Subsequent Cervical Disc Herniation following Single-Level ACDF

Abstract

Introduction Subsequent herniated cervical disc (HCD) and revision anterior cervical discectomy and fusion (ACDF) is not an uncommon disease and procedure. And we, as a spinal surgeon, have some difficulties in decision-making, because of the airway, esophagus, and vocal cord problems. Adjacent segment disease is well known as the pathologic process, in which the changes in the other segment may occur at the cranial or caudal segment. In this study, we discuss about the subsequent HCD which requires surgical treatment following single-level ACDF. Materials and Methods From 2006 to 2012, 27 Korean patients, who were operated for subsequent HCD following previous ACDF, were enrolled. The subsequent HCD was detected not only in adjacent segments just around fused spine but also in the skipped segments. A total of 23 patients were approached anteriorly (22 revision ACDF and 1 anterior foraminotomy) and 4 patients were approached posteriorly for posterior keyhole surgery. All 23 patients with anterior approach were evaluated for vocal cord palsy before anterior revision surgery. We retrospectively reviewed and analyzed the pre- and postoperative data. Results The subsequent HCD significantly occurred on the caudal segment in patients with C3–4 and C4–5 fused patients and on the cranial segment in C6–7 and C7–T1 fused patients ( p = 0.045). In C5–6 fused patients, the subsequent HCD occurred similarly, both caudally and cranially (5 cranially, 6 caudally). The use of plate in primary ACDF has no significant effect on either the caudal or the cranial segment ( p = 0.168). The direction of approach in primary ACDF (right vs. left) was mainly on contralateral side to the patient's symptom ( p = 0.007), whereas there was no laterality of approach in the revision ACDF according to the symptom and previous ACDF ( p = 0.767). Vocal cord palsy developed only in one patient with anterior keyhole surgery, who had been approached right in primary ACDF and left in revision surgery and there was right-sided vocal cord damage. Conclusion Revision ACDF was the major surgical method for subsequent HCD. There was no relationship between the laterality of the approach according to the previous operation and development of vocal cord palsy. The vocal cord palsy was detected in a significantly lower incidence (4.3%, 1/23) compared with the results of other studies. The subsequent HCD had a tendency of developing in the caudal segments in C3–4, 4–5 fused patients and in cranial segment in C6–7, C7–T1 fused patients. In C5–6 fused patients, the subsequent HCD occurred both caudally and cranially.