The Brain

Pain is more than just messages being sent to the brain from sensitive areas of the body. It is the result of a complex interaction between the brain, the body, and your emotions and experiences.

Changes in Brain Structure

As discussed in 'The Body', endometriosis lesions and inflammation contribute to pain. However, research has shown that certain changes in the brain structure also play an important role in feeling pain. Researchers found lower levels of grey matter in the part of the brain involved within feeling pain among people with endometriosis that feel chronic pain compared to those that do not feel chronic pain1, 2. This means that changes in the brain structure may also contribute to feeling pain separate from the endometriosis lesions.

Gate Control Theory

When nerves in the body notice that sensitive areas are being touched, they send messages to the spinal cord. The spinal cord can then either allow, reduce or block those messages  travelling to the brain. The Gate Control Theory explains how the spinal cord acts as a ‘gate’ that controls the messages getting through to the brain3. When the gate is closed, the brain does not receive messages from the spinal cord. When the messages received by the spinal cord reach a certain level, the gate opens and the messages are transferred to the brain. The brain processes these messages and this is how you feel pain. In some people, pain messages get blocked by the spinal cord and people don’t feel as much pain3. In others, more pain messages are allowed to pass through to the brain which can make people feel more pain.

A person’s thoughts and emotions can change how open or closed this spinal gate is. Someone who experiences pain might experience negative thoughts and emotions. This might change the spinal gate to be more open, which allows more pain messages to get through to the brain. This increases the chance that they might feel more pain. 

This is real pain. It is not in your head. Pain can be changed.

  1. As-Sanie S, Harris RE, Napadow V, Kim J, Neshewat G, Kairys A, Williams D, Clauw DJ, Schmidt-Wilcke T. Changes in regional gray matter volume in women with chronic pelvic pain: a voxel-based morphometry study. Pain. 2012 May;153(5):1006-14. doi: 10.1016/j.pain.2012.01.032
  2. As-Sanie S, Kim J, Schmidt-Wilcke T, Sundgren PC, Clauw DJ, Napadow V, Harris RE. Functional Connectivity is Associated With Altered Brain Chemistry in Women With Endometriosis-Associated Chronic Pelvic Pain. J Pain. 2016 Jan;17(1):1-13. doi: 10.1016/j.jpain.2015.09.008.
  3. Trachsel LA, Cascella M. Pain Theory. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: