No association between peridural scar and outcome after lumbar microdiscectomy

Abstract

The association between postoperative scar formation on MRI and outcome was investigated in 54 out of one hundred patients operated on with microdiscectomy in a prospective cohort study with a one year follow up. The patients were classified as failures or successes at the 12 months follow up according to a clinical overall score. All the 14 failures were investigated with MRI, and 40 patients classified as successes were picked at random for MRI. Patients with signs of recurrent disc herniation on MRI were excluded. The MRI scans were rated according to the presence or absence of scar formation within the spinal canal and the degree of scar enhancement by two independent neuroradiologists ignorant of treatment outcome. No evidence of scar formation was found in 4 patients, a small amount in 11, intermediate in 38 and extensive scar tissue in 1 patient. Slightly enhancing scar tissue was found in 18 patients, intermediate in 27 patients and strong enhancement in 5 patients. No association between the amount or enhancement of peridural scar formation and clinical outcome was found. Both the total clinical score and the difference between pre- and post-operative clinical score were used in the calculations. Testing the different subsets in the clinical overall score, as well as the patient satisfaction VAS score, did not reveal any association.