Abstract：
BACKGROUND: Recent literature highlights anomalous cranial nerves in the sinonasal region, notably in the sphenoid and maxillary sinuses, linked to anatomical factors. However, data on the suspended infraorbital canal (IOC) variant is scarce in cross-sectional imaging. Anatomical variations in the sphenoid sinuses, including optic, maxillary, and vidian nerves, raise interest among specialists involved in advanced sinonasal procedures. The infraorbital nerve\'s (ION) course along the orbital floor and its abnormal positioning within the orbital and maxillary sinus region pose risks of iatrogenic complications. A comprehensive radiological assessment is crucial before sinonasal surgeries. Cone-beam computed tomography (CBCT) is preferred for its spatial resolution and reduced radiation exposure.
OBJECTIVE: The aim of this study was to describe the prevalence of anatomical variants of the infraorbital canal (IOC) and report its association with clinical condition or surgical implication.
METHODS: We searched Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS databases from their inception up to June 2023. Two authors independently performed the search, study selection, data extraction, and assessed the methodological quality with assurance tool for anatomical studies (AQUA). Finally, the pooled prevalence was estimated using a random effects model.
RESULTS: Preliminary results show that three types are prevalent, type 1: the IOC does not bulge into the maxillary sinus (MS); therefore, the infraorbital foramen through the anterior wall of MS could be used for identification of the ION. Type 2: the IOC divided the orbital floor into medial and lateral aspects. Type 3: the IOC hangs in the MS and the entire orbital floor lying above the IOC. From which the clinical implications where mainly surgical, in type 1 the infraorbital foramen through the anterior wall of MS could be used for identification of the ION, while in type 2, since the lateral orbital floor could not be directly accessed an inferiorly transposition of ION is helpful to expose the lateral orbital wall directly with a 0 scope; or using angled endoscopes and instruments, however, the authors opinion is that direct exposure potentially facilitates the visualization and management in complex situations such as residual or recurrent mass, foreign body, and fracture located at the lateral aspect of the canal. Lastly, in type 3, the ION it\'s easily exposed with a 0° scope.
CONCLUSIONS: This systematic review identified four IOC variants: Type 1, within or below the MS roof; Type 2, partially protruding into the sinus; Type 3, fully protruding into the sinus or suspended from the roof; and Type 4, in the orbital floor. Clinical recommendations aim to prevent nerve injuries and enhance preoperative assessments. However, the lack of consistent statistical methods limits robust associations between IOC variants and clinical outcomes. Data heterogeneity and the absence of standardized reporting impede meta-analysis. Future research should prioritize detailed reporting, objective measurements, and statistical approaches for a comprehensive understanding of IOC variants and their clinical implications. Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/UGYFZ .
OBJECTIVE: The aim of this study was to describe the prevalence of anatomical variants of the infraorbital canal (IOC) and report its association with clinical condition or surgical implication.
METHODS: We searched Medline, Scopus, Web of Science, Google Scholar, CINAHL, and LILACS databases from their inception up to June 2023. Two authors independently performed the search, study selection, data extraction, and assessed the methodological quality with assurance tool for anatomical studies (AQUA). Finally, the pooled prevalence was estimated using a random effects model.
RESULTS: Preliminary results show that three types are prevalent, type 1: the IOC does not bulge into the maxillary sinus (MS); therefore, the infraorbital foramen through the anterior wall of MS could be used for identification of the ION. Type 2: the IOC divided the orbital floor into medial and lateral aspects. Type 3: the IOC hangs in the MS and the entire orbital floor lying above the IOC. From which the clinical implications where mainly surgical, in type 1 the infraorbital foramen through the anterior wall of MS could be used for identification of the ION, while in type 2, since the lateral orbital floor could not be directly accessed an inferiorly transposition of ION is helpful to expose the lateral orbital wall directly with a 0 scope; or using angled endoscopes and instruments, however, the authors opinion is that direct exposure potentially facilitates the visualization and management in complex situations such as residual or recurrent mass, foreign body, and fracture located at the lateral aspect of the canal. Lastly, in type 3, the ION it\'s easily exposed with a 0° scope.
CONCLUSIONS: This systematic review identified four IOC variants: Type 1, within or below the MS roof; Type 2, partially protruding into the sinus; Type 3, fully protruding into the sinus or suspended from the roof; and Type 4, in the orbital floor. Clinical recommendations aim to prevent nerve injuries and enhance preoperative assessments. However, the lack of consistent statistical methods limits robust associations between IOC variants and clinical outcomes. Data heterogeneity and the absence of standardized reporting impede meta-analysis. Future research should prioritize detailed reporting, objective measurements, and statistical approaches for a comprehensive understanding of IOC variants and their clinical implications. Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/UGYFZ .
摘要：
背景：最近的文献强调了鼻窦区的颅神经异常，尤其是在蝶窦和上颌窦，与解剖学因素有关。然而,在横断面成像中，有关悬浮眶下管（IOC）变体的数据很少。蝶窦的解剖变异，包括光学，上颌,和vidian神经，提高参与先进鼻窦手术的专家的兴趣。眶下神经（ION）沿眶底的过程及其在眶和上颌窦区域内的异常定位会导致医源性并发症的风险。在鼻窦手术之前，全面的放射学评估至关重要。锥形束计算机断层扫描（CBCT）因其空间分辨率和减少的辐射暴露而优选。
目的：本研究的目的是描述眶下管（IOC）解剖变异的患病率，并报告其与临床状况或手术意义的关系。
方法：我们搜索了Medline，Scopus,WebofScience,谷歌学者，CINAHL,和LILACS数据库从成立到2023年6月。两位作者独立进行了搜索，研究选择，数据提取,并使用解剖学研究保证工具（AQUA）评估方法学质量。最后,使用随机效应模型估计合并患病率.
结果：初步结果表明，三种类型普遍存在，类型1：IOC不会凸出到上颌窦（MS）；因此，通过MS前壁的眶下孔可用于鉴定ION。类型2：国际奥委会将眶底分为内侧和外侧。类型3：国际奥委会悬挂在MS中，整个轨道地板位于国际奥委会上方。其中的临床意义主要是手术，在1型中，通过MS前壁的眶下孔可用于鉴定ION，而在类型2中，由于不能直接进入外侧眶底，ION的下移位有助于用0镜直接暴露外侧眶壁；或使用成角度的内窥镜和仪器，然而,作者认为，直接暴露可能有助于在复杂情况下的可视化和管理，如残留或复发的肿块，异物,和位于运河侧面的骨折。最后,在类型3中，离子它很容易用0°范围暴露出来。
结论：本系统评价确定了四种IOC变体：1型，在MS屋顶内或下方；2型，部分伸入窦内；3型，完全伸入窦内或从屋顶悬吊；4型，在眶底。临床建议旨在预防神经损伤并加强术前评估。然而,缺乏一致的统计方法限制了IOC变异与临床结局之间的稳健关联.数据异质性和缺乏标准化报告阻碍了荟萃分析。未来的研究应该优先考虑详细的报告，客观测量，和统计方法，以全面了解IOC变体及其临床意义。开放科学框架（OSF）：https://doi.org/10.17605/OSF。IO/UGYFZ。
目的：本研究的目的是描述眶下管（IOC）解剖变异的患病率，并报告其与临床状况或手术意义的关系。
方法：我们搜索了Medline，Scopus,WebofScience,谷歌学者，CINAHL,和LILACS数据库从成立到2023年6月。两位作者独立进行了搜索，研究选择，数据提取,并使用解剖学研究保证工具（AQUA）评估方法学质量。最后,使用随机效应模型估计合并患病率.
结果：初步结果表明，三种类型普遍存在，类型1：IOC不会凸出到上颌窦（MS）；因此，通过MS前壁的眶下孔可用于鉴定ION。类型2：国际奥委会将眶底分为内侧和外侧。类型3：国际奥委会悬挂在MS中，整个轨道地板位于国际奥委会上方。其中的临床意义主要是手术，在1型中，通过MS前壁的眶下孔可用于鉴定ION，而在类型2中，由于不能直接进入外侧眶底，ION的下移位有助于用0镜直接暴露外侧眶壁；或使用成角度的内窥镜和仪器，然而,作者认为，直接暴露可能有助于在复杂情况下的可视化和管理，如残留或复发的肿块，异物,和位于运河侧面的骨折。最后,在类型3中，离子它很容易用0°范围暴露出来。
结论：本系统评价确定了四种IOC变体：1型，在MS屋顶内或下方；2型，部分伸入窦内；3型，完全伸入窦内或从屋顶悬吊；4型，在眶底。临床建议旨在预防神经损伤并加强术前评估。然而,缺乏一致的统计方法限制了IOC变异与临床结局之间的稳健关联.数据异质性和缺乏标准化报告阻碍了荟萃分析。未来的研究应该优先考虑详细的报告，客观测量，和统计方法，以全面了解IOC变体及其临床意义。开放科学框架（OSF）：https://doi.org/10.17605/OSF。IO/UGYFZ。
