MRI findings in failed back surgery syndrome.

The failed back surgery syndrome (FBSS) is a difficult diagnostic problem both clinically and radiologically. Forty-three patients were evaluated prospectively with magnetic resonance imaging (MRI) and forty-five scans were obtained. Fifteen patients (33%) showed recurrent disc prolapse; 15 (33%) patients postoperative epidural fibrosis; 8 (18%) both recurrent disc prolapse and epidural scarring; 4 (9%) patients spinal stenosis, 2 whom also had both epidural fibrosis and recurrent disc prolapse; 2 (4%) normal scans; 2 (4%) patients arachnoiditis and 1 (2%) patient postoperative pseudomeningocoele formation. Gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA)-enhanced MRI was particularly helpful in differentiating recurrent disc prolapse and epidural fibrosis. Surgical findings in 11 patients were available. MRI correctly predicted recurrent disc prolapse in 6 patients, epidural fibrosis in 4 patients and spinal stenosis in 1 patient illustrating the value of this modality in the evaluation of FBSS.