Headaches and migraines trigger more suffering than pain in any other part of the body, new research has revealed.
Scientists claim that discomfort will always feel worse in the head – regardless of if someone is struck at the same force and impact on the knee, arm or anywhere else.
They discovered a previously unknown network of nerves that sends pain signals from our heads directly to the part of the brain that deals with emotion.
The findings may help to explain why headaches are considered to be one of the most unpleasant forms of pain, researchers said.
Scientists from Duke University said that until now it was unknown why people rate pain as worse when it affects our heads.
A previously unknown network of nerves sends pain signals from our heads and faces directly to the part of the brain that deals with emotion, a study has found
It was previously thought that our heads and faces were simply more sensitive.
But now research has found a previously unknown network of nerves link the face to the brain’s emotional centres.
Wrtiting in Nature Neuroscience, the researchers write: ‘Humans generally rank head and facial pain as much more severe and emotionally draining than body pain.’
The most painful conditions
They say that two of the ‘arguably’ most painful conditions are trigeminal neuralgia and cluster headaches.
Trigeminal neuralgia is very painful condition which typically causes electric shock-like pain in one or more branches of the trigeminal nerve, usually on one side of the face.
Brain scans of humans whose faces are given a painful stimulus show greater stimulus of the amygdala – the brain area that deals with emotion.
The latest research – in mice – found that the mouse’s face and head has a direct nerve pathway to the brain’s emotional centres.
Other parts of the body only had an indirect link.
The researchers say that the findings may pave the way toward more effective treatments for pain mediated by the craniofacial nerve, such as chronic headaches and neuropathic face pain.
Fan Wang, Professor of Neurobiology at Duke said: ‘Usually doctors focus on treating the sensation of pain, but this shows the we really need to treat the emotional aspects of pain as well.’
She added: ‘There has been this observation in human studies that pain in the head and face seems to activate the emotional system more extensively.
‘But the underlying mechanisms remained unclear.’
How was the study carried out?
To examine the neural circuitry underlying the two types of pain, Dr Wang and her team tracked brain activity in mice after irritating either a paw or the face. They found that irritating the face led to higher activity in the brain’s parabrachial nucleus (PBL), a region that is directly wired into the brain’s instinctive and emotional centres.
Finding the direct link was a revelation, Dr Wang said.
Dr Wang said that ‘It was a eureka moment because the body neurons only have this indirect pathway to the PBL, whereas the head and face neurons, in addition to this indirect pathway, also have a direct input.
The findings may help to explain why pain in our heads and face are considered to be one of the most unpleasant forms of pain, researchers said
‘This could explain why you have stronger activation in the amygdala and the brain’s emotional centers from head and face pain.’
In research which could one day lead to new treatments for pain, the scientists found that stopping the signals on the pathway reduced the face pain in the mice.
The first biological explanation
Dr Wolfgang Liedtke, co-author, of Duke University Medical Centre said: ‘We have the first biological explanation for why this type of pain can be so much more emotionally taxing than others.
‘This will open the door toward not only a more profound understanding of chronic head and face pain, but also toward translating this insight into treatments that will benefit people.’
Dr Qiufu Ma, of Harvard Medical School, who was not involved in the study said: ‘Some of the most debilitating forms of pain occur in the head regions, such as migraine.
‘The discovery of this direct pain pathway might provide an explanation why facial pain is more severe and more unpleasant.’