The Impact of Single-Level ACDF on Neural Foramen and Disc Height of Surgical and Adjacent Cervical Segments: A Case-Series Radiological Analysis

Abstract

Background: ACDF has become one of the established procedures for the surgical treatment of symptomatic cervical spondylosis, showing excellent clinical results and effective improvements in neural functions and neck pain relief. The main purpose of ACDF is neural decompression, and it is considered by some authors as an indirect result of the intervertebral distraction and cage insertion and the consequent restoration of the disc space and foramen height. Methods: Radiological data from 28 patients who underwent single-level ACDF were retrospectively collected and evaluated. For neural foramen evaluation, antero-posterior (A-P) and cranio-caudal (C-C) diameters were manually calculated; for intervertebral disc height the anterior, centrum and posterior measurement were calculated. All measurements were performed at surgical and adjacent (above and below) segments. NRS, NDI and also the mJOA and Nurick scale were collected for clinical examination and complete evaluation of patients’ postoperative outcome. Results: The intervertebral disc height in all its measurements, in addition to the height (C-C diameter) of the foramen (both right and left) increase at the surgical segment when comparing pre and postop results (p < 0.001, and p = 0.033 and p = 0.001). NRS and NDI radiculopathy scores showed improved results from pre- to post-op evaluation (p < 0.001), and a negative statistical correlation with the improved disc height at the surgical level. Conclusions: The restoration of posterior disc height through cage insertion appears to be effective in increasing foraminal height in patients with symptomatic preoperative cervical foraminal stenosis.

Keywords: ACDF; cervical cage; cervical foramen; cervical spondylosis; foramen height; foraminal stenosis; intervertebral distraction; neural decompression.

Figure 1

Neural cervical foramen was centered using MIP and MPR CT reconstructions.

Figure 2

In (a) the outline of the foramen is drawn in yellow and in (b) the measurement of the intervertebral foramen antero-posterior (A-P) and cranio-caudal (C-C) diameters are drawn in red, which means foramen width and height, respectively, are shown with red lines. In (c) the red lines show the antero, centrum and postero disc height measurement.

Figure 3

Pre- (grey) and post-operative (green) graphic representation of NRS evaluation in our cohort. In (a) the center of the peak between pre- and post-operative value there is a shift from 7 (preoperatively) to 3 (postoperatively). Description of what is contained in the first panel; in (b) it is shown how in most cases NRS scores were reduced after surgical treatment, meaning a reduction in pain levels.

Figure 4

Case illustration. Pre-(a, yellow box) and post-(b, red box) operative comparison of the foramen height (C-C diameter) at C4-C5, on the right side for illustrative purposes only, after the implant of a single-level cage.