Types of chronic pain

Chapter 10 endnote 21, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

A few well-known examples [of chronic pain] are fibromyalgia, migraine headaches, and chronic back pain.

There are three types of chronic pain:

• Neuropathic pain, which is caused by disease of the somatosensory system.
• Inflammatory pain, which is due to inflammation.
• Idiopathic pain, which has no detectable cause.

These types are distinguished from nociceptive pain, which is caused by damage or threat of damage to non-neural body tissues. For more on definitions and types of pain, visit the International Association for the Study of Pain.

Scientists and physicians struggle with understanding neuropathic pain, in part because they may take a very limited (and essentialist) approach to defining the somatosensory system. For example, it is anatomically justified to include motor cortex as part of the somatosensory system. Motor cortex not only controls movements of the body (i.e., striate muscles attached to the skeleton), but also movements in the body (i.e., body-budgeting movements). Therefore we can speculate that motor cortex could play a role in chronic pain.