Residual anterior cord compression after laminoplasty for cervical spondylotic myelopathy: evaluation of risk factors according to the most severely stenotic vertebral segment

Abstract

OBJECTIVE Residual anterior spinal cord compression (RASCC) after cervical laminoplasty, which has been confirmed on postoperative MRI, is reportedly associated with poor clinical outcomes. To date, only a few studies have described the risk factors associated with RASCC. The aim of this study was to identify the factors that can predict the occurrence of RASCC after laminoplasty for cervical spondylotic myelopathy (CSM), focusing on the location of the most stenotic segment. METHODS In this retrospective, single-center study, 120 patients who underwent C3–7 laminoplasty for multilevel CSM were included. Different techniques were used for C3 decompression, i.e., partial (dome-laminotomy) or complete (laminoplasty/laminectomy) decompression. RASCC was diagnosed using MRI conducted 3 weeks postoperatively. The patients were divided into two groups according to the segment with the most severe stenosis (Seg-MSS; C3–4 vs C4–7). Demographics, radiological data, and C3 decompression technique were compared between the two groups. Furthermore, intergroup comparisons were performed based on Seg-MSS. A logistic regression model was constructed to identify the factors predicting RASCC after patient stratification according to Seg-MSS. RESULTS Forty patients (33.3%) had RASCC. The patients with Seg-MSS at C3–4 (51.3%) had a significantly higher incidence of RASCC (p = 0.003) than those with Seg-MSS at C4–7 (24.7%). Logistic regression analysis showed that in patients with Seg-MSS at C3–4, C3 partial decompression demonstrated a greater association with RASCC as opposed to complete decompression. Conversely, in patients with Seg-MSS at C4–7, kyphotic segmental lordotic angle was associated with an increased risk of RASCC. CONCLUSIONS The risk factors for RASCC differed depending on the location of the most stenotic segment (C3–4 vs C4–7). If there is segmental kyphosis at the most stenotic segment at C4–7, anterior decompression and fusion should be considered. If C3–4 is the most stenotic segment, anterior surgery is also recommended, but alternatively, one can choose laminoplasty with complete C3 laminectomy and resection of the C2–3 ligamentum flavum.