The Power Of The Brain In Tackling Pain
The unpleasant sensation of pain which is disliked by all can be due to a minor injury. However, in some cases, it could also be suggestive of a serious underlying disease. Pain can occur in any part of the body, but the brain plays an important role in experiencing the quality and severity of the pain.
Any part of our body can perceive a painful stimulus, as pain receptors are present in the skin all over the body. However, a sensation can be realized as ‘pain’ only at the level of the brain.
Neural Pathways Carrying Pain Sensations
Pain receptors are present in the skin and the pain received by these receptors is carried by the sensory nerves to the spinal cord. From the spinal cord, these nerve fibres carrying pain sensations reach the brain (thalamus, insula and anterior cingulate gyrus). It is at the level of the brain, where the ‘severity’ and ‘character’ of the pain is fully appreciated.
It is also interesting to note that the pain areas of the brain shift, as the pain becomes chronic from acute or sub-acute. In a short-duration pain, the pain is perceived at the level of sensory areas of the brain such as insula and thalamus. However, as the pain becomes chronic (long-duration), the pain areas are represented in the amygdala, medial prefrontal cortex and basal ganglia which are more involved with emotions.
Central Post Stroke Pain (CPSP)
Central post stroke pain, most commonly occurs after strokes (lack of blood supply or bleeding) in the thalamus area of the brain. In this disease, patients experience severe pain, (described as burning, tingling or scalding), on one half of the body (opposite to the side of the affected thalamus). The pain may last for months to years and is very difficult to treat. Medications such as pregabalin or duloxetine can provide partial pain relief.
The Brain Modifies The Way One Reacts To Pain
The ways in which people respond to pain differs. Some people cannot tolerate even a mild degree of pain! For instance, there was once a patient who had pain in her big toe for two years, for this pain she had consulted about 20 doctors before consulting me. She carried a ‘thick’ file of medical reports and every possible test had already been done. The detailed clinical examination, as well as all possible investigations, was normal. However, she was too disturbed with this pain and was unable to manage her daily activities. Finally, she required several sessions of counselling to get rid of this psychosomatic pain. On the other hand, I have managed several patients with severe cancer pain (supposedly the cause of most severe pain), who enter my office with a big smile. They hardly complain and are able to live well, despite the severe pain.
This difference in the way one responds to pain can be explained at the basis of brain and mind functioning. The mood of a person too, influences pain perception. A happy person is likely to tolerate pain much better than a person who is sad or unhappy. Similarly, a person under stress or one who is anxious, is affected more adversely with pain.
Adverse Effects Of Pain On The Brain
Chronic pain can adversely affect the brain structure and functions. Studies have shown that hippocampus volumes are reduced in a victim of chronic pain. The hippocampus is involved in memory and emotional responses. Therefore, people with chronic pain are likely to suffer from increased anxiety and learning and memory problems.
Grey matter volumes of certain brain regions such as prefrontal cortex are also reduced in patients with chronic pain. This part of the brain is involved in executive functioning, which relies on past learned tasks, remembering that information and enabling a person to appropriately respond to complete a new task. A person with chronic pain may suffer from executive dysfunction, making him/her take longer to process information and complete a new task.
Nevertheless, the good news is that these changes are temporary and reversible, once the pain is over. Therefore, it is important to identify the underlying cause of pain and appropriately treat them.
Meditation And Pain Relief
Mindfulness meditation has the power to alleviate pain through its effects on various brain areas. Meditation reduces pain by activating the orbitofrontal cortex and anterior cingulate cortex. These brain areas are associated with the self-control of pain. Mindfulness meditation also deactivates the thalamus, as a result of which pain sensation is not allowed to reach higher brain centres.
The pain areas of the brain shift as the pain becomes chronic from acute or sub-acute
Brain Changes Due To Yoga And Pain Tolerance
Chronic pain and yoga have opposing effects on the brain structure. Chronic pain leads to reduction in the grey matter of the brain, whereas yoga leads to an increase in grey matter. Grey matter increase in the insula among yogis, this is why they have pain tolerance.
The brain plays an important role in perception of pain and emotional responses associated with it. Damage to the brain due to stroke or head injury could alter pain responses. Chronic pain affects areas concerned with emotion too, as opposed to short-duration pain. Yoga and meditation are excellent non-drug measures by which one can increase pain tolerance, effects which are mediated through changes in brain structure and function.