Anatomical study on the relationship between the dorsal root ganglion and the intervertebral disc in the lumbar spine☆

OBJECTIVE To describe the location of the dorsal root ganglion in relation to the intervertebral disc, including the "triangular" safety zone for minimally invasive surgery in the lumbar spine. METHODS Eight adult cadavers were dissected bilaterally in the lumbar region, using a posterolateral approach, so as to expose the L3L4 and L4L5 spaces, thereby obtaining measurements relating to the space between the intervertebral disc, pedicles cranial and caudal to the disc, path of the nerve root, dorsal ganglion and safety triangle. RESULTS The measurements obtained were constant, without significant differences between levels or any laterality. The dorsal ganglion occupied the lateral border of the triangular safety zone in all the specimens analyzed. CONCLUSION Precise localization of the ganglion shows that the safety margin for minimally invasive procedures is less than what is presented in studies that only involve measurements of the nerve root, thus perhaps explaining the presence of neuropathic pain after some of these procedures.