Segmental anomaly leading to wrong level disc surgery in cauda equina syndrome.

STUDY DESIGN: A case report of unrecognized lumbarization of the S-1 vertebral body leading to wrong-level disc surgery in a patient with acute cauda equina syndrome secondary to a large disc extrusion at the L4-L5 interspace. Laminectomy and excision were initially performed at the level of L5-L6.

OBJECTIVES: To review the importance of detection of lumbosacral transitional vertebrae when performing interventional procedures in the lumbar spine.

SUMMARY OF BACKGROUND DATA: Lumbosacraljunction transitional vertebrae have been well documented. Likewise, surgery at the wrong intervertebral level has been reported as a reason for failure of lumbar spine surgery. There is also brief mention in the literature of lumbar disc surgery performed at incorrect levels in part secondary to junctional anomalies. However, there is no recorded case of wrong-level disc surgery in acute cauda equina syndrome occurring as a result of an unrecognized lumbarization or sacralization of transitional vertebrae.

METHODS: A case report of wrong level disc surgery in a patient with lumbarization of the S-1 sacrum is presented. The literature, clinical course, and imaging studies are reviewed and techniques for detection of transitional vertebral bodies are discussed.

CONCLUSION: The presence an undetected congenital spinal anomaly, lumbarization of the S-1 vertebral body, resulted in mistaken intraoperative identification of the L4-5 space in this patient resulted in decompression at the wrong level requiring a second surgery. Lumbosacral transitional vertebrae can often be overlooked on plain radiographs and magnetic resonance imaging of the lumbar spine. It is essential to be alert to the possibility of transitional vertebrae when evaluating these imaging studies, particularly in the operative treatment disc disease.