Intradural lumbar disc herniations: the role of MRI in preoperative diagnosis and review of the literature.

The goal of this article is to report our experience on intradural lumbar disc herniation, consider the causes of this pathology, and analyze it from clinical, diagnostic, and therapeutic perspectives with a particular emphasis on the role of MRI in preoperative diagnosis. We analyzed nine patients treated surgically for intradural lumbar disc hernia. All of them underwent surgery, and hemilaminectomy was performed. In six cases, the diagnosis of intradural herniation was definitive and, in the three remaining, it was confirmed at surgery. In five cases, CT (with no contrast medium) of the lumbar area revealed disc herniation, but none could it confirm its intradural location. Myelography was performed in two cases but also could not prove intradural extrusion. Magnetic resonance imaging study was used in four cases. In five, the postoperative outcome has been excellent. Patients 6 and 9 recovered anal function postoperatively; patient 6 suffered from occasional and mild micturition urgency. The three patients previously operated (1, 2, 7) showed good outcome. Presently, we believe that radiologic diagnosis of intradural herniation is possible in carefully selected patients, thanks to MRI with gadolinium.