Discography an investigative technique for Herniated nucleus pulposus. Since that time, new imaging techniques that are more appropriate for this diagnosis have been developed. Discography is currently used to determine whether the disk is the source of pain in patients with predominantly axial back or neck pain.
Discography should be performed only if adequate attempts at conservative therapy and Noninvasive diagnostic tests, such as MRI, have failed to reveal the etiology of back pain.
Specific indications for discography include the following:
- Persistent, severe symptoms when other diagnostic tests have failed to clearly confirm a suspected disk as a source of the pain
- Evaluation of Abnormal Disks or Recurrent pain from a previously operated disk or lateral disk herniation
- Assessment of patients in whom surgery has failed, to determine whether pseudoarthrosis or a symptomatic disk in a posteriorly viewed segment could be the source of pain
- Assessment of disks prior to fusion to determine whether the disks of the proposed fusion segment are symptomatic and whether the disks adjacent to this segment can support a fusion
- Assessment of candidates for minimally invasive surgery who have a confirmed disk herniation
- Discography Procedure Technique
- Prophylactic antibiotics should be considered.
- Double-needle technique always should be used.
- The injection should be performed with water-soluble contrast medium.
- Accurate needle placement is required to avoid annular injections, which could produce false-positive results.
- Injection against the vertebral end plate can cause a false-positive response.
- Discography should be followed by CT scanning if possible
- The information recorded should include the following:
- Resistance to the injection (ie, end point)
- Amount of contrast material injected (ie, maximum volume)
- Volume at which the patient experienced pain (ie, pain volume)
- Pattern of dye distribution (eg, diffusion, location of fissure, extravasation, herniations, Schmorl nodule)
- Pressure at which patient experienced “pressure sensation”
- Pressure at which patient experienced “pain”
- Pain response (ie, location, character, distribution, intensity, and concordance or discordance with the patient’s typical pain and pain pattern)
- Pain intensity recorded on a 0-10 scale
- Very careful attention should be paid to interpreting the pain response during the injection of each disk, including whether the pain is similar to or exactly like the symptoms for which the patient seeks relief. The location of the pain and its intensity should be noted.
- Pain at low pressures is most likely due to chemical irritation. Low resistance generally is associated with a tear through the outer annulus. Pain at high pressures may be due to mechanical irritation, end-plate deflection, or stimulation of pressure receptors.
- Generally, if a large volume of contrast can be injected, the disk is degenerated or has a fissure extending through the outer annular wall.
- The specificity of discography findings could be increased if CT scanning findings are correlated. Annular disruption reaching the outer annulus fibrosus is a key factor in pain generation. Disk morphology, including annular disruptions extending beyond the outer annulus, may permit increased discography specificity.