Study finds that higher-frequency electric current stimulation of the spinal cord reduces pain faster

An animal study in the August issue of Anesthesiology suggests that higher-frequency electric current stimulation of the spinal cord reduced pain quicker and better reached nerves not affected by traditionally used frequencies. A higher frequency and intensity controlled pain faster and more effectively, the study found.

Today, it is estimated 100 million Americans suffer from chronic pain.* During spinal cord stimulation, a device implanted in the back delivers electric pulses to nerves and the spinal cord to block pain. This therapy is most commonly used in patients who suffer from chronic pain of the back, arms and legs.

In a rat model of neuropathic pain, researchers evaluated the effects the conventional stimulation frequency of 50 Hz (50 cycles per second) versus frequencies of 1 kHz (1,000 cycles per second) and 10 kHz (10,000 cycles per second) had on relief of mechanical hypersensitivity, a common neuropathic pain manifestation in patients. All experiments were approved by the local Institutional Animal Care and Use Committee prior to initiating the studies.

In addition, the researchers investigated which nerve groups and mechanisms for achieving pain relief were affected by the higher frequencies. Results indicated the higher 1 kHz-level of spinal cord stimulation relieved pain behavior in rats quicker than the conventional frequency. Interestingly, the 10 KHz frequency was less effective at reducing pain than the 1 kHz frequency, according to the study.

"Chronic pain can significantly reduce quality of life and place an economic burden on individuals," said study author Yun Guan, M.D., Ph.D., associate professor, Department of Anesthesiology/Critical Care Medicine, Johns Hopkins University, Baltimore. "A better understanding of the frequency- and intensity-dependent features of spinal cord stimulation can help physician anesthesiologists better treat patients and achieve long-term pain relief."

An accompanying editorial commented favorably on the study's results.

"Currently, electric therapies are limited to a narrow frequency that provides relief for only some patients, and for most it is just partial relief," said J. David Clark, M.D., Ph.D., Veterans Affairs Palo Alto Healthcare System, Palo Alto, Calif. "This study shows that in the future we may be able to control a whole new segment of nerves, and therefore pain, via a different mechanism. This gives pain physicians a 'one, two' punch to control either or both nerve groups more quickly so we can potentially offer our patients a more effective outcome."

Dr. Clark added that more research is needed before the study's data can be transferred to use in humans, but that the higher-frequency electric current "may become another tool for the physician anesthesiologist to give patients a broader range of pain relief."