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. 2023 Oct;17(5):975-984.
doi: 10.31616/asj.2023.0030. Epub 2023 Aug 28.

Radiological Study of Atlas Arch Defects with Meta-Analysis and a Proposed New Classification

Worawit Suphamungmee  1 , Laphatrada Yurasakpong  1   2   3 , Kanchanaphan Poonudom  1   3   4 , R Shane Tubbs  5   6   7   8   9 , Joe Iwanaga  5   6   10   11 , Nutmethee Kruepunga  1   3 , Arada Chaiyamoon  2 , Athikhun Suwannakhan  1   3
Affiliations

Radiological Study of Atlas Arch Defects with Meta-Analysis and a Proposed New Classification

Worawit Suphamungmee et al. Asian Spine J. 2023 Oct.

Abstract

This study consists of a retrospective cohort study, a systematic review, and a meta-analysis which were separately conducted. This study aimed to investigate the prevalence of atlas arch defects, generate an evidence-based synthesis, and propose a common classification system for the anterior and combined atlas arch defects. Atlas arch defects are well-corticated gaps in the anterior or posterior arch of the atlas. When both arches are involved, it is known as a combined arch defect. Awareness of these defects is essential for avoiding complications during surgical procedures on the upper spine. The prevalence of arch defects was investigated in an open-access OPC-Radiomics (Radiomic Biomarkers in Oropharyngeal Carcinoma) dataset comprising 606 head and neck computed tomography scans from oropharyngeal cancer patients. A systematic review and meta-analysis were performed to generate prevalence estimates of atlas arch defects and propose a classification system for the anterior and combined atlas arch defects. The posterior arch defect was found in 20 patients (3.3%) out of the 606 patients investigated. The anterior arch defect was not observed in any patient, while a combined arch defect was observed in one patient (0.2%). A meta-analysis of 13,539 participants from 14 studies, including the present study, yielded a pooled-posterior arch defect prevalence of 2.07% (95% confidence interval [CI], 1.22%-2.92%). The prevalences of anterior and combined arch defects were 0.00% (95% CI, 0.00%-0.10%) and 0.14% (95% CI, 0.04%-0.25%), respectively. The anterior and combined arch defects were classified into five subtypes based on their morphology and frequency. The present study showed that atlas arch defects were present in approximately 2% of the general population. For future studies, larger sample sizes should be used for studying arch defects to avoid the small-study effect and to predict the prevalence accurately.

Keywords: Cervical atlas; Computed tomography; Meta-analysis; Systematic review.

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Conflict of interest statement

The present study did not meet the criteria for ethical approval according to the self-assessment form issued by the Mahidol University Central Institutional Review Board (MU-CIRB). Data sharing will be available upon reasonable request to the corresponding author. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Furthermore, the authors declare no conflicts of interest in this manuscript.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Figures

Fig. 1
Fig. 1
Computed tomography images showing the midline posterior arch defect (A), sided posterior arch defect (C), bilateral posterior arch defects associated with anterior arch defect (E), and their three-dimensional (3D) reconstructions (B, D, and F). Red and blue arrowheads indicate the anterior arch defect and posterior arch defect, respectively. Interactive 3D files are available on Figshare (https://doi.org/10.6084/m9.figshare.c.6758133) (Supplement 1).
Fig. 2
Fig. 2
Preferred Reporting Items for Systematic Reviews and Meta-Analysis diagram showing identification of studies, inclusion, and exclusion.
Fig. 3
Fig. 3
Forest plot of the prevalence of the posterior arch defect showing region-based and diagnostic tool-based prevalence.
Fig. 4
Fig. 4
(A–E) A proposed classification system for anterior arch defects and combined arch defects of the atlas based on all forms of anterior arch defect reported in the literature.
See this image and copyright information in PMC

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