ABSTRACT
Investigations for chronic pain are limited by what particular tests can and cannot show, and by the nature of conditions that cause chronic pain. Conventional investigations have limitations in the pursuit of pain, and conditions that cause chronic pain typically do not express abnormalities in conventional tests. In patients with chronic pain, previously unrecognized fractures are very unlikely to be the cause of pain. Radiography, just in case the patient has a fracture, is not justified. In that context, the rules for acute pain serve as sensible initial guidelines for chronic pain. Diagnostic blocks are the most powerful tool by which to pinpoint the mechanism or the source of chronic pain, but in order to be valid, diagnostic blocks must be controlled. Spinal pain can be investigated using disk stimulation and controlled diagnostic blocks. The cardinal diagnostic criteria are inordinate pain, allodynia, and a history, at some time, of swelling and color changes, apart from temperature changes.
