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Ed. Note: The following is a press
release from the University of Bristol.
January 24, 2006 --
New research shows that it is
undamaged nerve fibres that cause ongoing spontaneous pain, not those that
are injured.
These unexpected findings, by Dr
Laiche Djouhri, Professor Sally Lawson and colleagues from the University of
Bristol, UK, are reported in the Journal of Neuroscience today [25 January,
2006].
Previous research into ongoing
chronic pain has tended to focus on the damaged nerve fibres after injury or
disease and overlooked the intact fibres. This new understanding may help
pharmaceutical companies formulate novel pain killers.
Professor Lawson said: “The cause
of this ongoing pain and why it arises spontaneously was not understood
before. Now that we know the type of nerve fibres involved, and especially
that it is the undamaged fibres that cause this pain, we can examine them to
find out what causes them to continually send impulses to the brain. This
should help in the search for new analgesics that are effective for
controlling ongoing pain.”
"Chronic pain is a
devastating and widespread problem, affecting one in five adults across
Europe."
Ongoing pain is a burning or
sharp stabbing/shooting pain that can occur spontaneously after nerve
injury. Unlike ‘evoked’ pain caused, for example, by hitting your thumb with
a hammer, ongoing pain is particularly difficult to live with because it is
often impossible to treat with currently available pain killers.
Djouhri and Lawson show that the
nerve cells responsible are ‘nociceptors’ or damage detectors. There are
thousands of these nerves cells, each of which has a very long, fine nerve
fibre emerging from it. These fibres run within nerves and connect the skin
or other tissues to the spinal cord.
When activated through damage or
disease, these nerve fibres fire electrical impulses that travel along the
fibre from the site of injury to the spinal cord, from where information is
sent to the brain. The faster the undamaged fine fibres fire, the stronger
the ongoing pain becomes.
Dr Djouhri added: “The cause of
this firing appears to be inflammation within the nerves or tissues, caused
by dying or degeneration of the injured nerve fibres within the same nerve.”
The mechanism described by
Djouhri and Lawson occurs following nerve injury and in nerve and tissue
inflammation. Further research is now needed to establish how generally this
mechanism may contribute to ongoing pain associated with a wide variety of
diseases such as back pain or shingles.
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