INFLUENCE OF FIBRINOLYTIC FACTORS ON SCAR FORMATION AFTER LUMBAR DISKECTOMY - A MAGNETIC-RESONANCE-IMAGING FOLLOW-UP-STUDY WITH CLINICAL CORRELATION PERFORMED 7 YEARS AFTER SURGERY

Study Design. Prospective cohort study. Objectives. To assess the amou nt of scar tissue by viewing magnetic resonance images, and to evaluat e the correlation between the amount of scar tissue and clinical outco me, surgical technique, and fibrinolytic factors. Summary of Backgroun d Data. The influence of fibrinolytic factors on magnetic resonance im ages has not been investigated previously. The relation between clinic al outcome and findings on magnetic resonance imaging remains uncertai n. Methods. Magnetic resonance imaging at 0.5 Tesla was performed to p roduce sagittal and axial spin-echo T1-weighted images before and afte r contrast enhancement on 78 patients 7 years after traditional lumbar discectomy with partial or full laminectomy. Before surgery all patie nts had been tested for fibrinolytic factors. Results. The overall cli nical success rate of the surgery was 73%. No evidence of scar formati on was seen in 19 patients, a small amount was seen in 36 patients, a moderate amount in 17 patients, and a large amount was observed in 6 p atients. Ten patients who had undergone surgery at two disc levels and 18 who had been treated with full laminectomy exhibited more scar tis sue than those patients who had undergone surgery on a single level (P = 0.033) and those who had undergone a partial laminectomy, respectiv ely (P = 0.017). The amount of scar formation also was associated with a poor outcome (P = 0.017) and with low preoperative values of tissue plasminogen activator antigen (P = 0.003) and tissue plasminogen acti vity (P = 0.048) in samples collected after venous occlusion. The inte nsity of contrast enhancement, however, was not influenced by these or any other parameters. Conclusion. The amount of scar formation after lumbar discectomy seems to be related to the clinical outcome, the siz e of the surgical exposure, and some fibrinolytic factors.