We do not yet understand why some people develop painful tears and others do not. It appears that damaged discs may become painful due to the irritation of small nerves in the damaged outer wall of the disc or due to irritation and pressure on nerves that grow into the disc with scar tissue. A solution to this pain would be to strengthen the torn, weakened disc wall and to deaden the painful nerves. Discs are the shock absorbers between each vertebral body. The history of a patient's pain, their physical exam, x-rays and MRI scans can suggest the presence of painful damaged discs.
Confirmation is provided by a diagnostic disc injection test - also called a discogram.
This involves the placement of a thin needle into the disc using an X-Ray machine followed by the injection of contrast dye. The contrast fills disc tears if present. Pressure inside the disc may trigger discomfort if the disc is sensitive. Undamaged discs are not usually painful. Discograms are performed by placing small needles into the intervertebral discs under fluoroscopy guidance.