How does a discogram function?

With you conscious . This is a test that you have to verbally respond to when placed on a table that x-rays pass through & a needle is guided sterilely into the disc under local anesthesia with some light IV sedation & confirmed to be in the right place with contrast injected followed by sterile water to see what response is given as to whether the disc is the cause of pain. A normal disc does not have pain elicited.
Necessay dx test. Confirms a target disc as the cause of your pain. It is a pre op procedure to confirm which disc hurts causing backache can't go off MRI appearance. Diagnostic test before fusion or replacement to treat back ache surgically.