EARLY POSTOPERATIVE MRI FINDINGS FOLLOWING SURGERY FOR HERNIATED LUMBAR DISC PART II - A GADOLINIUM-ENHANCED STUDY

The aim of our study was to evaluate the contrast-enhanced MR imaging (MRI) findings, in the early postoperative period, in unselected patie nts undergoing lumbar microdiscectomy (15/16 had total resolution of t heir symptoms). Contrast-enhanced imaging studies were performed, in a ll 16 patients of our series, before surgery, and at the third postope rative day and, two months after surgery. Postoperative paraspinal mus cles enhancement was present in all patients. In the postoperative per iod, nerve root enhancement was present in 5/16 patients at the early survey and persisted in one after two months. A pseudohernia depicted as epidural intermediate signal intensity tissue, was seen in 13 patie nts at the third day MRI, and only in eight after two months. This pse udohernia enhanced peripherally in 8/13 patients and enhanced homogene ously in the remaining five at the first postsurgical examination; in the late MRI the peripheral enhancement was appreciable in only two pa tients while a homogeneous enhancement was observed in six. Clinical s ymptoms resolved completely in 14/16 patients on clinical evaluation a t the third postoperative day, while the remaining two patients showed residual symptoms and signs of radicular compression. At the early MR I these two patients showed intradural nerve root enhancement. Two mon ths later, one patient did not show the previously described nerve roo t enhancement and improved clinically, while the other had a positive Straight Leg Raising Sign with persistent intradural nerve root enhanc ement. In conclusion, no correlation between clinical course and contr ast-enhancement of pseudohernia and extradural nerve root was apprecia ble, although intradural nerve root enhancement seems to represent a c linically relevant finding.