Clinical impact of contrast-enhanced MR imaging reports in patients with previous lumbar disk surgery

We wanted to assess the clinical impact of the reports of contrast-enhanced MR imaging on the decision to repeat surgery and on the results of repeat surgery in patients with previous lumbar disk surgery.

We interviewed 257 patients who had undergone lumbar disk surgery and who showed symptoms suggesting persistent or new disk herniation. We conducted our interviews 6-18 months after patients had undergone contrast-enhanced MR imaging. We then correlated patient outcome with original MR findings.

Fifty-two patients underwent new surgical procedures after their MR examination. Findings of disk herniation on MR images were associated with a significantly greater frequency of repeat surgery. The size of main herniation seen on MR images was also a significant variable. Patients with Worker's Compensation Insurance files had significantly worse prognoses: Only two (8%) of 26 of these patients reported 50% improvement 1 year after repeat surgery. However, only 6 (23%) of 26 non-Worker's Compensation patients reported 50% improvement 1 year after surgery.

Despite its documented high anatomic accuracy, the clinical usefulness of enhanced MR imaging for patients with previous lumbar disk surgery needs further evaluation. In our series, findings of disk herniations on enhanced MR examinations were associated with a greater frequency of repeat surgery, but such surgery relieved symptoms in few patients. The influence of enhanced MR imaging on the decision for repeat surgery and on the type of surgery may be misleading. Selection criteria for repeat surgery need to be reassessed using rigorous outcome research protocols.