CES in the Treatment of Pain-Related Disorders
Cranial electrotherapy stimulation (CES) is now being used and studied as a treatment for centrally-mediated pain syndromes that have historically been refractory to intervention, such as fibromyalgia, multiple sclerosis, spinal cord injuries, and global reflex sympathetic dystrophy. The safety assured by the low level of current and positive effects seen on the electroencephalogram also make CES a potentially efficacious treatment for headaches and dental pain. This review of the available data on CES suggests that sufficient research findings are now available to establish the usefulness of CES in pain management as a stand-alone or add-on treatment. This paper presents supporting data for a sequence of different ways that CES has been evaluated in pain man-agement. These include rigorous double-blind crossover studies, open clinical trials, physician surveys, patient self-report surveys, reductions in anesthetic requirements, and dental applications for a variety of challenging pain-related disorders.
Cranial electrotherapy stimulation (CES) involves the application of small amounts of current, usually less than one milli-ampere (1,000 microamperes), through the head via ear clip electrodes, for the purpose of treating a variety of psychological and medical disorders. CES came to the United States in the late 1960s under the somewhat misleading name, electrosleep. It had been developed in the Soviet Union in the 1950s and quickly spread throughout the former Eastern Bloc, then into Europe, Asia, and much of the West. It was already in use in Japan when it finally arrived in the US in the 1960s. By the late 1960s, it was being researched in both animal and human subjects at several U.S. medical schools, including the University of Texas at San Antonio,1 the University of Wisconsin2 and the University of Tennessee.3 Major research reviews in 1985,4 1995,5 2002,6 and most recently in 2006-2007,7-17 summarized the progress of CES in American medicine. The US Food and Drug Administration now certifies CES devices that have met its standards to be sold by prescription for the treatment of anxiety, insomnia, and depression. CES has been approved for sale without a prescription in all of Europe, Canada, Mexico, Australia, Scandinavia, parts of Asia, South America, Latvia, Turkey, the Middle East, and Africa.18
The treatment of pain is the most rapidly evolving application of CES. In addition to a direct effect on various brain centers and relays, this modality may also raise the pain threshold due to the stress-reducing effects that occur when anxiety and depression are reduced. While patients exhibit significant responses to the usual research protocol of one hour treatment daily for three or four weeks, chronic pain management often requires CES to be used over longer periods of time from devices that are prescribed for home use. The progressive pathology underlying many chronic pain disorders limits CES to palliative relief. However, for long term pain management, CES has the added benefits of being anxiolytic, antidepressive, and helpful in insomnia, as well as being safe and cost-effective.
Dr. Ronald Melzack became interested in central pain mechanisms from his studies of phantom limb pain in which, for example, a left leg amputee could experience intense pain seemingly in the missing left foot.19 Melzack theorized the importance of a pain homunculus in the cortex that represents every part of the body. Afferent fibers ascend from a given body area site to its corresponding site on the homunculus. In this theory, neuromodules—residing in a larger neuromatrix that encompass the homunculus—normally send pain messages to the forebrain when sufficiently stimulated. The sources of stimulation are afferent pain fibers ascending to the neuromatrix by way of the spinothalamic tract.
When the afferent input from a specific body site is terminated, the neuromodule involved extends dendrites to other neuromodules in an apparent attempt to make up for the new lack of stimulation. Referred pain can result from such new cortical connections.20