Non-drug Treatment Reduces Initial Pain Responses

A simple, noninvasive technique providing low-level electrical stimulation of the brain produces significant pain-reducing effects in humans, reports the November issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).

With further research and development, transcranial electrostimulation (TES) could provide a valuable, non-drug approach to reducing pain and the need for pain medications, according to the study by pain researchers at Stanford University.

In the study, ultraviolet light was used to create a small, painful area of sunburn on the upper thigh in healthy volunteers. The researchers used this technique-a standard model used to test the pain-relieving effects of drugs-to evaluate the effects of TES on pain responses.

In TES, a mild electrical current is delivered through electrodes placed around the patient's head. Two different stimulation frequencies were tested: 60 and 100 hertz (Hz). The subjects felt only a mild tingling sensation during electrical stimulation. The pain-relieving effects of TES were evaluated by means of sensory testing, with hot temperature and mechanical force applied to the sunburned skin and to undamaged skin.

The results showed that TES significantly reduced pain responses in both sunburned skin and non-burned skin in a frequency-dependent manner. Only 60 Hz TES was effective, while 100 Hz TES had little or no pain-relieving effect.

“The effects of TES on both heat and mechanical pain suggest that it may be able to diminish the exaggerated responses of the central nervous system to painful stimuli, which play an important role in the development and maintenance of many pain states,” said lead author Dr. Vladimir Nekhendzy, in a press release.

The effect was limited to the time that TES was being applied. “However, there is a possibility that TES could provide lasting benefits to patients receiving multiple treatments,” Nekhendzy said.

There is a great need for new and safe approaches to pain control-driven in part by the rapidly increasing use of potent morphine-related opioid drugs for pain management, according to an accompanying Editorial by Dr. Felipe Fregni of Harvard University. The idea of brain stimulation for pain control is not new: TES is in some ways similar to other types of noninvasive "brain stimulation" under study, such as transcranial magnetic stimulation and transcranial direct current stimulation. Although confirmatory research is needed, the new study "adds important data for the development of noninvasive cortical stimulation as an analgesic method," Fregni writes.

"The possibility of non-pharmaceutical approaches to pain relief is very exciting," said Dr. Steven L. Shafer of Columbia University, Editor-in-Chief of Anesthesia & Analgesia, in a press release. "The next step is to move beyond these volunteer trials to see if transcranial electrostimulation is effective in patients suffering from chronic pain."

Source: International Anesthesia Research Society (IARS)

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