of properly positioning the region of interference in a patient's body using conventional methods renders the process both tedious and time-consuming. It may, for example, be necessary to remove and reposition the electrodes several times before the region of interference is in adequately close proximity to the area of the patient's body under treatment. Even then, due to the unpredictability of the process, therapists must frequently settle for somewhat less than desirable positioning of the region of interference when treating a patient.