UNDERSTANDING PAIN MODULATION

The pain modulation pathway refers to a complex system in the nervous system that regulates the perception and intensity of pain. It involves several mechanisms and pathways that can either enhance or inhibit pain signals as they travel from the site of injury to the brain.

Key Components of Pain Modulation Pathways:

1. *Ascending Pathways*: These pathways carry pain signals from peripheral receptors (nociceptors) to the spinal cord and then to the brain. Key structures include:

- *Spinothalamic Tract*: Transmits pain and temperature sensations to the thalamus.

- *Spinoreticular Tract*: Involved in the emotional aspect of pain.

2. *Descending Pathways*: These pathways originate in the brain and can inhibit or enhance pain signals at the spinal cord level. Key structures include:

- *Periaqueductal Gray (PAG)*: Activates descending pathways that can inhibit pain.

- *Rostral Ventromedial Medulla (RVM)*: Modulates the transmission of pain signals by influencing spinal cord neurons.

3. *Neurotransmitters and Neuromodulators*: Various chemicals play roles in pain modulation, including:

- *Endorphins and Enkephalins*: Natural opioids that reduce pain perception.

- *Serotonin and Norepinephrine*: Involved in the descending inhibitory pathways.

4. *Gate Control Theory*: Proposed by Melzack and Wall, this theory suggests that non-painful input can close the "gates" to painful input, thereby preventing pain sensation from traveling to the central nervous system.

5. *Psychological Factors*: Emotions, attention, and past experiences can influence pain perception and modulation. Chronic pain can alter these pathways, leading to heightened sensitivity.

What it means for chronic pain?

To put in simple terms, pain modulation pathway is a counter measure by our brain to reduce the intensity of the pain once brain already sense the pain. As such pain intensity reduces after the initial period. However, at one point, our body will run out of these neurotransmitters. The brain will start to feel intense pain again.

By restrengthening pain modulation partway, pain physicians able to reduce chronic pain. We use medicines such as Serotonin Reuptake Inhibitors (SSRI) to increase neurotransmitter level, hence increasing pain inhibition. At the same time, SSRI being an anti-depressant will also reduce the psychological effect of chronic pain.