Strong Feelings - Latest Findings On Pain Sensitivity

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Strong Feelings - Latest Findings On Pain Sensitivity

http://www.medicalnewstoday.com/medicalnews.php?newsid=50643

The recent discovery of the amplification of even low levels of pain

has prompted the organisation of an upcoming symposium in Vienna

on " Risk Assessment in Pain Therapy " . This international expert

meeting will aim to optimise pain therapy by taking account of this

previously unknown phenomenon. As a result the findings of an

Austrian Science Fund FWF project, which were recently published in

SCIENCE, may soon be benefiting patients who suffering severe chronic

pain.

Constant pain can really get on your nerves - literally. The

phenomenon of pain sensitivity enhancement is responsible for this.

In the case of persistent pain impulses, it brings about permanent

changes in the neurons responsible for transmitting the pain signals.

This leads to an increase in pain sensitivity and the sensation of

pain can even persist long after the actual pain signals has faded

out.

Strong and Weak

Pain sensitivity enhancement is a feature of both weak and strong

pain, but the model used to explain how this phenomenon arises is

based solely on the testing of strong pain impulses. In reality,

though, low level pain does not give rise to all of the neural

processes which are postulated by the previous explanatory model.

Now, a team under Prof. Jürgen Sandkühler of the Department of

Neurophysiology at the Medical University of Vienna has published

findings in the June 2006 edition of SCIENCE which explain the

existence of pain amplification even at low levels of pain.

Commenting on the research, Prof. Sandkühler said: " We were able to

show in a controlled laboratory system that the amplification arises

even when the pain is quite weak. We actually used electrical

impulses that were 50 times weaker than those previously employed to

induce this response. Weak pain signals like these are symptomatic of

the healing of wounds and of inflammation. "

Prof. Sandkühler's group was also able to identify the cells

responsible for this previously unknown phenomenon. They are located

in the lamina I of the spinal dorsal horn, and ensure that signals

from peripheral pain fibres are transmitted to spinal nerve tracts

leading to the brain.

Illuminating Evidence

As part of this large-scale project, Sandkühler and his team were

also able to indicate which cellular mechanism is behind low-level

pain enhancement. Cells were loaded with dyes which emit light when

exposed to sufficient concentrations of calcium ions. This made it

possible to show that the concentration of calcium ions in these

lamina I cells also increases dramatically in response to weak pain

impulses. This is one of a multitude of cases in which calcium ions

are involved in cellular signal transmissions. Here, the calcium ions

activate enzymes which amplify the pain impulses.

These new findings are of fundamental importance for pain therapy. As

Sandkühler put it: " Treating patients with pain killers for a short

period of time after an operation, for example, is not an effective

means of avoiding pain enhancement. Pain therapy must be continued

without interruption until the pain has largely subsided. "

In order that these recommendations may be implemented quickly, Prof.

Sandkühler is playing a part in organising an expert meeting on the

topic. The " Risk Assessment in Pain Therapy " symposium will take

place on 10th November 2006, with the aim of evaluating the

opportunities and risks of current therapeutic procedures in the

light of these new findings. In cooperation with IGOST (the

Interdisciplinary Society for Orthopaedic Pain Therapy), Sandkühler

has succeeded in attracting representatives of DGSS (the German

Society for the Study of Pain), ÖSG (the Austrian Pain Society) and

internationally renowned pain researchers to this event in Vienna.

This should mean that the findings of this FWF project can soon feed

through into specific recommendations for clinical therapy.