How Does the Severity of Neuroforaminal Compression in Cervical Radiculopathy Affect Outcomes of Anterior Cervical Discectomy and Fusion

Abstract

Study design: This study is a retrospective cohort study.

Purpose: This study aims to determine whether preoperative neuroforaminal stenosis (FS) severity is associated with motor function patient-reported outcome measures (PROMs) following anterior cervical discectomy and fusion (ACDF).

Overview of literature: Cervical FS can significantly contribute to patient symptoms. While magnetic resonance imaging (MRI) has been used to classify FS, there has been limited research into the impact of FS severity on patient outcomes.

Methods: Patients undergoing primary, elective 1-3 level ACDF for radiculopathy at a single academic center between 2015 and 2021 were identified retrospectively. Cervical FS was evaluated using axial T2-weighted MRI images via a validated grading scale. The maximum degree of stenosis was used for multilevel disease. Motor symptoms were classified using encounters at their final preoperative and first postoperative visits, with examinations ≤3/5 indicating weakness. PROMs were obtained preoperatively and at 1-year follow-up. Bivariate analysis was used to compare outcomes based on stenosis severity, followed by multivariable analysis.

Results: This study included 354 patients, 157 with moderate stenosis and 197 with severe stenosis. Overall, 58 patients (16.4%) presented with upper extremity weakness ≤3/5. A similar number of patients in both groups presented with baseline motor weakness (13.5% vs. 16.55, p =0.431). Postoperatively, 97.1% and 87.0% of patients with severe and moderate FS, respectively, experienced full motor recovery (p =0.134). At 1-year, patients with severe neuroforaminal stenosis presented with significantly worse 12-item Short Form Survey Physical Component Score (PCS-12) (33.3 vs. 37.3, p =0.049) but demonstrated a greater magnitude of improvement (Δ PCS-12: 5.43 vs. 0.87, p =0.048). Worse stenosis was independently associated with greater ΔPCS-12 at 1-year (β =5.59, p =0.022).

Conclusions: Patients with severe FS presented with worse preoperative physical health. While ACDF improved outcomes and conferred similar motor recovery in all patients, those with severe FS reported much better improvement in physical function.

Keywords: Anterior cervical discectomy and fusion; Cervical spine; Motor function; Neuroforaminal stenosis; Radiculopathy.

Fig. 1

Schematic of Kim et al. grading system for cervical neural foraminal stenosis (FS) in cervical axial magnetic resonance imaging. (A, B) Grade 0: no FS with intact nerve width: (A) shows no narrowing of neural foramen, and (B) shows mild narrowing. (C) Grade 1: moderate FS whereby the narrowest width of neural foramen is 51%–100% of the extraforaminal nerve root width. (D) Grade 2: severe FS, whereby narrowest width of neural foramen is less than 50% of the extraforaminal nerve root width. Reproduced from Kim S, et al. Korean J Radiol 2015;16:1294-302 [9].

Fig. 2

A 57-year-old male with patent neural foramina suggesting grade 0 cervical neural foraminal stenosis. Width of the neural foramen equivalent to the extra-foraminal nerve width.

Fig. 3

A 73-year-old female with grade 1 cervical neural foraminal stenosis. The left neural foramen demonstrates narrowing but is still at least 50% of the width of the extraforaminal nerve root.

Fig. 4

A 41-year-old male with grade 2 cervical neural foraminal stenosis. In this patient, the narrowest width of the right sided neural foramen is significantly compressed. The width of neural foramen is significantly less than 50% of the width of extraforaminal nerve root.