BACKGROUND
Anterior cervical corpectomy provides the most direct and thorough surgical approach for anterior decompression when spinal cord compression is found directly behind the vertebral body. However, anterior cervical fusion has been shown to be associated with the development of new degenerative changes at levels immediately adjacent to the fused segments. The incidence of adjacent segment disease (ASD) following anterior cervical corpectomy has not been widely reported. We set out to determine the incidence of clinical ASD following anterior cervical corpectomy.

METHODS
We retrospectively reviewed all available medical charts and radiographic studies of all cases of anterior cervical corpectomy performed at the Barrow Neurological Institute over a 4-year period with a minimum 24-month follow-up. Factors assessed included the success of arthrodesis, the presence of degenerative changes on serial follow-up radiographs, and the development of new neurological symptoms.

RESULTS
Seventy-six patients met the criteria for inclusion: 54 had undergone a 1-level corpectomy, 18 underwent

a 2-level corpectomy, and 4 underwent a 3- or 4-level corpectomy. Arthrodesis was performed with either allograft or autograft and anterior cervical plating. All patients achieved successful fusion. Follow-up was available for a minimum of 2 years in all cases, with a mean length of 3.6 years. Sixteen patients (21%) eventually developed radiological and clinical evidence of degenerative changes at adjacent levels. In 10 of 11 patients who developed clinical symptoms within 2 years, the changes represented progression of preexisting, asymptomatic degenerative disease. Five patients developed degenerative changes more than 5 years after surgery; these were all associated with an unrelated new insult to the cervical spine such as trauma.

CONCLUSIONS
Anterior cervical corpectomy with fixation can accelerate degenerative changes identified preoperatively at adjacent, asymptomatic levels of the cervical spine.

LEVEL OF EVIDENCE
Retrospective cohort study (level 2b).

Key Words Cervical spine spondylosis, anterior cervical fusion, corpectomy, adjacent segment disease. SAS Journal. Winter 2008. 2:23–27. DOI: SASJ-2007-0108-RR

Gwynedd E. Pickett, MD, FRCS(C), Neil Duggal, MD, MSc, FRCS(C), Nicholas Theodore, MD, Volker K.H. Sonntag, MD

From the Division of Neurosurgery, London Health Sciences Centre, London, Ontario, Canada (Pickett and Duggall), and the Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona (Theodor and Sonntag)

Address correspondence and reprint requests to Neil Duggal, MD, Division of Neurosurgery, University of Western Ontario, 339 Windermere Road, London, Ontario, Canada, N6A 5A5 (email: neil.duggal@lhsc.on.ca)

This manuscript was submitted July 20, 2007, and accepted for publication November 5, 2007.

This study was approved by the Office of Research Ethics at the University of Western Ontario.