[Rare complication of anterior spinal surgery: Horner syndrome]

Horner syndrome due to injury to the cervical sympathetic trunk (CST) is a very rare complication of anterior cervical decompression and fusion (ACDF). We have not mentioned the possibility of Horner syndrome as a postoperative complication in patients before surgery. We present a patient with Horner syndrome after ACDF and discuss the anatomical background of the CST and the causes and preventative measures against postoperative Homer syndrome. A 48-year-old man presented with disturbance of fine movement and reduction of grasping power in the right hand. MRI revealed osteophytes and a prolapsed disc compressing the spinal cord at C5-6 and C6-7. Two-level ACDF with inclusion of titan cages was performed via a right-sided exposure. Anisocoria (right > left) and right blepharoptosis were observed immediately after surgery. Postoperatively, disturbance of fine movement was resolved. Japanese Orthopaedic Association (JOA) score improved from 12 to 16. Horner syndrome disappeared at 6 months after surgery. The CST runs 10-15 mm lateral to the medial edge of the longus colli muscle (LCM) and exists in the loose fascia and approaches most medially at C6. During the decompressive procedure under microscopic viewing, the right blade of a retractor was found to come out of the medial edge of the LCM on the level of C6. It is postulated that the blade injured the right CST. Knowledge of the anatomical relation between the CST and the LCM is very important to avoid Horner syndrome in ACDF. The tip of a retractor blade must be placed between the medial edge of the LCM and the vertebral body.