Lower Back Pain (LBP) is a highly prevalent condition (60 to 80% adults). Current treatments for IDD/DDD are invasive, costly, and marginally effective.
A healthy normal disc has a water-rich, gelatinous central portion called the nucleus pulposus that allows it to absorb spinal stress. Excessive pressure or injuries to the disc can cause the annulus to tear. The annulus is generally the first portion of the disc to be injured. Small tears in the ligament material of the annulus heal as scar tissue and are not as strong as normal ligament tissue. With additional injuries, the annulus becomes weaker over time as more scar tissue forms. As a result, the nuclear material may extrude from its central location, creating pressure on parts of the annulus that are pain-sensitive. When this occurs, it can lead to well-documented disc pathology that is one of the primary causes for back pain.
Diagnosis of Discogenic Pain with Provocation Discography
Discogenic pain due to internal disc derangement can only be diagnosed definitively with discography. A noninvasive diagnostic X-ray may show a decrease in the height of space between vertebrae, but will not detect a torn disc. Magnetic resonance imaging (MRI) allows a more direct visualization of the disc. On MRI, a hydrated and healthy disc will appear white while a disc that is degenerated due to water loss will appear darker. However, a dark disc on MRI does not necessarily mean that it is a pain generator. A disc defect may appear as a bulge, or may produce a negative or equivocal MRI. Certain cases of internal disc disruption or IDD (i.e., tears in the annulus) can be identified on MRI by a signal of high intensity in the posterior annulus. Morphologically, this high intensity zone (HIZ) appears on sagittal section as nuclear material running circumferentially in the posterior annulus. Presence of the HIZ has been found to correlate strongly with symptomatic annular fissures on discography. Although MRI is a well-established diagnostic modality in patients with suspected disc lesions, it is accepted that many abnormal discs on MRI are not symptomatic and discs that appear normal on MRI have been shown to be abnormal on discography.