Neurological Deficit From a Purely Vascular Etiology After Unilateral Vessel Ligation of Segmental Arteries During Anterior Thoracolumbar Fusion of the Spine

Study Design: Comprehensive analysis of patients records who underwent anterior approach to the thoracolumbar spine at a single institution.

Objectives: To report on neurological deficit from a purely vascular insult to the spinal cord occurring after anterior thoracolumbar spinal surgery that did not involve additional correction or other etiologies.

Summary and Background Data: The largest study in the literature by Winter et.al., regarding the risks of neurovascular injury during anterior exposure to the thoracolumbar spine, reports that there exists no risk with unilateral ligature of the segmental arteries. However this study included any lumbar surgery that involved L2. A number of smaller studies have reported on isolated cases of neurological deficit after unilateral segmental artery ligature. This is the only study reporting on the occurrence of anterior spinal cord syndrome after unilateral ligature of segmental arteries in patients not undergoing additional deformity-correcting surgery during anterior thoracolumbar spine fusion.

Methods: The records and operative notes of 265 consecutive patients were reviewed. All adult patients, average age 40.2 yrs (18 y.o.a.- 85 y.o.a.) who have had surgery that involved anterior approach to the thoracic spine were included. There were 177 female patients and 88 male patients. All surgeries involved the area of T10-T12. Only patients without pre-operative neurological abnormalities were reviewed. During the surgery only unilateral segmental arteries were ligated mid-body, away from the foramen and the aorta. Records were reviewed to determine the location of surgery, the number of segmental arteries ligated and the side of the approach. All patients were operated upon between the periods of 1985-2002. Of the 265 patients who underwent thoracolumbar spine surgery 72 % of the approaches were left sided. An average of 3.5 unilateral segmental artery ligations were performed per procedure.

Results: Two patients out of 265 had major neurological deficit after anterior thoracolumbar approach. Both patients had staged procedures. Posterior spinal fusion on a separate day then anterior spinal fusion to the thoracolumbar spine. One patient had a history of prior anterior surgery on the ipsilateral side. No additional corrective maneuvers were performed during the anterior approach. One deficit occurred immediately post-operatively and the other occurred 24 hours after surgery. No changes occurred with neuromonitoring during the procedures. Neither patient was hypotensive intra-operatively or post-operatively.

Conclusion: Contrary to the Winter study, neurological deficit after anterior exposure to the thoracolumbar spine occurred in 0.75 % of patients in this study exclusively from unilateral left sided ligation of the T10-T12 segmental vessels. Both patients had common risks to include prior kyphosis correcting surgery, revision surgery, and left sided approach including T10-T12.