RESUMEN
PURPOSE: The rationale for the use of Gadolinium (Gd) in the MRI evaluation of non surgically treated herniated disk is based on the known presence of inflammatory granulation tissue and neoangiogenesis which plays an important role in both pain and the spontaneous resorption of the hernia. THE AIM: of this study was to determine the usefulness of Gd in MRI examination for detecting the inflammatory reaction around the discal hernia. MATERIALS AND METHODS: Thirty-eight patients (mean age 45 years; range 20-70 years) with non surgically treated herniated disk were evaluated with MRI between January 2000 and July 2004. T2w-FAST-SE sagittal and T1w-SE transaxial and sagittal images were acquired before and after the administration of Gd. RESULTS: Twenty out of 22 patients with acute sciatic pain (symptoms =/< 40 days) showed significant peri-hernial enhancement which facilitated the differential diagnosis with other extradural lesions, such as synovial cysts (2/22 cases), as well as the correct definition of the extension of discal hernia in the spinal canal. In the remaining 16 with chronic sciatic pain (symptoms > 6 months) the discal hernia did not show peri-hernial enhancement. CONCLUSIONS: In MRI evaluation of the herniated disk, peri-hernial enhancement is correlated with inflammatory reaction around the hernia which is associated with acute symptoms. The absence of peri-hernial enhancement in chronic herniated disk is due to the poorly vascular fibrotic tissue. Therefore, peri-hernial enhancement facilitates the differential diagnosis in uncertain cases and represents a reliable prognostic index of response to non-surgical therapy and of the possible spontaneous resorption of discal hernia.
