The endorphin system in the brain and its counterpart enkephalin system in the spine help to shut down pain awareness in acute situations. Had a bad headache that suddenly disappeared? That is that system kicking in. This system is called the Diffuse Noxious Inhibitory Control (DNIC) (you either love or hate that term – it’s impossible to remember). It is frequently deficit in Fibromyalgia and Irritable bowel sydrome. Now it appears commonly deficit in a variety of pain situations.
Prevalence of Generalized Central Hypersensitivity and Efficiency of Diffuse Noxious Inhibitory Control in Chronic Pain
J. Schliessbach et al
IASP poster Montreal 2010
- Pain Pressure sensitivity on the base of the second toe was defined over a normal population (Nezon in submission)
- Normally people, undergoing a cold pressor test (hand pain induced by immersion in cold water), – will kick in DNIC and be less sensitive over the second toe area. In “normals” there is, but in 25% of subjects with chronic pain, there isn’t – a “complete absence”
Comment – One of the areas that controls DNIC is in the paraquaductal gray (PAG). For some annoying reason PAG is hooked up to mood and anxiety centers which inhibit its operation. – Maybe it’s important in an acute situation to feel the pain so you can fight or flight…
I suspect, in certain people with chronic pain, the only time the PAG/DNIC functions is when they are really relaxed. This adds some credibility for the need for relaxation and meditation programs in chronic pain.