"Neural therapy is a system of diagnosing and treating local disturbances of the autonomic nervous system. In German and Spanish speaking countries it is considered a part of conventional medicine, even as it is virtually unknown in the English-speaking world.
Central to the theory of neural therapy is the concept of the "interference field". An interference field is a focus of electrophysiological instability somewhere in the body that destabilizes or blocks autonomic nervous system function - locally or systemically. Typical locations for interference fields are scars, teeth, internal organs, autonomic ganglia, nerve roots, or any place where there is (or has been) an injury or irritation. Somatic dysfunction is a type of interference field and can be treated equally effectively by neural therapy as by manipulation.
The classical neural therapy treatment is injections of dilute procaine into the interference field. Procaine acts as a membrane stabilizer, in a similar way to lidocaine in treating ventricular arrhythmias. Any medical condition that has an autonomic nervous system component may potentially be caused by an interference field. Examples include migraine, facial pain, backache and various forms of myofascial pain syndrome, as well as asthma, indigestion, bowel dysfunction, menstrual problems, irritable bladder, etc.
Interference fields have lower electrical potentials than surrounding tissues. Currents flow from areas of higher voltage to areas of lower voltage and seem to send confusing signals to the body's nervous system. The body sometimes reacts in inappropriate ways, resulting in chronic pain and/or illness. Interference fields can be found almost anywhere in the body. Often, they are far from the part of the body where you feel symptoms.
For example, an old appendix scar might cause migraine headache, or a wisdom tooth extraction scar might cause chronic low-back pain. Because these relationships are totally unpredictable, doctors need to search for interference fields everywhere in the body. Interference fields are very common and the conditions that they cause are mostly untreated in mainstream medicine except by drugs, merely suppressing symptoms.
Neural therapy works similarly to osteopathic manipulation—by treating local disturbances of autonomic nervous system function. In his groundbreaking book, Dr. Kidd explains the traditional neural therapy technique of injecting procaine and other substances into interference fields to reverse the bioelectrical instability underlying pain and illness. He also presents his own neural therapy approach that achieves the same outcome without needles."
(Excerpted from Robert Kidd, MD, CM who is in private practice in Renfrew, Ontario, Canada. He is well known in orthopaedic medicine circles and attracts difficult to treat patients from all over North America. He is a past president of both the Canadian and American Associations of Orthopaedic Medicine and has been active for many years practicing, teaching, researching and writing about orthopaedic medicine and neural therapy.)