Research may lead to improved treatment option for phantom limb pain

Electrical stimulation on the skin surface at the elbow can produce feeling in the hand—including rare "natural" sensations—according to a study just published in the Journal of Rehabilitation Research and Development.

The hope is that surface electrical stimulation (SES) may someday be harnessed to provide "natural sensations" in body areas distant from where the stimulation occurs. If this could happen, it would lead to improved treatment for phantom limb pain, according to Katharine H. Polasek, assistant professor of engineering at Hope College in Holland, MI.

"The goal of our research is to develop a non-invasive, home-based therapy for treating phantom limb pain," says Polasek, who adds that such a reality is a still a ways off.

Phantom limb pain refers to discomfort felt in a limb that has been amputated. While the limb is gone, Sufferers from this condition may experience pain, tingling, cramping, heat and cold—virtually any sensation that an existing limb could have.

Polasek and a team of undergraduate researchers at Hope College conducted 46 testing sessions with 35 people to learn whether SES at their elbows could produce "referred sensation" in their hands without causing discomfort elsewhere. They also wanted to see whether it was possible to produce a "natural sensation" such as touch in the hand or the feeling of pressing and not simply a tingling or prickling perception.

Electrodes were attached to subjects at either the sites of the ulnar or median nerves at the elbow position and electronic stimulation was applied under carefully controlled conditions. In every session, the participants felt sensation in their hands.

"The actual feeling varied from tingling to itchiness to pressing," reports Polasek. "Natural sensations were reported but the vast majority of subjects experienced tingling or prickling sensations."

Dr. Polasek says there is some indication that small modulation of the amplitude or width of the electronic pulses provides a more natural sensation. That will be explored in future experiments with the hope of increasing the occurrence of natural sensations.