Failed back surgery syndrome: differentiating epidural fibrosis and recurrent disc prolapse with Gd-DTPA enhanced MRI.

The failed back surgery syndrome (FBSS) is a difficult diagnostic problem. Two of the more common causes of FBSS are epidural fibrosis and recurrent disc prolapse. Forty-five gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) enhanced magnetic resonance (MR) scans were performed on 43 patients to evaluate the effectiveness in differentiating recurrent disc prolapse from epidural fibrosis. Operative findings were available in 11 patients and they confirmed the pre-operative radiological diagnosis of recurrent disc prolapse in 6, epidural fibrosis in 4 and facet joint hypertrophy in 1 patient. Although the number of surgically verified cases is small, our initial experience of 100% diagnostic accuracy reflects the tremendous potential of this investigative tool. Separating epidural fibrosis from recurrent disc prolapse is crucial as patients with the former are expected to benefit from further surgery. Patients with epidural fibrosis, on the other hand, generally do not gain relief from another operation.