Scientists believe they may have found a way to treat neuropathic pain, a mystery illness that affects thousands.
Neuropathic pain can be debilitating
The pain, which is caused by subtle nerve damage, can be agonising and in many cases fails to improve over time.
Scientists at the University of Arizona say they have successfully treated the condition in rats.
Writing in the journal Nature Medicine, they said that while further research is needed it could lead to new treatments for humans.
Scientists do not know exactly what causes neuropathic pain. It has no physical cause although it appears to be triggered by a number of physical conditions.
Viral infections such as shingles, surgery and diabetes have all been known to lead to the problem.
The condition can cause serious problems for those with the condition. For some, even the slightest touch can produce excruciating pain. For others, it can lead to serious disability.
Dr Frank Porreca and colleagues carried out tests on rats to see if they could find a way to treat the condition.
They used a surgical technique to damage the spinal cord of rats and induce neuropathic pain.
As a result of damage to the rats' nerves, they became hypersensitive to heat and pressure.
However, when the rats were treated with artemin, a nerve growth factor which is also found in humans, the hypersensitivity was relieved.
The benefits were seen even after rats had been treated two weeks after their surgery and lasted for at least 28 days.
The researchers said that the technique did not appear to have any negative effects.
"The clinical management of neuropathic pain is particularly challenging," said Dr Porreca.
"Our results indicate that systemic artemin may represent a new approach effective treatment of clinical neuropathic pain."
However, much more research is needed before this treatment could be used on humans. In the first instance, further animal tests are needed to determine if it is safe.
Only then would doctors consider testing it on patients.
It is by no means certain that the treatment would work in humans.
Neuropathic pain affects about 2.4% of the population. However, the chances of developing it increase with age, affecting 8% of older people.