[MRI of the operated lumbar spine and enhancement of intradural nerve roots. 478 cases].

Authors report a study of 478 MR imaging in failed back surgery syndrome. Enhancing nerve roots were detected in 73.8%, with a significant higher percentage in male patients, and long postoperative delay. There was no significant correlation with age, enhancement of epidural scar (epidural scar was seen in 75.7%) and disk herniation (seen in 25.9%). Alteration of blood-nerve-barrier causes enhancement, but the mecanism is nuclear: mechanical, biological, immunological or Wallerian degeneration. Diagnostic and prognostic value of enhancement are not proven and a study of asymptomatic patients is necessary.