Laser pulses measure brain waves to determine pain response

Scientists at the University of Manchester in England have shown, using laser pulses to measure brain waves, that the abnormalities in the way the brain experiences pain may be to blame for the chronic pain suffered by osteoarthritis patients. Their findings suggest the need for new therapies to target brain mechanisms to enable the brain to cope more effectively with chronic pain, including mindfulness-based talking therapies.

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Chronic pain can affect up to 30% of the population at any one time, with most complaints relating to arthritis. Patients can become more disabled as their pain spreads to other areas and find it difficult to cope as it interrupts sleep and other normal daily routines.

Prof. Anthony Jones of the University’s Human Pain Group, based at Salford Royal NHS Foundation Trust, says: "The extent of pain experienced by sufferers of arthritis has always been thought to result from the direct consequences of joint destruction. However, the extent of pain is often poorly related to the amount of damage and can spread to nearby regions of the body where there is no evidence of arthritic disease. We wanted to look at what might be causing this."

Researchers thought that the spreading and intensification of pain in arthritis may be similar to that experienced by sufferers of fibromyalgia, a widespread chronic pain condition associated with psychological distress and sleep disturbance—where there is currently no consensus about the cause of the pain. Earlier research had suggested that patients with fibromyalgia have abnormalities in the way in which the brain deals with pain, so the Manchester team looked at the overlaps in how pain is processed in the brain, between osteoarthritis and fibromyalgia, to help them understand why some sufferers of arthritis can experience much worse pain than others.

In the research team's study, they measured brain waves in response to short, painful laser pulses to the skin in patients with osteoarthritic or fibromyalgic pain and those with no pain. They found that while anticipating the painful pulse, a brain area called the insula cortex increased its activity, and this predicted the extent and intensity of the patients’ own chronic pain.

The study suggests that there are common abnormalities in the way the brain expects pain in fibromyalgia and osteoarthritis, which can be considered potential common brain mechanisms for these conditions. Prof. Wael El-Deredy of the University of Manchester says, “More research is needed, but this suggests we should be putting more resources into a common approach to developing new therapies that target these potential brain mechanisms."

Professor Alan Silman, medical director of Arthritis Research UK, which funded the research, says, "Focusing research on targeting abnormal brain mechanisms rather than more conventional approaches looking at joint damage could be a major step forward that could reduce people’s dependency on anti-inflammatories and painkillers."

Full research details appear in the European Journal of Neuroscience; for more information, please visit http://onlinelibrary.wiley.com/doi/10.1111/ejn.12420/abstract.

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