Duke University bioengineers and surgeons have developed a new animal model for the painful nerve condition, known as sciatica, which could offer insights to help researchers diagnose and treat it.
Sciatica is characterised by numbness or pain from the lower back to the feet, radiating leg pain or difficulty in controlling the leg.
It is often caused by compression, or pinching, of any of the five nerve roots that combine to make up the sciatic nerve. These roots are the parts of the nerve that pass through openings in the spine to the spinal cord.
Dr. Mohammed Shamji, a neurosurgery resident, led the surgical simulation of nerve compression in rats, and observed that the animals' gait became asymmetric, and that they over-responded to temperature changes and touch in their limbs after the surgery.
And for the first time, they found that the physical symptoms experienced by the affected animals were apparently linked to an increase in levels of interleukin-17 (IL-17)-a protein involved in regulating the inflammatory response.
Already, increased IL-17 levels have been implicated in such autoimmune diseases as rheumatoid arthritis and asthma.
"This finding suggests a possible role for immune system activation in contributing to symptoms of sciatica. This offers new insight into the pathophysiology of the disease, and may also identify novel therapeutic targets to treat it," said Shamji.
"If immune system activation is involved, and it turns out to be an important part of the condition, it is possible that existing or new drugs that can block this immune response could offer relief to patients. This new model should help us find answers for a disorder that has few good treatments," said a co-author of the study.
The results of the study were published online in the journal Spine.