Redundant Nerve Roots of Cauda Equina Mimicking Intradural Disc Herniation: A Case Report
A 50-year-old man who worked at a rice-cake shop has suffered from increasing low back pain and radiating pain on his left leg for five years. He had a nerve root block on L5 level five years ago, and the pain subsided temporarily. He was having conservative treatment but mild chronic pain still lasted and gradually aggravated and abruptly extended to the right leg a few days before his admission. Radiating pain was on posterior and lateral aspect of the leg and toe.\nHe had no significant medical history or trauma history of spine. But he has been lifting heavy things repeatedly at work. A neurological examination revealed no paresthesia or motor weakness. A straight leg raise test was positive on the left side and the bilateral knee and ankle jerk was normal. Micturition and defecation were not disturbed.\nSagittal and axial T2-weighted magnetic resonance image reveals broad base central disc protrusion at L4-5 level, and about 0.7×0.5×2.5 cm sized ovoid nonenhancing lesion in dorsal aspect of L5-S1, which seemed to be intradural disc herniation rather than intradural mass (). Although the image clearly demonstrated neither the classical ring enhancement of the intradural fragments on gadolinium contrast MRI or discontinuity of the PLL disrupted at the disc level, this finding was thought as an intradural disc herniation rather than an intradural extramedullary (IDEM) tumor such as meningioma. CT myelography showed central disc herniation at L4-5 and intradural lesion looked like intradural disc or intradural mass within the thecal sac below L4/5 ().\nA decompressive laminectomy was carried out at L4-5 levels and a herniated disc at L4-5 was removed. And we found the fragments of ruptured disc and adhesion with the dura. To determine whether there was a coexisting intradural disc rupture, we carried out an intradural exploration. After durotomy, a long, edematous and tortuous nerve root had forced out through a dural incision (). We explored the thecal sac, but there was no other intradural abnormality such as intradural disc herniation or intradural mass.\nAfter rearrangement of RNRs of the cauda equina to be released from the tangled position, the dura was carefully closed without tension.\nThe radiating pain was improved immediately in the postoperative period. The patient made an uneventful recovery and returned to normal activities. One year after surgery, he had no further pain.