Scientists make key find on managing chronic pain

Scientists in Singapore have potentially opened the door to managing chronic pain better after finding a new link between a part of the brain and pain response.

The team from the Yong Loo Lin School of Medicine at the National University of Singapore (NUS) found that the medial septum, which is connected to the cortex of the brain, plays a role in moderating the level of pain a person feels.

This section of the brain has long been associated with learning, memory, fear and anxiety. But this study is the first to look at how it affects chronic pain.

The team of six researchers, led by Associate Professor Sanjay Khanna from the Department of Physiology, found that, by manipulating the medial septum - for example with the use of drugs or by destroying a specific type of neurons - the behaviour and brain function associated with pain was reduced. This included the behaviour of avoidance, and emotions of distress.

PAIN IS SUBJECTIVE

This is because survival is important on the battleground, so pain recedes to the background, while in the hospital setting, survival is not as threatened by the environment, so pain comes to the foreground.

ASSOC PROF SANJAY KHANNA, from the NUS Yong Loo Lin School of Medicine, on why soldiers who suffered deep wounds on the battlefield did not complain much of pain

"What our findings point towards is that the medial septum is a gateway to modulating the emotional distress component of pain," said Prof Khanna. "It becomes a potential target to decrease the function of this area to relieve pain."

The paper was published last month in Scientific Report, an online journal.

Chronic pain is typically defined by persistent pain lasting six months or longer. It is often a result of tissue damage, nerve damage, and, at times, is a side effect of medical treatments such as chemotherapy.

Prof Khanna noted that according to a 2012 report, only one in four patients experienced more than 50 per cent pain relief with the drug treatments available now.

"Imagine, there are 75 per cent of patients with unmet needs," he said.

Equally important is the team's discovery that while damaging the specific neurons in the medial septum decreased pain, it did not affect "normal pain physiology".

This means the protective function of pain, such as how pain from touching a hot stove causes a person to withdraw his hand, is not affected.

Prof Khanna noted that more research has been done over the last decade to fully understand how the brain is linked to pain. The field of pain studies previously largely focused on the spinal cord.

He said the shift is partly because the medicines that have come out of studies into the spinal cord have not provided adequate pain relief or have had side effects.

Also, pain is a subjective experience, which means the brain has an important role to play, he said.

Prof Khanna said one classic example to explain this was an observation by a doctor that soldiers on the frontline suffered deep wounds but did not complain much of pain, while those taken to a clinic complained more of pain.

"This is because survival is important on the battleground, so pain recedes to the background, while in the hospital setting, survival is not as threatened by the environment, so pain comes to the foreground," he said.

The next step, he added, is to further study the medial septum to find out if there are other types of neurons in it that also "facilitate" pain, and how the different neurons work with other parts of the brain.

The scientists are working with researchers from NUS, the National University Health System, Nanyang Technological University and the Agency for Science, Technology and Research, or A*Star.

A version of this article appeared in the print edition of The Straits Times on November 16, 2015, with the headline 'Scientists make key find on managing chronic pain'. Print Edition | Subscribe