Connection between herniated nucleus pulposus and nerve roots in far lateral lumbar disc herniation

Abstract

Background: Far lateral lumbar disc herniation (FLLDH) compresses the nerve root or dorsal ganglion outside the spinal canal at the same level as the herniation, producing severe pain on the anterolateral thigh. The pain is so severe that many patients cannot even walk. The severity of pain is attributed not only to compression, but also some chemical inflammation. Objective: To report a case of FLLDH whose nerve root was depicted during discography.Case report: A 55-year-old-man presented with severe pain from the left buttock to the left anterolateral thigh and leg. Abnormal shadowing suggested left FLLDH at the L5/S1 level on magnetic resonance imaging. During discography, a shadow suggestive of the left fifth lumbar nerve sheath was depicted. Comparing the computed tomography (CT) after discography and CT after rootgraphy, the root sheath-like shadow on discography was confirmed as the nerve root sheath. After nerve root block, pain decreased and the patient was discharged. Conclusions: The combination of mechanical compression and chemical inflammation by the herniated nucleus pulposus is considered responsible for severe pain in the disc herniation and also in FLLDH. Depiction of the nerve root during discography of FLLDH means that a connection exists between the herniated nucleus pulposus and affected nerve root sheath. Inflammation around the extruded nucleus pulposus penetrates the contacted nerve root sheath; this inflammation is thought to be one of the causes of severe pain in FLLDH. We recommend conservative therapies such as intradiscal or foraminal injection of local anesthetics with steroid for patients with radicular symptoms of FLLDH.