LONG-TERM CHANGES AFTER CHEMONUCLEOLYSIS IN THE MRI

6.5 years after lumbar chemonucleolysis (CNL) we examined 40 patients by MRI. All MRI studies were performed by a 1.0 tesla MRI. We document ed the height of the discs, the chondrosis, the intradiscal MRI signal , as well as the intraosseous signal within the vertebral bodies (end plate reaction). Preoperative MRI studies (T(vor)) and/or postoperativ e MRI studies within the first postoperative year (T1) of 18 patients were available. We found an overall reduction of the sagittal disc hei ght of 26%. This reduction was 19% in the male patients and 45% in the female patients (p<0.02). Comparing the T1-studies with the T6,5-stud ies, we could still reveal a proceeded reduction of 13%. In those pati ents who underwent three MRI studies, there was a reduction of 20% bet ween T(vor) and T1. Among one half of the patients we found a further decrease in disc height of 15% between T1 and T6.5, whereas the other half showed an increasing disc volume of 15%. At time of follow up (T6 .5) all treated discs showed a reduced MRI signal (STIR) within the di sc. The signal further decreased comparing the MRI signal (STIR) preop eratively with the follow up evaluation in 64.3% of the cases. However , we found an increase of the signal in 70% of the cases between T1 an d T6.5. 6.5 years after CNL we documented an end plate reaction in alm ost 70% of all patients. There was no correlation between end plate re action and age of the patients, level of CNL, amount of injected chymo papain or the clinical outcome.