Cadaveric Evidence of Complete Transection of the Lumbar Sympathetic Trunk After Extreme Lateral Transpsoas Approach to the Lumbar Spine: A Word of Caution

Lateral transpsoas approaches to the lumbar spine are believed to entail less risk of injury to the lumbar sympathetic trunk and plexus than anterior approaches. However, even the lateral approach can occasionally injure the sympathetic trunk. We report a literature review and cadaveric case of complete resection of the left sympathetic trunk at L3 following lateral transpsoas approach performed by a well-trained spine surgeon. A left lateral approach to the lumbar spine for a two-level total discectomy at L3-L4 and L4-L5 was undertaken on a fresh-frozen cadaver by an experienced spinal surgeon. The procedure followed standard spinal technique under fluoroscopy guidance. The cadaver was placed in a right lateral position and an operative corridor to the lateral aspect of the psoas major muscle was developed. Blunt dissection was carried through the muscle and standard total discectomy was completed at the target levels. Following the procedure, the lumbar spine and adjacent structures were anatomically dissected. It was found that the sympathetic trunk had been completely transected at the L3 level during the surgical procedure. Other major structures such as the femoral nerve, obturator nerve, and roots of the lumbar spinal nerves had not been injured. The above case highlights the proximity of the sympathetic trunk to lateral transpsoas approaches and the possibility of injury to it. We review the literature on postoperative cases of lumbar sympathetic dysfunction (SD) following such procedures and posit that some of these are due to direct iatrogenic injury.