The Basic Types of Pain

There are two well-recognized broad categories of pain: the common sensical sort (the pain of damage), and the somewhat more exotic kind that comes from damage to the system that reports and interprets damage, the nervous system. It’s the difference between engine trouble and trouble with that light on your dashboard that says there’s engine trouble. More specifically:

1. Nociceptive pain arises from various kinds of trouble in tissues, reported to the brain by the nervous system.1 This is the type of pain everyone is most familiar with, everything from bee stings and burns and toe stubs to repetitive strain injury, nausea, tumours, and inflammatory arthritis. Nociceptive pain typically changes with movement, position, and load.
2. Neuropathic pain arises from damage to the nervous system itself, central or peripheral, either from disease, injury, or pinching.2 The simplest neuropathies are mechanical insults, like hitting your funny bone or sciatica, but this is a big category: anything that damages neurons, from multiple sclerosis to chemotherapy to alcoholism to phantom limb pain. It’s often stabbing, electrical, or burning, but nearly any quality of pain is possible. Unfortunately, it’s also more likely to lead to chronic pain: nerves don’t heal well.3

Migraine? Still tough to classify! Some experts consider it a major category of its own, parallel to nociceptive and neuropathic pain,4 but it’s probably just a complicated neuropathy.5

Obviously these kinds of pain can overlap. Some medical problems, like injuries, can affect both nerves themselves and other tissues, causing both kinds of pain. However, it’s surprising how little overlap there is: look at any list of the most painful conditions [NHS] and they all fit pretty clearly into one category or the other.

Pain is predictably unpredictable, thanks to brains. Regardless of type, all pain is weird in some typical ways, because it’s all under the total control of our brains,6 and brains have complicated and conflicting priorities for us that we are oblivious to.7 The result is that pain is often weird, a somewhat paranoid guess about how much danger we’re in, and that’s when everything’s working correctly. If the nervous system is damaged (neuropathic pain), then the brain is getting bad information, and pain gets even weirder. But when the nervous system misbehaves, pain can get so wonky that a whole new category of pain might be needed.