Methods: We report a case of postoperative left-sided Horner syndrome (blepharoptosis, miosis, and anhidrosis) after revision surgery for cervical spondylotic myelopathy. A C4 corpectomy and an anterior cervical fusion from C3 to C5 were performed through a left longitudinal approach in a patient with a surgical history of an anterior discectomy and a fusion from C5 to C6. One year after the revision surgery, the patient had recovered from the anhidrosis and the miosis, but the blepharoptosis was not fully resolved.

Conclusions: Horner syndrome resulting from surgical injury to the ipsilateral cervical sympathetic chain is a very rare complication of anterior spine surgery that has been reported when the lower cervical levels have been approached. Awareness of this important cervical structure may help to avoid this complication.